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Fig. 34.4 A, A pharyngeal tonsil following
adenoidectomy by curettage. The rostral surface
is to the left; surface folds radiate forwards from a
median recess (arrow). In this example, the
1 impression left by contact with the left Eustachian
cushion is evident laterally (arrowhead). B, A
transnasal endoscopic view of a pharyngeal tonsil.
Key: 1, pharyngeal tonsil (in posterior naris); 2,
2 inferior concha (posterior view); 3, posterior end of
nasal septum. (A, Specimen provided by Professor
MJ Gleeson, School of Medicine, King’s College
3 London. B, Courtesy of Mr Simon A Hickey.)
A B
The free surface of the pharyngeal tonsil is marked by folds that debridement and, most commonly, blind curettage. When using the
radiate forwards and laterally from a median blind recess, the pharyn latter, it is important to avoid hyperextension of the cervical spine, as
geal bursa (bursa of Luschka), which extends backwards and up. The this throws the arch of the atlas into prominence and may result in
recess is present in the fetus and the young but only occasionally present damage to the prevertebral fascia and anterior spinal ligaments, with
in the adult, and marks the rostral end of the embryological notochord. resultant infection and cervical instability. Extreme lateral curettage can
The number and position of the folds and of the deep fissures that sepa result in damage to the tubal orifice and excessive bleeding because the
rate them vary. A median fold may pass forwards from the pharyngeal vasculature is denser laterally. Removal of the pharyngeal tonsil in
bursa towards the nasal septum, or instead a fissure may extend forwards children can result in an impairment in the ability of the soft palate to
from the bursa, dividing the nasopharyngeal tonsil into two distinct close the pharyngeal isthmus fully (velopharyngeal insufficiency, VPI),


halves that reflect its paired developmental origins (see Fig. 34.4). causing excessive nasality of speech (Gray and PinboroughZimmerman
The prenatal origins of the pharyngeal tonsil are described on page 1998).
615. After birth, it initially grows rapidly, but usually undergoes a degree
of involution and atrophy from the age of 8–10 years (although hypo
plasia may still occur in adults up to the seventh decade). Relative to PHARYNGOTYMPANIC TUBE
the volume of the nasopharynx, the size of the tonsil is largest at 5 years,
which may account for the frequency of nasal breathing problems in The pharyngotympanic tube (see Figs 34.9A, B, 37.6–37.7) connects
preschool children, and the incidence of adenoidectomy in this age the tympanic cavity to the nasopharynx. It has several functions related
group. to maintaining the health of the middle ear, including pressure equali
zation on both aspects of the tympanic membrane, mucociliary clear
Vascular supply and lymphatic drainage The arterial supply ance and ‘drainage’, and protection from the influences of the
of the pharyngeal tonsil is derived from the ascending pharyngeal nasopharyngeal environment and loud sounds. Approximately 36 mm
and ascending palatine arteries, the tonsillar branches of the facial long, it descends anteromedially from the tympanic cavity to the
artery, the pharyngeal branch of the maxillary artery and the artery of nasopharynx at an angle of approximately 45° with the sagittal plane
the pterygoid canal (see Figs 34.6–34.7). In addition, a nutrient or and 30° with the horizontal (these angles increase with age and elonga
emissary vessel to the neighbouring bone, the basisphenoidal artery, tion of the cranial base). It is formed partly by cartilage and fibrous
which is a branch of the inferior hypophysial arteries, supplies the bed tissue, and partly by bone.
of the pharyngeal tonsil and is a possible cause of persistent post The cartilaginous part, which is approximately 24 mm long, is


adenoidectomy haemorrhage in some patients. formed by a triangular plate of cartilage, the greater part of which is in
Numerous communicating veins drain the pharyngeal tonsil into the posteromedial wall of the tube. Its apex is attached by fibrous tissue
the internal submucous and external pharyngeal venous plexuses. They to the circumference of the jagged rim of the bony part of the tube, and
emerge from the deep lateral surface of the tonsil and join the external its base is directly under the mucosa of the lateral nasopharyngeal wall,
palatine (paratonsillar) veins, and pierce the superior constrictor either forming a tubal elevation (torus tubarius; Eustachian cushion) behind
to join the pharyngeal venous plexus, or to unite to form a single vessel the pharyngeal orifice of the tube (see Fig. 31.1). The upper part of the
that enters the facial or internal jugular vein; they may also connect cartilage is bent laterally and downwards, producing a broad medial
with the pterygoid venous plexus. lamina and narrow lateral lamina. In transverse section, it is hooklike
and incomplete below and laterally, where the canal is composed of
Microstructure The pharyngeal tonsil is covered laterally and in fibrous tissue. The cartilage is fixed to the cranial base in the groove
feriorly mainly by ciliated respiratory epithelium that contains scattered between the petrous part of the temporal bone and the greater wing of
small patches of nonkeratinized stratified squamous epithelium. Its the sphenoid, and ends near the root of the medial pterygoid plate. In
superior surface is separated from the periosteum of the sphenoid and adults, the cartilaginous and bony parts of the tube are not in the same
occipital bones by a connective tissue hemicapsule. The fibrous frame plane, the former descending a little more steeply than the latter. The
work of the tonsil, consisting of a mesh of collagen type III (reticular) diameter of the tube is greatest at the pharyngeal orifice and least at


fibres supporting a lymphoid parenchyma similar to that in the palatine the junction of the two parts (the isthmus), increasing again towards
tonsil, is anchored to the hemicapsule. the tympanic cavity. At birth, the pharyngotympanic tube is about half
The nasopharyngeal epithelium lines a series of mucosal folds its adult length; it is more horizontal and its bony part is relatively
around which the lymphoid parenchyma is organized into follicles and shorter but much wider.
extrafollicular areas. Internally, the tonsil is subdivided into 4–6 lobes The bony part, approximately 12 mm long, is oblong in transverse
by connective tissue septa, which arise from the hemicapsule and pen section, with its greater dimension in the horizontal plane. It starts from
etrate the lymphoid parenchyma. Seromucous glands lie within the the anterior tympanic wall and gradually narrows to end at the junction
connective tissue, and their ducts extend through the parenchyma to of the squamous and petrous parts of the temporal bone, where it has
reach the nasopharyngeal surface. a jagged margin for the attachment of the cartilaginous part. The carotid
canal lies medially.
Functions The pharyngeal tonsil forms part of the circumpharyngeal The mucosa of the pharyngotympanic tube is continuous with the
lymphoid ring (Waldeyer’s ring) and therefore presumably contributes nasopharyngeal and tympanic mucosae. The bony canal is lined by a
to the defence of the upper respiratory tract. The territories served by prolongation of the low cuboidal, ciliated mucosa that lines the middle
its lymphocytes are uncertain but may include the nasal cavities, ear. The histology changes to pseudostratified, ciliated, columnar epi
nasopharynx, pharyngotympanic tubes and the middle and inner ears. thelium typical of the upper respiratory tract after the bony/cartilaginous
junction. Within the cartilaginous tube, the floor contains numerous
Adenoidectomy Surgical removal of the pharyngeal tonsil (adenoid) mucusproducing goblet cells and is heavily rugated, whereas the walls


is commonly performed to clear nasopharyngeal obstruction and as in the upper half of the tube contain fewer goblet cells and are generally
part of the treatment of chronic secretory otitis media. A variety of smooth. Mucosal folding is a feature of the childhood tube; the
methods are employed, including suction diathermy, suction micro increased surface area and concomitant increased numbers of ciliated


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Thornwaldt’s cyst is an embryonic remnant of the persisting cranial
end of the notochord that sometimes develops if the pharyngeal bursa
is occluded (Fig. 34.5). Usually benign and asymptomatic, these cysts
can become infected; symptoms include halitosis, occipital headache
and postnasal drip (Yuca and Varsak 2012).
Inferior turbinate
Maxillary antrum
Lateral pterygoid
Thornwaldt’s cyst
Sphenoidal sinus
Longus capitis
Thornwaldt’s cyst
A B
Fig. 34.5 Thornwaldt’s cyst. A, axial view; B, sagittal view.


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cells are presumed to facilitate improved clearance of the mucociliary surface is covered with a ciliated columnar epithelium. Taste buds are
blanket. Folds decrease with age up to the age of 20 years, when adult found on the oral aspect of the soft palate.
characteristics are reached. Mucous glands predominate in neonates; In most individuals, two small pits, the fovea palatini, may be seen,
mucous, serous and mixed glands are present in equal amounts in one on each side of the midline; they represent the orifices of ducts
young children; and serous glands predominate in later life (Orita et al from some of the minor mucous glands of the palate. In its usual
2002). The smoothness of the wall in the upper half of the tube may relaxed and pendant position, the anterior (oral) surface of the soft
function in pressure equalization and gas exchange. The pharyngeal palate is concave and has a median raphe. The posterior aspect is convex
orifice is a narrow slit, level with the palate and without a tubal eleva and continuous with the nasal floor, the anterosuperior border is
tion. A lymphoid mass, the tubal tonsil, is found near the pharyngeal attached to the posterior margin of the hard palate, and the sides blend
orifice; it is variable and sometimes considerable. (For further reading with the pharyngeal wall. The inferior border is free and hangs between
see Sade (1989), Bluestone (1998), O’Reilly and Sando (2010).) the mouth and pharynx. A median conical process, the uvula, projects
downwards from its posterior border (see Fig. 31.3). It may be congeni
Relations Salpingopharyngeus is attached to the inferior part of the tally bifid and associated with submucous cleft palate, hypoplastic
cartilaginous tube near its pharyngeal opening. Posteromedially are the orifice of the pharyngotympanic tube and absence of the salpingo
petrous part of the temporal bone and levator veli palatini, which arises pharyngeal folds.


