Anatomy quiz for chapter 4

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Foundation of Speech and hearing quiz 10 questions. 30 minutes to complete. Some are fill in the blanks. Once you move to the next question you cannot go back. Read chapter 4 and watch the below video lesson.

video lesson

119

4

Velopharyngeal-Nasal Function
and Speech Production

introDuCtion

The velopharyngeal-nasal apparatus is located within
the head and neck and comprises a system of valves
and air passages. This system interconnects the throat
(pharynx) and the atmosphere through the nose.
Although most textbooks focus on the velopharyngeal
part of this system, this chapter covers the complete
velopharyngeal-nasal apparatus as a single functional
entity. The chapter begins by discussing the fundamen-
tals of velopharyngeal-nasal function, and then turns
to consideration of velopharyngeal-nasal function and
speech production. The chapter concludes with a review.

FunDamentaLs oF
VeLopHarynGeaL-nasaL FunCtion

This section covers the fundamentals of velopharyn-
geal-nasal function and lays the groundwork for subse-
quent consideration of velopharyngeal-nasal function
in speech production. Topics include the anatomy of
the velopharyngeal-nasal apparatus, forces and move-
ments of the velopharyngeal-nasal apparatus, adjust-
ments of the velopharyngeal-nasal apparatus, control
variables of velopharyngeal-nasal function, neural sub-
strates of velopharyngeal-nasal control, and ventilation
and velopharyngeal-nasal function.

anatomy of the
Velopharyngeal-nasal apparatus

The valves and air passages of the velopharyngeal-
nasal apparatus are linked together such that some of
the components are arranged in mechanical series (one
after another) and some are arranged in mechanical
parallel (side by side). This section begins by discuss-
ing the skeletal superstructure that supports the velo-
pharyngeal-nasal apparatus. From there, the section
proceeds to separate discussions of the anatomy of the
pharynx, velum, nasal cavities, and outer nose.

Skeletal Superstructure

Figure 4–1 depicts the skeletal superstructure of the
velopharyngeal-nasal apparatus. This superstructure
consists of the first six cervical vertebrae and various
bones of the skull. The skull bones include bones of the
cranium (braincase) and facial complex (forehead, eyes,
nose, mouth, and upper throat). These bones are individ-
ually intricate structures that are rigidly joined together
into a unified framework. This framework contributes
to the walls, floor, and roof of the velopharyngeal-nasal
apparatus through a system of structural processes,
plates, and projections, and provides for the attach-
ment of muscles of the velopharyngeal-nasal appa-
ratus. Some of the most important bony structures of

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120

Maxillary bone

Vomer bone

Styloid process

Nasal choana

Palatine bone

Zygomatic bone

Nasal
bone

Zygomatic
bone

Alveolar
process

Mandible

Frontal
bone

Temporal
bone

Maxillary
bone

Cervical
vertebrae

Cervical
vertebrae

Temporal
bone

Styloid
process

Mastoid
process

Front view Side view

Bottom view
(mandible and vertebrae removed)

Mastoid process

FiGure 4–1. Skeletal superstructure of the velopharyngeal-nasal apparatus. The mandible (lower jaw) is shown for
reference in front and side views. The bottom view shows the mandible and vertebrae removed.

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4 Velopharyngeal-Nasal Function and Speech Production 121

the apparatus include the temporal bones (sides of
the lower braincase), frontal bone (front of the upper
braincase), palatine bones (back of the floor of the nasal
cavities), maxillary bones (front of the floor of the nasal
cavities), sphenoid bone (back wall of the nasal cavities),
ethmoid bone (upper side walls of the nasal cavities and
upper part of their medial wall), vomer bone (lower part
of the medial wall of the nasal cavities), inferior con-
chae (lower side walls of the nasal cavities), and nasal

bones (bridge of the outer nose). The bony structures
mentioned can be seen in various perspectives in Figure
4–1, in other figures in this chapter, and in depictions
of the bony skeleton of the oral apparatus in Chapter 5.

Pharynx

Figure 4–2 depicts some of the salient structural fea-
tures of the pharynx (throat). The pharynx is a tube of

Ramus of
mandible

Root of tongue
(lingual tonsil)

Laryngeal
aditus

Esophagus

Pyriform sinus

Epiglottis

Faucial isthmus

Nasal choana

Back view
(opened from behind)

Foramen magnum
(skull opening for spinal cord)

Velum

FiGure 4–2. Salient features of the pharynx as revealed from a back
view in which the posterior pharyngeal wall is opened from behind. The
skull, mandible, and selected muscles are shown for reference.

Duane C. spriestersbach (1916–2011)

Duane C. Spriestersbach had a distinguished
career as a clinical investigator of communication
problems of children with cleft palate and cranio-
facial disorders. “Sprie,” as he was affectionately
called, served for many years at the University of
Iowa as the program director of a large federally
funded research grant on cleft palate. His leader-
ship fostered much of the research done over two
decades on normal velopharyngeal function for
speech production and on mechanisms involved in
control of the velopharyngeal apparatus in indi-

viduals with velopharyngeal incompetence. Many
of the names in this chapter’s reference list cut their
research teeth under his guidance. Spriestersbach
was an exceptional thinker who had an enormous
impact on translating the products of research into
practical clinical applications for those with speech
disorders caused by cleft palate. In his spare time,
he took to the stage, where he performed in the
Iowa City Community Theatre, and to the card
table, where he played a legendary mean hand
of poker.

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Foundations of Speech and Hearing: Anatomy and Physiology122

tendon and muscle that extends from the base of the
skull to the cricoid cartilage in the front and to the
sixth cervical vertebra in the back. The mix of tendon
and muscle varies along the length of the pharynx.
The upper end of the structure is made up solely of
connective tissue, called the pharyngeal aponeurosis,
which effectively suspends the pharyngeal tube from
above (the way the rim of a basketball goal suspends
the net). Muscular tissue increases in proportion down
the length of the pharynx until it predominates. At the
lower end, the pharynx is solely muscular and is con-
tinuous with the esophagus (gullet), where its front
and back walls are in contact. This contact is broken
during activities such as swallowing and regurgitation.

The pharyngeal tube is widest at the top and nar-
rows down its length. It is oval in cross-section, being
larger side to side than front to back. The front wall of
the pharynx is partially formed by the back surfaces of
the velum (defined below), tongue, and epiglottis. Oth-

erwise, the structure is open at the front and connects,
from top to bottom, with the nasal cavities, oral cavity,
and laryngeal aditus (upper entrance to the larynx).

The pharynx comprises three cavities that are
designated, from top to bottom, as the nasopharynx,
oropharynx, and laryngopharynx. The boundaries of
these cavities are shown in Figure 4–3. The nasophar-
ynx lies behind the nose and above the velum. Because
the velum is mobile, the lower boundary of the naso-
pharynx is somewhat arbitrary. Thus, a common con-
vention is to specify this boundary by a reference line
extending between the upper surface of the hard palate
and the most forward point on the uppermost vertebra.

The nasopharynx always remains patent, a feature
that distinguishes it from the other subdivisions of the
pharynx. The pharyngeal orifices of the auditory tubes
(also called the eustachian tubes) are located on the
lateral walls of the nasopharynx. These tubes enable
pressure equilibration between the middle ears and

Nasopharynx

Oropharynx

Laryngopharynx

Tongue

Velum

Nasal cavities

Epiglottis

Esophagus

Cricoid cartilage

Hyoid bone

FiGure 4–3. Boundaries of the nasopharynx, oropharynx, and laryngo-
pharynx. The boundary between the nasopharynx and oropharynx can be
arbitrary; in this figure it is defined by an imaginary line extending backward
at the level of the hard palate. The boundary between the oropharynx and
laryngopharynx is the hyoid bone, and the lower boundary of the laryngophar-
ynx is the base of the cricoid cartilage.

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4 Velopharyngeal-Nasal Function and Speech Production 123

atmosphere. Across the back surface of the nasophar-
ynx, between the pharyngeal orifices of the auditory
tubes, lies a large mass of lymphoid tissue called the
pharyngeal tonsil. This tissue is also referred to as the
nasopharyngeal tonsil and, when abnormally enlarged,
is designated as adenoid tissue (or just the adenoids). At
the front, the nasopharynx connects to the nasal cavities
through the nasal choanae (funnel-like openings). These
are two oval-shaped apertures that are about twice as
long (top to bottom) as they are wide (side to side)
and are oriented in the vertical plane (see Figure 4–2).
The nasal choanae are also referred to as the posterior
nares (nostrils) or internal nares.

The oropharynx forms the middle part of the pha-
ryngeal tube. The upper boundary of the oropharynx
is coextensive with the lower boundary of the naso-
pharynx. The lower boundary of the oropharynx is the
hyoid (tongue) bone. As shown in Figure 4–4, the front
of the oropharynx opens into the oral cavity through the
faucial isthmus, the narrow passage situated between
the velum and the base of the tongue. This isthmus is
bounded on the left and right sides by the anterior and
posterior faucial pillars, pairs of muscular bands that
resemble pairs of legs. The palatine tonsils are located
between the anterior and posterior faucial pillars on
each side of the isthmus. They are also often called the

faucial tonsils and are “the” tonsils most often referred
to colloquially. The back surface of the tongue is the site
of yet another tonsil, the so-called lingual tonsil. This
tonsil is a broad aggregate of lymph glands distributed
across much of the root of the tongue. The oropharynx
is the only subdivision of the pharynx that can be seen
without special equipment. The back wall of the oro-
pharynx is best viewed when the velum is elevated, as
in “open your mouth wide and say ‘ah.’”

The laryngopharynx constitutes the lowermost
part of the pharynx. The upper boundary of the laryn-
gopharynx is the hyoid bone and the lower boundary
is the base of the cricoid cartilage, where the pharynx
is continuous with the esophagus. At the front, the
laryngopharynx is bounded by the back surface of the
tongue (and the lingual tonsil), the laryngeal aditus
(formed by the epiglottis and aryepiglottic folds), and
the pyriform sinuses (pear-shaped cavities located lat-
eral to the aryepiglottic folds).

Muscle tissue is an important part of the pharynx
and encircles it, much like bands of cord encircle the
casing (tread and sidewalls) of a radial automobile tire.
In effect, the pharynx is an elongated structure with
the architecture of a sphincter. Its overall arrangement
is similar to that of the gut. This should come as no

Tongue

Hard palate

Velum
(soft palate
and uvula)

Palatine
tonsil

Back wall of
oropharynxPosterior

faucial pillar

Anterior
faucial pillar

FiGure 4–4. The oropharynx as seen from the front. The oropharynx
is best viewed when instructed to, “open your mouth wide and say ‘ah.’”
The narrow opening between the velum and the tongue (top to bottom)
and between the anterior faucial pillars (side to side) is called the faucial
isthmus.

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Foundations of Speech and Hearing: Anatomy and Physiology124

surprise, because the pharynx is a component of the
digestive system.

Velum

The velum, which means curtain, is a pendulous flap
consisting of the soft palate and uvula (meaning little
grape). In this case, the velum is the curtain that hangs
down from the back of the roof of the mouth, as illus-
trated in Figures 4–3 and 4–4. A broad sheet of con-
nective tissue, the palatal aponeurosis, forms a fibrous
skeleton for the velum.

show me your Hand

They were twin girls. Each had speech that was
a dead ringer for the speech of the other and that
was characterized by multiple misarticulations
and hypernasality. What was the cause? Had
they developed some sort of twin speech? Did
one have a problem that the other was imitating?
Oral examinations revealed identical structural
anomalies. Each girl had a short velum. Nasoen-
doscopic examinations further revealed that, for
each girl, the velum elevated only occasionally
during speech production, but never came close
to the posterior pharyngeal wall. The girls’
parents were with them and being interviewed
by a student clinician and her supervisor.
The moment the mother spoke, there were
suspicions. She had a severe speech disorder
characterized by multiple misarticulations and
hypernasality, and exhibited pronounced nasal
grimacing when speaking. She allowed an oral
examination. She had a short velum. It was three
of a kind.

Patterns of muscle fiber distribution differ along
the length of the velum (Kuehn & Moon, 2005). These
include: (a) a front portion that is void of muscle fibers,
(b) a middle third that is rich with muscle fibers that
course in various directions (including across the mid-
line) and include insertions into the lateral margins of
the structure, (c) muscle fibers that taper off toward the
front and back of the structure, and (d) a uvular (back)
portion that is sparsely interspersed with muscle fibers.

