Chapter 13 Pharynx

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HISTORY

The anatomic and surgical history of the pharynx is shown in Table 13-1.

Table 13-1. Anatomic and Surgical History of the Pharynx

Morgagni 1717 Described the pharyngeal sinus of Morgagni, a space in the nasopharynx between the upper border of the superior constrictor muscle and the

base of the s kull

Rosenmller 1808 Described the lateral pharyngeal recess (fossa of Rosenmller)

Zukerkandl 1882 Described the pharyngeal tonsil

Mikulicz 1886 Reconstructed esophageal and pharyngeal stomas with inverted skin flaps

Beck 1905 Used reversed gastric tube

Jianu 1912

Gavriliu &

Georgescu

1951

Roux 1907 Used jejunum as pedicle graft

Herzen 1908

Vullie t 1911 Used transverse co lon for reconstruct ion

Kelling 1911

Trotter 1913 Reconstructed the posterior and anterior hypopharyngeal wall with horizontal skin flaps

Kirschner 1920 Pioneered gastric transplantation, bringing the stomach to the neck

Wookey 1942 Developed a two-staged repair: doubled a long, full-thickness cervical pedicle flap and sutured it to the pharynx and esophagus, closing the

raw surface; repaired the fistula later by undercutting and suturing the skin margins

Hynes 1950 Performed pharyngoplasty by muscle transplantation, producing a sphincterlike mechanism

Goligher &

Robin

1954 Used left colon for reconstruction via presternal route

Asherson 1954 Performed partial excision of the posterior wall of the pharynx for carcinoma and used the proximal laryngotrachea l tube for reconstruction

Seidenberg

et al.

1959 Developed microvascular technique using jejunum and anastomosing the mesenteric vesse ls to the superior thyroid artery and ante rior facial

vein

Ong & Lee 1960 Performed pharyngogastric anastomosis after esophagopharyngectomy for correction of the laryngopharynx and cervical esophagus

Iskeceli 1962 Experimented with jejunal transplant to the pharynx in experimental animals

Bakamjian 1965 Used deltopectoral flap for pharyngoesophageal reconstruction

Ogura &

Dedo

1965 Used thoracoacromial flap to repair a pharyngostoma

Yamagishi et

al.

1970 Replaced esophagus up to the pharynx with a totally detached isoperistaltic gastric tube

Ariyan 1979 Used pectoralis major muscle flap for pharyngoesophageal reconstruction

McLear et al. 1991 Used jejunal free flap for reconstruction of hypopharyngeal stricture

Anthony et

al.

1994 Performed pharyngoesophageal reconstruction with radial forearm free flap

Wax et al. 1996 Reconstructed the oropharynx with lateral arm free flap

History table compiled by David A. McClusky III and John E. Skandalakis.

References

Missotten FEM. Historical review of pharyngo-oesophageal reconstruction after resection for carcinoma of pharynx and cervical oesophagus. Clin Otolaryngol

1983;8:345-362.

Pigott RW. The results o f pharyngoplasty by muscle transp lantation by W ilfred Hynes. Br J Plast Surg 1993;46:440-442.

Schmidt JE. Medical Discoveries: Who and W hen. Springfield, IL: Charles C. Thomas, 1959.

EMBRYOGENESIS

Normal Development

To understand the anatomy of the pharynx and its associated arteries and nerves and to avoid possible complications related to surgical treatment of

congenital lesions in this relatively inaccessible area, a thorough knowledge of the basic embryologic development of the pharynx is imperative. The pharynx

is a product of differentiation of the embryonic foregut. It occupies a major portion of the foregut in the first few weeks of embryonic development and

precedes the appearance of the more caudal regions. The cranial portion of the foregut transforms from a flat tube into a complicated collection of

structures between the fourth and sixth weeks of embryogenesis.


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The branchial arch system. The arch system appears in the fourth and fifth gestational weeks as four prominent arches, each consisting of muscular and

cartilaginous components, a nerve, and a n artery. (From Sadler TW. Langman's Med ical Embryology, 8th ed. Philadelphia: Lippincott Williams & W ilkins, 2000; with

permission.)

In the adult pharynx, the eustachian tube and the tonsillar fossa represent derivatives of the first and second branchial pouches respectively. The third

pouch is near the entry of the piriform recess, and the fourth is near the apex. Laryngeal ventricles may be related to the fifth and sixth pouches.

Congenital Anomalies of the Pharynx

Anomalies of the Lateral Branchial Apparatus

Epithelium-lined cysts, sinuses, and fistulas may occur as a result of malfunction in the normal differentiation process of the branchial apparatus.

Understanding the anomalies of the branchial apparatus helps the surgeon predict the location and course of these lesions and surrounding important norma

structures, and thus to avoid their injury at surgery.

First Cleft and Pouch Defects

The fistulas, sinuses, and cysts of the first branchial cleft are intimately related to the external auditory canal and the facial nerve; they are presented in

the chapter on the neck. First pouch defects are rare, but may present as nasopharyngeal cysts (Fig. 13-2). The opening of the sinuses can be near the

eustachian cushion.

Fig. 13-2.

Conge nital cervicoaural fistula or cyst. This is a persiste nt remnant of the ventral portion of the first branchial cleft. The tract may or may not open into the external

auditory canal. (Modified from Skandalakis JE, Skandalakis PN, Skandalakis LJ. Surgical Anatomy and Technique: A Pocket Manua l, 2nd Ed. New York: Springer,

2000; with pe rmission.)

Second Cleft and Pouch Defects

Second cleft and pouch defects may involve the pharynx. Therefore these lesions and their courses are pertinent to understanding the pharynx.


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COMPLETE FISTULAS

Almost all complete branchial fistulas are derived from the ventral portion of the second cleft and pouch. The external opening is in the lower third of the

neck, anterior to the sternocleidomastoid muscle. The fistula passes through the deep fascia to reach the carotid sheath. Above the hyoid, the tract turns

medially. It passes over and in front of the hypoglossal nerve and between the carotid bifurcation. It enters the pharynx on the anterior face of the

superior half of the posterior tonsillar pillar. Alternatively, the opening can be into the tonsil itself. Figure 13-3 depicts the course of the fistula of the

second branchial cleft and pouch.

Fig. 13-3.

Anomalies of the pharyngeal clefts and pouches. 2, fistulas of the second pharyngeal cleft and pouch. 3, fistula of the third pharyngeal cleft and pouch. 9,

glossopharyngea l nerve. 12, hypog lossal nerve. IC, internal carotid artery; EC, external carotid artery. (Modified from O'Rahilly R, Mller F. Human Embryology &

Teratology, 2nd ed. New York: Wiley-Liss, 1996; with pe rmission.)

SINUSES OPENING INTO THE PHARYNX

Sinuses opening into the pharynx are rarely seen. They usually open into the upper half of the posterior tonsillar pillar or into the tonsil itself.

CYSTS

The cysts of the second pouch may present clinically as a bulging in the posterior tonsillar pillar. Most are encountered in the neck and may extend

between external and internal carotid arteries (Fig. 13-4).

Fig. 13-4.


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Incomplete closure of the second branchial cleft or pouch may leave cysts. Type I, superficial, at the border of the sternocleidomastoid muscle. Type II, between

the muscle and the jugular vein. Type III, in the bifurcation of the carotid artery. Type IV, in the pharyngeal wall. Types I, II, and III a re of se cond-cleft origin. Type

IV is from the second pouch. M, ste rnocleidomastoid muscle; V, jugular vein; A, carotid artery. (Modified from Skandalakis JE, Gray SW, Rowe JS Jr. Anatomical

Complications in General Surgery. New York: McGraw-Hill, 1983; w ith permission.)

Third Cleft and Pouch DefectsA complete fistula of the third cleft and pouch has never been reported. Such a fistula, theoretically, would pass below the eleventh cranial nerve, over the

superior laryngeal nerve and hypoglossal nerve, and posteromedial to the internal carotid artery. It would then open into the pharynx in the upper part of

the piriform recess (Fig. 13-3).

Internal sinus tracts derived from the third pouch have been reported. They originated from the apex of the left piriform recess in all cases.

Fourth Cleft and Pouch Defects

A complete fistula of the fourth cleft and pouch has not been reported. Theoretically, the route of this fistula (Fig. 13-5) would be from the apex of the

piriform recess, through the cricothyroid membrane (inferior to the cricothyroid muscle), descending into the tracheoesophageal groove and looping around

the artery of the fourth arch, passing cephalodorsal to the carotid, looping over the hypoglossal nerve, descending in the neck, passing through the strap

muscles and platysma, and exiting low in the neck, anterior to the sternocleidomastoid muscle.

Fig. 13-5.