partly from the medial lamina of the tube. Anterolaterally, tensor veli The anterior third of the soft palate contains little muscle and con
palatini separates the tube from the otic ganglion, the mandibular nerve sists mainly of the palatine aponeurosis. This region is less mobile and
and its branches, the chorda tympani nerve and the middle meningeal more horizontal than the rest of the soft palate and is the chief area
artery. acted on by tensor veli palatini.
A small bony prominence, produced by the pterygoid hamulus, can
Vascular supply The osseous part of the pharyngotympanic tube is be felt just behind and medial to each upper alveolar process, in the
supplied by the tubal artery (a branch of the accessory meningeal artery) lateral part of the anterior region of the soft palate. The pterygoman
and the caroticotympanic branches of the internal carotid artery. The dibular raphe (a tendinous band between buccinator and the superior
cartilaginous part of the tube is supplied by the deep auricular and constrictor) passes downwards and outwards from the hamulus to the
pharyngeal branches of the maxillary artery, the ascending palatine posterior end of the mylohyoid line (see Fig. 34.8). When the mouth
artery (usually a branch of the facial artery but sometimes branching is opened wide, this raphe raises a fold of mucosa that indicates the
directly from the external carotid artery) and the ascending pharyngeal internal, posterior boundary of the cheek; it is an important landmark
branch of the external carotid artery. The veins of the pharyngotympanic for an inferior alveolar nerve block (Ch. 31). (For further reading, see
tube usually drain to the pterygoid venous plexus. WoodJones (1940).)
Innervation The pharyngotympanic tube is innervated by filaments Palatine aponeurosis A thin, fibrous, palatine aponeurosis, com
from the tympanic plexus and from the pharyngeal branch of the posed of the expanded tendons of the tensor veli palatini muscles,


pterygopalatine ganglion. The tympanic plexus ramifies on the prom strengthens the soft palate. It is attached to the posterior border and
ontory in the middle ear cavity and is formed by the tympanic branch inferior surface of the hard palate behind any palatine crests, and
of the glossopharyngeal nerve and caroticotympanic nerves of sympa extends medially from behind the greater palatine foramina. It is thick
thetic origin (see Fig. 37.13). in the anterior twothirds of the soft palate but very thin further back.
Near the midline, it encloses the musculus uvulae. All the other palatine
Equalization of pressure At rest, the cartilaginous part of the muscles are attached to the aponeurosis.
pharyngotympanic tube is closed at the nasopharyngeal orifice. In
normal individuals, the tube opens in order to equalize middle ear Palatoglossal and palatopharyngeal arches The lateral wall
pressure to ambient pressure. Analysis of slowmotion videoendoscopy of the oropharynx presents two prominent folds, the palatoglossal and
reveals four stages in tubal opening. Initially, the soft palate is elevated, palatopharyngeal folds (anterior and posterior pillars of the fauces,
the lateral pharyngeal wall moves medially and the medial lamina of respectively) (see Figs 31.3, 34.6). The palatoglossal arch, the anterior
the pharyngotympanic tube rotates medially (levator veli palatini is fold, runs from the soft palate to the side of the tongue and contains
thought to open the distal part of the tube). The lateral wall of the palatoglossus. The palatopharyngeal arch, the posterior fold, projects
pharyngotympanic tube moves laterally, so that the orifice is dilated more medially and passes from the soft palate to merge with the lateral
both laterally and vertically. Tubal dilation propagates from distal to wall of the pharynx; it contains palatopharyngeus. A triangular tonsillar
proximal by the action of dilator tubae. Finally, the proximal cartilagi fossa (tonsillar sinus) lies on each side of the oropharynx between the


nous tube adjacent to the junctional region opens. Opening usually diverging palatopharyngeal and palatoglossal arches, and contains the
lasts for 0.3–0.5 sec but is prolonged during yawning. Closure depends palatine tonsil.
on adhesion of the intraluminal mucous blanket, elastic forces of the
Vascular supply The arterial supply of the soft palate is usually
supporting tissues, and hydrostatic pressure of venous blood.
derived from the ascending palatine branch of the facial artery. Some
times, this is replaced or supplemented by a branch of the ascending
OROPHARYNX pharyngeal artery, which descends forwards between the superior
border of the superior constrictor and levator veli palatini, and accom
panies the latter to the soft palate. The veins of the soft palate usually
Boundaries
drain to the pterygoid venous plexus.
The oropharynx extends from below the soft palate to the upper border Innervation General sensation from most of the soft palate is carried
of the epiglottis (see Figs 34.1–34.2). It opens into the mouth through by branches of the lesser palatine nerve (a branch of the maxillary
the oropharyngeal isthmus, demarcated by the palatoglossal arch, and nerve) and from the posterior part of the palate by pharyngeal branches
faces the pharyngeal aspect of the tongue. Its lateral wall consists of the from the glossopharyngeal nerve and from the plexus around the tonsil
palatopharyngeal arch and palatine tonsil (see Fig. 31.3). Posteriorly, it (formed by tonsillar branches of the glossopharyngeal and lesser pala
is level with the bodies of the second, and upper part of the third, cervi tine nerves). The special sensation of taste from taste buds in the oral
cal vertebrae (see Fig. 34.2). surface of the soft palate is carried in the lesser palatine nerve; the taste
fibres initially travel in the greater petrosal nerve (a branch of the facial
nerve) and pass through the pterygopalatine ganglion without synaps
SOFT PALATE ing. The lesser palatine nerve also carries the secretomotor supply to


most of the mucosa of the soft palate, via postganglionic branches from
The soft palate is a mobile flap suspended from the posterior border of the pterygopalatine ganglion. Postganglionic secretomotor parasympa
the hard palate, sloping down and back between the oral and nasal thetic fibres may pass to the posterior parts of the soft palate from the
parts of the pharynx (see Figs 34.2–34.3). The boundary between the otic ganglion (which receives preganglionic fibres via the lesser petrosal
hard and soft palate is readily palpable and may be distinguished by a branch of the glossopharyngeal nerve). Postganglionic sympathetic
change in colour, the soft palate being a darker red with a yellowish fibres run from the carotid plexus along arterial branches supplying the
tint. The soft palate is a thick fold of mucosa enclosing an aponeurosis, palate.
muscular tissue, vessels, nerves, lymphoid tissue and mucous glands;
Uvulopalatopharyngoplasty
almost half its thickness is represented by numerous mucous glands
that lie between the muscles and the oral surface of the soft palate. The
Available with the Gray’s Anatomy e-book latter is covered by a stratified squamous epithelium, while the nasal


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The pharyngeal airway is kept patent in awake individuals by the com
bined dilating action of genioglossus, tensor veli palatini, geniohyoid
and stylohyoid, which act to counter the negative pressure generated in
the lumen of the pharynx during inspiration. The tone in the muscles
is reduced during sleep, and is also affected by alcohol and other seda
tives, hypothyroidism and a variety of neurological disorders. If the
dilator muscle tone is insufficient, the walls of the pharynx may become
apposed. Intermittent pharyngeal obstruction may cause snoring, and
complete obstruction may cause apnoea, hypoxia and hypercarbia,
which lead to arousal and sleep disturbance. Obstructive sleep apnoea
(OSA) is a serious syndrome affecting up to 4% of middleaged people;
it has potentially lifethreatening consequences. The pathophysiological
causes of OSA include an anatomically small upper airway, in which
augmented pharyngeal dilator muscle activation can maintain airway
patency when the individual is awake but not when asleep, coupled
with instability in the respiratory control system. Individuals with OSA
may demonstrate some or all of the following anatomical features: an
increase in soft palate length and thickness; a shortened mandible; a
lowered hyoid bone position; and increases in the volume of fat in soft
palate and parapharyngeal fat pads in the retropalatal and retroglossal
region. While these studies differ in their assessment of the relative
incidence and significance of these factors, they all confirm that the
anatomical changes in OSA have the combined effect of both narrowing
and shortening the airway. At the same time, physiological mechanisms
that exist to ensure that the airways remain dilated and patent seem to
suffer a sleepinduced fall in activity in OSA sufferers. The muscles
primarily responsible for maintaining a dilated airway under normal
conditions are the muscles affecting the position of the hyoid bone, the
infrahyoid and suprahyoid muscles, the muscles of the tongue, espe
cially genioglossus, and the muscles that move the soft palate. (For


further reading, see Ison et al (1997), Fogel et al (2004), Johal et al
(2007), Malhotra and White (2002).)
Surgical techniques involving reduction in the length of the soft
palate, removal of the tonsils and plication of the tonsillar pillars can
be used to raise the intrinsic dilating tone in the pharyngeal wall and
to reduce the bulk of (and to stiffen) the soft palate. This will reduce
the tendency of the soft palate to vibrate and generate noise during
periods of incipient collapse of the pharynx. An alternative treatment
is to deliver air to the pharynx at above atmospheric pressure via a
closely fitting facemask, thus inflating the pharynx and countering its
tendency to collapse.


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Pharyngeal branch of descending palatine artery by a layer of fibrous tissue, the tonsillar hemicapsule. The latter is sepa
rable with ease for most of its extent from the underlying muscular wall
Tonsillar branch of the lesser palatine nerve Tonsillar fascia
of the pharynx, which is formed here by the superior constrictor, and
sometimes by the anterior fibres of palatopharyngeus, with styloglossus
Superior constrictor on its lateral side. Anteroinferiorly, the hemicapsule adheres to the side
of the pharynx of the tongue and to palatoglossus and palatopharyngeus. In this
region, the tonsillar artery, a branch of the facial artery, pierces the
Palatoglossus superior constrictor to enter the tonsil, accompanied by venae comi
Palatine tonsil tantes. An important and sometimes large vein, the external palatine or
paratonsillar vein, descends from the soft palate lateral to the tonsillar
Tonsillar branches of
ascending pharyngeal artery hemicapsule before piercing the pharyngeal wall. Haemorrhage from
this vessel from the upper angle of the tonsillar fossa may complicate
Tonsillar branches of tonsillectomy. The muscular wall of the tonsillar fossa separates the
ascending palatine artery tonsil from the ascending palatine artery, and, occasionally, from the
Dorsal lingual branches tortuous facial artery itself, which may lie near the pharyngeal wall at
of the lingual artery the lower tonsillar level. The glossopharyngeal nerve lies immediately
lateral to the muscular wall of the tonsillar fossa (see Figs 34.3A, 34.6);
it is at risk if the wall is pierced, and is commonly temporarily affected
Tonsillar ramus,
by oedema following tonsillectomy. The internal carotid artery lies
glossopharyngeal nerve
approximately 25 mm behind and lateral to the tonsil. In some indi
viduals, the styloid process may be elongated and deviate towards the
tonsillar bed.
Glossopharyngeal nerve
Microstructure
Palatopharyngeus