Nasal Cavities

The nasal cavities, also termed the nasal fossae (pro-
nounced like posse), lie behind the outer nose. They
constitute the inner nose and are two large chambers
that run side by side. The two nasal cavities are sepa-
rated from each other by the nasal septum (not often

perfectly vertical). As shown in Figure 4–5, this parti-
tion has: (a) a front part composed of cartilage, (b) an
upper back part that is the perpendicular plate of the
ethmoid (sieve-like) bone, and (c) a lower back part
that is the vomer (ploughshare-like) bone. The floor
of the nasal cavities is broad and slightly concave and
formed by the hard palate. This floor consists of two
sets of bones. The palatine processes of the maxillary
bones (left and right upper jaws) form the front three-
fourths of the hard palate, and the horizontal processes
of the palatine bones form the back one-fourth of the
structure. (This can be seen in the bottom image in Fig-
ure 4–1). The roof of the nasal cavities, in contrast to
the floor, is quite narrow and formed by the cribriform
plate of the ethmoid bone. The configuration of the two
cavities is similar to the roofline of an A-frame house.

By far the most complex formations within the
nasal cavities are located on its lateral walls. These for-
mations are convoluted and labyrinthine and contain
many nooks and crannies. Three shell-like structures
give rise to this complexity. These structures are por-
trayed in Figure 4–6 and include the superior, middle,
and inferior nasal conchae, formations that extend
along the length of the nasal cavities. The nasal con-
chae, also called the nasal turbinates, have correspond-
ing meatuses (passages) named for the conchae with
which they are associated. The enfolding structure of

Cartilage

Vomer
bone

Ethmoid
bone

Frontal bone

Nasal bone

Maxillary
bone

Teeth
Palatine bone

FiGure 4–5. Components of the nasal septum (parti-
tion between the two nasal cavities). The nasal septum con-
sists of cartilage at the front and bone (ethmoid and vomer)
in the back. Selected other bones and teeth are shown for
reference.

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4 Velopharyngeal-Nasal Function and Speech Production 125

the nasal cavities provides a large surface area to the
inner nose and has a rich blood supply. A final struc-
ture of interest in each nasal cavity is the nasal vesti-
bule, a modest dilation just inside the aperture of the
anterior naris.

Outer Nose

Unlike the other components of the velopharyngeal-
nasal apparatus, the outer nose is familiar to everyone,
especially the surface features of the structure. The
outer nose is hard to ignore because it is in the cen-
ter of the face and projects outward and downward
conspicuously. The more prominent surface features
of the outer nose include the root, bridge, dorsum,
apex, alae, base, septum, and anterior nares, as shown
in Figure 4–7.

The root (point of attachment) of the outer nose is
to the bottom of the forehead. Following downward
along the center line are the bridge (upper bony part),
dorsum (prominent upper surface), and apex (tip).
The alae (wings) form much of the sides of the nose
and contribute significantly to its general shape. The
base of the nose constitutes the bottom of the struc-
ture, partitioned down the middle (more or less) by
the lowermost part of the nasal septum, and includ-
ing the anterior nares (nostrils). The anterior nares are
also referred to as the external nares and are somewhat

Superior nasal
concha

Inferior nasal
concha

Nasal vestibule

Middle nasal
concha

FiGure 4–6. Superior, middle, and inferior nasal con-
chae (also called nasal turbinates). These conchae contain
many nooks and crannies and create a large surface area
to the inner nose.

Root

Ala

Anterior naris

Base

Bridge

Dorsum

Apex

Septum

FiGure 4–7. Surface features of the outer nose.

Disposing of things

Mucus (a slimy substance) is formed in the nose
to the tune of about half a pint a day (more when
you have a cold). Particles filtered by the nose
are collected in a blanket of mucus and moved
through the nose by the action of cilia (tiny hair
cells that collectively form a fringe). Things that
get trapped are moved along toward the back of
the throat and then swallowed into the stomach.
Some material dries before reaching the back of
the throat and fractionates into pieces contain-
ing filtered particles. This happens at different
spots within the nose and in residues of various
consistencies. Prim and proper folks refer to these
residues as nasal exudates or pieces of dried nasal
mucus. Most of us refer to them as “boogers.”
They are best gently blown into a tissue to rid
them from the nose, but we all know other
manual methods that are commonly practiced.

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Foundations of Speech and Hearing: Anatomy and Physiology

pear-shaped apertures that are typically about twice
as long (front-to-back) as they are wide (side-to-side).
Margins of the anterior nares include stiff hairs, called
vibrissae. These hairs arrest the passage of particles rid-
ing on air currents.

Forces and movements of the
Velopharyngeal-nasal apparatus

Much of the functional potential of the velopharyn-
geal-nasal apparatus lies in its capacity for movement.
This movement is caused by forces applied to and by
different components of the apparatus.

Forces of the Velopharyngeal-Nasal Apparatus

The forces operating on the velopharyngeal-nasal
apparatus are of two types: passive and active. Passive
force is inherent and always present (although subject
to change), whereas active force is applied depending
on the will and ability of the individual.

Passive Force

The passive force of velopharyngeal-nasal function
arises from several sources. These include the natural
recoil of muscles, cartilages, and connective tissues,
the surface tension between structures in apposition, the
pull of gravity, and aeromechanical forces within the
upper airway (throat, mouth, and nose).

The distribution, sign, and magnitude of passive
force depend on the prevailing mechanical conditions,
including the positions, deformations, and levels of
activity of different components of the velopharyngeal-
nasal apparatus. For example, the pull of gravity dif-
ferentially influences velopharyngeal-nasal function
when body position is changed. Such influences are
considered in detail in another section.

Active Force

The active force of velopharyngeal-nasal function
arises from muscles distributed within different com-
ponents of the velopharyngeal-nasal apparatus. This
active force results from the contraction of muscle
fibers. The contribution of specific muscles to such
force generation is not completely understood. Never-
theless, based on individual muscle architecture, con-
sequences of muscle activation, and observations of the
electrical activity of muscles during various activities,
the probable roles of specific muscles can be specified
with reasonable certainty.

The function described here for individual mus-
cles assumes that the muscle under consideration is

activated and involved in a shortening (concentric)
contraction. The influence of individual muscle actions
depends on whether or not related muscles are active,
on the mechanical status of different components of the
velopharyngeal-nasal apparatus, and on the nature of
the activity being performed. The muscles of the phar-
ynx, velum, and outer nose are considered below.

Muscles of the Pharynx. Figure 4–8 portrays the mus-
cles of the pharynx. They are the superior constrictor,
middle constrictor, inferior constrictor, salpingo­
pharyngeus, stylopharyngeus, and palatopharyngeus
muscles. These muscles influence the size and shape of
the lumen (cavity) of the pharyngeal tube. Of course,
other structures along the front side of the pharynx can
also influence the lumen of the pharynx through their
adjustments (velum, tongue, and epiglottis).

The superior constrictor muscle is located in the
upper part of the pharynx. It is a complex muscle with
multiple origins that arise from the front of the pha-
ryngeal tube. Front points of attachment include the
medial pterygoid plate (of the sphenoid bone), the
pterygomandibular ligament (a tendinous inscription
between the superior constrictor muscle and the buc­
cinator muscle, described in Chapter 5), the mylohy-
oid line (site of attachment of the mylohyoid muscle,
described in Chapter 5, on the inner surface of the body
of the mandible), and the side of the back part of the
tongue. Fibers from the multiple origins of the supe­
rior constrictor muscle course backward, toward the
midline, and upward to insert into the fibrous median
raphe (seam) of the posterior pharyngeal wall. There,
they join with fibers of the paired muscle from the
opposite side. The uppermost fibers of the superior
constrictor muscle are horizontal and located at the
level of the velum. When the superior constrictor mus-
cle contracts, it reduces the regional cross section of the
pharyngeal lumen by forward movement of the poste-
rior pharyngeal wall and forward and inward move-
ment of the lateral pharyngeal wall on the same side.
The paired superior constrictor muscles encircle the
posterior and lateral walls of the upper pharynx (recall
the radial tire analogy from above), so that their simul-
taneous contraction constricts the lumen of that part of
the pharyngeal tube in the manner of a sphincter.

The middle constrictor muscle is a fan-shaped
structure located midway along the length of the
pharyngeal tube. Fibers of the muscle arise from the
greater and lesser horns of the hyoid bone and the sty-
lohyoid ligament (which runs between the downward
and forward projecting styloid process of the temporal
bone and the lesser horn of the hyoid bone) and radiate
backward and toward the midline where they insert
into the median raphe of the pharynx. The uppermost

126

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127

Side view

Palatopharyngeus

Superior
constrictor

Middle
constrictor

Inferior
constrictor

Superior
constrictor

Middle
constrictor

Inferior
constrictor

Back view

Salpingopharyngeus

Stylopharyngeus

FiGure 4–8. Muscles of the pharynx. The superior constrictor, middle constrictor, inferior constrictor, salpingopha-
ryngeus, and palatopharyngeus muscles constrict the pharynx, whereas the stylopharyngeus muscle dilates the pharynx.
Some of these muscles can also move the pharynx in other ways (see Figure 4–9).

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Foundations of Speech and Hearing: Anatomy and Physiology128

fibers of the middle constrictor muscle course obliquely
upward and overlap the lower fibers of the superior
constrictor muscle, whereas the lowermost fibers of
the muscle run obliquely downward beneath the fibers
of the inferior constrictor muscle. The middle fibers
of the middle constrictor muscle run horizontally. The
overlapping arrangement of the muscle fibers between
the middle constrictor and superior constrictor mus-
cles and between the inferior constrictor and middle
constrictor muscles is akin to the way roof shingles
partially overlap. When the middle constrictor muscle
contracts, it decreases the cross section of the pharynx
regionally, by virtue of forward movement of the pos-
terior pharyngeal wall and forward and inward move-
ment of the lateral pharyngeal wall. When the middle
constrictor muscle acts in conjunction with its paired
mate on the opposite side, the pharyngeal lumen is
regionally constricted like a sphincter.

The inferior constrictor muscle is the most pow-
erful of the three constrictor muscles of the pharynx.
The fibers of this muscle arise from the sides of the
thyroid and cricoid cartilages. The inferior constrictor
muscle is sometimes thought of as consisting of two
muscles, referred to as the thyropharyngeus and crico­
pharyngeus muscles. From the origins noted, fibers of
the inferior constrictor muscle diverge in a fanlike con-
figuration and course backward and toward the mid-
line. There, they interdigitate with fibers from the
inferior constrictor muscle of the opposite side at the
median raphe of the pharyngeal tube. The middle and
upper fibers of the inferior constrictor muscle ascend
obliquely, whereas the lowermost fibers run horizon-
tally and downward and are continuous with those of
the esophagus. When the inferior constrictor muscle
contracts, it draws the lower part of the posterior wall
of the pharynx forward and pulls the lateral walls of
the lower pharynx forward and inward. This action,
in conjunction with that of the inferior constrictor
muscle on the opposite side, constricts the lumen of
the lower pharynx.

The salpingopharyngeus muscle is a narrow
muscle that arises from near the lower border of the
pharyngeal orifice of the auditory tube. The fibers of
the muscle course downward vertically and insert into
the lateral wall of the lower pharynx where they blend
with fibers of the palatopharyngeus muscle (discussed
below). When the salpingopharyngeus muscle con-
tracts, it pulls the lateral wall of the pharynx upward
and inward. When acting simultaneously with its
paired muscle from the opposite side, its effect is to
decrease the width of the pharynx.

The stylopharyngeus muscle is a slender muscle
that runs a relatively long course. It originates from the
styloid process of the temporal bone and runs down-

ward, forward, and toward the midline. Most fibers of
the muscle insert into the lateral wall of the pharynx at
and near the juncture of the superior constrictor and
middle constrictor muscles. Some fibers extend lower
in the pharyngeal wall and insert into the thyroid car-
tilage. When the stylopharyngeus muscle contracts, it
pulls upward on the pharyngeal tube and draws the
lateral wall of the pharynx toward the side. Together
with similar action of its paired mate from the opposite
side, it widens the lumen of the pharynx in the region
where the muscle fibers insert into the lateral walls
of the pharyngeal tube. There is also an upward pull
placed on the pharynx (and larynx) when the stylopha­
ryngeus muscles contract.