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The pathway of a fourth b ranchial pouch abnormality. (Modified from Donegan JO. Congenital neck masses . In: Cummings CW (ed). Otolaryngology - Head and

Neck Surgery, 2nd Ed . St Louis: Mosby Year Book, 1993; with permission.)

Surgical Considerations

A thorough understanding of the embryology of the branchial structures is essential for the head and neck surgeon. To aid in the complete surgical excision

of these structures and to avoid complications, it is important to understand their normal course.

First branchial cleft anomalies may come in close proximity to the facial nerve. Therefore, facial nerve identification and dissection is essential to avoid

facial paralysis.

Second branchial cleft anomalies, which are the most common, start in the mid-neck (anterior to the sternocleidomastoid muscle) and course up to the

tonsillar fossa. It is important to remove the entire tract up to the tonsil.

Third branchial cleft anomalies start lower in the neck and pass posteromedial to the internal carotid artery and travel caudally to end in the piriform recess

Fourth branchial cleft anomalies are extremely rare and may present as recurrent thyroiditis. There are no clinical reports of tracts that follow the entire

theoretical course (see section above). Instead most start in the piriform apex, usually the left side, and end after only a short distance in the paratrachea

region.

Direct laryngoscopy is useful for finding the opening of the tract in the apex of the piriform recess (Fig. 13-6). Cannulation of the tract with a Fogartycatheter is helpful for localization of the tract during neck dissection in the left paratracheal region. Identification of the recurrent laryngeal nerve is

important to avoid nerve injury, but may be difficult with previous infection.

Fig. 13-6.

Piriform apex fistula (marked by arrow). (From Jacobs IN, Gray R, Wyly B. Approach to branchial pouch anomalies that cause airway obst ruction during infancy.

Otolaryngol Head Neck Surg 1998;118(5):682-685; with pe rmission.)

Ventral Defects

The embryogenesis and abnormalities of development of the thyroid, parathyroids, and thymus are beyond the scope of this chapter. Information about the

thyroid and parathyroids is included in the chapter on the neck; the thymus is considered in the chapter on the mediastinum. However, the anomalies of the

descent of the medial anlage, the thyroid, are important in the discussion of the pharynx as it pertains to the lingual thyroid because the entire thyroid ma

locate in the oropharynx and cause an obstruction of the airway.

Lingual thyroid refers to the failure of the thyroid to descend to its normal location. This gland may be within the tongue, at the normal location of the

foramen cecum (Figs. 13-7A, B). It is usually the only thyroid tissue present in the patient. Inadvertent excision of the gland may result in permanent

hypothyroidism. Hormonal suppression is usually effective in decreasing the size of the lingual thyroid. Surgery may be selectively used in cases of airway

obstruction or swallowing difficulties refractory to hormonal suppression.

Fig. 13-7.


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Ectopic thyroid gland. A, Sites a long the pa th of descent of the thyroid from the foramen cecum (lingual thyroid) to the normal location. Hyperdescent to a s ite

benea th the s ternum is also indicated. B, The method o f exposure o f a lingual thyroid gland and the scheme for control of hemorrhage. (Modified from Lemmon WT

Paschal GW Jr. Lingual thyroid. Am J Surg 1941:52;82-85; with permission.)

SURGICAL CONSIDERATIONS

During the normal descent of the thyroid gland portions of the tract may remain (may fail to obliterate). These remnants are known as thyroglossal duct

cysts. The tract starts in the midline neck and extends to the foramen cecum. It is essential to excise the complete tract and incorporate the central body

of the hyoid bone. This is known as a Sistrunk procedure. Failure to excise the central body of the hyoid bone and follow the tract up the foramen cecum

increases the recurrence rate.

Regions of the Nasopharynx

The nasopharynx, oropharynx, and laryngopharynx together form the common aerodigestive tract known as the pharynx (Fig. 13-8). These three separate

regions are, from the surgeon's perspective, quite different and individually complex. Each region is unique with respect to the lesions that arise there, and

each has specific structural and functional considerations. The following pages discuss these three structures.

Fig. 13-8.


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Alimentary and respiratory system in the head and neck. Medial aspect; sagittal se ction slightly to the right o f the median plane . (Modified from Frick HF, Kummer B

Putz RV (eds). Wo lf-Heidegger's Atlas o f Human Anatomy. Base l, Switzerland: Karger, 1990; w ith permission.)

Development of Nasopharynx

The nasopharynx is full of developmental and morphologic c omplexity. It c ontains:

Pouch of Luschka (pharyngeal bursa) (Fig. 13-9)

Fossa (pharyngeal recess) of Rosenmuller (Fig. 13-8)

Waldeyer's tonsillar ring (Fig. 13-10)

Eustachian (tubal) tonsil (Fig. 13-10)

Luschka's "g land" (the pha ryngeal or third tonsil) (Fig. 13-10)

Eustachian cushion (torus tuba rius) (Fig. 13-8)

Pha ryngeal (extrasellar) hypophysis (Fig. 13-8)

Fig. 13-9.

Pharyngeal bursa and pharyngeal hypophysis as seen in a sagittal section of the head of an infant. (Modified from Hollinshead WH. Anatomy for Surgeons. New

York: Harper & Row , 1968; with pe rmission.)


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Fig. 13-10.


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Waldeye r's tonsillar ring. A,sagittal view. B,axial view. (A,Modified from Hollinshead W H. Anatomy for Surgeons . New York: Harper & Row, 1968; B,Modified from

Skandalakis JE, Gray SW, Rowe JS Jr. Anatomical Complications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

Developmental c onsiderations (Fig. 13-11) include:

Rostral tip of the notochord

Hypophysial pouch (Rathke's pouch)

Craniopharyngeal canal

Presphenoid-basisphenoid synchondrosis

Spheno-occipital synchondrosis

Tubotympanic recess

Pneumatization of the superadjacent sphenoid sinus (age 7-8)

Development of the first two pharyngeal pouches on each side

Fig. 13-11.

A,Sagittal section through the cephalic part of a 6-week embryo showing Rathke's pouch as a dorsal outpocketing of the oral cavity and the infundibulum as a

thickening in the floor of the diencepha lon. Band C, Sagittal sections through the developing hypophysis (a remnant of Rathke's pouch) in the 11th and 16th

wee ks of development, respe ctively. Note formation of the pars tuberalis, encircling the s talk of the pa rs nervosa . (Modified from Sadler TW. Langman's Medical

Embryology, 8th ed. Philadelphia: Lippincott Williams & Wilkins, 2000.)

The nasopharynx may also include the adenoids, Rathke's cleft cysts, chordomas, or craniopharyngioma.

Nomina Anatomicarefers to the nasopharynx as the pars nasalis pharyngis, the nasal part of the pharynx. Although the nasopharynx is a part of the

pharynx, remember that it is a purely respiratory passage. Under normal circumstances, it is not a part of the digestive tract, as is the pharynx.

The pharynx arises as the expanded cephalic end of the embryonic foregut (Fig. 13-12). The nasal cavities develop separately from the foregut, arising

from the nasal pits which deepen into nasal sacs. Since the early 1900s, controversies have existed as to whether the nasopharynx should be considered

strictly a part of the nasal cavity, or if it should be regarded as part of the pharynx. From embryogenesis, it is known that some of the original cavity is

taken up into the lower part of the nasal cavities. A portion of the original pharyngeal cavity comes to lie above the level of the definitive palate. It is this

portion of the pharynx that contributes to at least a portion of the nasopharynx and unites with the deepest part of the nasal sacs.

Fig. 13-12.


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A,Sagittal section through the nasal pit and lower rim of the medial nasa l prominence o f a 6-week embryo. The primitive nasa l cavity is sepa rated from the oral

cavity by the oronasal membrane. B,Similar section as in A,show ing the oronasal membrane breaking down. C,A 7-week embryo with a primitive nasal cavity in

open connection with the oral cavity. D,Sagittal section through the face of a 9-week embryo, showing separation of the definitive nasal and oral cavities by the

primary and s econdary pa late. Definitive choanae are at the junction o f the o ral cavity and the pharynx. (Modified from Sadler TW. Langman's Med ical Embryology,

8th ed. Philadelphia: Lippincott Williams & Wilkins, 2000; with permission.)

The caudal extent of the nasopharynx is above the plane of the soft palate (Fig. 13-8) at the level of the opening of the eustachian tube (derived from the

first pharyngeal pouch). Therefore, the nasopharynx is derived from the embryonic pharynx below the level of the eustachian tube orifice.

Rostral to the eustachian tube orifice, the nasopharynx develops from the deep extension of the nasal cavities. The preceding conclusions are based on th

histology and innervation of the two components of the nasopharynx. The nasal (anterior) nasopharynx possesses the highly vascular respiratory mucosa

that is rich in lymphatics and resembles the nasal cavity. Transition occurs at the level of the eustachian tube, where the posterior nasopharynx has

strat ified squamous epithelium resembling that of the oropharynx.