Each tonsil is a mass of lymphoid tissue associated with the oropha
ryngeal mucosa and fixed in its position, unlike most other examples
of mucosaassociated lymphoid tissue. It is covered on its oropharyn
geal aspect by nonkeratinized stratified squamous epithelium. The
whole of the tonsil is supported internally by a delicate meshwork of
fine collagen type III (reticulin) fibres which are condensed in places to
form more robust connective tissue septa that also contain elastin.
Fig. 34.6 The tonsillar bed, sagittal section. These septa partition the tonsillar parenchyma, and merge at their ends
with the dense irregular fibrous hemicapsule on the deep aspect of the
tonsil and with the lamina propria on the pharyngeal surface. Blood
vessels, lymphatics and nerves branch or join within the connective
tissue condensations. The hemicapsule forms its lateral boundary with
PALATINE TONSIL the oropharyngeal wall, and with the mucosa that covers its highly
invaginated free surface.
The right and left palatine tonsils form part of the circumpharyngeal The 10–20 crypts formed by invagination of the free surface mucosa
lymphoid ring. Each tonsil is an ovoid mass of lymphoid tissue situated are narrow tubular epithelial diverticula that often branch within the
in the lateral wall of the oropharynx (Fig. 34.6; see Figs 31.3, 31.5). Size tonsil and frequently are packed with plugs of shed epithelial cells,
varies according to age, individuality and pathological status (tonsils lymphocytes and bacteria, which may calcify. The epithelium lining the
may be hypertrophied and/or inflamed). It is therefore difficult to crypts is mostly similar to that of the oropharyngeal surface, i.e. strati
define the normal appearance of the palatine tonsil. For the first 5 or 6 fied squamous, but there are also patches of reticulated epithelium,
years of life, the tonsils increase rapidly in size. They usually reach a which is much thinner, and which has a complex structure that is of


maximum at puberty, when they average 20–25 mm in vertical, and great importance in the immunological function of the tonsil.
10–15 mm in transverse, diameters, and they project conspicuously
into the oropharynx. Between the ages of 1 and 11 years, the tonsil and Reticulated epithelium Reticulated epithelium lacks the orderly
adenoid grow proportionally to the lower facial skeleton (Arens et al laminar structure of stratified squamous epithelium. Its base is deeply
2002). Tonsillar involution begins at puberty, when the reactive lym invaginated in a complex manner so that the epithelial cells, with their
phoid tissue begins to atrophy, and by old age only a little tonsillar slender branched cytoplasmic processes, provide a coarse mesh to
lymphoid tissue remains. accommodate the infiltrating lymphocytes and macrophages. The basal
The long axis of the tonsil is directed from above, downwards and lamina of this epithelium is discontinuous. Although the oropharyn
backwards. Its medial, free, surface usually presents a pitted appearance. geal surface is unbroken, the epithelium may become exceedingly thin
The pits, 10–20 in number, lead into a system of blindending, often in places, so that only a tenuous cytoplasmic layer separates the pha
highly branching, crypts that extend through the whole thickness of the ryngeal lumen from the underlying lymphocytes. Epithelial cells are
tonsil and almost reach the connective tissue hemicapsule. In a healthy held together by small desmosomes, anchored into bundles of keratin
tonsil, the openings of the crypts are fissurelike and the walls of the filaments. Interdigitating dendritic cells (antigenpresenting cells, APCs)
crypt lumina are collapsed so that they are in contact with each other. are also present (Ch. 4). The intimate association of epithelial cells and
The human tonsil is polycryptic. The branching crypt system reaches its lymphocytes facilitates the direct transport of antigen from the external
maximum size and complexity during childhood. The mouth of a deep environment to the tonsillar lymphoid cells, i.e. reticulated epithelial


tonsillar cleft (intratonsillar cleft, recessus palatinus) opens in the upper cells are functionally similar to the microfold (M) cells of the gut. The
part of the medial surface of the tonsil. It is often erroneously called total surface area of the reticulated epithelium is very large because of
the supratonsillar fossa, and yet it is not situated above the tonsil but the complex branched nature of the tonsillar crypts, and has been esti
within its substance. The mouth of the cleft is semilunar, curving paral mated at 295 cm2 for an average palatine tonsil.
lel to the convex dorsum of the tongue in the sagittal plane. The upper
wall of the recess contains lymphoid tissue that extends into the soft Tonsillar lymphoid tissue There are four lymphoid compartments
palate as the pars palatina of the palatine tonsil. After the age of 5 years, in the palatine tonsils. Lymphoid follicles (Ch. 4), many with germinal
this embedded part of the tonsil diminishes in size. There is a tendency centres, are arranged in rows roughly parallel to neighbouring connec
for the whole tonsil to involute from the age of 14 years, and for the tive tissue septa. Their size and cellular content varies in proportion to
tonsillar bed to flatten out. During young adult life, a mucosal fold, the the immunological activity of the tonsil. The mantle zones of the fol
plica triangularis, stretches back from the palatoglossal arch down to licles, each with closely packed small lymphocytes, form a dense cap,
the tongue. It is infiltrated by lymphoid tissue and frequently represents always situated on the side of the follicle nearest to the mucosal surface.
the most prominent (anteroinferior) portion of the tonsil. It rarely These cells are the products of Blymphocyte proliferation within the
persists into middle age. germinal centres. Extrafollicular, or Tlymphocyte, areas contain a spe
The lateral or deep surface of the tonsil spreads downwards, upwards cialized microvasculature including high endothelial venules (HEVs),


and forwards. Inferiorly, it invades the dorsum of the tongue; superiorly, through which circulating lymphocytes enter the tonsillar parenchyma.
it invades the soft palate; and, anteriorly, it may extend for some dis The lymphoid tissue of the reticulated crypt epithelium contains pre
tance under the palatoglossal arch. This deep, lateral aspect is covered dominantly IgG and IgAproducing B lymphocytes (including some


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lary nerve pass through, but do not synapse in, the pterygopalatine
Maxillary artery
ganglion; they are distributed through the lesser palatine nerves and
form a plexus (the circulus tonsillaris) around the tonsil together with
the tonsillar branches of the glossopharyngeal nerve. Nerve fibres from
Descending palatine
this plexus are also distributed to the soft palate and the region of the
artery
oropharyngeal isthmus. The tympanic branch of the glossopharyngeal
nerve supplies the mucous membrane lining the tympanic cavity. Infec
Lesser palatine tion, malignancy and postoperative inflammation of the tonsil and
arteries tonsillar fossa may therefore be accompanied by pain referred to the
ear.
Palatoglossus
Tonsillectomy
Ascending pharyngeal Surgical removal of the pharyngeal tonsils is commonly performed to
artery prevent recurrent acute tonsillitis or to treat airway obstruction by
Palatopharyngeus hypertrophied or inflamed palatine tonsils. Occasionally, the tonsil may
be removed to treat an acute peritonsillar abscess, which is a collection
Palatine tonsil of pus between the superior constrictor and the tonsillar hemicapsule.
Many methods have been employed, the most common being dissec
Tonsillar branch tion in the plane of the fibrous hemicapsule, followed by ligation or
electrocautery to the vessels divided during the dissection. The nerve
Ascending palatine supply to the tonsil is so diffuse that tonsillectomy under local anaes
artery thesia is performed successfully by local infiltration rather than by
blocking the main nerves. Surgical access to the glossopharyngeal nerve
Facial artery may be achieved by separating the fibres of superior constrictor.
Waldeyer’s ring
Dorsal lingual branches
of the lingual artery
Waldeyer’s ring is a circumpharyngeal ring of mucosaassociated lym
Lingual artery phoid tissue that surrounds the openings into the digestive and respira
tory tracts. It is made up anteroinferiorly by the lingual tonsil, laterally


by the palatine and tubal tonsils, and posterosuperiorly by the pharyn
External carotid artery
geal tonsil and smaller collections of lymphoid tissue in the intertonsil
lar intervals.
Fig. 34.7 The arterial supply to the palatine tonsil. LARYNGOPHARYNX
Boundaries
mature plasma cells), T lymphocytes and antigenpresenting cells. There
are numerous capillary loops in this subsurface region. The laryngopharynx is situated behind the entire length of the larynx
(known clinically as the hypopharynx) and extends from the superior
Vascular supply and lymphatic drainage border of the epiglottis, where it is delineated from the oropharynx by
The arterial blood supply to the palatine tonsil is derived from branches the lateral glossoepiglottic folds, to the inferior border of the cricoid
of the external carotid artery (see Fig. 34.6; Fig. 34.7). Three arteries cartilage, where it becomes continuous with the oesophagus (see Figs
enter the tonsil at its lower pole. The largest is the tonsillar artery, which 34.1–34.2). The laryngeal inlet lies in the upper part of its incomplete
is a branch of the facial, or sometimes the ascending palatine, artery. It anterior wall, and the posterior surfaces of the arytenoid and cricoid
ascends between medial pterygoid and styloglossus, perforates the su cartilages lie below this opening.
perior constrictor at the upper border of styloglossus, and ramifies in
the tonsil and posterior lingual musculature. The other arteries found Piriform fossa A small piriform fossa lies on each side of the laryn
at the lower pole are the dorsal lingual branches of the lingual artery, geal inlet, bounded medially by the aryepiglottic fold and laterally by
which enter anteriorly, and a branch from the ascending palatine artery, the thyroid cartilage and thyrohyoid membrane. Branches of the in
which enters posteriorly to supply the lower part of the palatine tonsil. ternal laryngeal nerve lie beneath its mucous membrane. At rest, the


The upper pole of the tonsil also receives branches from the ascending laryngopharynx extends posteriorly from the lower part of the third
pharyngeal artery, which enter the tonsil posteriorly, and from the cervical vertebral body to the upper part of the sixth. During deglutition,
descending palatine artery and its branches, the greater and lesser pala it may be elevated considerably by the hyoid elevators.
tine arteries. All of these arteries enter the deep surface of the tonsil,
branch within the connective tissue septa, narrow to become arterioles Inlet of larynx The obliquely sloping inlet of the larynx lies in the
and then give off capillary loops into the follicles, interfollicular areas anterior part of the laryngopharynx and is bounded above by the epi
and the cavities within the base of the reticulated epithelium. The capil glottis, below by the arytenoid cartilages of the larynx, and laterally by
laries rejoin to form venules, many with high endothelia, and the veins the aryepiglottic folds (see Fig. 34.1). Below the inlet, the anterior wall
return within the septal tissues to the hemicapsule as tributaries of the of the laryngopharynx is formed by the posterior surface of the cricoid
pharyngeal drainage. The tonsillar artery and its venae comitantes often cartilage.
lie within the palatoglossal fold, and may haemorrhage if this fold is
damaged during surgery.
PHARYNGEAL FASCIA
Unlike lymph nodes, the palatine tonsils do not possess afferent
lymphatics or lymph sinuses. Instead, dense plexuses of fine lymphatic
vessels surround each follicle and form efferent lymphatics, which pass The two named layers of fascia in the pharynx are the pharyngobasilar
towards the hemicapsule, pierce the superior constrictor, and drain to and buccopharyngeal fascia. The fibrous layer that supports the pharyn
the upper deep cervical lymph nodes directly (especially the jugulo geal mucosa is thickened above the superior constrictor to form the


digastric nodes) or indirectly through the retropharyngeal lymph nodes. pharyngobasilar fascia (see Fig. 34.10). It is attached to the basilar part
The jugulodigastric nodes are typically enlarged in tonsillitis, when they of the occipital bone and the petrous part of the temporal bone medial
project beyond the anterior border of sternocleidomastoid and are to the pharyngotympanic tube, and to the posterior border of the
palpable superficially 1–2 cm below the angle of the mandible; when medial pterygoid plate and the pterygomandibular raphe. Inferiorly, it
enlarged, they represent the most common swelling in the neck. diminishes in thickness but is strengthened posteriorly by a fibrous
band attached to the pharyngeal tubercle of the occipital bone, which
Innervation descends as the median pharyngeal raphe of the constrictors. This
The tonsillar region is innervated by tonsillar branches of the maxillary fibrous layer is really the internal epimysial covering of the muscles and
and glossopharyngeal nerves (see Fig. 34.6). The fibres from the maxil their aponeurotic attachment to the base of the skull. The thinner,