The palatopharyngeus muscle runs the length of
the pharynx. It is a pharyngeal muscle as well as a mus-
cle of the soft palate (and in that context is called the
pharyngopalatine muscle). The muscle is considered
here from the pharyngeal perspective. The palatopha­
ryngeus muscle arises mainly from the soft palate. The
uppermost fibers are directed horizontally and inter-
mingle with fibers of the superior constrictor muscle.
A major fiber course is downward and toward the side
through the posterior faucial pillar. Below the pillar,
the fibers continue into the lower half of the pharynx
and spread to the lateral wall of the structure and the
thyroid cartilage. Some have suggested that the por-
tion of the muscle that attaches to the thyroid cartilage
be given recognition of its own as the palatothyroi­
deus muscle (Cassell & Elkadi, 1995), whereas others

Having it Both Ways

A muscle is usually thought of as having
an origin and an insertion. The origin is its
anchored end and the insertion is its movable
end. This is all well and good in textbooks, but
in real life things are a bit more complicated.
What may be the anchored end of a muscle for
one activity may be the movable end of that
muscle for another activity. A lot of it has to do
with what neighboring muscles are doing. Thus,
a muscle’s function may change from time to
time because various forces cause the mobility of
its two ends to change in relation to one another.
The convention adopted in this book is to reflect
such change by alternately labeling a muscle
in accordance with its perceived primary func-
tion in a given context. Some purists may not
embrace this convention, but it carries instruc-
tive power and simply points out that in the
busy world of the muscle, turn about is fair play.

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4 Velopharyngeal-Nasal Function and Speech Production 129

disagree (Moon & Kuehn, 2004). When the velum is
relatively stable, contraction of the palatopharyngeus
muscle results in two movements. The uppermost
fibers of the muscle draw the lateral pharyngeal wall
inward to complement the action of the superior con­
strictor muscle, whereas the lowermost fibers pull
upward on the lateral pharyngeal wall and elevate the
pharynx. (Attachments to the thyroid cartilage also
effect an upward and forward pull on the larynx).

Figure 4–9 illustrates the general force vectors for
the six muscles of the pharynx discussed in this sec-
tion. This illustration summarizes the potential active
forces operating on the pharynx and shows the combi-
nations of forces that could be in play at any moment
to decrease or increase the lumen of the pharynx and/
or change its positioning.

Muscles of the Velum. The muscles of the velum are
shown in Figure 4–10. They are the palatal levator,

palatal tensor, uvulus, glossopalatine, and pharyn­
gopalatine muscles. These muscles influence the posi-
tioning, configuration, and mechanical status of the
velum.

The palatal levator muscle (also called the leva­
tor veli palatini muscle) forms much of the bulk of the
velum. The palatal levator muscle is a flattened cylin-
drical structure that arises from the petrous (hard) por-
tion of the temporal bone and from the cartilaginous
portion of the auditory tube. From there, it courses
downward, forward, and toward the midline, pass-
ing on the outside of the posterior naris. Fibers of the
palatal levator muscle insert into the side of the velum
and spread out where they join those of the palatal
levator muscle from the opposite side. The spread of
muscle fibers in each of the palatal levator muscles
is to the midline and beyond to the other side of the
velum (Kuehn & Moon, 2005). Fibers extend from
behind the hard palate to the front of the uvula, en-

Side view Front view

Superior constrictor

Middle constrictor

Inferior constrictor

22

33

11

55

66

44 Salpingopharyngeus

Stylopharyngeus

Palatopharyngeus

55

22

11

33

66 55

44

66

44

FiGure 4–9. Summary of force vectors of the muscles of the pharynx.
The superior constrictor (1), middle constrictor (2), and inferior constric-
tor (3) muscles constrict the pharynx. The salpingopharyngeus (4) and
palatopharyngeus (6) muscles pull upward and inward on the pharynx.
The stylopharyngeus muscle (5) pulls upward and outward on the pharynx.

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Foundations of Speech and Hearing: Anatomy and Physiology130

compassing approximately the middle 40% of the
velum (Boorman & Sommerlad, 1985) or more (Kuehn
& Kahane, 1990). The paired palatal levator muscles
form a muscular sling from their cranial attachments
through the velum. Each palatal levator muscle inserts
into the velum at an angle of about 45°. When the
palatal levator muscle contracts, it draws the velum
upward and backward. Simultaneous contraction
of the paired palatal levator muscles lifts the velum
toward the posterior pharyngeal wall along an angular
trajectory.

The palatal tensor muscle (also termed the tensor
veli palatini muscle) lies on the outer side of the pal­
atal levator muscle. It arises from the pterygoid and
scapular fossae and angular spine of the sphenoid bone
as well as the cartilaginous portion of the auditory
tube. From there, fibers course vertically downward to
terminate in a tendon and insert into the hook-shaped
hamulus of the medial pterygoid plate of the sphenoid
bone. The tendon of the palatal tensor muscle (along

with a sparse number of palatal tensor muscle fibers)
courses inward and inserts into the hard palate and the
velum (Barsoumian, Kuehn, Moon, & Canady, 1998).
The palatal tensor muscle has an important role in
opening the auditory tube. Earlier conceptions of the
function of the palatal tensor muscle also suggested
that its contraction would tense the velum, because it
was thought that the muscle itself wrapped around
the hamulus to contribute to the horizontal portion of
the structure. However, the fact that the palatal tensor
muscle is now known to insert on the hamulus, with
only a few fibers continuing on to insert into the velum,
indicates that it does not have the mechanical means to
tense the velum to any significant degree. In contrast,
the tendon does seem to play an important mechanical
role. The prominent size of this tendon suggests that it
may relieve stress at the junction between the hard and
soft palates, stress induced by frequent up-and-down
movements of the velum. The stress-relief function is
believed to be akin to a reinforced collar at the junction

Uvulus Pharyngopalatine

Palatal
levator

Palatal
tensor

Glossopalatine

Back view

Side view

FiGure 4–10. Muscles of the velum. They are the palatal levator, palatal tensor, uvulus, glossopalatine, and pharyn-
gopalatine muscles. Most of these muscles act primarily to move the velum upward and backward and downward and
forward. Their individual actions are shown schematically in Figure 4–11.

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4 Velopharyngeal-Nasal Function and Speech Production 131

between an electrical plug and the wire extending from
it (Kuehn, 1990).

The uvulus muscle is the only intrinsic muscle of
the velum. (Both ends of it fibers are within the velum).
Fibers of the muscle originate to the side of the posterior
nasal spine formed by the palatine bones and behind
the hard palate near the sling formed by the palatal
levator muscles and about a fourth of the way along
the length of the soft palate from the front. The muscle
courses downward and backward, extending through
much of the length of the soft palate. Very few fibers of
the uvulus muscle actually enter the uvula proper, from
which the muscle historically derived its name (Azzam
& Kuehn, 1977; Huang, Lee, & Rajendran, 1997). This
has prompted some to argue (and seemingly rightfully
so) that calling this muscle the uvulus muscle is both
a misnomer and anatomically misleading (Moon &
Kuehn, 2004). When the uvulus muscle contracts, it has
several effects that can be realized alone or in combina-
tion. These include (a) shortening the velum, (b) lifting
the velum, and (c) increasing the thickness (bulk) of the
velum in the third quadrant of its length.

The glossopalatine muscle is both a muscle of the
tongue and a muscle of the velum, and is discussed
here as a muscle of the velum. Fibers of the glossopala­
tine muscle arise from the side of the tongue where they
are closely blended with longitudinal fibers of the dor-
sum of the tongue. They course upward and inward,
forming the substance of the anterior faucial pillar, and
insert into the lower surface of the palatal aponeurosis.
The location of attachment to the soft palate is reported
to vary across individuals, with some having inser-
tions forward near the hard palate and others having
insertions rearward near the uvula (Kuehn & Azzam,
1978). When the dorsum of the tongue is relatively
fixed, contraction of the glossopalatine muscle places
a downward and forward pull on the velum. Although
the glossopalatine muscle has force potential on the
velum, that potential is limited in comparison to the
force potential of the pharyngopalatine muscle (Moon
& Kuehn, 2004).

The pharyngopalatine muscle (discussed above
as the palatopharyngeus muscle in the context of the
pharynx) is considered here in the context of the velum.
Its fibers arise from the lower half of the lateral wall of
the pharynx and thyroid cartilage and course upward
and toward the midline where they pass through the
posterior faucial pillar and insert into the soft palate
(also the superior constrictor muscle). Fibers do not
approach or cross the midline of the soft palate, but
insert more laterally within the structure (Kuehn &
Kahane, 1990). One notion of mechanical prominence
is that there is a downward directed sling formed by

the pharyngopalatine muscles that is antagonistic to
the upward directed sling provided by the palatal leva­
tor muscles (Fritzell, 1969), although this idea has been
questioned on anatomical grounds (Moon & Kuehn,
2004).

When the pharyngeal attachment of the pharyn­
gopalatine muscle is relatively fixed, contraction of its
fibers (especially those which are vertically oriented)
pulls downward and backward on the velum. The
action suggested here is founded on assumed muscle
vector pulls inferred from anatomical observations.
This approach may or may not be wholly correct.

Figure 4–11 graphically illustrates the general
force vectors for the four muscles that are known to
operate on the velum. The palatal tensor muscle is not
included in this figure because it does not appear to
have a significant role in velar function.

Muscles of the Outer Nose. All of the muscles of the
outer nose can be used for facial expression to convey
meaning. For the purposes of this chapter, however,
interest in these muscles is in their potential to influ-
ence velopharyngeal-nasal function. Five outer nose
muscles, shown in Figure 4–12, have this potential and
it is these muscles that are discussed here.

The levator labii superioris alaeque nasi muscle
(the longest name of any muscle in animals) is a thin
structure located at the side of the outer nose between
the orbit of the eye and the upper lip. Its origin is
from the frontal process and infraorbital margin of the
maxilla. From there, the muscle courses downward
and toward the side, subdividing into two muscular
slips. One slip inserts into the upper lip (blending
with the orbicularis oris muscle, described in Chap-
ter 5) and the other slip (of more interest here) inserts
into the cartilage of the nasal ala (see Figure 4–7).
Contraction of this latter muscular slip draws the
ala upward on the same side of the outer nose (like
lifting a side flap on a tent) and enlarges the cor-
responding anterior naris.

The anterior nasal dilator muscle is a small
muscle positioned on the lower lateral surface of the
outer nose. It arises from the lower edge of the lateral
nasal cartilage and runs downward and outward. Fol-
lowing a short course, it inserts into the deep surface
of the skin near the outer margin of the naris on the
same side. Contraction of the anterior nasal dilator
muscle enlarges the anterior naris on that side of the
outer nose.

The posterior nasal dilator muscle is a small
muscle located on the lower lateral surface of the outer
nose. It lies behind the anterior nasal dilator muscle.
Fibers of the posterior nasal dilator muscle originate

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Foundations of Speech and Hearing: Anatomy and Physiology132

from the nasal notch of the maxilla and adjacent sesa-
moid cartilages of the outer nose. From this origin, they
follow a short course and insert into the skin near the
lower part of the alar cartilage along the outer margin
of the naris on the same side. Contraction of the pos­

terior nasal dilator muscle enlarges the corresponding
anterior naris.

The nasalis muscle is located on the side of the
outer nose. It originates from the maxilla, above and
lateral to the incisive fossa. Fibers run upward and

22

11

44
44

22

11

33

11

33

Palatal levator

Uvulus

Glossopalatine

Pharyngopalatine

22

33

11

44

Side view

Front view

Left oblique view

33
44

FiGure 4–11. Summary of force vectors of the muscles of the velum. The palatal levator muscle (1) pulls
the velum upward and backward. The uvulus muscle (2) shortens, lifts, and increases the thickness of the velum.
The glossopalatine muscle (3) pulls the velum downward and forward and the pharyngopalatine muscle
(4) pulls the velum downward and backward. The palatal tensor muscle is not included in this figure because
it is not thought to have a significant effect on the velum.

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4 Velopharyngeal-Nasal Function and Speech Production 133

toward the midline and insert into an aponeurosis that
is continuous with its paired muscle from the opposite
side. When the nasalis muscle contracts, it draws down
the cartilaginous part of the outer nose on the same
side and decreases the aperture of the corresponding
anterior naris. Under extreme action, contraction of this
muscle and its counterpart from the opposite side may
bring the two alae of the outer nose together or com-
press them against one another.

The depressor alae nasi muscle is a short muscle
that originates from the incisive fossa of the maxilla
and radiates upward to insert into the back part of the
ala and the cartilaginous septum of the outer nose.
When the depressor alae nasi muscle contracts, it
draws the ala of the outer nose downward on the
side of action and decreases the aperture of the cor-
responding naris.

Movements of the
Velopharyngeal-Nasal Apparatus

Movements of the pharynx, velum, and outer nose are
considered here apart from the forces that cause them.
The relation of forces to movements is considered in
the next section on adjustments.