Congenital Anomalies of the Nasopharynx

Anomalous nasopharyngeal development may be assoc iated with abnormalities of the posterior nasal apertures, including choanal atresia, unilateral or

bilateral (Fig. 13-13), and malformation of the posterior aspect of the skull base. Gross abnormalities such as iniencephaly or anencephaly can also be

assoc iated with nasopharyngeal wall malformations.

Fig. 13-13.


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Axial CT (computed tomography) showing bilateral choanal atresia. White a rrows indicate at retic plates . V, vomer. (Courtesy Ian N. Jacobs.)

SURGICAL ANATOMY

Surface Anatomy of the Nasopharynx

The nasopharynx extends from the choanae (posterior nasal apertures) (Fig. 13-14) and slopes upward and backward. Its shape follows the slope of media

and lateral boundaries formed by the posterior edges of the vomer and the medial pterygoid plates, respectively (Figs. 13-14, 13-15).

Fig. 13-14.

Base of the skull. (Modified from Frick HF, Kummer B, Putz RV (eds). Wolf-Heidegge r's Atlas of Human Anatomy, Basel, Switzerland: Karger, 1990; with permission.)

Fig. 13-15.


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Skull, medial aspect; sagittal section s lightly to the left of the median plane. (Modified from Frick HF, Kummer B, Putz RV (eds). Wo lf-Heidegger's Atlas of Human

Anatomy. Basel, Switzerland: Karger, 1990; with permission.)

The anterior plane of the soft palate (Fig. 13-8) produces the lower extent of the nasopharynx. This plane intersects the anterior arch of the atlas in its

posterior extent. This is the narrowest part of the nasopharynx. It is called the isthmus, and it leads to the oropharynx below.

The nasopharynx is just inferior to the sphenoid bone (Fig. 13-15) and the posterior part of the sphenoid sinus. The hypophysial fossa (Fig. 13-15) and

pituitary gland are more cephalad to the sphenoid. The basilar portion of the occipital bone (Fig. 13-15) slopes downward, forming the anterior margin of

the foramen magnum (Figs. 13-14, 13-15), which is located posterosuperiorly to the nasopharynx.

Anterosuperiorly, the vomer articulates with the undersurface of the sphenoid bone (Fig. 13-15). Posterior to this articulation lies the pharyngeal sphenoida

fossa. In this fossa lies the pharyngeal hypophysis (Fig. 13-8). Posterior to it, in the same tissue plane, one finds a collection of lymphoid tissue known as

the pharyngeal tonsil (Fig. 13-8).

Move inferiorly on the posterior wall of the nasopharynx to find the isthmus. Located below the basiocciput (Fig. 13-14) is the anterior arch of the atlas

(Fig. 13-8), and immediately behind it, the dens.

Numerous ligaments are locat ed in this region. The anterior longitudinal ligament is the ligamentous st ructure most closely related to the posterior wall of

the nasopharynx.

The side walls of the nasopharynx are also extremely important. The most prominent structure is the opening of the auditory (eustachian) tube (Fig. 13-

14). This is located just behind the inferior nasal turbinate (concha) (Fig. 13-15). The overhang above and behind the orifice is known as the torus tubarius

(Figs. 13-8, 13-16). This is formed by the bulge of the fibrocartilage of the auditory tube itself. Gerlach's tonsil (eustatchian or tubal tonsil) (Figs. 13-8, 13

10) is a collection of lymphoid tissue located in the mucous membrane over the pharyngeal orifice of the eustachian tube. The fossa of Rosenmuller

(pharyngeal recess) (Fig. 13-8, Fig. 13-17) is located behind the tubal orifice. This is a fairly deep and laterally directed structure. The superior pharyngeal

constrictor (Fig. 13-18) lies in the side wall of the nasopharynx. Dense pharyngobasilar fascia, which is attached to the skull base above and to the

pterygoid plate laterally (Fig. 13-14), is located on the inner aspect of the superior constrictor. The gap in the fascia allows the eustachian tube to pass.

On the outer aspect of the superior constrictor muscle is the weaker buccopharyngeal fascia. It provides a flimsy covering for the wall of the nasopharynx.

Fig. 13-16.


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Pharyngea l cavity, dorsal as pect. The wa ll of the pharynx has been cut a long the mid-dorsal line and opene d. (Modified from Frick HF, Kummer B, Putz RV (eds).

Wolf-Heidegger's Atlas of Human Anatomy. Basel, Switzerland: Karger, 1990; with pe rmission.)

Fig. 13-17.

Pharyngeal cavity, dorsal aspect. The wall of the pharynx has been cut along the middorsal line and opened; the mucous membrane and the superior pharyngeal

constrictor muscle ha ve been partially removed in o rder to expose the different muscles. (Modified from Frick HF, Kummer B, Putz RV (eds). Wo lf-Heidegger's Atlas

of Human Anatomy. Basel, Switze rland: Karger, 1990; with pe rmission.)

Fig. 13-18.


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Muscular wall of the pharynx, dorsal as pect. (Modified from Frick HF, Kummer B, Putz RV (eds). Wolf-Heidegge r's Atlas of Human Anatomy. Basel, Switzerland:

Karger, 1990; with permission.)

An important feature of the nasopharynx is the development of the first two pharyngeal pouches on either side of this cavity (Fig. 13-8, Fig. 13-9). This

relationship is important with respect t o the development of Waldeyer's ring (Figs. 13-10A & 13-10B). This is an incomplete ring of lymphoid tissue

composed of the pharyngeal tonsil, eustachian tonsil, palatine tonsil, and lingual tonsil.

Lying close to the nasopharynx are two noteworthy embryologic structures: the rostral segment of the notochord and the craniopharyngeal canal (Fig. 13-

11). Tumors (chordoma and craniopharyngioma, respect ively) may arise from these. Both may involve t he nasopharynx.


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When the nasopharynx is examined indirectly with a mirror or endoscopically, several significant features become apparent. The perichoana with the

posterior tips of the inferior, middle, and superior turbinates (conchae) (Figs. 13-8, 13-16) are readily seen. The posterior vomer sharply divides the

posterior choanae (Fig. 13-14). Enlargement of the turbinates (conchae), adenoids, or polyps, or a mucopurulent nasal discharge can be readily apparent in

this region. Adenoids usually begin to atrophy after thirteen years of age, and if present in an adult, neoplasia should be considered. Enlarged adenoids in

an adult may also raise suspic ion for lymphoepithelial hyperplasia associated with an HIV infect ion. On the exam, juvenile nasopharyngeal angiofibromas c an

be seen as smooth pulsatile masses, which should never be biopsied because the vascularity of the tumor and the brisk bleeding that accompanies biopsy

creates the potential for severe hemorrhage.

Several important landmarks in addition to the torus t ubarius (Fig. 13-16) can be seen when t he nasopharynx is examined during nasopharyngoscopy. The

salpingopharyngeus muscle (Fig. 13-17) is seen to sweep posteriorly and inferiorly from the post erior part of t he torus, forming a raised mucosal fold (Fig.

13-16). The pharyngeal recess previously mentioned is actually formed between the pharyngeal wall and the elevation produced by this fold. Gerlach's tons

underlies this fold. Slight elevation of mucosa in the center of the eustachian tube opening is produced by the underlying levator veli palatini muscle (Figs.13-8, 13-17). Looking at the roof of the nasopharynx, depression in the midline is frequently seen. This concavity is known as the pharyngeal bursa (Fig.

13-8). The mucosa of this bursa is infiltrated by lymphatic nodules at its periphery, which if sufficiently hyperplastic, forms the adenoids. A persistent

remnant of the embryonic notochord in this area may occasionally be seen as a cystic midline nasopharyngeal mass. This is known as the Thornwaldt's cys

and is usually seen later in life.

Residual epithelial elements of Rathke's pouch (Fig. 13-11), an evagination of the stomodeal roof that contributes to the anterior pituitary gland, can give

rise to a craniopharyngioma. These usually occur just superior to the pharyngeal bursa in the midline of the nasopharynx, and may also be present as

nasopharyngeal masses (Fig. 13-9).


Nasopharyngoscopy, whether with direct flexible or rigid telescopes, allows visualization of the structures and landmarks described above. An indirect mirror

exam will also allow excellent visualization of the nasopharynx. However, the latter is limited by the experience of the examiner, the inverted nature of the

mirror image, and the cooperat ion of the patient if the exam is done outside the operat ing room.