Pharynx
578
4
nOITCES
external part of the epimysium is the buccopharyngeal fascia, which geal plexus nerves; motor dysfunction of the pharynx and larynx,
covers the superior constrictor and passes forwards over the pterygo resulting from loss of motor innervation via the pharyngeal plexus and
mandibular raphe to cover buccinator. the recurrent laryngeal branch of the vagus to the intrinsic muscles of
the larynx; and voice changes reflecting involvement of the laryngeal
branches of the vagus. These tumours may also give rise to snoring as
PHARYNGEAL TISSUE SPACES
a result of narrowing of the nasopharynx.
Several surgical approaches have been described for the management
Pharyngeal tissue spaces can be subdivided into peripharyngeal and of parapharyngeal space tumours, including transcervical, transparotid,
intrapharyngeal spaces. The anterior part of the peripharyngeal space is transcervical–transmandibular and transoral approaches. Transoral
formed by the submandibular and submental spaces, posteriorly by the robotic surgery uses the oral cavity as a surgical corridor; as yet, there
retropharyngeal space and laterally by the parapharyngeal spaces. The have been relatively few studies from the transoral perspective of the
retropharyngeal space is an area of loose connective tissue that lies relevant surgical anatomy (Dallan et al 2011, Moore et al 2012, Wang
behind the pharynx and anterior to the prevertebral fascia, extending et al 2014).
upwards to the base of the skull and downwards to the retrovisceral
space in the infrahyoid part of the neck. Each parapharyngeal space
MUSCLES OF THE SOFT PALATE AND PHARYNX
passes laterally around the pharynx and is continuous with the retro
pharyngeal space. However, unlike the retropharyngeal space, it is a
space that is restricted to the suprahyoid region. It is bounded medially The muscles of the soft palate and pharynx are levator veli palatini,


by the pharynx, laterally by the pterygoid muscles (where it is part of tensor veli palatini, palatoglossus, palatopharyngeus, musculus uvulae,
the infratemporal fossa) and by the sheath of the parotid gland, super salpingopharyngeus, stylopharyngeus, and the superior, middle and
iorly by the base of the skull, and inferiorly by suprahyoid structures, inferior constrictors.
particularly the sheath of the submandibular gland; it may be helpful
Levator veli palatini
to think of it as shaped like an inverted pyramid extending from the
base of the skull to the greater cornu of the hyoid bone. The parapha Levator veli palatini arises by a small tendon from a quadrilateral
ryngeal space is divided into an anterior, or prestyloid, compartment roughened area on the medial end of the inferior surface of the petrous
and a posterior, or retrostyloid, compartment (Maran et al 1984). The part of the temporal bone, in front of the lower opening of the carotid
prestyloid compartment contains the retromandibular portion of the canal (see Fig. 34.3; Figs 34.8–34.10). Additional fibres arise from the
parotid gland, fat and lymph nodes. The retrostyloid compartment inferior aspect of the cartilaginous part of the pharyngotympanic tube
contains the internal carotid artery, the internal jugular vein, the glos and from the vaginal process of the sphenoid bone. At its origin, the
sopharyngeal, vagus, accessory and hypoglossal nerves, the sympathetic muscle is inferior rather than medial to the pharyngotympanic tube and
chain, fat and lymph nodes. Any of these structures may be damaged only crosses medial to it at the level of the medial pterygoid plate. It
by penetrating injuries directed posterolaterally in the region; more passes medial to the upper margin of the superior constrictor and
lateral injuries may result in penetration of the parotid gland.
An intrapharyngeal space potentially exists between the inner surface
of the constrictor muscles and the pharyngeal mucosa. Infections in this


space either are restricted locally or spread through the pharynx into Tensor veli palatini
the retropharyngeal or parapharyngeal spaces. The peritonsillar space is Pharyngotympanic tube
an important part of the intrapharyngeal space; it lies around the pala Maxillary artery Mandibular nerve
tine tonsil between the pillars of the fauces. Infections in the intratonsil Pterygomandibular raphe Levator veli palatini
lar space usually spread up or down the intrapharyngeal space, or Buccinator Middle meningeal artery
through the pharynx into the parapharyngeal space.
Tissue spaces between the layers of cervical fascia are described on
page 446; tissue spaces around the larynx are described on page 594.
SPREAD OF INFECTION
Infection that spreads into the parapharyngeal space will produce pain
and trismus. There may be swelling in the oropharynx that extends up
to the uvula, displacing it to the contralateral side, and dysphagia.
Posterior spread from the parapharyngeal space into the retropharyn
geal space will produce bulging of the posterior pharyngeal wall, dys
pnoea and nuchal rigidity. Involvement of the carotid sheath may Digastric (posterior
belly) (cut)
produce symptoms caused by thrombosis of the internal jugular vein
and cranial nerve symptoms involving the glossopharyngeal, vagus, Stylopharyngeus
accessory and hypoglossal nerves. If the infection continues to spread Superior constrictor
unchecked, mediastinitis will ensue. A virulent infection in the retro Glossopharyngeal nerve
pharyngeal space may spread through the prevertebral fascia into the Pterygoid hamulus
underlying danger space; infection in this tissue space may descend into
the thorax and even below the diaphragm, and results in chest pain, Styloglossus
severe dyspnoea and retrosternal discomfort. Hyoglossus (cut)
Pharyngeal infection from mucosaassociated lymph tissues such as Stylohyoid ligament
the palatine tonsil, or as a result of a penetrating injury (e.g. from an Stylohyoid
Middle constrictor


ingested foreign body), may result in the spread of infection into the
tissue spaces of the neck adjacent to the pharynx. This is an extremely Thyrohyoid membrane
serious situation because there is potential for rapid spread throughout Internal laryngeal nerve
the neck and, more dangerously, to the superior mediastinum, to cause
Superior laryngeal vessels
overwhelming lifethreatening infection.
Thyropharyngeus
PARAPHARYNGEAL SPACE TUMOURS Cricopharyngeus
Cricoid cartilage
Tumours that develop in the parapharyngeal tissue space may remain Recurrent laryngeal nerve
asymptomatic for some time. When they do present, it may be with a Trachea
diffuse pattern of symptoms, reflecting the effects of compression on
Oesophagus
the lower cranial nerves, e.g. dysarthria, resulting from impairment of
tongue movements secondary to hypoglossal nerve damage; dysphagia,
with overspill and aspiration of ingested material into the airway, result
ing from loss of sensory information from the territory of the pharyn Fig. 34.8 Muscles of the pharynx, lateral view.


Muscles of the soft palate and pharynx
579
43
rETPahC
A
Palatopharyngeus
Musculus uvulae Tendon of tensor veli palatini
Pterygoid hamulus
Tensor veli palatini
Lateral lamina of cartilaginous
part of pharyngotympanic tube Levator veli palatini
Medial lamina of cartilaginous Cartilaginous part of
part of pharyngotympanic tube pharyngotympanic tube
External opening of carotid canal
B
Medial lamina of cartilaginous
part of pharyngotympanic tube
Lateral lamina of cartilaginous
part of pharyngotympanic tube
Levator veli palatini
Tensor veli palatini
Tensor veli palatini
Medial pterygoid plate
Lateral pterygoid plate
Pterygoid hamulus
Salpingopharyngeus
Bursa of tensor veli palatini
Musculus uvulae
Palatopharyngeus (cut)
Fig. 34.9 Muscles of the soft palate. A, Inferior view. B, Superior view.
anterior to salpingopharyngeus. Its fibres spread in the medial third of Tensor veli palatini
the soft palate between the two strands of palatopharyngeus to attach
Tensor veli palatini arises from the scaphoid fossa of the pterygoid
to the upper surface of the palatine aponeurosis as far as the midline,
process and posteriorly from the medial aspect of the spine of the sphen
where they interlace with those of the contralateral muscle. Thus, the
oid bone (see Figs 32.3A, B, 34.3, 34.8–34.10). Between these two sites,
two levator muscles form a sling above and just behind the palatine
it is attached to the anterolateral membranous wall of the pharyngo
aponeurosis.
tympanic tube (including its narrow isthmus where the cartilaginous
medial twothirds meets the bony lateral third). Some fibres may be
Vascular supply The blood supply of levator veli palatini is derived
continuous with those of tensor tympani. Inferiorly, the fibres converge


from the ascending palatine branch of the facial artery and the greater
on a delicate tendon that turns medially around the pterygoid hamulus
palatine branch of the maxillary artery (Freelander 1992).
to pass through the attachment of buccinator to the palatine aponeur
osis and the osseous surface behind the palatine crest on the horizontal
Innervation Levator veli palatini is innervated via the pharyngeal
plate of the palatine bone. There is a small bursa between the tendon
plexus.
and the pterygoid hamulus (see Fig. 1318 in Cummings Otolaryngol
ogy Head & Neck Surgery 5e).
Actions The primary role of the levator veli palatini muscles is to
The muscle is thin and triangular, and lies lateral to the medial
elevate the almost vertical posterior part of the soft palate and pull it
pterygoid plate, pharyngotympanic tube and levator veli palatini. Its
slightly backwards; during swallowing, the soft palate is elevated so that
lateral surface contacts the upper and anterior part of medial pterygoid,
it touches the posterior wall of the pharynx, separating the nasopharynx
the mandibular, auriculotemporal and chorda tympani nerves, the otic
from the oropharynx. By additionally pulling on the lateral walls of
ganglion and the middle meningeal artery.
the nasopharynx posteriorly and medially, the levator veli palatini
muscles also narrow that space. The muscle has little or no effect on Dilator tubae Some fibres of tensor veli palatini that arise from the
the pharyngotympanic tube, although it might allow passive opening. hamulus of the medial pterygoid plate are attached to the short lateral