Movements of the Pharynx

The pharynx is a highly mobile tube. As illustrated in
Figure 4–13, this mobility is vested in structures of the
pharynx itself and in structures that comprise its lower
and front boundaries. These movement capabilities are:
(a) lengthening and shortening through downward
and upward movements of the larynx, (b) inward and
outward movements of the lateral pharyngeal walls,
(c) forward and backward movements of the posterior
pharyngeal wall, and (d) forward and backward move-
ments of velum, tongue, and epiglottis. Because the
pharynx is a hollow tube, movements of the pharynx
are manifested in changes in the shape of its internal
cavity. This internal cavity can be constricted or dilated
at multiple sites as the result of different combinations
of movements of the structure. For example, one part of
the pharynx may be constricted, another part dilated,
and yet another part alternately constricted and dilated
during an activity.

Movements of the Velum

The velum is a fleshy flap that is largely muscular. Most
of the time, it hangs pendulously in the oropharyngeal
space, but for many activities it moves substantially.

Anterior nasal
dilator

Posterior
nasal dilator

Levator labii
superioris

alaeque nasi

Nasalis

Depressor
alae nasi

FiGure 4–12. Muscles of the outer nose. Three muscles dilate the nares (levator labii
superioris alaeque nasi, anterior nasal dilator, and posterior nasal dilator muscles)
and two constrict the nares (nasalis and depressor alae nasi muscles) when contracted.

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Foundations of Speech and Hearing: Anatomy and Physiology134

Tongue

Skull

Side
wall

Epiglottis

Esophagus

Velum

Side
wall

Back
wall

Larynx

Skull

Mouth of
esophagus

(behind)

Cricoid lamina

Front view Side view

FiGure 4–13. Movements of the pharynx. These movements can be downward and
upward, inward and outward, and forward and backward and can lengthen, shorten, widen,
and constrict the pharyngeal tube. Some of these movements are carried out by parts
of the pharynx and others are carried out by nearby structures (velum, tongue, epiglottis,
and larynx).

sonar in a teacup

Early study of lateral pharyngeal wall movement was problematic because
x-ray techniques of the day did not provide good frontal views of the
pharynx. Two speech scientists and a medical physicist from the University
of Wisconsin provided the first clean data on lateral pharyngeal wall
movement through the use of pulsed ultrasound. The technique sounded
the depth of a point on the pharyngeal wall (like tracking a submarine). To
learn the technique, they attended a short course on obstetrics where the
uses of ultrasound were being taught as a pioneering means for scanning
the abdomen of pregnant women. The first monitoring of lateral pharyn-
geal wall movement during speech production was done at that short
course, on an individual immersed (except for the face) in a water-filled
gunner ’s turret of a bomber (envision an enormous teacup). Gels were just
then starting to be used to transmit ultrasound into the body for medical
purposes.

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4 Velopharyngeal-Nasal Function and Speech Production 135

Movements of the velum are mainly along an upward-
backward or downward-forward path, in which those
in one direction closely trace those in the other. The
angular trajectory is reported to be slightly curvilin-
ear (Kent, Carney, & Severeid, 1974) or linear (Kuehn,
1976). Maximum upward movement of the velum
places the upper surface of the structure within the
nasopharynx (above the boundary specified by con-
vention to separate the oropharynx and nasopharynx).

Lubker Bumps

Scientists often name phenomena for those who
were first to describe them or to figure out what
they meant. In this regard, the inauguration of
the term “Lubker Bumps” seems long overdue.
Most who have studied velopharyngeal-nasal
function using aeromechanical techniques have
encountered very small variations in nasal
airflow (usually oscillating around zero airflow)
when the velopharynx is closed airtight. These
variations, as described by James F. Lubker,
result from movements of the velum up and
down within a closed velopharynx, acting like a
piston in a cylinder to push very small quantities
of air in and out of the nasopharynx. The nasal
airflow tracings that characterize such piston
movements show tiny bumps up and down
around zero airflow that reflect true airflows,
but ones not generated by the passage of air
through the velopharynx. Lubker ’s reputation
deserves to be bumped up a notch for his astute
observation.

The velum is a flap and in some ways it resembles
a trapdoor, but it does not move like a trapdoor, as if
it were swinging from a hinge. Rather, as depicted in
Figure 4–14, the shape of the velum actually changes
when it moves. The farther up and back it moves, the
more “hooked” its appearance (as viewed from the
side) and the farther down and forward it moves, the
more “pendulous” its appearance (as viewed from the
side). This is because the major lifting force that pulls
the velum upward is applied toward the middle of the
velum. The hooked appearance of the velum results in
identifiable landmarks during movement. The top of
the hook (on the upper surface of the velum) is referred
to as the velar eminence and the undersurface of the
hook (on the lower surface of the velum) is designated
as the dimple of the velum.

Movements of the Outer Nose

Movements of the outer nose result mainly from out-
ward or inward movements of the nasal alae that may
change the cross sections of the apertures of the ante-
rior nares (nostrils). Under most circumstances, these
movements are small. Exceptions occur during certain
breathing events, when signaling emotions (disdain,
contempt, and anger), and when using the nares to
slow the flow of air from the outer nose by increasing
resistance at its exit ports.

adjustments of the
Velopharyngeal-nasal apparatus

The velopharyngeal-nasal apparatus is capable of
many adjustments. The present discussion is limited
to those adjustments that influence the degree of cou-
pling between the oral and nasal cavities (through the
velopharyngeal port) and between the nasal cavities
and atmosphere (through the apertures of the anterior
nares). Adjustments of lower parts of the pharynx are
considered in Chapters 5 and 8.

Nasopharynx

Oropharynx

Velar eminence

Velar dimple

FiGure 4–14. Elevated configuration of the velum as
viewed from the side. Note its “hooked” appearance. The
upper surface of the hook is called the velar eminence and
the undersurface of the hook is called the velar dimple.

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Foundations of Speech and Hearing: Anatomy and Physiology136

Coupling Between the Oral
and Nasal Cavities

The degree of coupling between the oral and nasal cav-
ities can be adjusted by changing the size of the velo-
pharyngeal port (the usual opening between the oral
and nasal cavities). The range of possibilities extends
from a fully open port to a fully closed port.

The velopharyngeal port is open most of the time
to accommodate nasal breathing. Closure of the port
can be brought about through action of the velum and/
or pharynx. Combined action of the two structures
is often described as a flap-sphincter action, the flap

being movement of the velum and the sphincter being
movement of the pharynx.

There is no universal pattern for achieving velo-
pharyngeal closure. On the contrary, several movement
strategies for achieving closure of the velopharyngeal
port have been identified that involve different actions
or combinations of actions of the velum, lateral pha-
ryngeal walls, and posterior pharyngeal wall (Croft,
Shprintzen, & Rakoff, 1981; Finkelstein et al., 1995;
Poppelreuter, Engelke, & Bruns, 2000; Shprintzen, 1992;
Skolnik, McCall, & Barnes, 1973). These movement
strategies are illustrated in Figure 4–15 and include:
(a) elevation of the velum alone, (b) inward movement
of the lateral pharyngeal walls alone, (c) elevation of
the velum combined with inward movement of the lat-
eral pharyngeal walls, and (d) elevation of the velum
combined with inward movement of the lateral pha-
ryngeal walls and forward movement of the posterior
pharyngeal wall.

The prevailing wisdom is that these different
movement strategies for achieving velopharyngeal clo-
sure are rooted in differences in anatomy (Finkelstein et
al., 1995). It should also be noted that different move-
ment strategies for achieving closure of the velopha-
ryngeal port are not fixed within individuals, but can
change over time as velopharyngeal anatomy changes.

The positioning of the velum in the adjustment of
oral-nasal coupling is most often attributed to action
of the paired palatal levator muscles (Dickson, 1972).
Thought typically has been that lifting of the velum fol-
lows from the contractile force provided by these mus-
cles and accounts for its midportion usually attaining
the highest elevation during closure of the velopharyn-
geal port (Bell-Berti, 1976; Fritzell, 1963; Lubker, 1968;
Seaver & Kuehn, 1980). Although action of the palatal
levator muscle seems to be clearly associated with the
flap component of the flap-sphincter closure adjust-
ment, correlations between palatal levator activity
and the elevation of the velum are weaker (albeit posi-
tive) than would be expected were the palatal leva­
tor muscle alone responsible for positioning the velum
(Fritzell, 1979; Lubker, 1968). This suggests that other
muscles must also be active in positioning the velum.
Research, in fact, supports this inference. For example,
different combinations of muscle activity among the
palatal levator, glossopalatine, and pharyngopala­
tine muscles have been found to be associated with
the same positioning of the velum (Kuehn, Folkins, &
Cutting, 1982). This and other evidence (Moon, Smith,
Folkins, Lemke, & Gartlan, 1994b) suggest that there is
a trading relationship among these three muscles that
contribute to movements of the velum. Clearly, classi-
cal notions of the velum being controlled by the palatal
levator muscle alone is not adequate.

Back wall of pharynx

Side wall
of pharynx

(right)

Side wall
of pharynx

(left)

Top surface of velum

A

B

C

D

FiGure 4–15. Patterns of velopharyngeal closure as
seen from above. These patterns are velar elevation (A),
inward movement of the lateral pharyngeal walls (B), com-
bined velar elevation and inward movement of the lateral
pharyngeal walls (C), and velar elevation combined with
inward movement of the lateral pharyngeal walls and for-
ward movement of the posterior pharyngeal wall (D).

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4 Velopharyngeal-Nasal Function and Speech Production 137

Coupling Between the Nasal
Cavities and Atmosphere

The degree of coupling between the nasal cavities and
atmosphere can be adjusted by changing the size of the
anterior nares. The range of possibilities extends from
fully open nares to fully closed nares. It is also possible
to have different degrees of coupling for the two nares
(one being open more than the other).

Where’s the rest?

Many studies have examined the correlation
between velopharyngeal incompetence and
articulation skill in children with repaired cleft
palates. The highest correlation found in these
studies is 0.5. Square that number and you find
that velopharyngeal incompetence predicts only
25% of the variance in articulation skill. Where’s
the rest? Some have suggested it’s to be found in
“learning.” We believe 75% is far too much to be
attributed to such a notion. Rather, we suspect
that the rest is confounded by the fact that the
children studied were never categorized with
regard to the magnitude of their nasal airway
resistance. Not knowing or controlling for this
factor would have an important influence on
the strength of the correlation obtained between
velopharyngeal incompetence and articulation
skill. Where’s the rest of the variance of interest?
We think it’s probably in the nose and has been
overlooked.

The anterior nares, like the velopharynx, are rel-
atively open most of the time to accommodate nasal
breathing. Dilation or constriction of the nares can be
brought about through actions of muscles of the outer
nose. Such actions can be either opposed or supple-
mented by aeromechanical forces associated with
breathing. For example, muscles that dilate the anterior
nares may activate to resist the tendency of the nares
to collapse in response to low air pressures (created
by high airflows) in their lumina. The need for such
activation can be appreciated by sniffing briskly while
watching the outer nose in a mirror. Both the nares
and alae of the outer nose tend to be sucked inward
by the lowering of nasal pressures. More forceful
inspirations require increasingly forceful contractions
of nasal dilators to maintain patent nares (Bridger,
1970).

Control Variables of
Velopharyngeal-nasal Function

Several control variables are important in velopharyn-
geal-nasal function. Their relative significance depends
on the particular activity being performed and its goal,
whether it is breathing, speaking, singing, blowing,
sucking, swallowing, gagging, whistling, playing a
wind instrument, or blowing glass. For example, speak-
ing involves control variables based on acoustic goals,
whereas tidal breathing does not. For another example,
the force with which the velopharynx is closed may
be an important variable for an activity that calls for
very high oral air pressure (glass blowing), but be a
less important variable for an activity with low oral
air pressure demands (whispering). For persons with
a normally functioning velopharyngeal-nasal appa-
ratus, the most significant features of control pertain
to the velopharyngeal portion of the apparatus. There
are times, however, when control of the outer nose can
become important.

For purposes of this chapter, attention is devoted
to three control variables that influence aeromechanical
and acoustic aspects of velopharyngeal-nasal function.
These include: (a) the magnitude of the airway resis-
tance offered by the velopharyngeal-nasal apparatus,
(b) the magnitude of the muscular pressure exerted by
the velopharyngeal sphincter to accomplish and main-
tain velopharyngeal closure, and (c) the magnitude of
the acoustic impedance offered by the velopharyngeal-
nasal apparatus.

Velopharyngeal-Nasal Airway Resistance

Resistance is defined, in a mechanical sense, as opposi-
tion to movement and results in a loss of energy through
friction. Velopharyngeal-nasal airway resistance has to
do with opposition to the mass flow of air (the breath)
through structures of the velopharyngeal-nasal airway.
This is analogous to the resistance to airflow through
the laryngeal airway, discussed in Chapter 3.