The best way to examine the nasopharynx in detail is under general anesthesia with the patient in a supine position. The soft palate (Figs. 13-8, 13-16)

can be retracted by passing catheters through the nares into the oral cavity and out through the mouth. The ends of such catheters are clamped and a

mirror is used by the examiner located at the head of the patient to survey the nasopharynx, denote the structural features, and to perform a variety of

procedures. These procedures include adenoidectomy, biopsies of any areas suspicious for malignancy, removal or marsupialization of polyps and cysts,

cannulation of eustachian tubes, and surgery for nasopharyngeal stenosis (Fig. 13-19). A thorough examination of the three dimensional structure of the

nasopharynx under general anesthesia is essential in planning a surgical repair, such as with laterally-based pharyngeal flaps.

Fig. 13-19.

Severe nasopharyngeal stenosis; complete cicatrix of the nasopharynx. (Modified from McLaughlin KE, Jacobs IN, Todd NW, Gussack GS, Carlson G. Management of

nasopharyngeal and oropharyngeal stenosis in children. Laryngoscope. 107:1322-1331, 1997; with permission.)

Nasopharyngeal examination under general anesthesia is also useful for choanal atresia surgery, although in these cases the catheters cannot always be

passed through the nose; different maneuvers to retract the palate may be necessary.

With respect to malignancies confined to the nasopharynx, it is imperative that a complete nasopharyngeal exam is performed and that the examiner is fully

aware of the normal anatom and variations of the naso har nx. In the case of atients who resent with neck masses su estive of mali nanc a


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nasopharyngeal exam must always be a part of their head and neck examination. It is also extremely important to examine the nasopharynx of t he pat ients

who present with nasal obst ruction, epistaxis, or serous otitis media. All of these may result from benign or malignant processes in this region. For example

angiofibromas may cause intermittent epistaxis as well as nasal obstruction. A process near the eustachian tube orifice, such as nasopharyngeal carcinoma

or lymphoma, may have unilateral serous otitis media as its only symptom.

Important Anatomic Relationships

Nasopharyngeal walls are c omposed of four layers from inside to outside:

Mucosa

Submucosa or fibrous layer (pharyngobas ilar fascia)

Muscular layer

Buccopharyngeal fascia covering the constrictor muscles

The mucous membrane containing ciliated respiratory and nonciliated c olumnar epithelium is the inner lining. Submucosal connec tive tissue made of

pharyngobasilar fascia is well defined in its attachment to the skull base (Fig. 13-18). External to the superior constrictor muscle is the buccopharyngeal

fascia (Fig. 13-16). Attachment of the nasopharynx to the skull base is extremely important. Significant relationships to the middle cranial fossa, to the

dehiscence between the petrous temporal bone and foramen lacerum (Fig. 13-14), and to the carotid canal are apparent (Fig. 13-14).

The nasopharynx is attached in the midline to the pharyngeal tubercle on the basal surface on the body of the occipital bone (Fig. 13-18). This attachmen

extends bilaterally to the petrous temporal bone (Fig. 13-15), and turning forward, continues to the posterior margin of the medial pterygoid plate (Fig. 13-

14) and the pterygoid hamulus (Fig. 13-15). The fossa of Rosenmuller (Figs. 13-8, 13-17) lies in the roof of the nasopharynx. Because the internal carotid

artery (Fig. 13-20) passes through the foramen lacerum it is close to the nasopharyngeal wall. Expanding masses in the nasopharynx, therefore, can involve

and jeopardize the carotid.

Fig. 13-20.


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Coronal, slightly oblique section through the middle cranial fossa, showing the cavernous and cerebral portions of the internal carotid artery and cavernous sinus.

Nasopharyngeal lesions may also involve the retropharyngeal or parapharyngeal spaces (Figs. 13-22, 13-23). This can occur since the buccopharyngeal

fascia covering the external surface of the nasopharynx is connected to the prevertebral fascia of the deep layer of the deep cervical fascia. This creates

a space between the two fasc ial layers, known as the retropharyngeal space. Another space located laterally occurs between the buccopharyngeal fascia

and the fascia of the pterygoid muscles. Near the nasopharynx, that space is called the parapharyngeal space. Tumors or infections can invade this space

readily.

Fig. 13-22.

Fascial spaces o f the head and neck region. (Modified from Hollinshea d WH. Anatomy for Surgeons. New York: Harper & Row, 1968; with permission.)

Fig. 13-23.


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Sagittal view of fascial spaces o f head and neck region. (Based on Hollinshead WH. Anatomy for Surgeons, Vol. 1, 2nd ed. New York: Harper & Row, 1968.)

Important structures that pass between the skull base and the superior constrictor muscles can usually be seen on anatomic specimens. Removing the

mucosa from the medial aspect will reveal the tensor veli palatini (Fig. 13-17) and levator veli palatini muscles, ascending palatine artery, and ascending

pharyngeal artery (Fig. 13-24). The salpingopharyngeus muscle (Fig. 13-17) can also be revealed.

Fig. 13-24.


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Blood vessels and nerves on the dorsolateral wall of the pharynx, dorsal aspect. The right side especially emphasizes the blood vessels, the left side the nerves.

(Modified from Frick HF, Kummer B, Putz RV (eds). Wolf-Heidegger's Atlas of Human Anatomy. Basel, Switzerland: Karger, 1990; w ith permission.)

The main muscles of the nasopharynx are the tensor and levator veli palatini muscles (Fig. 13-17). These are located in the space between the skull base

and the superior constrictor muscle, which will be described under "Myofascial Framework." This space is sealed by the pharyngobasilar fascia (Fig. 13-18).

These muscles originate from the pterygoid fossa between the lateral and medial pterygoid plates (Fig. 13-14). They insert into the soft palate (Figs. 13-8,

13-16).

The head and neck surgeon must be familiar with several important considerations. The anterior soft palate is tensed by the action of the tensor veli

palatini muscle. This muscle is thought to have an important role in eustachian tube opening and thereby in pressure equalization between the middle ear

and the nasopharynx. Other authors implicate the levator veli palatini in this function.

The levator veli palatini crosses the superior border of the superior constrictor muscle and enters the nasopharyngeal mucosa and the lateral border of the

soft palate. Contraction of the levator veli palatini muscles elevates the soft palate and seals the oral cavity from the oropharynx. This principle is

important when treating patients with velopharyngeal insufficiency and its associated deglutition and speech problems.

Two arteries travel the space below the skull base. These are the ascending pharyngeal, arising from the bifurcation of the internal and external carotid

arteries, and the ascending palatine artery, a branch of the facial artery (Fig. 13-24). These vessels are the main contributors of blood supply to the

nasopharynx.

Although the anatomy of the skull base is beyond the scope of this chapter, familiarity with the location of two structures is important. The foramen

spinosum (Fig. 13-14) is a conduit for the middle meningeal artery (Fig. 13-20). The foramen ovale (F ig. 13-14) provides passage to the mandibular branch

of the trigeminal nerve (Fig. 13-21). These foramina may allow spread of malignancies with origins in the intracranial nasopharynx.

The nasopharynx is relatively insensitive, with the main sensory innervation provided by the branches of maxillary division of the t rigeminal nerve (Fig. 13-

25): the greater and lesser palatine nerves. Cranial nerve IX, the glossopharyngeal nerve (Fig. 13-24), supplies sensory innervation to the mucosal wall as

far superiorly as the eustachian tube. Procedures on the nasopharynx, such as mucosal biopsies and adenoidectomies, however, are relatively painless and

postoperat ive requirements for analgesics are minimal.

Fig. 13-25.


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Arteries a nd ne rves in the lateral wa ll of the nasal cavity, palate, and infratemporal fossa, medial aspect. (Modified from Frick HF, Kummer B, Putz RV (eds). Wolf-

Heidegger's Atlas o f Human Anatomy. Base l, Switzerland: Karger, 1990; with permission.)


A very important point in a nasopharyngeal surgical procedure, such as adenoidectomy, is the proximity of the atlanto-axial joint (Fig. 13-8). Muscle spasm

or infect ion after surgery may result in at lanto-axial dislocation, known as Grisel's syndrome. Patients with trisomy 21 (Down syndrome) are at higher risk fothis unusual complication.

A variety of benign and malignant neoplasms may occur in the nasopharynx (Tables 13-3 and 13-4). Congenital lesions such as chordomas and

craniopharyngiomas may also be present. Malignancies of the salivary glands as well as melanomas and esthesioneuroblastomas (olfactory neuroblastomas)

may also be found in the nasopharynx.