Pharynx
580
4
nOITCES
Pharyngobasilar Attachment of
fascia pharyngeal raphe to
pharyngeal tubercle (occipital bone)
Levator veli palatini
Styloid
process
Tensor veli palatini
Stylohyoid (cut)
Superior
Stylohyoid ligament constrictor
Stylopharyngeus
Styloglossus
Fibres of middle
constrictor from
stylohyoid ligament
Middle
constrictor
Stylohyoid (cut)
Greater cornu
of hyoid bone
Pharyngeal raphe
Inferior constrictor
(thyropharyngeus) Inferior constrictor
(thyropharyngeal part)
Inferior constrictor Killian’s triangle
(cricopharyngeus) Inferior constrictor
(cricopharyngeal part)
Laimer’s triangle Fundiform part
(cricopharyngeal sphincter,
Killian’s sling)
Oesophagus
Trachea
Fig. 34.10 Muscles of the pharynx and the pharyngobasilar fascia, posterior view.
lamina of the cartilage of the pharyngotympanic, to a condensation of the tongue, while others pass deeply into its substance to intermingle
connective tissue lateral to the tubal wall and to a portion of Ostmann’s with fibres of the intrinsic transverse muscle.
fat pad; these fibres are sometimes referred to as dilator tubae.
Vascular supply Palatoglossus receives its blood supply from the
Vascular supply The blood supply of tensor veli palatini is derived ascending palatine branch of the facial artery and from the ascending
from the ascending palatine branch of the facial artery and the greater pharyngeal artery.
palatine branch of the maxillary artery (Freelander 1992).
Innervation Palatoglossus is innervated via the pharyngeal plexus,
Innervation The motor innervation of tensor veli palatini is derived and is therefore unlike all the other muscles of the tongue, which are
from the mandibular nerve via the nerve to medial pterygoid, and supplied by the hypoglossal nerve.
reflects the development of the muscle from the first branchial arch.
Actions Palatoglossus elevates the root of the tongue and approxi


Actions Tensor veli palatini is said to have three anchoring points on mates the palatoglossal arch to its contralateral fellow, thus shutting off
which it isometrically contracts: the pterygoid hamulus, Ostmann’s fat the oral cavity from the oropharynx.
pad and medial pterygoid (O’Reilly and Sando 2010). Acting together,
Palatopharyngeus
the two tensor veli palatini muscles tauten the soft palate, principally
its anterior part, and depress it by flattening its arch. Acting unilaterally, Palatopharyngeus and its overlying mucosa form the palatopharyngeal
the muscle pulls the soft palate to one side. Although contraction of arch (see Fig. 31.3). Within the soft palate, palatopharyngeus is com
both muscles will slightly depress the anterior part of the soft palate, it posed of two fasciculi that are attached to the upper surface of the pala
is often assumed that the increased rigidity aids palatopharyngeal tine aponeurosis; they lie in the same plane but are separated from each
closure. A primary role of the tensor is to open the pharyngotympanic other by levator veli palatini (see Figs 34.3, 34.9). The thicker, anterior
tube, e.g. during deglutition and yawning, via its dilator tubae compo fasciculus arises from the posterior border of the hard palate as well
nent, and so aid equalization of air pressure between the middle ear as the palatine aponeurosis, where some fibres interdigitate across the
and nasopharynx. midline. The posterior fasciculus is in contact with the mucosa of
the pharyngeal aspect of the palate, and joins the posterior band of
Palatoglossus
the contralateral muscle in the midline. The two layers unite at the
Palatoglossus is narrower at its middle than at its ends (see Figs 34.3, posterolateral border of the soft palate, and are joined by fibres
34.6). Together with its overlying mucosa, it forms the palatoglossal of salpingopharyngeus. Passing laterally and downwards behind the


arch or fold (see Fig. 31.3). It arises from the oral surface of the palatine tonsil, palatopharyngeus descends posteromedial to and in close
aponeurosis, where it is continuous with its contralateral fellow. It contact with stylopharyngeus, to be attached with it to the posterior
extends forwards, downwards and laterally in front of the palatine tonsil border of the thyroid cartilage. Some fibres end on the side of the
to the side of the tongue. Some of its fibres spread over the dorsum of pharynx, attached to pharyngeal fibrous tissue, and others cross the


Muscles of the soft palate and pharynx
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43
rETPahC
midline posteriorly, decussating with those of the contralateral muscle. thyroid cartilage. The glossopharyngeal nerve curves round the posterior
Palatopharyngeus thus forms an incomplete internal longitudinal mus border and the lateral side of stylopharyngeus, and passes between the
cular layer in the wall of the pharynx. superior and middle constrictors to reach the tongue.
Passavant’s muscle (palatopharyngeal sphincter) The exist Vascular supply Stylopharyngeus receives its arterial supply from
ence of Passavant’s muscle remains controversial (Cho et al 2013). It the pharyngeal branch of the ascending pharyngeal artery.
has been described as a part of the superior constrictor and palatopha
ryngeus muscles (see Fig. 34.3B). An alternative view holds that it is a Innervation Stylopharyngeus is innervated by the glossopharyngeal
distinct palatine muscle that arises from the anterior and lateral parts nerve.
of the upper surface of the palatine aponeurosis, lies lateral to levator
veli palatini, blends internally with the upper border of the superior Actions Stylopharyngeus elevates the pharynx and larynx.
constrictor, and encircles the pharynx as a sphincterlike muscle. What
ever its origin, when it contracts, it forms a ridge (Passavant’s ridge) Superior constrictor
when the soft palate is elevated. The change from columnar, ciliated, The superior constrictor is a quadrilateral sheet of muscle and is thinner
‘respiratory’ epithelium to stratified, squamous epithelium that takes than the other two constrictors. It is attached anteriorly to the pterygoid
place on the superior aspect of the soft palate occurs along the line of hamulus (and sometimes to the adjoining posterior margin of the
attachment of the palatopharyngeal sphincter to the palate. The muscle medial pterygoid plate), the posterior border of the pterygomandibular
is hypertrophied in cases of complete cleft palate. raphe, the posterior end of the mylohyoid line of the mandible and, by


a few fibres, to the side of the tongue (see Figs 34.1, 34.3, 34.6, 34.8,
Vascular supply Palatopharyngeus receives its arterial supply from 34.10, 31.6). The fibres curve back into a median pharyngeal raphe that
the ascending palatine branch of the facial artery, the greater palatine is attached superiorly to the pharyngeal tubercle on the basilar part of
branch of the maxillary artery and the pharyngeal branch of the ascend the occipital bone.
ing pharyngeal artery.
Relations The upper border of the superior constrictor is separated
Innervation Palatopharyngeus is innervated via the pharyngeal from the cranial base by a crescentic interval that contains levator veli
plexus. palatini, the pharyngotympanic tube and an upward projection of
pharyngobasilar fascia. The lower border is separated from the middle
Actions Acting together, the palatopharyngei pull the pharynx constrictor by stylopharyngeus and the glossopharyngeal nerve (see Fig.
up, forwards and medially, and thus shorten it during swallowing. 34.8). Anteriorly, the pterygomandibular raphe separates the superior
They also approximate the palatopharyngeal arches and draw them constrictor from buccinator, and, posteriorly, the superior constrictor
forwards. lies on the prevertebral muscles and fascia, from which it is separated
by the retropharyngeal space. The ascending pharyngeal artery, pharyn
Musculus uvulae
geal venous plexus, glossopharyngeal and lingual nerves, styloglossus,
Musculus uvulae arises from the posterior nasal spine of the palatine middle constrictor, medial pterygoid, stylopharyngeus and the stylo
bone and the superior surface of the palatine aponeurosis, and lies hyoid ligament all lie laterally, and palatopharyngeus, the tonsillar
between the two laminae of the aponeurosis (see Figs 34.1, 34.9). It capsule and the pharyngobasilar fascia lie internally.


runs posteriorly above the sling formed by levator veli palatini and
inserts beneath the mucosa of the uvula. The two sides of the muscle Vascular supply The arterial supply of the superior constrictor is
are united along most of its length. derived mainly from the pharyngeal branch of the ascending pharyn
geal artery and the tonsillar branch of the facial artery.
Vascular supply The blood supply of musculus uvulae is derived
from the ascending palatine branch of the facial artery and the descend Innervation The superior constrictor is innervated via the pharyngeal
ing palatine branch of the maxillary artery.
plexus.
Innervation The nerve supply to musculus uvulae is innervated via
Actions The superior constrictor constricts the upper part of the
the pharyngeal plexus.
pharynx.
Actions By retracting the uvular mass and thickening the middle third Middle constrictor
of the soft palate, musculus uvulae aids levator veli palatini in palato
The middle constrictor is a fanshaped sheet attached anteriorly to the
pharyngeal closure. The two muscles run at right angles to each other
lesser cornu of the hyoid and the lower part of the stylohyoid ligament
and their contraction raises a ‘levator eminence’ that helps seals off the
(the chondropharyngeal part of the muscle), and to the whole of the
nasopharynx.
upper border of the greater cornu of the hyoid (the ceratopharyngeal
Salpingopharyngeus part) (see Figs 34.3A, 34.8, 34.10, 31.6). The lower fibres descend deep
to the inferior constrictor to reach the lower end of the pharynx; the
Salpingopharyngeus arises from the inferior part of the cartilage of the
middle fibres pass transversely, and the superior fibres ascend and
pharyngotympanic tube near its pharyngeal opening and passes down
overlap the superior constrictor. All fibres insert posteriorly into the
wards within the salpingopharyngeal fold to blend with palatopharyn
median pharyngeal raphe (Sakamoto 2014).


geus (see Figs 34.1, 34.3A, 34.9).
Vascular supply Salpingopharyngeus receives its arterial supply Relations The glossopharyngeal nerve and stylopharyngeus pass
through a small gap between the middle and superior constrictors, and
from the ascending palatine branch of the facial artery, the greater pala
the internal laryngeal nerve and the laryngeal branch of the superior
tine branch of the maxillary artery and the pharyngeal branch of the
thyroid artery pass between the middle and inferior constrictors. The
ascending pharyngeal artery.
prevertebral fascia and longus colli and longus capitis are posterior;
Innervation Salpingopharyngeus is innervated via the pharyngeal the superior constrictor, stylopharyngeus and palatopharyngeus are
internal; and the carotid vessels, pharyngeal plexus of nerves and some
plexus.
lymph nodes are lateral. Near its hyoid attachment, the middle constric
Actions Salpingopharyngeus elevates the pharynx, and may also assist tor lies deep to hyoglossus, from which it is separated by the lingual
artery.
tensor veli palatini to open the cartilaginous end of the pharyngotym
panic tube during swallowing.
Vascular supply The arterial supply of the middle constrictor is
Stylopharyngeus derived mainly from the pharyngeal branch of the ascending pharyn
Stylopharyngeus is a long slender muscle, cylindrical above and flat geal artery and the tonsillar branch of the facial artery.
below. It arises from the medial side of the base of the styloid process,
descends along the side of the pharynx, and passes between the superior Innervation The middle constrictor is innervated via the pharyngeal
and middle constrictors to spread out beneath the mucous membrane plexus.
(see Figs 34.3, 34.8, 34.10, 31.6). Some fibres merge into the constric
tors and the lateral glossoepiglottic fold, while others join fibres of Actions The middle constrictor constricts the middle part of the
palatopharyngeus and are attached to the posterior border of the pharynx during swallowing.