Adjustments of the velopharyngeal port, nasal
cavities, and/or outer nose can create a change in
airway resistance between the oral cavity and atmo-
sphere through the nasal route, as portrayed in Fig-
ure 4–16. Changing the cross section and/or length of
the velopharyngeal port, changing the engorgement
of the nasal cavities, or changing the cross section of
the anterior nares can all have consequences for velo-
pharyngeal-nasal airway resistance. Airflow also alters
the resistance because resistance is airflow depen-
dent. Specifically, resistance increases and decreases
with increases and decreases in the rate at which the

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Foundations of Speech and Hearing: Anatomy and Physiology138

air moves, even when the physical dimensions of the
velopharyngeal-nasal airway remain unchanged.

The range of potential airway resistance values is
large and can go from very low (following the admin-
istration of a decongestant) to infinity (completely

obstructed). Infinite airway resistance is usually effected
through airtight closure of the velopharyngeal port.
Infinite velopharyngeal-nasal airway resistance can also
be achieved in the case of an open velopharynx under
circumstances where there is complete nasal blockage.

Outer
nose

Nasal
cavities

Mass
airflow

Velopharyngeal
port

FiGure 4–16. Airflow through the velopharyngeal-nasal apparatus. The resistance
of the velopharyngeal-nasal apparatus to air flowing through it can be altered by
adjustments of the velopharyngeal port, the nasal cavities, and the outer nose. Changes
in the rate at which air flows through the apparatus can also alter the resistance.

the Flap Flap

Pharyngeal flaps are secondary surgical procedures usually performed on
persons with repaired cleft palates who persist with velopharyngeal incom-
petence or insufficiency following primary surgery. Flaps are constructed
using tissue from the posterior pharyngeal wall (peeled away like the skin
on a banana) and attaching it to the velum to form a bridge. Flaps have also
been used in children with cerebral palsy who have paresis (weakness) of
the velar muscles. Such flaps have been found to improve speech in such
children, but they also have been found to have a major negative side effect.
They may raise the resistance to breathing through the nose and cause some
children to switch from nose breathing to mouth breathing. Mouth breathing
opens the door (pun intended) to drooling. The negative social consequences
of drooling are often judged to outweigh the positive social consequences of
improved speech. Thus, flaps sometimes have had to be removed.

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4 Velopharyngeal-Nasal Function and Speech Production 139

Velopharyngeal Sphincter Compression

Once airtight velopharyngeal closure is attained, the
force of that closure can be adjusted to meet the needs
of the situation. This force, depicted in Figure 4–17,

is represented by the compressive muscular pressure
exerted to maintain the velopharyngeal sphincter in a
closed configuration. The muscular pressure exerted
at any moment must exceed the magnitude of the air
pressure difference across the velopharyngeal sphincter

Side wall
of pharynx

(right)

Back wall
of pharynx

Side wall
of pharynx

(left)

Top surface
of velum

FiGure 4–17. Compressive muscular pressure during velopharyngeal closure. The
greater the pressure difference across the velopharynx, the higher the compressive
pressure needed to maintain velopharyngeal closure. The inset shows the velopharynx
as if viewed from above.

some things are not Quite What they seem

There seems to be a relatively large number of
musicians who complain of “air leaks out the nose”
while playing wind instruments. Such complaints
are red flags for what is often called stress-induced
velopharyngeal incompetence. Sometimes
physical measurements confirm that, in fact, the
velopharynx is open during sound production.
But sometimes physical measurements show that,
surprisingly, the velopharynx is closed during
sound production, despite what the musician is

feeling. Why the mismatch? A study of trombonists
may have found the answer. By sensing changes in
air pressure at the anterior nares, Bennett and Hoit
(2013) discovered that some trombonists open the
velopharynx at the beginning of expiration before
the sound begins, and then close the velopharynx
right as the sound starts. What they felt was
correct: the velopharynx was open. But it was not
open while they were actually playing. Sometimes
the senses play tricks on us.

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Foundations of Speech and Hearing: Anatomy and Physiology140

(whether it be positive or negative) to prevent the velo-
pharynx from being forced (blown or sucked) open.
Thus, only a low compressive force is required to effect
airtight velopharyngeal closure for an activity involv-
ing low oral air pressure, whereas a high compressive
force is required for an activity involving high positive
oral air pressure.

Velopharyngeal-Nasal Acoustic Impedance

Acoustic (sound) impedance, like airway resistance,
involves opposition to flow. However, it involves
opposition to the flow of sound rather than to mass
airflow. Thus, the acoustic impedance offered by the
velopharyngeal-nasal apparatus pertains to the rapid
to-and-fro bumping of air molecules in which each
stays in a very restricted region and passes energy on
to its neighbors. The opposition to acoustic flow is fre-
quency dependent. As portrayed in Figure 4–18, acous-
tic impedance influences flow propagation of sound
waves (not breath). The acoustic impedance of concern
here is that distributed across the velopharyngeal port,
nasal cavities, and outer nose.

The velopharyngeal port can be adjusted to influ-
ence the degree of acoustic coupling between the oral
and nasal cavities. When the port is closed (see Figure
4–18A), the oral and nasal airways are separated. Thus,
nearly all of the sound energy passes through the oral
airway and mouth and the acoustic impedance looking

Oral
cavity

Sound
energy

Mouth

Outer
nose

Nasal
cavities

Sound
energy

Velopharyngeal
port

Velopharyngeal
closure

Mouth

Nasal
cavities

Sound
energy

Outer
nose

Velopharyngeal
port

Oral
cavity

A

B

C

FiGure 4–18. Oral-nasal sound wave propagation
through the velopharyngeal-nasal pathway (velopharynx,
nasal cavities, and outer nose) and oral pathway (oral cav-
ity and mouth). The conditions shown are the velopharynx
closed with sound routed through the oral pathway (A), the
oral pathway closed with sound routed through the velo-
pharyngeal-nasal pathway (B), and both pathways open so
that sound is routed through both simultaneously (C).

Which Hunt

It is often stated that velopharyngeal incompe-
tence or insufficiency allows air to pass into the
nasal cavities, causing hypernasality. This is a
misconception. Significant quantities of air can
pass into the nasal cavities through the velopha-
rynx during utterance without a perception of
hypernasality. Also, hypernasality may be heard
during utterance when no air is passing into the
nasal cavities, such as when the covering tissue
of a submucous cleft palate vibrates and excites
the nasal cavities into sympathetic vibration.
Flow of air into the nose does not cause hyper-
nasality. In fact, hypernasality may be present
when inspiratory speech is produced and
airflow is passing through the nasal cavities in
the opposite direction from usual. It’s instructive
to go through written discussions about velo-
pharyngeal dysfunction and see which authors
get it right and which authors get it wrong.
Think of it as sort of a “which” hunt.

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4 Velopharyngeal-Nasal Function and Speech Production 141

into the nasal cavities from their velopharyngeal end is
nearly infinite. (A small amount of sound energy may
be transmitted through the closed velopharynx via
sympathetic vibration, such as when the velum acts
like a drumhead.)

When the velopharyngeal port is open (see Fig-
ures 4–18B and C), the oral and nasal cavities are free to
exchange sound energy and interact with one another
acoustically, and sound energy may pass through the
nasal cavities to atmosphere. Changes in the size of the
velopharyngeal port are important to determining how
sound energy is divided between the oral and nasal
cavities. Also important are configurations of the oral
and nasal cavities themselves and the extent to which
each impedes the flow of sound energy. In the case of
the nasal part of the system, degree of engorgement of
the nasal cavities and status of the anterior nares are
relevant factors.

neural substrates of
Velopharyngeal-nasal Control

Velopharyngeal-nasal movement is controlled by the
nervous system, but the nature of that movement and
the nature of its control differ with the activity being
performed. That is, different parts of the nervous
system take charge of different components of the
velopharyngeal-nasal apparatus for different types of
activities such as sneezing, blowing, swallowing, and
speaking.

Although different parts of the central nervous
system are responsible for the control of different
velopharyngeal-nasal activities, control commands
are, nonetheless, sent through the same set of cranial
nerves to muscles. These nerves originate in the brain-
stem and course outward to provide motor innerva-
tion to the pharynx, velum, and outer nose. As shown
in Table 4–1, motor innervation of the pharynx and
velum is effected through the pharyngeal plexus, a
network that includes fibers from cranial nerves IX
(glossopharyngeal), X (vagus), and possibly XI (acces-
sory). An exception is found in the case of the palatal
tensor muscle, whose motor innervation is provided by
cranial nerve V (trigeminal). There may also be addi-
tional motor innervation to the pharynx and velum
through cranial nerve VII (facial), especially related
to the palatal levator and uvulus muscles. Motor
innervation to the outer nose is effected by cranial
nerve VII.

One might think that information about the motor
nerve supply to different parts of the velopharyngeal-
nasal apparatus would be straightforward and agreed
upon. This is, indeed, the case for motor innervation
to the outer nose, but not for motor innervation to
the pharynx and velum. This is because the linkage
between specific cranial nerves and the motor supply
to specific muscles is equivocal in some cases (Cassell &
Elkadi, 1995; Dickson, 1972; Moon & Kuehn, 2004) and
because conducting research on motor nerve function
in the velopharyngeal-nasal region of human beings is
extremely difficult (Kuehn & Perry, 2008).

taBLe 4–1. Summary of the Motor and Sensory Nerve
Supply to the Pharynx, Velum, and Outer Nose Components of
the Velopharyngeal-Nasal Apparatus. Cranial nerves include V
(trigeminal), VII (facial), IX (glossopharyngeal), X (vagus), and
possibly XI (accessory).

INNERVATION

COMPONENT MOTOR SENSORY

Pharynxa IX, X, (XI)b V, VII, IX, X

Veluma IX, X, (XI)
(except palatal tensor
muscle, which is
innervated by V)

V, VII, IX, X

Outer Nose VII V

aThere may be additional motor innervation from cranial nerve VII to certain
muscles of the pharynx and velum, especially the palatal levator muscle and
uvulus muscle (Shimokawa, Yi, & Tanaka, 2005).
bThe branches of cranial nerve IX and X (and possibly XI) that innervate
parts of the velopharynx are sometimes called the pharyngeal plexus.

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Foundations of Speech and Hearing: Anatomy and Physiology142

Sensory innervation to the pharynx and velum is
effected through cranial nerves V, VII, IX, and X, and
sensory innervation to the outer nose is effected through
cranial nerve V. Neural information traveling along the
sensory nerve supply from the pharynx, velum, and
outer nose comes from receptors that respond to vari-
ous types of stimuli, including mechanical stimuli. For
example, receptors located in the mucosa of the velum
and pharynx respond to light touch and receptors
located in and near the velopharyngeal-nasal muscles
relay information about muscle length and tension.

Much of incoming information from the velopha-
ryngeal-nasal apparatus is not sensed or perceived.
This seems to be especially true for the velopharyngeal
portion of the apparatus. For example, the potential for
sensing the position of the velum in space (propriocep-
tion) and its movement (kinesthesia) is believed to be
rudimentary or nonexistent. Empirical evidence for
this can be found in studies in which normal speakers
have been shown to have difficulty controlling velo-
pharyngeal movements voluntarily (Ruscello, 1982;
Shelton, Beaumont, Trier, & Furr, 1978). Thus, it seems
likely that control of the velopharyngeal apparatus
relies more heavily on other types of information, such
as that associated with the sensing of air pressure and
airflow (Liss, Kuehn, & Hinkle, 1994; Warren, Dalston,
& Dalston, 1990) and that associated with the sensing
of the acoustic signal (Netsell, 1990) via cranial nerve
VIII (auditory-vestibular).

Ventilation and
Velopharyngeal-nasal Function

Recall from Chapter 2 that ventilation is the movement
of air in and out of the pulmonary apparatus for the
purpose of gas exchange. This movement of air can be
routed through the nose, the mouth, or both.

Resting tidal breathing usually occurs through the
nose alone. This may seem somewhat counterintui-
tive, given that the airway resistance through the nasal
pathway is much greater than through the oral path-
way. Nevertheless, the nasal route typically prevails.
This is because it provides advantages for both inspi-
ration and expiration. Advantages of nasal inspiration
are that it converts the temperature of incoming air to
that of the body, increases the humidity of incoming
air, and filters dust, bacteria, and other contaminants
from the incoming air before they reach the lungs and
lower airways. An advantage of nasal expiration is that
it helps slow the flow of expired air to ensure adequate
alveolar gas exchange (Hairfield, Warren, Hinton,
& Seaton, 1987) by providing an additional braking
mechanism (Jackson, 1976) to accompany the laryngeal

braking mechanism that also serves to slow expiration
(Gautier, Remmers, & Bartlett, 1973).