Table 13-3. Benign Non-Epithelial Tumors, Involving the Nasal Cavity, Paranasal Sinuses, and Nasopharynx 156 Cases

Vascular tumors 81

Capillary hemangioma 30

Cavernous hemangioma 5

Venous hemangioma 3

Benign hemangioendothelioma 3

Angiomatosis 1

Glomus tumor 1

Angiofibroma 38

Osseous and fibro-osseous tumors 52

Osteoma 31

Fibrous dysplasia 9

Ossifying fibroma 7

Osteoblastoma 1

Giant cell tumor 4

Chondroma 7

Myxoma 7

Fibroma 5

Leiomyoma 2

Lipoma 1

Rhabdomyoma 1

Source:Fu YS, Perzin KH. Non-epithelial tumors of the nasal cavity, paranasal sinuse s, and nasopha rynx: a clinicopatho logic study. I. General features and vascular

tumors. Cancer 33:1275-1288, 1974; with pe rmission.

Table 13-4. Malignant Tumors of Nasopharynx from the Mayo Tissue Registry, 1972 to 1981

Tumor Type Number (%)

Squamous cell carcinoma* 120 (71)

Lymphoma 31 (18)

Miscellaneous 18 (11)

Adenocarcinoma 6

Plasma cell myeloma 3


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Superficial cervical and facial lymph nodes . (Modified from Genden EM, Thawley SE, O'Leary MJ. Malignant neoplasms of the o ropharynx. In: Cummings CW,

Fredrickson JM, Harker LA, Krause CJ, Richardson MA, Schuller DE (eds). Otolaryngology: Head and Neck Surgery, 3rd ed . St Louis: Mosby, 1998; with permission.)

Large primary tumors of the nasopharynx obstruct the choanae and nasal airway and can lead to nasal obstruction as well as to epistaxis. Superior

extension via the foramen lacerum into the cranium can lead to cranial nerve involvement. Most commonly, cranial nerve VI is the first to be involved with

resulting lateral rectus muscle palsy and diplopia. Ophthalmoplegia can oc cur from involvement of c ranial nerves III and IV. High neck and fac ial pain

signifies involvement of cranial nerve V. As the tumor enlarges, cranial nerves VII, IX, X, and XI can be affected (Figs. 13-24, 13-25, 13-27).

Fig. 13-27.


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A,Sagittal view showing parapharyngeal and retropharyngeal spaces and associated anatomic structures. B,Axial view of the parotid gland and the carotid artery

and o f the peritonsillar, retropharyngeal (space 3), danger (space 4), prevertebral (space 5), and pa rapharyngea l (lateral pha ryngeal) spaces. BPF,

buccopharyngea l fascia; RPS, Retropharyngeal space; DS, Danger s pace; PVS, Prevertebral space; CN, cranial nerve.

The nasopharynx is an extremely complex three dimensional structure with close proximity to the brain, carotid artery, sphenoid sinus, and a variety of

other important structures and nerves (Fig. 13-21). It is involved in breathing, deglutition, and phonation. Hence, it is imperative that a surgeon operating

in this area be thoroughly familiar with the embryologic, anatomic, and physiologic aspects of the nasopharyx. This avoids potentially disastrous

complications.

Oropharynx-Laryngopharynx

The next two regions of the pharynx to be discussed are the oropharynx, continuous with the oral cavity above, and the laryngopharynx, continuous with

the esophagus below. The pharynx is a myofascial framework enclosing the pharyngeal lumen and its contents. The external surfaces of the pharynx make

up the portions of the borders of important deep neck spaces which are involved in various disease processes. Understanding the anatomy and relationship

of the pharynx is important in making sound judgments regarding surgical approaches to the pharynx and adjacent structures.

The following section discusses the anatomy of the pharynx, first describing the myofascial framework. Then we describe the important structures

traversing this framework en route to the pharynx, the structures constituting the oropharynx and laryngopharynx, and the important structures bordering

the pharynx.

Myofascial Framework

The pharyngeal wall is composed of stratified squamous epithelium, which covers the internal surface of the myofascial layer. This layer extends from the

skull base superiorly to the level of the inferior border of the cricoid cartilage inferiorly (Fig. 13-8). This myofascial layer is composed of three paired U-

shaped muscles that open anteriorly: the superior, middle, and inferior pharyngeal constrictor muscles (Figs. 13-18, 13-28). These muscles form a

telescoping structure with the lower muscles overlapping the upper muscles at the inferior border. All three sets of muscles insert posteriorly on a midline

posterior pharyngeal raphe, suspending superiorly from the pharyngeal tubercle of the basiocciput.

Fig. 13-28.


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Muscles of the tongue, pharynx, and larynx, lateral aspect. (Modified from Frick HF, Kummer B, Putz RV (eds). Wolf-Heidegge r's Atlas of Human Anatomy. Basel,

Switzerland: Karger, 1990; with pe rmission.)


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These paired pharyngeal constrictor muscles are covered internally and externally by fascial layers. Internally, the constrictor muscles are covered by the

pharyngobasilar fascia, which is thick superiorly and thin inferiorly and covers the muscles the length of the pharynx. Superiorly, the pharyngobasilar fascia

attaches to the pharyngeal tubercle of the occiput (Fig. 13-28), extends along the petrous portion of the temporal bone, and attaches anteriorly to the

medial pterygoid plate (Fig. 13-14) and the pterygomandibular raphe. The upper, thick portion of this fascia suspends the superior constrictor muscle from

the skull base. The external surface of the muscle is covered by the buccopharyngeal fascia. This fascia covers the pharynx at the level of the superior

constrictor muscle and fuses below this level with the middle layer of deep cervical fascia. This third fascia forms the remainder of the external fascial

covering of the pharynx.

The superior pharyngeal const rictor muscles originate from the medial pterygoid plate and pterygomandibular raphe anteriorly. Their fibers extend posteriorl

in a horizontal and slightly superior and inferior direct ion to insert on the posterior midline pharyngeal raphe (Fig. 13-18). These muscles surround the

oropharynx.

The middle pharyngeal constrictor muscles originate anteriorly from the greater and lesser cornua of the hyoid bone (Fig. 13-28). Their fibers extendposteriorly in three separate groups (superior, middle, and inferior) to attach on the posterior midline raphe (Fig. 13-18). The middle constrictors are at the

level bridging the junction between t he lower oropharynx and upper laryngopharynx.

The inferior pharyngeal constrictor muscles are the thickest of the pharyngeal constrictors and the best developed. These arise anteriorly from the oblique

line of the thyroid and cricoid cartilages (Fig. 13-28). They then extend posteriorly in a horizontal, superior, and inferior direction to insert on the posterior

midline raphe. The cephalic portion of the inferior constrictor muscle is termed the cricopharyngeus muscle. The cricopharyngeus muscle forms the upper

esophageal sphincter. It extends from the cricoid cartilage in a horizontal direction and interdigitates with the transverse esophageal muscle layer.

Intervals between the overlapping layers of pharyngeal constrictor muscles are traversed by structures entering the pharynx. The interval between the

superior and middle constrictor muscles is traversed by the stylopharyngeus muscle (Fig. 13-18). This muscle originates from the styloid process and

extends inferiorly and anteriorly in an oblique fashion to attach to the medial aspect of the middle constrictor muscle. The glossopharyngeal nerve supplies

sensory innervation to the base of the tongue and pharynx and also traverses this interspace (Fig. 13-24). The glossopharyngeal nerve and the lingual

artery course together, running deep to the hyoglossus muscle (Fig. 13-28). The stylohyoid ligament, which attaches to the lesser cornu of the hyoid bone

also traverses this interval between the superior and middle pharyngeal constrictor muscles. Lying at the inferior pole of the palatine tonsil, the interval

provides a pathway of extension for an infectious process from the peritonsillar area to the parapharyngeal space, lateral to the superior constrictor muscle

The interval between the middle and inferior pharyngeal constrictor muscles is occupied by the thyrohyoid membrane (Fig. 13-28). The structures traversin

this membrane include the internal laryngeal nerve and superior laryngeal artery and vein (Fig. 13-24). The internal branch of the superior laryngeal nerve

enters the thyrohyoid membrane and supplies sensory innervation to the supraglottic larynx and the piriform recess mucosa. The external branch of the

superior laryngeal nerve continues inferiorly, lateral to the constrictor muscles, and accompanies the superior thyroid vessels (Fig. 13-24) to innervate the

cricothyroid muscle (F ig. 13-28). The internal branch of the superior laryngeal nerve penetrates the thyrohyoid membrane approximately 1 cm inferior and

medial to the greater cornu of the hyoid bone. Infiltration of local anesthetic in this area will create a superior laryngeal nerve block and anesthetize the

laryngopharynx and supraglottic larynx. This is also the area of the t hyrohyoid membrane where an external laryngocele will extend from the endolaryngeal

cavity to t he extralaryngeal space.