Pharynx
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nOITCES
Inferior constrictor when the swallowing mechanism becomes discoordinated, generates a
zone of elevated pressure adjacent to the mucosa in the dehiscence. The
The inferior constrictor is the thickest of the three constrictor muscles
result is the development of a pulsion diverticulum (a pouch of prolaps
and is usually described in two parts: thyropharyngeus and crico
ing mucosa), which breaches the thin muscle wall adjacent to the sixth
pharyngeus (see Figs 34.3A, 34.8, 34.10, 31.6). Thyropharyngeus arises
cervical vertebra and expands, usually a little to the left side, into the
from the oblique line of the thyroid lamina, a strip of the lamina
parapharyngeal potential space. This may trap portions (or all) of the
behind this, and by a small slip from the inferior cornu. Some addi
passing food bolus, resulting in regurgitation of old food, aspiration
tional fibres arise from a tendinous cord that loops over cricothyroid.
pneumonia, halitosis and weight loss. Treatment may involve open
Cricopharyngeus arises from the side of the cricoid cartilage between
excision or inversion of the pouch to prevent it filling, coupled with
the attachment of cricothyroid and the articular facet for the inferior
division of the circular fibres of cricopharyngeus, to prevent the buildup
thyroid cornu. Some authors have described cricopharyngeus as consist
of pressure in the region and recurrence of the pouch.
ing of a superficial upper oblique portion – the pars oblique – and a
The majority of hypopharyngeal diverticula arise either between the
lower, deeper, transverse portion – the pars fundiformis. The upper part
two parts of cricopharyngeus (where the upper oblique and lower trans
attaches to the median raphe while the lower part forms a circular band
verse fibres diverge) or below cricopharyngeus (where the longitudinal
that lacks a median raphe. The area demarcated by the pars oblique and
fibres of the oesophagus diverge in Laimer’s triangle). Some arise


pars fundiformis of cricopharyngeus is termed Killian’s dehiscence (or
between cricopharyngeus and thyropharyngeus. Diverticula are usually
Killian’s triangle). A second triangular area, Laimer’s triangle, can be
midline but may arise laterally below cricopharyngeus.
identified beneath cricopharyngeus between the longitudinal fibres of
the oesophagus as they pass laterally on either side to attach to the
cricoid cartilage; only the circular muscle of the oesophagus forms PHARYNGEAL PLEXUS
the wall here. Both triangles are postulated to be sites of weakness in
the wall of the pharynx and oesophagus, and are therefore areas where
Almost all of the nerve supply to the pharynx, whether motor or sensory,
diverticula could potentially form. Both cricopharyngeus and thyro
is derived from the pharyngeal plexus, which is formed by the pharyn
pharyngeus spread posteromedially to join the contralateral muscle.
geal branches of the glossopharyngeal and vagus nerves with contribu
Thyropharyngeus is inserted into the median pharyngeal raphe, and its
tions from the superior cervical sympathetic ganglion. The plexus lies
upper fibres ascend obliquely to overlap the middle constrictor;
on the external surface of the pharynx, especially on the middle con however, cricopharyngeus blends with the circular oesophageal fibres
strictor. Filaments from the plexus ascend or descend external to the
around the narrowest part of the pharynx.
superior and inferior constrictors before branching within the muscular
Relations The buccopharyngeal fascia is external; the prevertebral layer and mucosa of the pharynx.
fascia and muscles are posterior; the thyroid gland, common carotid The pharyngeal branch of the vagus supplies all the muscles of the
artery and sternothyroid are lateral; and the middle constrictor, stylo soft palate (excluding tensor veli palatini, which is supplied by the
pharyngeus, palatopharyngeus and the fibrous lamina are internal. The mandibular division of the trigeminal via the nerve to medial ptery


internal laryngeal nerve and laryngeal branch of the superior thyroid goid) and all the muscles of the pharynx (excluding stylopharyngeus,
artery reach the thyrohyoid membrane by passing between the inferior which is supplied by the glossopharyngeal nerve). It emerges from the
and middle constrictors. The external laryngeal nerve descends on the upper part of the inferior vagal ganglion and consists of axons arising
superficial surface of the muscle, just behind its thyroid attachment, and from neuronal cell bodies in the nucleus ambiguus. The nerve passes
pierces its lower part. The recurrent laryngeal nerve and the laryngeal between the external and internal carotid arteries to reach the upper
branch of the inferior thyroid artery ascend deep to its lower border to border of the middle pharyngeal constrictor and subsequently divides
enter the larynx. into numerous filaments that contribute to the pharyngeal plexus. It
also gives off a minute filament, the ramus lingualis vagi, which joins
Vascular supply The arterial supply of the inferior constrictor is the hypoglossal nerve as it curves round the occipital artery.
derived mainly from the pharyngeal branch of the ascending pharyn Contemporary evidence does not support the description of a cranial
geal artery and the muscular branches of the inferior thyroid artery. root of the accessory nerve as the conduit for the major motor drive to
the pharyngeal plexus, albeit via the vagus nerve. The plexiform con
Innervation Both parts of the inferior constrictor are usually inner nections that may be demonstrated between the accessory nerve and
vated via the pharyngeal plexus. Although controversial, available evi the vagus nerve within the posterior cranial fossa are too variable and
dence in humans suggests that cricopharyngeus is also supplied by the insubstantial to support this function.
recurrent laryngeal nerve and the external branch of the superior laryn
geal nerve (Sakamoto 2013).
ANATOMY OF SWALLOWING (DEGLUTITION)
Actions Thyropharyngeus constricts the lower part of the pharynx.
Cricopharyngeus is the main component of the upper oesophageal Swallowing involves a series of activities that occur within a matter of


sphincter, or pharyngooesophageal highpressure zone, the other parts seconds. Traditionally described as a reflex, the process is more properly
being thyropharyngeus and the proximal cervical oesophagus. (The regarded as a programmed motor behaviour. Swallowing is initiated
extent to which the lower fibres of thyropharyngeus and the upper fibres when food or liquid stimulates sensory nerves in the oropharynx. In a
of the oesophageal musculature are involved in closing the upper end 24hour period, an average person will swallow between 600 and 1000
of the oesophagus appears to depend on the physiological state, whereas times but, of these, only some 150 will relate to feeding; the remainder
cricopharyngeus always participates in closure.) The upper oesophageal occur to clear continuously produced saliva and are less frequent at
sphincter is defined manometrically as a region of elevated intraluminal night (Sato and Nakashima 2006, 2007).
pressure, 2–4 cm long, located at the junction of the hypopharynx and Eating and drinking are basic human pleasures, and problems asso
cervical oesophagus. ciated with swallowing can impact dramatically on the quality of life.
Cricopharyngeus contains about 40% of endomysial connective Swallowing disorders are usually symptoms of other complex diseases;
tissue, much of which is elastic, but it lacks muscle spindles (Bonning an inability to swallow may adversely affect nutritional status and there
ton et al 1988, Brownlow et al 1989). It contains both slowtwitch type fore indirectly exacerbate the underlying disease. Aside from the risk of
I and fasttwitch type II fibres, a structural arrangement that underpins asphyxiation through choking, swallowing disorders can also be a direct
the various functions of the upper oesophageal sphincter, i.e. maintain cause of morbidity and mortality as a result of aspiration of food, liquid
ing constant basal tone, yet being able to relax and contract rapidly or possibly refluxed gastric acid contents, causing bacterial infection or
during swallowing, belching and vomiting. The tonic activity of tissue damage.
cricopharyngeus between swallows prevents influx of air during inspir Swallowing in the adult human has usually been studied in relation


ation and tracheobronchial aspiration and pharyngeal reflux of to swallowing solid or liquid food carried out on command. For
oesophageal contents during oesophageal peristalsis. For further descriptive purposes, the process has been traditionally divided into
reading, see Lang and Shaker (2000). four phases: oral preparatory, oral transit/transfer, pharyngeal and
oesophageal (in this traditional view some have only recognized three
Hypopharyngeal diverticula phases, combining the two oral phases of preparation and transit into
Hypopharyngeal diverticula occur in the lower portion of the pharynx a single oral phase). While this sequence of events may still be appro
through areas of weakness in the pharyngeal wall. The pharyngeal priate for describing the swallowing of liquids, it does not accurately
mucosa that lies between cricopharyngeus and thyropharyngeus is rela represent the way in which solid food is prepared for swallowing,
tively unsupported by pharyngeal muscles and is called the dehiscence where suitably processed food is passed in stages to the oropharynx
of Killian. A delay in the relaxation of cricopharyngeus, which can occur and valleculae until a swallow is initiated. Oral and pharyngeal stages


anatomy of swallowing (deglutition)
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overlap when swallowing solid food, but perhaps less so when swal Loss of the nerve supply to buccinator as a result of damage to the facial
lowing saliva or other liquids. It therefore seems appropriate to speak nerve results in painful and repeated lacerations of the cheeks. It was
of an oral preparatory and an oral transit phase when describing the thought that the soft palate was depressed throughout this phase. It is
swallowing of liquids, but inappropriate when considering the swal now recognized that the posterior seal is not tight, and that the oral
lowing of solid food. (For further reading, see Hiiemae and Palmer cavity and oropharynx remain in communication, permitting addition
(1999, 2003), Matsuo and Palmer (2008), Mioche et al (2002), Palmer of material to the bolus while chewing continues. Spillage occurs
et al (2007).) because the soft palate is not in continuous contact with the posterior
part of the tongue, as was once thought (Hiiemae and Palmer 1999).
Bolus formation appears to involve several cycles of transporting food
ORAL PREPARATORY PHASE from the anterior to the posterior part of the tongue through the palato
glossal and palatopharyngeal arches until a bolus accumulates on the
In the oral preparatory phase, liquids are taken into the mouth and held oropharyngeal surface of the tongue (retrolingual loading), the val
there either on the floor of the mouth or against the hard palate by the leculae and within the oropharynx. Throughout this phase, the lateral
upward movement of the tongue. During swallowing, the muscles that and rotatory tongue movements that deliver the food to the teeth for
dilate the pharyngotympanic tube are activated during a pause in res grinding and reduction are crucial for normal bolus formation because
piration in the expiratory phase. Throughout this first phase, the soft they ensure that the food is positioned under the occlusal surfaces of
palate is fully lowered by contraction of palatoglossus and palatopha the teeth. If effective tongue movements do not occur, chewing will be