Although nasal breathing is the norm, there are
times it becomes necessary to switch to mouth breath-
ing (or combined mouth and nose breathing) to main-
tain adequate ventilation. This occurs when the nasal
pathway resistance becomes too high due to high air
flow, nasal pathway constriction, or both. Interest-
ingly, the magnitude of resistance that leads to switch-
ing from solely nasal breathing to nasal-oral breathing
turns out to be slightly lower than the resistance value
that leads to the sensation of breathing discomfort
(Warren, Hairfield, Seaton, Morr, & Smith, 1988; War-
ren, Mayo, Zajac, & Rochet, 1996). This means that the
switch from nasal breathing to oral–nasal breathing
occurs before any awareness of breathing difficulty.

the masked man’s nose

Nose masks are often used in research and
clinical endeavors. Such masks must be sealed
airtight against the face so that air doesn’t leak
around their edges. But therein lies a potential
problem. How the face gets compressed beneath
the edges of a mask can influence how air
moves through the outer nose. Try the follow-
ing: breathe in and out through your nose to
experience your usual nasal resistance to airflow.
Next, touch your face below both your eyes and
slowly slide that skin toward the middle of your
face — but don’t touch your outer nose. Notice
how it gets harder to breathe when you do this.
How your facial skin gets “scrunched” greatly
influences your nasal resistance, even though
you may not actually touch your outer nose.
The same is true for how you position a mask on
someone else. Be careful. Don’t scrunch the skin
around the outer nose. Otherwise, you may raise
nasal resistance to airflow.

VeLopHarynGeaL-nasaL FunCtion
anD speeCH proDuCtion

The velopharyngeal-nasal apparatus adjusts the oral–
nasal distribution of aeromechanical and acoustic ener-
gies during speech production. For the production of
oral speech sounds, the velopharyngeal valve is usually
closed and aeromechanical and acoustic energies are
channeled through the oral cavity (mouth). In contrast,
for the production of nasal speech sounds, the velopha-

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4 Velopharyngeal-Nasal Function and Speech Production 143

rynx is open and aeromechanical and acoustic energies
are channeled through the nasal cavities (nose).

The velopharyngeal-nasal apparatus has two
important roles during speech production. One is
to manage the airstream to produce oral consonant
sounds, that require high oral pressure. Such manage-
ment requires that the velopharynx be closed, or nearly
so, and that aeromechanical energy be directed through
the oral channel. The other role is to manage the flow
of acoustic energy into the oral and nasal cavities. This
is important for the production of vowels and both oral
and nasal consonants.

This section focuses on a series of topics perti-
nent to velopharyngeal-nasal function and speech
production. These include consideration of sustained
utterances and running speech activities, followed by
separate discussions about the influences of gravity,
development, age, and sex on velopharyngeal-nasal
function in speech production.

Velopharyngeal-nasal Function
and sustained utterances

Sustained vowels and consonants are usually produced
with relatively stable configurations of the velopharyn-
geal-nasal apparatus. Observations are typically made
of the velopharyngeal portion of the apparatus.

Velopharyngeal function for sustained vowels has
been studied mainly through the use of x-ray and aero-
mechanical techniques. Observations have shown that
the velum moves upward and backward toward the
posterior pharyngeal wall in anticipation of vowel pro-
duction (Bzoch, 1968; Lubker, 1968; Moll, 1962). At the
same time, the lateral pharyngeal walls move inward1
and the posterior pharyngeal wall may move forward
slightly (Iglesias, Kuehn, & Morris, 1980). The velum
is usually elevated maximally in its midportion dur-
ing vowel production and contact with the posterior
pharyngeal wall (if it occurs) is typically achieved
by velar tissue that is approximately two-thirds of the
distance from the hard palate to the uvula (Graber,
Bzoch, & Aoba, 1959). There is also a tendency for the
velum to be elevated to a higher position when sus-

tained vowels are produced at higher vocal effort levels
(Tucker, 1963).

Airtight closure of the velopharyngeal port may or
may not occur during sustained vowel production. The
probability of airtight closure favors high vowels (such
as /i/ in peek) over low vowels (such as /ae/ in cat).
For example, Moll (1962), in an x-ray motion picture
study of the velopharynx in young adults, found some
were opening the velopharyngeal port during less than
15% of high vowel productions and nearly 40% of low
vowel productions.

Whether or not airtight velopharyngeal closure
is achieved, high vowels and low vowels contrast in
still other ways. Compared to low vowel production,
high vowel production is associated with: (a) greater
velar height, (b) greater extent of velar contact with the
posterior pharyngeal wall when the two surfaces are in
apposition, and (c) smaller distance between the velum
and the posterior pharyngeal wall when closure is not
complete (Iglesias et al., 1980; Lubker, 1968; Moll, 1962).
High vowel production also involves greater velopha-
ryngeal sphincter compression (closing force) than
low vowel production when velopharyngeal closure
is complete (Gotto, 1977; Kuehn & Moon, 1998; Moon,
Kuehn, & Huisman, 1994a; Nusbaum, Foly, & Wells,
1935). Velar height differences during sustained vowel
productions are relatively strongly correlated with
the electrical activity of the palatal levator muscles
(Bell-Berti, 1976; Fritzell, 1969; Lubker, 1968). Less than
perfect correlations may relate to partial influences of
other muscles involved in trading relationships with
the palatal levator muscle in velar height adjustments
(Fritzell, 1969; Kuehn et al., 1982).

Two possible mechanisms have been proposed
to account for the differences observed in velar height
between high and low vowel productions. These
are portrayed in Figure 4–19. One is that the velum
elevates to different degrees because of anatomical
constraints imposed through interconnections to struc-
tures below (Harrington, 1944; Kaltenborn, 1948; Lub-
ker, 1968; Moll, 1962). Likely candidates include the
glossopalatine and pharyngopalatine muscles that
have originating attachments from below the velum.
The glossopalatine muscle is considered to be the more

1 The suggestion has been made (Dickson & Dickson, 1972) that the palatal levator muscles are responsible for both elevation of the velum
and inward movements of the lateral pharyngeal walls. Those in support of this suggestion contend that inward movements of the lateral
pharyngeal walls occur in a region of the pharynx above the fiber course of the superior constrictor muscles (Honjo, Harada, & Kumazasa,
1976; Isshiki, Harita, & Kawano, 1985). A contrary viewpoint is that elevation of the velum and inward movements of the lateral pharyngeal
walls are simply coordinated actions of the palatal levator muscles (to elevate the velum) and the superior constrictor muscles (to move the
lateral pharyngeal walls inward). Those in support of this viewpoint contend that inward movements of the lateral pharyngeal walls occur
below the velar eminence associated with insertion of the palatal levator muscles into the velum (Shprintzen, McCall, Skolnick, & Lenicone,
1975; Skolnick, 1970; Skolnick et al., 1973) and that the timing of movements of the velum and lateral pharyngeal walls are poorly correlated
during speech production in normal individuals (Iglesias et al., 1980). We support this latter viewpoint in our description of velopharyngeal-
nasal function and point the interested reader to Moon and Kuehn (2004) for further discussion on this topic.

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Foundations of Speech and Hearing: Anatomy and Physiology144

important of the two candidates. The hypothesis is that
the glossopalatine muscle tethers the velum so that
low vowels (involving low tongue positions) restrict
elevation of the velum and lead to lesser degrees of
closure of the velopharyngeal port. The influence

of tethering is less for high vowels (involving high
tongue positions) because less restriction is placed on
velar elevation.

The second mechanism proposed to account for
velar height differences between high and low vowel

High vowels

Minimum mechanical
tethering of velum

from below

Higher oral acoustic
impedance

Low vowels

Smaller velopharyngeal
opening

Non-nasal speech

Lower oral acoustic
impedance

Larger velopharyngeal
opening

Non-nasal speech

Maximum mechanical
tethering of velum

from below

Tongue
(Glossopalatine)

Pharynx
(Pharyngopalatine)

Or

Or

FiGure 4–19. Possible mechanisms to explain why high vowels, when compared to low
vowels, are associated with a greater velar height and greater contact between the velum
and posterior pharyngeal wall (or smaller distance between them if there is no contact).
One possible mechanism (left side of figure) relates to the tethering of the velum to struc-
tures below through connections created by the glossopalatine muscle. Another possible
mechanism (right side of figure) relates to the acoustic product and the need to ensure that
the vowel is not perceived as nasal.

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4 Velopharyngeal-Nasal Function and Speech Production 145

productions has an acoustic-perceptual basis. That is,
it may be that the velum elevates to different degrees
because of acoustic requirements involved in ensur-
ing that the utterance is not perceived as nasal (Cur-
tis, 1968; Lubker, 1968; Moll, 1962). This speculation is
based on the results of electrical analog studies of the
nasalization of vowels conducted by House and Ste-
vens (1956) and more recently with a computational
speech production model by Bunton and Story (2012).
Both studies demonstrated that less nasal coupling
(velopharyngeal opening) is required to produce the
auditory-perceptual judgment of nasal quality on high
vowels than on low vowels. Thus, the velar height dif-
ferences observed for high and low vowels could be
purposive adjustments to control the degree of nasal-
ization in the face of different tongue adjustments that
influence the flow of acoustic energy through the oral
and nasal cavities. In effect, at any given moment the
particular shape of the oral and pharyngeal cavities
(primarily due to position of the tongue) influences
how the velopharynx must adjust to maintain the per-
ception of non-nasal speech.

Velopharyngeal function has also been exam-
ined during sustained consonant production. The
consonants most often studied have been fricatives,
especially /s/ and /z/, and nasals /m/ and /n/.
Aeromechanical studies of nasal airflow during speech
production (Hoit, Watson, Hixon, McMahon, & John-
son, 1994; Thompson & Hixon, 1979) revealed airtight
velopharyngeal closure on all sustained /s/ produc-
tions and essentially all sustained /z/ productions of
children and adults ranging in age from 3 to 97 years.
Airtight closure of the velopharyngeal port (shown in
Figure 4–14 and 4–18A) is clearly a priority on speech
sounds that rely on management of the oral airstream
for their production. Support for this is also found in
an x-ray study (Iglesias et al., 1980) wherein sustained
/z/ production had a higher velar elevation and more
forward displacement of the posterior pharyngeal
wall than did any of four sustained vowels that were
studied.

Sustained nasal consonants are produced with
large openings of the velopharyngeal port, as illus-
trated in Figure 4–20. The position of the velum is the
same (or slightly higher) for sustained /m/ produc-
tions (Lubker, 1968) and sustained /n/ productions
(Iglesias et al., 1980) compared to that observed for
resting tidal breathing through the nose, and palatal
levator muscle activity is not discernible via electro-
myographic recordings (Lubker, 1968). Predictably,
sustained nasal consonant productions are accom-
panied by substantial nasal airflow (Hoit et al., 1994;
Thompson & Hixon, 1979).

Velopharyngeal-nasal Function
and running speech activities

Running speech activities require rapid adjustments
of the velopharyngeal-nasal apparatus. A few minutes
spent watching x-ray or real-time magnetic resonance
imaging (MRI) recordings of running speech activities
reveals that velopharyngeal articulation is every bit as
fast and intricate as are movements of the mandible,
tongue, and lips. In fact, velar elevating and lowering
gestures can each occur within a time interval of about
1/10 of a second (Kuehn, 1976). During running speech
production, the velopharyngeal port closes to various
degrees for oral speech sounds and opens to various
degrees for nasal speech sounds. The precise pattern
of opening and closing and the degree to which the
velopharyngeal port is opened or closed relate to the
nature of the speech sounds being spoken, the influ-
ence of surrounding sounds on a current sound being
spoken, and the rate at which they are produced (Kent
et al., 1974).

When consonants and vowels are combined, as
they are in running speech activities, primacy of control
of the velopharyngeal-nasal apparatus is vested in con-
sonant productions. This is because the production of
many consonant elements relies heavily on appropriate
management of the airstream. Sacrificing the aerome-
chanical requirements of these consonants by opening

Velum

FiGure 4–20. Velar position for sustained nasal conso-
nant production. The velum is lowered to allow airflow and
acoustic energy to pass through the velopharynx.

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Foundations of Speech and Hearing: Anatomy and Physiology146

the velopharynx may result in sacrificing the intel-
ligibility of speech. In contrast, sacrificing closure for
vowel productions may increase nasalization but has
only a minimal affect on speech intelligibility. Those
consonant elements that rely most on aeromechanical
management of the airstream are often referred to as
the pressure consonants because they are characteristi-
cally produced with high oral air pressure and little
or no velopharyngeal opening. Stop-plosive, fricative,
and affricate speech sounds (see Chapter 5) are catego-
rized as pressure consonants. In contrast, nasal conso-
nants are produced with low oral air pressure and a
relatively wide-open velopharyngeal port.