The interval between the inferior constrictor muscles and the transverse fibers of the esophageal muscle transmits a neurovascular bundle. This bundle

includes the recurrent laryngeal nerve (Fig. 13-29). This nerve supplies sensory innervation to the glottis and subglottis and motor innervation to the

intrinsic laryngeal muscles except the cricothyroid muscle. Also in this bundle are the inferior laryngeal artery and vein, branches of the thyrocervical trunk

of the subclavian vessels.

Fig. 13-29.


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Pharyngoesophageal segment showing potential areas of herniation. (Based on Hollinshead WH. Anatomy for Surgeons, Vol. 1, 2nd ed. New York: Harper & Row,

1968.)

The innervation of the pharyngeal muscles is from the pharyngeal plexus (Fig. 13-24). This is composed of the pharyngeal branches of the glossopharyngea

and vagus nerves. The glossopharyngeal nerve supplies only the stylopharyngeus muscle. The vagal contribution supplies all the other muscles, including

the muscles of the soft palate (Fig. 13-30), with the exception of the tensor palatini muscle, which is supplied by the mandibular branch of the trigeminal

nerve (Fig. 13-25). The inferior constrictor muscle also receives innervation from the external branch of the superior laryngeal nerve (Fig. 13-24). The

cricopharyngeus muscle may receive some innervation from the recurrent laryngeal nerve. Sensory innervation of the pharynx is supplied by the

glossopharyngeal nerve through the pharyngeal plexus. This supplies the mucosa of the oropharynx and laryngopharynx with the exception of the piriform

recess mucosa. The piriform recess mucosa receives its innervation from the internal branch of the superior laryngeal nerve, which traverses the submucos

in the anterior wall of the piriform recess (Fig. 13-16).

Fig. 13-30.

Muscles of the s oft palate (cut away to show the levato r veli palatini). (Modified from Hollinshead W H. Anatomy for Surgeons. New York: Harper & Row, 1968; with

permission.)

The vascular supply of the pharyngeal walls is from the ascending pharyngeal artery and the superior thyroid artery, branches of the external carotid artery

(Fig. 13-24). The inferior thyroid artery, a branch of the thyrocervical trunk, also provides arterial supply to the laryngopharynx. The venous drainage of th

pharynx is through the pharyngeal plexus on the posterior surface of the pharynx. This drains into the pterygoid plexus, the superior and inferior thyroid

veins, the facial vein, and directly into the internal jugular vein (Fig. 13-31).

Fig. 13-31.


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Blood vessels and nerves of the neck, ventrolateral aspect. Parotid gland, sternocleidomastoid muscle, supra- and infrahyoid muscles have been partially removed.

(Modified from Frick HF, Kummer B, Putz RV (eds). Wolf-Heidegger's Atlas of Human Anatomy. Basel, Switzerland: Karger, 1990; w ith permission.)

The lymphatic drainage of the pharynx varies depending on the anatomic level. The posterior drainage is through the retropharyngeal lymph nodes (nodes o

Rouvier), located behind the pharynx at the level of the carotid bifurcation. Drainage of the lateral pharyngeal structures is to the jugulodigastric and

midjugular lymph nodes in the deep jugular chain (Fig. 13-26).


Zenker's diverticulum (Fig. 13-32) may form in the area of Killian's dehiscence (Fig. 13-29), an area of weakness between the inferior constrictor muscle an

the f ibers of the cricopharyngeus muscle. It is usually on the left side. This is a pulsion diverticulum. It results from increased intraluminal pharyngeal

pressures above the level of the cricopharyngeus and increased cricopharyngeal muscle pressures. This causes a gradual weakening of this area and

herniation of mucosa and submucosa t hrough the weakened area t o form a diverticulum. This problem is usually remedied by performing a c ricopharyngealmyotomy with or without resection or suspension of the herniated mucosa.

Fig. 13-32.


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Zenker's diverticulum.

Oropharynx

The oropharynx is a continuation of the oral cavity anteriorly, the nasopharynx superiorly, and the laryngopharynx inferiorly (Fig. 13-8). It is located at

approximately the level of the 2nd and 3rd cervical vertebrae. Its boundaries extend superiorly from the junction of the hard and soft palate (Fig. 13-8, 13-

16) to the inferior margin at the level of the plane of the hyoid bone. Anteriorly, it extends to the junction of anterior and posterior regions of the tongue a

the level of the circumvallate papillae (Fig. 13-16).

The oropharynx contains the:

Soft palate and uvula

Palatine tonsils and tonsillar fossae

Base of tongue

Valleculae


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Lateral and posterior oropharyngeal walls

SOFT PALATE

The soft palate (Figs. 13-8, 13-16, 13-30) is an essential muscular structure which extends from the level of the hard palate (Fig. 13-8) anteriorly to a

midline protuberance, the uvula, posteriorly. Laterally, the soft palate blends with the tonsillar area. The soft palate prevents nasopharyngeal reflux of air

and food by closing off the oropharynx from the nasopharynx during speech and swallowing.

The soft palate is composed of stratified squamous mucosa which covers a muscular framework of the following five muscles:

Levator veli palatini

Tensor veli palatini

Musculi uvulae

Palatoglossus

P alatopharyngeus

Except for the tensor veli palatini, these muscles are innervated by the vagus nerve to the pharyngeal plexus.

The levator veli palatini muscle (Figs. 13-17, 13-30) forms most of the bulk of the soft palate. It arises from the floor of the petrous portion of the temporal

bone and medial portion of the cartilaginous eustachian tube, medial to the pharyngobasilar fascia. It travels inferomedially in an oblique fashion to fuse wit

the contralateral muscle in the posterior portion of the soft palate.

The tensor veli palatini muscle (Fig. 13-17) is the only soft palate muscle innervated by the mandibular branch of the trigeminal nerve rather than the vagu

nerve. It arises from the medial pterygoid plate (Fig. 13-14), spine of the sphenoid bone, and lateral portion of the cartilaginous eustachian tube, lateral to

the pharyngobasilar fascia. It descends inferiorly to hook around the hamulus of the pterygoid bone (Fig. 13-30) and extends medially as a narrow tendon

to insert on the posterior hard palate as the palatine aponeurosis. This muscle functions to laterally tense the palate and also to open the eustachian tube

orifice. Children with cleft palates have poor function of the tensor veli palatini muscle, due to the muscle's midline dehiscence. This results in poor

eustachian tube opening and chronic middle ear effusions. The eustachian tube dysfunction improves after palatal surgical repair.

The musculi uvulae (Figs. 13-17, 13-30) arise from the posterior hard palate and palatine aponeurosis on each side of the midline, extend posteriorly, and

fuse as they form the uvula (Fig. 13-17). These function to draw the uvula upward and forward. Bifidity or notching of the uvula due to failure of these

muscles to fuse indicates a submucous cleft of the palate. Care should be taken when performing adenoidectomy to avoid postoperative velopharyngeal

insufficiency. Palpation of the palate is necessary to insure absence of submucous clefting even in the absence of a notching of the uvula.

The palatoglossus muscle (Figs. 13-30, 13-33) forms the anterior tonsillar pillar, creating the anterior border of the tonsillar fossa and demarcating the

anterior margin of the lateral oropharynx. It is a thin muscle arising from the inferior portion of the soft palate where it fuses to the contralateral

palatoglossus muscle, and projects inferiorly to attach to the lateral and dorsal tongue. It functions to draw the palate down and to narrow the pharynx.

Fig. 13-33.


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Bed of the palatine tonsil. (Modified from Hollinshea d WH. Anatomy for Surgeons . New York: Harper & Row, 1968; with permission.)

The palatopharyngeus muscle (Figs. 13-17, 13-30, 13-33) forms the posterior tonsillar pillar and part of the posterior portion of the tonsillar fossa. It arises

as two heads from the hard palate and palatine aponeurosis and more posteriorly from the contralateral palatopharyngeus muscle. The muscle inserts on

the fascia of the lower constrictor muscles. In addition to elevating the pharynx, the palatopharyngeus muscles function to draw the palate down and to

narrow the pharynx.

Blood supply of the soft palate is from the lesser palatine arteries (Fig. 13-25) and branches of the maxillary artery, which travel with the nerve though the

lesser palatine foramen. Sensory innervation is through the lesser palatine branches of the maxillary division of the trigeminal nerve.

TONSILS (PALATINE TONSILS)

The palatine tonsils (Figs. 13-8, 13-10, 13-16, 13-17), commonly referred to as the tonsils, are lymphatic structures containing indentations called crypts.

The tonsils reside in the tonsillar fossa, which is bounded anteriorly by the palatoglossal arch (Fig. 13-16) and posteriorly by the palatopharyngeal arch. Th

arches contain the muscles of their corresponding names and are also referred to as the anterior and posterior tonsillar pillars, respectively (Fig. 13-33).