ryngeus, and the posterior part of the tongue is simultaneously elevated; compromised. Movements of the tongue are also cyclical in phase with
the apposed soft palate and tongue form a tight seal that helps to the movements of the jaw and hyoid bone. As the jaw is depressed, the
prevent premature leakage of the bolus into the oropharynx before the tongue is also depressed and moves anteriorly. As the jaw is elevated,
airways are fully protected. Slight leakage of fluid does sometimes occur; the tongue is retracted so that it no longer lies under the anterior teeth
the tendency for there to be leakage because of imperfect sealing as they as are brought together by jaw elevation. These coordinated
increases with age. actions help to ensure that the tongue is not usually bitten during
chewing.
Chewing continues until all the food has been moved posteriorly, a
ORAL TRANSIT/TRANSFER PHASE process that can last from less than 1 second to as much as 10 seconds.
The oral preparatory, oral transport and pharyngeal phases of swallow
In the oral transit/transfer phase, the liquid in the oral cavity is trans ing therefore overlap when solid food is being swallowed. As pieces of
ported through the palatoglossal and palatopharyngeal arches into the food are prepared in the mouth, they are moved to the posterior part
oropharynx. Genioglossus raises both the tongue tip and the part of the of the tongue or on into the oropharynx in a similar manner to that
tongue immediately behind the tip so that they come into contact with used to transport liquids (see above). The end of this phase of swallow
the alveolar ridge. Orbicularis oris and buccinator remain contracted, ing is marked by the tongue propelling the prepared bolus of food to
keeping the lips and cheeks taut and the liquid central in the oral cavity. the posterior part of the oral cavity and then on into the oropharynx
The liquid is accommodated in a shallow midline gutter that forms to initiate the swallow. Contact with either the posterior wall of the
along the dorsum of the tongue, probably as a result of the cocontraction oropharynx or the mucosa overlying the palatoglossal and palatopha


of the styloglossi and the genioglossi, aided by the superior longitudinal ryngeal arches was once thought to be necessary to initiate a swallow;
and transverse fibres of the intrinsic muscles. The mandible is elevated it is now known that there is a great degree of variability in the position
and the mouth is closed. The floor of the mouth and the anterior and of the bolus at the time at which a swallow is initiated.
middle portions of the tongue are elevated by cocontraction of the
suprahyoid group of muscles (mylohyoid, digastric, geniohyoid and
stylohyoid); the effectiveness of the suprahyoid muscles is increased as PHARYNGEAL PHASE
they contract against a fixed mandible (the mouth does not have to be
closed to swallow, but it is much harder to swallow if it is open). Con The delivery of the bolus to the oropharynx triggers the pharyngeal
traction of stylohyoid elevates the more posterior parts of the tongue phase of the swallow. This phase, which is involuntary and is the most
and empties the longitudinal gutter. At the same time, the tongue flat critical stage of swallowing, involves the pharynx changing from being
tens, probably as a result of the contraction of hyoglossus and some of an air channel (between the posterior nares and laryngeal inlet) to a
the intrinsic lingual muscles, especially the vertical fibres. The elevated, food channel (from the fauces to the upper end of the oesophagus).
flattened tongue pushes the liquid against the hard palate, and the sides The airway is protected from aspiration during swallowing by hyolaryn
of the tongue seal against the maxillary alveolar processes, helping to geal elevation, and by resetting respiratory rhythm so that airflow ceases
move the liquid further posteriorly. Contraction of styloglossus and briefly as the bolus passes through the hypopharynx; the total time that
mylohyoid completes the elevation of the posterior part of the tongue. elapses from the bolus triggering the pharyngeal phase to the
At the same time, the posterior oral seal relaxes and the posterior tongue reestablishment of the airway is barely 1 second. Thus there are two


moves forwards; the overall effect is of a camlike action of the tongue, aspects of the process to be examined: the transport of the food down
sweeping or squeezing the liquid towards the pillars of the fauces, the pharynx and through the upper oesophageal sphincter, and the
finally delivering it to the oropharynx and initiating the pharyngeal absolute need to protect the airways throughout this time.
stage of swallowing, where the pharyngeal aperture is initially increased The nasopharynx is sealed off from the oropharynx by activation of
and then closed. the superior pharyngeal constrictor and contraction of a subset of pal
atopharyngeal fibres to form a variable, ridgelike structure (Passavant’s
ridge; Cho et al 2013), against which the soft palate is elevated. From
ORAL PHASES WHEN SWALLOWING SOLIDS an evolutionary perspective, this ridge represents the remnant of a
sphincter that encircled a more highly placed larynx; a high laryngeal
When solid food is swallowed, the process is slightly different from that position is the norm in other mammals and in the human infant (see
just described for swallowing liquids. Food is mixed with saliva and below), but not in the human adult. Interestingly, the pharyngeal ridge
reduced to smaller pieces by the processes of chewing. When it has been becomes hypertrophic in an infant with a cleft palate, presumably in
converted to a suitable consistency to be swallowed, it is transferred to an attempt to produce a seal to the nasal airway. Ineffective velopha
the oropharynx and valleculae, where it can be retained for a few ryngeal closure may result in nasal regurgitation of food.
seconds prior to swallowing. During this time, chewing may continue; The airway is sealed at the laryngeal inlet by closure of the glottis.
the bolus is progressively augmented in one or more stages until a The epiglottis is retroflexed over the laryngeal aditus as a result of
swallow is initiated and the pharyngeal phase begins. In this part of the passive pressure from the base of the tongue and active contraction of


‘oral phase for solid food’, the essential action is chewing; the mandible the aryepiglottic muscles (Ch. 35). The conventional view that laryngeal
is moved by the action of the jaw elevators and depressors (Ch. 32), closure during swallowing occurs from inferior to superior, i.e. the vocal
and the food is reduced by the grinding action of the teeth and simul folds adduct first and the epiglottis covers the arytenoids and glottis
taneously mixed with saliva. The lips are maintained as a tight labial last, has been challenged by studies using simultaneous electromyo
seal by the contraction of orbicularis oris; buccinator performs a similar graphy and fibreoptic endoscopic evaluation of swallowing (FEES),
function for the cheeks. In this way, the sulci are closed, the vestibule which have reported that the aryepiglottic folds close before vocal fold
normally remains empty, and any food that enters the vestibule is adduction during a swallow. The sequence of events that close the
returned to the oral cavity proper. Buccinator keeps the cheeks taut, glottis may alter according to the type of swallow and consistency of
ensuring that they are kept clear of the occlusal surfaces and that the the bolus (Steele and Miller 2010). To prevent aspiration of material,
food remains in place under the occlusal surfaces of the molar teeth. irrespective of its consistency, the hyoid bone and larynx are raised and


Pharynx
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4
nOITCES
pulled anteriorly with precise timing by the suprahyoid muscles and The oesophageal phase of swallowing is much more variable than the
the longitudinal muscles of the pharynx (Kendall et al 2001). In this other phases and lasts between 8 and 20 seconds.
way, the laryngeal inlet is brought forwards under the bulge of the
posterior tongue, i.e. out of the path of the bolus. This action helps
SWALLOWING PATTERN GENERATOR
expand the hypopharyngeal space and relax the upper oesophageal
sphincter, which is also raised by several centimetres. The bolus passes
over the reflected anterior surface of the epiglottis and is swept through The patterning and timing of striated muscle contraction during swal
the laryngopharynx to the upper oesophageal sphincter. lowing are generated at a brainstem level in a network of neural circuits
Breathing is suspended briefly during swallowing; the larynx is that collectively form a central swallowing pattern generator. Experi
closed, the soft palate is elevated and there is active neural inhibition mental neurophysiological and tracer studies in animals have shown
of ventilation. Swallowing is normally initiated during an expiration, that the swallowing pattern generator includes several brainstem motor
which is then inhibited while swallowing occurs (typically for a period nuclei and two groups of interneurones in the dorsal and ventral
of 0.5–1.5 seconds). The resumption of expiration provides a degree of medulla: a dorsal swallowing group and a ventral swallowing group.
protection against any residues of solid food that might remain The dorsal swallowing group is located in the nucleus of the solitary
uncleared within the pharynx following the swallow being inhaled into tract and possibly in the adjacent reticular formation, and contains
the airway. The bolus is moved by sequential contraction of the pha neurones that generate the swallowing pattern, probably triggered by
ryngeal constrictor muscles superiorly behind the bolus. At the same convergent information from both cortical and peripheral inputs. The
time, the pharynx is shortened and elevated as palatoglossus and pal afferent feedback from the branches of the superior laryngeal nerve that


atopharyngeus contract against the raised and fixed soft palate. The innervate the valleculae, epiglottis and supraglottic part of the larynx,
sequential contraction of the constrictor muscles is often assumed to and which relay through the nucleus of the solitary tract, facilitates
be the driving force that propels the bolus towards the oesophagus. laryngeal closure during swallowing (Jafari et al 2003). The ventral
However, evidence that the head of the bolus moves faster than the swallowing group is in the ventrolateral medulla above the nucleus
wave of pharyngeal contraction suggests that, at least in some situations, ambiguus and contains neurones that act as ‘switches’, distributing the
the kinetic energy imparted to the bolus as it is expelled from the mouth swallowing drive to motoneurone pools in the trigeminal, facial and
into the oropharynx may be sufficient to carry it through the pharynx. hypoglossal nuclei and in the nucleus ambiguus.
This energy is generated by pressure gradients created within the The patterns of activation in the smooth muscle of the lower part of
pharynx by the tongue driving force, the hypopharyngeal suction pump, the oesophagus are generated locally in intramural plexuses driven by
and the ‘stripping action’ of the pharyngeal constrictors (Nishino et al vagal autonomics.
1985).
Supramedullary influence on swallowing
The tongue driving force (tongue thrust pressure force) is a positive
pressure that squeezes the bolus towards the laryngopharynx. It is gen
erated by the upward movement of the tongue pressing the bolus Techniques including transcranial magnetic stimulation, cortical evoked
against the contracting pharyngeal wall and requires a tight nasopha potentials, positron emission tomography and functional magnetic
ryngeal seal (created by elevation of the soft palate). There is a view that resonance imaging (fMRI) have all been exploited in the study of voli
the tongue driving force is the most important factor responsible for tional swallowing in humans (Harris et al 2005, Thexton 1998, Thexton
moving the bolus down the pharynx. The hypopharyngeal suction and Crompton 1998). Thus far, these studies have shown that numer