The control of the velopharyngeal-nasal appara-
tus during running speech production is not simply a
sequencing of separate and independent position and
movement patterns for different speech sounds. To use
an analogy, velopharyngeal adjustments for sequences
of speech sounds are not like sequences of keyboard
characters that are produced when each is called on
to make an appearance (Hixon & Abbs, 1980). Rather,
the position and movement patterns for two or more
speech sounds may occur simultaneously, such that
their productions actually overlap and intermingle.
This is what was meant when it was stated above that
the patterning of opening and closing of the velopha-
ryngeal port for a particular sound is not only deter-
mined by the requirements for that sound, but also by
the influence of surrounding sounds. Part of this has
to do with how the brain prepares in advance for velo-
pharyngeal-nasal adjustments and part has to do with
how the mechanical-inertial properties of the velopha-
ryngeal-nasal apparatus influence its behavior. More is
said about these principles in Chapter 5.

Underlying the assembling of velopharyngeal-
nasal positions and movements is the principle that
consonants influence the velopharyngeal-nasal adjust-

ments of all speech sounds (consonants and vowels)
within their interval of preparation. The precise influ-
ence depends on both the type of consonant and type
of vowel. For example, the preparation period for oral
consonants results in smaller velopharyngeal port
openings for vowels that precede them, whereas the
preparation period for nasal consonants results in
larger velopharyngeal port openings for vowels that
precede them (Warren & DuBois, 1964). Furthermore,
when a nasal consonant is preceded by two consecu-
tive vowels, the opening of the velopharyngeal port
for the nasal consonant is initiated during the produc-
tion of the first vowel in the sequence (Moll & Daniloff,
1971). Even the presence of a word boundary within
a sequence does not affect this observation, although
velar lowering may be delayed somewhat at marked
junctural boundaries (McClean, 1973). The interac-
tions between different speech sound adjustments of
the velopharyngeal-nasal apparatus condition the posi-
tion and movement patterns observed such that, at any
instant, the configuration of the apparatus may con-
tain evidence of events that are coming and events that
have already taken place.

Understandably, the study of velopharyngeal-nasal
function for speech production has focused on the expi-
ratory phase of the breathing cycle, the phase of the
cycle during which speech is produced. Nevertheless,
the velopharyngeal-nasal apparatus also appears to play
an important role during the inspiratory phase of the
speech breathing cycle. Running speech breathing usu-
ally demands quick inspirations to minimize interrup-
tions to the flow of speech, and quick inspirations require
a low resistance pathway. The best way to create such a
low resistance pathway is to abduct the lips and open the
velopharynx simultaneously. And this is, in fact, what
people do. Thus, in contrast to resting tidal breathing,
during which inspirations are typically routed through

playing by Her own rule

She was a young woman with a profound bilateral hearing loss. She’d
received intensive behavioral therapy for imprecise articulation, but essen-
tially no progress was being made. A puzzled speech-language pathologist
made the referral. What was preventing improvement in speech? The
answer was found in a recording of nasal airflow. A large burst of airflow
was found to accompany each segment of speech that included a voiceless
consonant. The young woman had apparently developed a production rule
that said, “Only close your velopharynx for speech when your voice is on.”
It turned out to be a rule that could be changed by displaying nasal airflow
for her to monitor on a storage oscilloscope so that she could see her rule in
action and adopt a more appropriate one with some guidance. Her velopha-
rynx cooperated and her articulation improved.

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4 Velopharyngeal-Nasal Function and Speech Production 147

the nose exclusively, inspirations are routed through both
the mouth and nose during speaking (Lester & Hoit,
2014). This not only allows for quick inspirations, but
may also preserve some of the benefits of nasal inspira-
tions, such as air filtration and humidification.

Gravity and Velopharyngeal-nasal
Function in speech production

Velopharyngeal-nasal function changes with changes
in spatial orientation, primarily because of the influ-
ence of gravity. Each time the velopharyngeal-nasal
apparatus is reoriented within a gravity field, alternate
mechanical solutions are required to meet the goals for
adjusting the velopharyngeal port. Reorientation in
this context can result from a change in body position.
For example, the usual upright (standing or seated)
body position can be changed to semirecumbent,
supine, prone, side-lying (left and right lateral), and
head down positions, among others. Correspondingly,
the orientation of the velopharyngeal-nasal apparatus
will follow these changes.

Certain predictions can be made about the influ-
ence of body position on the velopharyngeal-nasal

apparatus. These predictions as they relate to the velum
are illustrated in Figure 4–21 for the upright and supine
body positions. When the apparatus is in an upright
position, the pull of gravity tends to lower the velum.
This means that muscle force exerted to elevate the
velum must overcome this pull, whereas muscle force
exerted to lower the velum augments this pull. When
in the supine body position, gravity acts to pull the
velum toward the posterior pharyngeal wall. Thus, in
supine, muscle force associated with movement of the
velum toward the posterior pharyngeal wall augments
the pull of gravity, and muscle force associated with
moving the velum away from the posterior pharyngeal
wall must overcome the pull of gravity.

Moon and Canady (1995) conducted a study of
the effects of body position (and, therefore, gravity)
on velopharyngeal muscle activity during speech
production. They studied the activation levels (using
electromyography) of the palatal levator and pha­
ryngopalatine muscles in upright and supine body
positions and hypothesized that activation would be
modulated by gravitational effects. Lower peak activa-
tion levels were observed in the supine body position
for the palatal levator muscle, suggesting that less acti-
vation was required when the pull of gravity was in the

SupineUpright

Tongue

Tongue

Velum

Velum

FiGure 4–21. Predicted influences of body position on the velum. In upright body positions, gravity exerts
a downward pull on the velum, whereas in the supine body position gravity pulls the velum toward the posterior
pharyngeal wall. Thus, gravity counteracts the efforts of the palatal levator muscles in upright and augments
them in supine.

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Foundations of Speech and Hearing: Anatomy and Physiology148

same direction (toward the posterior pharyngeal wall).
Also, the activation level of the pharyngopalatine
muscle was usually greater in the supine body position
where the pull of gravity was counter to movement of
the velum away from the posterior pharyngeal wall.
Overall, the observations of Moon and Canady gener-
ally support the notion that levels of muscle activity in
the velum are modulated in relation to the direction of
the pull of gravity, with the effect being robust in the
palatal levator muscle.

Reorientation of the velopharyngeal-nasal appa-
ratus in space is not restricted to changes in body
position. Reorientation can also mean that the body is
maintained in a fixed position and the head is moved
about different axes, thereby changing the spatial ori-
entation of the velopharyngeal-nasal apparatus. For
example, the head can be pitched about a lateral axis,
rolled about a longitudinal axis, and yawed about a
vertical axis. Simultaneous adjustments can also be
made through more than one axis (pitching the head
upward and yawing it to the right at the same time).

Rotation of the head about a lateral axis is an espe-
cially common activity that influences the spatial orien-
tation of the velopharyngeal-nasal apparatus (nod your
head yes to this statement). Full flexion and full exten-
sion of the neck (head rotated forward and backward,
respectively) delimit the range of possible orientations
associated with head rotation. Rotation through this
range places maximally contrasting gravitational forces
on the velopharyngeal-nasal apparatus, especially the
velum. When the head is rotated downward from its
usual position (toward a position in which the mandi-
ble would rest on the rib cage wall), the pull of gravity
on the velum is in a direction that tends to pull it away
from the posterior pharyngeal wall. In contrast, when
the head is rotated upward from its usual position
(toward a position in which the tip of the nose is maxi-
mally elevated), the pull of gravity on the velum is in a
direction that tends to pull it toward the posterior pha-
ryngeal wall. Whereas reorientation of the velopharyn-
geal-nasal apparatus is not noticeable to most people,
it may have a profound effect on those with borderline
velopharyngeal competence. For example, in someone
with a neuromotor-based weakness of the palatal leva­
tor muscles, rotation of the head upward may enhance
movement of the velum toward the posterior pharyn-
geal wall and, thereby, improve velopharyngeal-nasal
function for speech production. In contrast, rotation of
the head downward may do just the opposite.

Gravitational influences also affect the function of
the nasal cavities. For example, it has been shown that
nasal patency decreases and nasal airway resistance
increases in downright as compared to upright body
positions (Rudcrantz, 1969). This change in patency

appears to relate to vascular changes that cause nasal
congestion (Hiyama, Ono, Ishiwata, & Kuroda, 2002).

Development of
Velopharyngeal-nasal Function
in speech production

The infant’s velopharyngeal-nasal apparatus is not just
a small version of the adult’s apparatus, but differs in
its configuration and spatial relationships to surround-
ing structures. Several anatomical features and devel-
opmental changes in those features are relevant to how
the velopharyngeal-nasal apparatus functions in infants
and children. (See Chapter 5 for further discussion of
the development of upper airway structures.)

At birth, the larynx is located high within the neck,
and the velum and epiglottis are approximated (Kent &
Murray, 1982). Around 4 to 6 months of age, the velum
and epiglottis separate (Sasaki, Levine, Laitman, &
Crelin, 1977) as the larynx moves from the level of the
first cervical vertebra to the level of the third cervical
vertebra. This downward movement is accomplished
primarily by rapid growth in the vertical dimension
from about 4 cm in the pharynx of the newborn (Cre-
lin, 1973) to approximately three times that length in
the adult pharynx (Sasaki et al., 1977). During that
same period, the hard and soft palates grow quickly,
with the hard palate growing somewhat more quickly
than the soft palate and the growth rate of both becom-
ing more gradual after 2 years of age (Vorperian et al.,
2005). These developmental changes affect the geom-
etry and mechanical effectiveness of certain muscles.
For example, as the palates grow, the orientation of the
paired palatal levator muscle changes in ways that
improve their mechanical advantage for elevating the
velum (Fletcher, 1973).

Because the infant velum and epiglottis are approx-
imated early in life, it is often assumed that infants are
“obligate nasal breathers” (meaning that they breathe
through the nose by necessity). However, this is not
true. The preponderance of evidence indicates that
most infants can breathe through the mouth when
necessary. Specifically, when the anterior nares are
occluded, healthy infants open the mouth and use the
oral airway for breathing (Miller et al., 1985; Roden-
stein, Perlmutter, & Stanescu, 1985). Therefore, the
term preferential nasal breather is more appropriate to
describe the predominant (rather than exclusive) use
of the nasal airway for breathing in infants.

The birth cry is the first utterance for most human
newborns. X-ray images of this first utterance have
shown that it is made with an open velopharynx
(Bosma, Truby, & Lind, 1965). Acoustic and percep-

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4 Velopharyngeal-Nasal Function and Speech Production 149

tual studies of infant vocalizations during the first few
months of life have suggested that the velopharynx
continues to be open during cry (Wasz-Hockert, Lind,
Vuorenkoski, Partanen, & Valanne, 1964) and noncry
vocalizations up to about 4 months of age (Buhr, 1980;
Hsu, Fogel, & Cooper, 2000; Kent & Murray; 1982;
Oller, 1986). Aeromechanical studies (Bunton & Hoit,
2016; Thom, Hoit, Hixon, & Smith, 2006) have shown
that infants close the velopharynx at least occasionally
for noncry vocalizations as early as 2 months of age
and that the frequency of velopharyngeal closure for
noncry oral sound production increases up to about 18
months of age. Once children reach the age of 3 years,
the velopharynx closes for oral utterances and opens
for nasal sound production (Thompson & Hixon, 1979;
Zajac, 2000).

The temporal characteristics of velopharyngeal-
nasal function during speech production in children
ages 3 to 16 years have also been studied using aero-
mechanical techniques (Leeper, Tissington, & Munhall,
1998; Zajac, 2000; Zajac & Hackett, 2002). The speech
samples most often studied were nasal consonant–
stop consonant combinations, which required rapid
transitions between velopharyngeal opening and
velopharyngeal closure. Leeper et al. reported a ten-
dency toward shorter durations in temporal variables

with increasing age, but with the children generally
performing similarly to the adults studied by Warren,
Dalston, Trier, and Holder (1985). Subsequently, Zajac
and then Zajac and Hackett reported differences in
patterns of timing in the aeromechanical segments of
speech produced by children and adults, with adults
exhibiting shorter segments and less temporal variabil-
ity than children.