The tonsillar fossa is bounded superiorly by the soft palate, and inferiorly by the base of tongue mucosa. Tonsillar tissue frequently extends superiorly and

inferiorly into these structures.

Laterally, the tonsil has a capsule that is formed by the pharyngobasilar fascia. A layer of loose connective tissue separates the capsule from the superior

constrictor muscle. This potential space is the peritonsillar space. Spread of infection from the tonsils into this area results in a peritonsillar abscess,requiring transoral aspiration or incision and drainage. Due to the proximity of the medial pterygoid muscle to t he peritonsillar space (the medial pterygoid

muscle is located lateral to the superior constrictor muscle) (Fig. 13-18), peritonsillar abscesses present with trismus and bulging of the tonsil and soft

palate medially and inferiorly.

The inferior pole of the tonsil lies at the level of the interspace between the superior and middle constrictor muscles (Figs. 13-16, 13-18). Extension of a

peritonsillar abscess laterally in this interspace through the buccopharyngeal fascia results in a parapharyngeal space abscess (Fig. 13-34). This results in

more intense trismus because of the direct irritation of the medial pterygoid muscle. This also places the great vessels of the neck at risk due to their

location in the parapharyngeal space. Inferior dissection of infection through the carotid sheath may result in mediastinitis. The glossopharyngeal nerve

(Figs. 13-33, 13-34) also traverses this interspace between the superior and middle constrictor muscles at the inferior pole of the tonsil and is at risk in

deep dissection during a tonsillectomy.

Fig. 13-34.

The vascular supp ly of the pa latine tons il. (Modified from Hollinshea d WH. Anatomy for Surgeons . New York: Harper & Row, 1968; with permission.)

Five branches of the external carotid artery system supply blood to the tonsils. The main supply is inferiorly from the tonsillar branch of the facial artery

(Fig. 13-34). The ascending pharyngeal, dorsal lingual, ascending palatine branch of the facial artery, and descending palatine artery also supply the

tonsils. Lymphatic drainage of the tonsils is primarily to the jugulodigastric lymph nodes (Fig. 13-26).

Sensory innervation of the tonsil is through the glossopharyngeal nerve and from the greater and lesser palatine branches of the maxillary branch of the

trigeminal nerve (Fig. 13-25). The phenomenon of referred otalgia (Fig. 13-35) in cases of tonsillitis, tumors of the tonsil, and after tonsillectomy is

mediated through common projections of the oropharyngeal fibers of the glossopharyngeal nerve and Jacobsen's nerve. Jacobsen's nerve (Figs. 13-24, 13-

35) is the tympanic branch of the glossopharyngeal nerve that innervates the middle ear mucosa.


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Fig. 13-35.

Pathw ay of referred o talgia from the oropharynx. (Modified from DeSanto LW, Thawley SE, Genden EM. Treatment o f tumors of the oropharynx: Surgical Therapy.

In: Thawley SE, Panje WR, Batsakis JG, Lindberg RD, eds. Comprehens ive Management of Hea d and Neck Tumors, 2nd Ed. Philadelphia: WB Saunders, 1999; with

permission.)

BASE OF TONGUE

The base of tongue (Fig. 13-17) is the posterior one-third of the tongue which lies posterior to the circumvallate papillae (Fig. 13-16) and foramen cecum,

the area of origination of the thyroid gland. It extends posteriorly to the level of the valleculae, and laterally continues with the floor of mouth mucosa at

the inferior pole of the tonsils (Fig. 13-8). The base of tongue contains submucosal lymphatic collections referred to as lingual tonsils, which, together with

the palat ine tonsils and adenoids (pharyngeal and tubal tonsils), form the previously described Waldeyer's ring (Fig. 13-10), a first line of immunologic

defense. This is also an uncommon area of primary lymphoma presentation.

The sensory innervation of the base of tongue is through the glossopharyngeal nerve, which supplies general visceral afferent fibers and special visceral

afferent fibers for taste. Base of tongue musculature is innervated by the hypoglossal nerve (Fig. 13-24). Arterial supply of the base of tongue is through

the lingual arteries. The base of tongue has a rich lymphatic drainage system primarily to the jugulodigastric lymph nodes (Fig. 13-26). Lymphatic drainage

to both sides of the neck is the rule. This necessitates addressing both the ipsilateral and contralateral neck when treating tumors of the base of tongue,

due to the likelihood of bilateral metastases.

The base of tongue extends posteriorly into paired concavities (valleculae) along the base of the lingual surface of the epiglottis (Figs. 13-8, 13-16). The

valleculae are separated in the midline by a median glossoepiglottic fold and bounded laterally by lateral glossoepiglottic folds (pharyngoepiglottic folds) (Fig

13-16), which attach t he epiglottis to the base of tongue.

The remainder of the oropharynx consists of the posterior pharyngeal wall and lateral pharyngeal wall posterior to the posterior tonsillar pillar.

Laryngopharynx (Hypopharynx)

The laryngopharynx is the longest section of the pharynx, extending from the level of the hyoid bone (Fig. 13-8) superiorly to the inferior border of the

cricoid cartilage at the level of the sixth cervical vertebra. It is wider superiorly and narrows inferiorly. The upper part of the laryngopharynx is the most

caudal portion of the common aerodigestive tract. The lower part, including the piriform recessses and postcricoid area, is the beginning of the separated

digestive tract that leads to the esophagus. The laryngopharynx is divided into the following three separate areas (Fig. 13-16):

Posterior pharyngea l wall

Piriform recesses

Pos tcricoid area

The posterior pharyngeal wall extends from the level of the hyoid bone to the inferior border of the cricoid cartilage and is continuous laterally with the

lateral wall of the piriform recesses.

The piriform recessses are funnel-shaped structures that are open posteriorly to the remainder of the pharynx. They are bounded anteriorly and laterally by

the lamina of the thyroid cartilage, and medially by the aryepiglottic fold, arytenoid cartilage, and cricoid cartilage (Fig. 13-8). The superior extent is at the

level of the pharyngoepiglottic fold (Figs. 13-16, 13-17), and the inferior apex is at the level of the cricopharyngeus muscle (Figs. 13-29, 13-32). This apex

approximates the level of the laryngeal ventricle.

The postcricoid area includes the mucosa covering the area from the posterior cricoarytenoid joint superiorly to the inferior border at the cricoid cartilage

(Fig. 13-8). It is continuous laterally with the medial wall of the piriform recessses and inferiorly with the esophagus.

Sensory innervation of the laryngopharynx is from the glossopharyngeal (Fig. 13-24) and vagus nerves. The posterior pharyngeal wall is innervated by the

fibers of the glossopharyngeal nerve through the pharyngeal plexus. The piriform recessses and postcricoid mucosa are innervated by the internal branch of

the superior laryngeal nerve, which runs beneath the mucosa of the anterior piriform recess. Anesthesia of the piriform recesses and larynx can be obtained

by topically anesthetizing the piriform recess mucosa or by percutaneous superior laryngeal nerve block at the thyrohyoid membrane (Fig. 13-28). The

- -


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. , .

the superior laryngeal nerve, which runs along the lateral border of the inferior constrictor muscle (Fig. 13-24) with the superior thyroid vascular pedicle.

Previously described, the vascular supply to the laryngopharynx is through the superior and inferior thyroid arteries and their branches (Fig. 13-24). The

lymphatic drainage is through the thyrohyoid membrane to jugulodigastric and midjugular lymph nodes (Fig. 13-26), but also involves the

retropharyngeal/peritracheal and periesophageal lymph nodes. Tumors of the laryngopharynx commonly present at an advanced stage because the large

size of the laryngopharynx allows the malignancy to go unnoticed until obstruction occurs late in the disease process. Tumors present with dysphagia,

hemoptysis, voice change due to laryngeal invasion, and commonly as an enlarged metastatic lymph node in the neck. Referred otalgia (Fig. 13-35) is a

common presenting symptom of hypopharyngeal malignancies. This is due t o the common central project ions of the internal branch of the superior laryngea

nerve, which innervates the piriform recess, and Arnold's nerve (the auricular branch of the vagus nerve), which innervates a portion of the posterior

external auditory canal. Therefore, otalgia in the absence of the obvious ear pathology is an indication to carefully examine the upper aerodigestive tract

for pathology.


Injury to the external branch of the superior laryngeal nerve can occur in thyroidectomy if the superior thyroid neurovascular pedicle is ligated high. Avoid

injury to the superior laryngeal nerve when clamping the superior thyroid pedicle by observing the following precaution. Ligate the vascular pedicle at the

capsule of the superior pole of the thyroid gland, inferior to the point of divergence of the external branch of the superior laryngeal nerve away from the

vascular pedicle, toward the cricothyroid muscle.