pump is caused by the elevation and anterior movement of the hyoid ous cortical and subcortical regions (primary motor and sensory cor
and larynx, which creates a negative pressure in the laryngopharynx, tices, operculum, supplementary motor area and cingulate cortex,
drawing the bolus towards the oesophagus, aided by a more negative insula, parietal cortical areas, basal regions and cerebellum) are recruited
pressure inside the oesophagus. The pharyngeal constrictors generate a in swallowing, although, as yet, the functional contributions made by
positive pressure wave behind the bolus. Their sequential contraction each region have not been established, and it is not known how they
may facilitate clearance (‘stripping’) of the pharyngeal walls and piri influence the swallowing pattern generator. The most consistent cortical
form sinuses; if this is so, residues that remain in the valleculae must activation occurs in the primary motor and somatosensory cortices.
reflect inadequate tongue force generation at the end of the oral phase Perhaps not surprisingly, the greatest area of fMRI activation in the
of swallowing. primary motor cortex occurs over the portion of the precentral gyrus
At the end of this phase, the bolus is propelled towards the upper where the face, tongue and pharynx are represented; there is evidence
oesophageal sphincter. At rest, this sphincter is closed by active contrac for functional asymmetry between the right and left oral sensorimotor
tion. Cricopharyngeus relaxes prior to the bolus arriving and the cortices (Martin et al 2004). The activity of the swallowing pattern
sphincter is then opened actively by the combined action of the supra generator is coordinated with other medullary reflexes, e.g. it is difficult
hyoid muscles in moving the larynx anteriorly and superiorly, and to elicit a swallow when the cortical masticatory centres are stimulated.
passively by pressure from the arriving bolus. The upper oesophageal (For further reading on the motor control of oropharyngeal swallowing,
sphincter thus differs in its action from that of other sphincters where see Humbert and German (2013), and on the role of sensory feedback


opening is generally passive and a consequence of pressures generated from the oropharynx in swallowing, see Michou and Hamdy (2009).)
by the movements towards them of fluids or solids.
Gag reflex SWALLOWING IN THE NEONATE
In the adult, the tip of the epiglottis is significantly lower than the
Traditionally, the stimulus for triggering a swallow has been regarded
inferior edge of the soft palate. In the neonate, the larynx is high in the
as contact with the posterior wall of the pharynx, since this is usually
neck and the epiglottis may extend above the soft palate so that
where the gag reflex is triggered. However, many regions of the orophar
the laryngeal airway is in direct continuity with the posterior nares
ynx, when appropriately stimulated by the presence of food or liquid,
(Figs 34.11–34.12); a potential space is therefore formed between the
are capable of triggering a swallow, although some regions are more
soft palate above, the epiglottis behind and the tongue anteroinferiorly.
sensitive than others, e.g. the area over the palatoglossal arches. More
In other mammals with an oropharyngeal anatomy similar to that of
over, there appears to be little relationship between a functioning gag
the human infant, up to 14 cycles of tongue movement or oral phases
reflex and the ability to swallow normally. Individuals with a reduced
cause the accumulation of food in this space. Subsequent emptying
or absent gag reflex can swallow safely; conversely, the presence of a
of the space is a single event followed by movement of the bolus down
brisk and clear gag reflex is not always associated with the ability to
the oesophagus. The ratio of accumulation cycles to swallow events in
swallow safely.
the human neonate is approximately 1.5 : 1, which is lower than in
other mammals but still implies some temporary accumulation. In the
OESOPHAGEAL PHASE case of a liquid bolus, accumulated material may be passed laterally to
the epiglottis through the piriform fossae rather than over the flexed
The third, or oesophageal, stage begins after the relaxation of the upper epiglottis, although it is not known whether this happens in the human


oesophageal sphincter has allowed the bolus to enter the oesophagus. infant. (For further reading, see Delaney and Arvedson (2008).)
This is a true peristaltic movement, in that a muscular relaxation in Swallow safety is critical at all ages. In the neonate, where coordin
front of the bolus and subsequent constriction behind the bolus move ation of suckling, swallowing and breathing is not fully developed, the
it towards the stomach. Sequential waves of contractions of the oesopha potential risk of airway obstruction and/or aspiration of ingested milk
geal musculature now propel the bolus down to the lower oesophageal or other material during swallowing is reduced because the intranarial
sphincter, which opens momentarily to admit the bolus to the stomach. larynx prevents the bolus from entering the larynx before and after a


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Dysphagia is a symptom of many diseases and can arise from anatom Loss of control of the pharyngeal phase of swallowing, e.g. due to
ical or functional deficits anywhere along the path from the oral cavity neurological disease or ablative head and neck surgery, may result in
to the stomach or from a failure of neural control resulting from con aspiration of food, especially fluids, leading to pneumonia. This
genital malformations, trauma, stroke or neurodegenerative diseases problem may be addressed surgically by pharyngostomy or epiglot
within the central nervous system. Loss of muscle strength affecting topexy. In cervical pharyngostomy, a tube may be passed through the
tongue propulsion or pharyngeal contraction will impair the initiation cervical skin, fascia and platysma directly into the piriform fossa (Patil
of the swallow and/or bolus transport. This will result in retention of et al 2006). This is achieved by passing a curved forcep into the piriform
residues within the pharynx following a swallow. Residues may also fossa and pushing it laterally, displacing the contents of the carotid
accumulate in the valleculae and piriform sinuses. Failure to protect the sheath and tenting up the platysma and cervical skin from the inside.
airways adequately may result in the penetration of swallowed material By cutting down on to the forcep, it is possible to grasp the feeding tube
food or liquid into the vestibule of the larynx. Aspiration will result if and pull it into the piriform fossa prior to feeding it on into the
the material then passes through the vocal folds, which may result in oesophagus. The tract formed by such a puncture epithelializes and may
airway obstruction or aspiration pneumonia. Penetration may some be used for longterm alimentation. In epiglottopexy, the neck and the
times occur in normal individuals. pharynx are opened to expose the laryngeal inlet, the aryepiglottic folds
are denuded of mucosa to encourage their adhesion, and the epiglottis
is sutured down to the aryepiglottic folds to shield the laryngeal inlet.
The resultant compromise of the airway can be offset by the creation


of an alternative airway via a tracheostomy. The pharyngeal wall and
cervical skin are reconstituted by suturing.


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Key references
A
A
B
Soft palate
Tongue
Larynx
Fig. 34.11 A sagittal section of the head of a neonate. Note the relatively
high position of the larynx, the opening being at the level of the soft
palate (A). Other abbreviations: B, epiglottis. (With permission from
Berkovitz BKB, Holland GR, Moxham BJ 2002 Oral Anatomy, Embryology Hyoid
and Histology, 3rd edn. Edinburgh: Mosby.)
B
swallow. (Neonates born at term demonstrate an increase in suck and
swallow rates over the course of the first 4 weeks; efficiency of feeding,
measured as volume of nutrient per suck and per swallow, doubles over
the course of the neonatal period (Qureshi et al 2002).)
The change towards adult anatomy and coordination of the phases
of swallowing starts a few months after birth (Kelly et al 2007). Dif
ferential growth in length of the human pharynx causes the larynx to
take up its low adult position and the epiglottis to lose contact with the
soft palate; the larynx reaches its final position around the time of
puberty. The adult anatomy does not allow any significant accumula
tion of food to occur immediately anterior to the epiglottis, which
means that the transport of food through the fauces has to bear a 1 : 1
relationship to pharyngeal and oesophageal transit. Moreover, the
lowered larynx compromises the previously protected airway; the hyoid
and larynx are therefore raised and pulled forwards during a swallow Soft palate
in order to minimize the risk of deglutitive aspiration.
Tongue
DYSPHAGIA
Available with the Gray’s Anatomy e-book
PHARYNGOSTOMY AND EPIGLOTTOPEXY Larynx
Hyoid
Available with the Gray’s Anatomy e-book
Fig. 34.12 A sagittal section of the head and neck in an infant (A) and
adult (B) human. The food way and the airway are shaded in red and
Bonus e-book image blue, respectively. A, In the infant human, the oral cavity is small and the


tongue and palate are flatter. B, In the adult human, the larynx is lower in
the neck, and the food way and airway cross in the pharynx. (Redrawn
with permission from Matsuo K, Palmer JB 2008 Anatomy and physiology
Fig. 34.5 Thornwaldt’s cyst.
of feeding and swallowing – normal and abnormal. Phys Med Rehabil Clin
N Am 19:691–707.)
KEY REFERENCES
Flint PW, Haughey BH, Lund VJ et al 2010 Cummings Otolaryngology: Head An older textbook that provides a valuable account of the anatomy of the
and Neck Surgery, vols 2 and 3, 5th ed. Philadelphia: Elsevier, Mosby. pharynx and of tissue spaces in the neck. It is also a thorough guide to the
Two volumes that contain comprehensive descriptions of the anatomy, earlier literature.
physiology and pathology of the pharynx and palate.
Matsuo K, Palmer JB 2008 Anatomy and physiology of feeding and swal
Graney DO, Retruzzelli GJ, Myers EW 1998 Anatomy. In: Cummings CW, lowing – normal and abnormal. Phys Med Rehabil Clin N Am 19:
Fredrickson JM, Harker LA et al (eds) Otolaryngology: Head and Neck 691–707.
Surgery, vol 2, 3rd ed. St Louis: Elsevier, Mosby; pp. 1327–48. A review of swallowing focussing on the process model of feeding.
A concise account of the anatomy of the pharynx, highlighting features of
O’Reilly RC, Sando I 2010 Anatomy and physiology of the Eustachian tube.
clinical relevance.
In: Flint PW, Haughey BH, Lund VJ et al (eds) Cummings Otolaryngol
Hollinshead WH 1982 Anatomy for Surgeons, vol I: The Head and Neck, ogy: Head and Neck Surgery, 5th ed. St Louis: Elsevier, Mosby; Ch. 131,
3rd ed. Philadelphia: Harper & Row. pp. 1866–75.
A review of the clinical anatomy and physiology of the pharyngotympanic tube.


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