Although airtight velopharyngeal closure is used
early in childhood for oral speech sound produc-
tion, the means for achieving this closure may change
across childhood. One example relates to children who
develop enlarged lymphoid tissue masses in the naso-
pharyngeal tonsils (adenoids). These tonsils typically
grow during the first decade of life and then begin
to atrophy (Jaw, Sheu, Liu, & Lin, 1999; Subtelny &
Koepp-Baker, 1956) until by adulthood they have fully
atrophied, as illustrated in Figure 4–22. Against this
background of anatomical change, velopharyngeal clo-
sure must go through a slow reorganization in those
children who have been accomplishing closure through
abutment of the velum and walls of the pharynx
against the enlarged adenoidal tissue. This accommo-
dation is obviously successful given the continuation
of airtight velopharyngeal closure during the normal
developmental schedule, but it may be interrupted if

Nasopharyngeal
tonsil

Adult Teenager Child

FiGure 4–22. Changes in nasopharyngeal tonsil mass during development. The nasopharyngeal tonsil is large in children
and atrophies with age. The velopharyngeal structures accommodate to these changes to achieve velopharyngeal closure.

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Foundations of Speech and Hearing: Anatomy and Physiology150

an adenoidectomy (removal of the adenoids) is per-
formed in a child who is at risk for velopharyngeal
problems (Andreassen, Leeper, MacRae, & Nicholson,
1994; Finkelstein, Berger, Nachmani, & Ophir, 1996;
Morris, 1975; Siegel-Sadewitz, & Shprintzen, 1986).

age and Velopharyngeal-nasal
Function in speech production

Aging affects the mature velopharyngeal-nasal appa-
ratus as it does other parts of the body. For example,
the pharyngeal muscles weaken with age and the pha-
ryngeal lumen enlarges (Zaino & Benventano, 1977),
sensory innervation declines (Aviv et al., 1994), and
muscle bulk and bone density decrease in this region

and elsewhere (Fremont & Hoyland, 2007). Such
changes would seem to have the potential to alter velo-
pharyngeal-nasal function for activities such as speech
production.

Hutchinson, Robinson, and Nerbonne (1978) were
the first to examine the potential influence of age on
velopharyngeal-nasal function in speech production
by measuring nasalance, an acoustic measurement of
the quotient of nasal sound pressure level to nasal +
oral sound pressure level. They found that older men
and women exhibited higher average nasalance val-
ues during reading compared to younger men and
women. This finding was interpreted as evidence that
velopharyngeal function for speech production dete-
riorates with age. Nevertheless, acoustic evidence to
the contrary (Seaver, Dalston, Leeper, & Adams, 1991)

When is a Bad nose Good and a Good nose Bad?

This chapter stresses the functional unity of the normal velopharyngeal-
nasal apparatus. This unity is often even better illustrated in an abnormal
velopharyngeal-nasal apparatus. Not all speakers with significant velopha-
ryngeal openings during oral consonant productions are destined to exhibit
significant speech problems. With the velopharynx and nose being in
mechanical series (being in line), an abnormally blocked nose may actually
counteract an abnormally opened velopharynx. That is, a bad nose can be
a good thing for speech, even if not for breathing. Conversely, a good nose
can be a bad thing for speech when there is significant velopharyngeal
impairment. The surgeon who attempts to “clean up” a bad nose and does
not take into account the status of the velopharynx, will sometimes figure
this out after the fact when confronted with a child whose speech is worse
after surgery.

He’s an old smoothie

He was a distinguished looking white-haired grandfather. He agreed to be
examined by graduate students learning to administer an examination for
velopharyngeal-nasal function. Students had been assigned different parts
of the examination and told to practice the administration of their part on at
least half a dozen people so they could get “calibrated.” One student who
had dutifully practiced on a group of her peers, proceeded to ask the gentle-
man to open his mouth while she turned on a flashlight and looked in. She
methodically looked at structures and made comments to the class as she
went along. When she shined the light on the gentleman’s hard palate, she
paused briefly and said to him, “That’s the smoothest hard palate I’ve ever
seen.” He smiled and said back, “That’s a denture, young lady.” And so
it was. He took it out and showed it to the class. The moral of this story is
don’t just practice on your classmates.

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4 Velopharyngeal-Nasal Function and Speech Production 151

and aeromechanical studies (using measures of airflow
and air pressure) confirmed that velopharyngeal func-
tion does not deteriorate with age by showing that the
velopharynx is essentially airtight during oral utter-
ance production in men and women as old as 97 years
(Hoit et al., 1994; Zajac, 1997).

What could explain the lack of agreement between
the conclusions of Hutchinson et al. (1978) — that velo-
pharyngeal function for speech production deteriorates
with age — and those of Hoit et al. (1994) and Zajac
(1997) — that velopharyngeal function does not change
with age? One possible explanation is that measures
of nasalance (an acoustic measure) do not necessar-
ily reflect velopharyngeal function per se, but can be
influenced by other factors that change with age. For
example, confounding variables could include: (a) an
increase in the sympathetic transfer of acoustic energy
from the oral cavity to the nasal cavities attendant to
changes in the density of palatal structures with age
(Tomoda, Morii, Yamashita, & Kumazawa, 1984), (b) a
change in the spectral content of speech sounds associ-
ated with known age-related decreases in vocal tract
formant frequencies (Endres, Bambach, & Flosser,
1967), and (c) the use of smaller mouth openings dur-
ing oral utterances by older individuals that would be
consistent with differences in characteristic mandibular
movement in older compared to younger individuals
(Karlsson & Carlsson, 1990). That is, it is quite possi-
ble that an elderly person could demonstrate elevated
nasalance values, even when the velopharynx is closed
airtight.

sex and Velopharyngeal-nasal
Function in speech production

Sex makes a difference when it comes to the size of
the velopharyngeal-nasal apparatus. For example,
men, when compared to women, have longer pha-
rynges (Fitch & Giedd, 1999), longer palatal levator
muscles (Bae, Kuehn, Sutton, Conway, & Perry, 2011;
Ettema, Kuehn, Perlman, & Alperin, 2002), longer hard
palates (Bae et al. 2011), larger soft palates (Kuehn
& Kahane, 1990), and longer noses (Zankl, Eberle,
Molinari, & Schinzel, 2002). But do these differences
influence velopharyngeal-nasal function for speech
production?

There have been many studies comparing velo-
pharyngeal function during speech production in men
and women. These include studies that used x-ray
techniques to track velar movement (Bzoch, 1968;
Iglesias et al., 1980; Kuehn, 1976; McKerns & Bzoch,
1970; Seaver & Kuehn, 1980), electromyography to

record velar muscle activity (Seaver & Kuehn, 1980),
and air pressure and airflow measures to determine
velopharyngeal status (open vs closed) and orifice
size (Andreasson, Smith, & Guyette, 1992; Hoit et al.,
1994; Thompson & Hixon, 1979; Zajac & Mayo, 1996).
Although their findings revealed some sex-related dif-
ferences, they were small, idiosyncratic, or contradic-
tory between studies. The only consistent sex-related
difference was that the magnitude of airflow during
nasal productions was greater in men than women.
This is to be expected, given that men have larger air-
ways than women.

Thus, the evidence indicates that men and women
differ in certain details of velopharyngeal-nasal func-
tion in speech production. However, it is not clear that
these differences make a difference functionally or
in their application to clinical concerns (McWilliams,
Morris, & Shelton, 1990).

reVieW

The velopharyngeal-nasal apparatus is located within
the head and neck, and comprises a system of valves
and air passages that interconnects the throat and
atmosphere through the nose.

The velopharyngeal-nasal apparatus includes the
pharynx, velum, nasal cavities, and outer nose.

Forces of the velopharyngeal-nasal apparatus are
of two types — passive and active, the former arising
from several sources and the latter arising from mus-
cles distributed within different parts of the velopha-
ryngeal-nasal apparatus.

Muscles of the pharynx include the superior
constrictor, middle constrictor, inferior constric­
tor, salpingopharyngeus, stylopharyngeus, and pala­
topharyngeus.

Muscles of the velum include the palatal leva­
tor, palatal tensor, uvulus, glossopalatine, and
pharyngopalatine.

Muscles of the outer nose include the levator labii
superioris alaeque nasi, anterior nasal dilator, poste­
rior nasal dilator, nasalis, and depressor alae nasi.

Movements of the pharynx enable its lumen to be
changed along its length, either by constriction or dila-
tion at different sites.

Movements of the velum involve shape changes
of the structure and are mainly along an upward-back-
ward or downward-forward path.

Movements of the outer nose influence the cross-
sections of the anterior nares and are involved in
breathing events and the signaling of emotions.

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Foundations of Speech and Hearing: Anatomy and Physiology152

Adjustments of the velopharyngeal-nasal appara-
tus can influence the degree of coupling between the
oral and nasal cavities and between the nasal cavities
and atmosphere.

Closure of the velopharyngeal port can be
achieved through a variety of movement strategies that
involve different actions or combinations of actions of
the velum, lateral pharyngeal walls, and posterior pha-
ryngeal wall, strategies that are conditioned by velo-
pharyngeal anatomy.

Closing and opening adjustments of the velopha-
ryngeal port are controlled by different factors, with
closing being controlled by muscular forces and open-
ing being controlled by passive forces and muscular
forces.

Adjustments of the anterior nares are involved in
different activities and play a prominent role in breath-
ing to resist the tendency of the outer nose to collapse
in response to low pressures in its lumina.

The control variables of velopharyngeal-nasal
function include airway resistance offered by the
velopharyngeal-nasal apparatus, muscular pressure
exerted by the velopharyngeal sphincter to maintain
closure, and acoustic impedance in opposition to the
flow of sound energy.

Different parts of the nervous system are respon-
sible for the control of different components of the
velopharyngeal-nasal apparatus and different activi-
ties, with motor and sensory innervation being effected
mainly through cranial nerves.

The warming, moistening, and filtering aspects
of nasal function are important to health, and nasal
breathing prevails until airway resistance becomes
excessive, whereupon a switch is made to oral-nasal
breathing.

The role of velopharyngeal-nasal function in
speech production is to control the degree of coupling
between the oral and nasal cavities and between the
nasal cavities and atmosphere.

The velopharynx is active during sustained utter-
ances, the patterning depending on the speech sound
being produced, and with high vowels showing greater
velar height, greater velar contact with the posterior
pharyngeal wall, and greater velopharyngeal sphincter
compression than low vowels.

Running speech activities involve combining
consonants and vowels with primacy of control being
vested in consonant productions, especially those that
are associated with high oral pressure and little or no
opening of the velopharyngeal port.

Position and movement patterns of the velopha-
ryngeal-nasal apparatus may reflect the occurrence of
two or more speech sounds simultaneously, such that

their productions overlap and intermingle and show
evidence of how the brain prepares in advance for velo-
pharyngeal-nasal adjustments and how the mechanical
properties of the velopharyngeal-nasal apparatus influ-
ence its behavior.

Gravity has effects on velopharyngeal-nasal func-
tion that are manifested through reorientation of the
position of the body or rotation of the head about dif-
ferent axes, and are attributed to mechanical and car-
diovascular factors.

Velopharyngeal-nasal closure for speech produc-
tion develops gradually during infancy and appears to
be relatively stable by 18 months of age with continu-
ing modifications of temporal events related to velo-
pharyngeal closure during childhood.

There is no credible evidence that velopharyngeal-
nasal function for speech production changes with age
in the mature velopharyngeal-nasal apparatus.

The sex of the speaker appears to have an influ-
ence on certain details of velopharyngeal-nasal func-
tion during speech production, but it is not clear that
these differences are functionally important or that
they are relevant to clinical concerns.

reFerenCes

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(1994). Aerodynamic, acoustic, and perceptual changes
following adenoidectomy. Cleft Palate-Craniofacial Journal,
31, 264–270.

Andreassen, M., Smith, B., & Guyette, T. (1992). Pressure-flow
measurements for selected oral and nasal sound segments
produced by normal adults. Cleft Palate-Craniofacial Journal,
29, 1–9.

Aviv, J., Martin, J., Jones, M., Wee, T., Diamond, B., Keen, M.,
& Blitzer, A. (1994). Age-related changes in pharyngeal and
supraglottic sensation. Annals of Otology, Rhinology, and Lar-
yngology, 103, 749–752.

Azzam, N., & Kuehn, D. (1977). The morphology of musculus
uvulae. Cleft Palate Journal, 14, 78–87.

Bae, Y., Kuehn, D., Sutton, B., Conway, C., & Perry, J. (2011).
Three-dimensional magnetic resonance imaging of velo-
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ing Research, 54, 1538–1545.

Barsoumian, R., Kuehn, D., Moon, J., & Canady, J. (1998).
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tor tubae muscles in relation to eustachian tube and velar
function. Cleft Palate-Craniofacial Journal, 35, 101–110.

Bell-Berti, F. (1976). An electromyographic study of velopha-
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Bennett, K., & Hoit, J. (2013). Stress velopharyngeal incom-
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Boorman, J., & Sommerlad, B. (1985). Levator palati and
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