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Because of the close relationship of the laryngopharynx to the larynx, and the advanced presentation of hypopharyngeal tumors, surgical resection often

involves total or near-total laryngopharyngectomy. The propensity for submucosal extension of disease in the esophagus creates tumors that involve the

inferior apex of the piriform recess and/or the postcricoid mucosa. These often require esophagectomy in addition to total laryngopharyngectomy to ensure

adequate margins of resection in the esophagus. Then total pharyngeal reconstruction can be performed. Use a free jejunal or tubed fasciocutaneous flap in

the case of cervical pharyngeal defects. For pharyngoesophageal defects, use gastric pull-up.

Physical Examination of the Oropharynx and Laryngopharynx

Examination of the oropharynx can easily be performed with the use of tongue depressors. Gentle compression of the middle third of the t ongue inferiorlywith slight anterior traction will allow adequate visualization of the tonsils, anterior base of tongue, soft palate, and posterior pharyngeal wall. For patients

with hyperactive gag reflexes, topical anesthetic can be used to improve visualization. Examination of the base of tongue and valleculae require gentle

anterior retraction of the tongue with a gauze pad and indirect examination with the use of a laryngeal mirror. The mirror is placed superiorly in the

oropharynx with the back of the mirror elevating the soft palate and uvula without contacting the posterior pharyngeal wall to avoid gagging the patient. In

addition to visualization, palpation of the tonsils and base of the tongue with the finger is helpful in detecting mucosal and submucosal abnormalities.

Examination of the laryngopharynx and larynx requires use of a laryngeal mirror or a fiberoptic laryngoscope through the nasal cavity. The larynx and vocal

cord motion should be evaluated. The piriform recesses can best be visualized with the patient phonating. This brings the aryepiglottic folds and arytenoid

cart ilages medial, thereby opening the piriform recesses. The presence of saliva pooling within a single piriform recess should raise suspic ion of a lesion

within that space. The presence of a unilateral paralyzed vocal cord should also raise suspicion of a tumor involving the piriform recess and extending to th

paraglottic space. The posterior pharyngeal wall can also be easily visualized with a mirror or flexible laryngoscope.

The postcricoid area is difficult to visualize with either of these techniques and requires direct laryngoscopy under general or topical anesthesia. The

laryngopharynx, in general, is best visualized with direct laryngoscopy. The laryngoscope is directly inserted into the vallecula. It can then be slid laterally

into the piriform recess, elevating it anteriorly to see the anterior portion of the piriform recess. When the laryngoscope is inserted deeper to the apex of

the piriform recess both the medial and lateral walls can be visualized. The laryngoscope can then be rotated medially into the postcricoid area, by lifting

the larynx anteriorly to open the postcricoid area and esophageal inlet. The laryngoscope is then moved into the contralateral piriform recess. The posterio

pharyngeal wall is also visualized when the larynx is lifted anteriorly by elevating the postcricoid mucosa.

When examining the neck, grasping the thyroid cartilage and moving it from side to side over the top of the cervical spine should produce normal laryngeal

crepitus as the cartilage of the larynx rolls over the bony cervical spine. Absence of this laryngeal crepitus suggests a posterior pharyngeal or postcricoid

mass that is preventing the cartilage-to-bone contact. This portion of the examination should be performed routinely during evaluation of the larynx and

pharynx.

PHARYNGEAL RELATIONSHIP TO DEEP NECK SPACES

The oropharynx has very important relationships to surrounding potential deep neck spaces, including the retrovisceral spaces (Fig. 13-22) and the

parapharyngeal space (lateral pharyngeal space). Although not part of the pharynx, these spaces may be involved with pathology that originates in the

pharynx or encroaches upon the pharynx. Knowledge of the anatomy of these spaces and their relationship to the pharynx is integral to understanding the

surgical approaches to these spaces and the perils and pitfalls of these approaches.

Retrovisceral Space

The area posterior to the pharynx (the retrovisceral space) (Fig. 13-22) can be separated into the following three spaces (Figs. 13-23, 13-27):

Retropharyngea l space

Danger space

Prevertebral space

The retropharyngeal space is bounded by the buccopharyngeal fascia anteriorly and by the alar layer of prevertebral fascia posteriorly. Laterally, it is

continuous with the parapharyngeal space. The parapharyngeal space extends from the skull base superiorly to the level of the tracheal bifurcation

(approximately the level of the fourth thoracic vertebra), where the alar layer of prevertebral fascia fuses with the middle layer of deep cervical fascia. The

retropharyngeal space contains lymph nodes (nodes of Rouvier) in addition to connective tissue. Infections and abscesses in the retropharyngeal space are

usually unilateral in presentation due to the posterior midline attachment of the midline raphe of the superior constrictor muscle to the prevertebral fascia.

The danger space is bounded anteriorly by the alar fascia and posteriorly by the prevertebral fascia. It extends superiorly from the skull base to the

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The prevertebral space is bounded anteriorly by the prevertebral layer of prevertebral fascia, posteriorly by the vertebral bodies, and laterally by the

transverse processes. It extends superiorly from the skull base to the coccyx inferiorly.

Involvement of these spaces with infection may occur from suppuration of retropharyngeal nodes, penetrating injury, or spread from adjacent spaces.

These spaces may be approached either transorally or transcervically.

Parapharyngeal Space (Lateral Pharyngeal Space)

The parapharyngeal, or lateral pharyngeal, space (Figs. 13-27, 13-36) is typically described as an inverted pyramid-shaped space located lateral to the

pharynx. Its superior extent is at the skull base, including a small portion of the temporal bone and a fascial connection from the medial pterygoid plate to

the spine of the sphenoid medially. It extends inferiorly to the level of the greater cornu of the hyoid bone at its junction with the posterior belly of the

digastric muscle. The superior medial border is formed by the fascia of the tensor veli palatini (Fig. 13-27) and medial pterygoid muscles and the

pharyngobasilar fasc ia. Inferiorly, the medial border is formed by the superior constrictor muscle. The anterior border is formed by the pt erygomandibularraphe. The lateral boundaries are the medial pterygoid muscle, the mandible, the deep lobe portion of the parotid gland, and a small portion of the digastric

muscle posteriorly. The posterior border is the prevertebral fascia.

Fig. 13-36.

Frontal view of the parapha ryngeal space. (Modified from Hollinshead WH. Anatomy for Surgeons . New York: Harper & Row, 1968; with permission.)

The parapharyngeal space is divided into a pre- and retrostyloid compartment (Fig. 13-27) by fascia extending from the styloid process to the tensor veli

palatini muscle. The pre-styloid compartment contains lymphatic tissue, the internal maxillary artery, and further branches of the mandibular branch of the

trigeminal nerve. The retrostyloid compartment contains the carotid artery, internal jugular vein, cranial nerves IX, X, XI, and XII, and the cervical

sympathetic chain (Figs. 13-27, 13-36).


Masses or infections in the parapharyngeal space present as a fullness or bulging in the lateral pharyngeal wall, displacing the tonsil medially and/or the soft

palate medially and inferiorly with contralateral deviation of the uvula. Trismus is a frequent finding, especially with parapharyngeal space abscesses or larg

tumors. These are caused by irritation or involvement of the medial pterygoid muscle, which forms the lateral extent of the parapharyngeal space.


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or tumors in this space may enter the carotid sheath and place the carotid arteries and the internal jugular vein at risk. Infections may also spread inferiorly

in this space through the mediastinum and the carotid sheath. Drainage of parapharyngeal abscesses or removal of tumors in the parapharyngeal space

should be performed by external approaches to ensure control of the great vessels and major nerves in the retrostyloid compartment. Do this especially in

the case of tumors where the neurovascular structures may be displaced.

Penetrating injuries through the lateral wall of the oropharynx may result in injury to structures in the parapharyngeal space. Injuries that are more posterio

result in damage to the carotid artery, internal jugular vein, or upper cranial nerves. Injuries that are more anterior may result in damage to the parot id

gland, duct, or intraparotid facial nerve. Patients with these types of injuries require observation and serial neurological examinations or carotid arteriogram

to rule out vascular injuries.

We quote Leitner and Johns2on pharyngolaryngectomy for carcinoma of the posterior pharyngeal wall:

Along with neck dissection, we use an extended posterolateral pharyngectomy which includes the primary site, the retropharyngeal lymph nodes, andthe cervical lymph nodes in the resected specimen. T2 and T3 carcinomas can be effectively removed en bloc with the retropharyngeal and neck

dissection specimen. Primary closure has been used in all cases, with minimal functional rehabilitation necessary, and postoperative radiotherapy is

given to the primary site and both sides of the neck.

Sessions et al.3wrote about metastasis in hypopharyngeal cancer:

All treatment plans for hypopharyngeal cancer must consider certain facts: The overwhelming majority of these lesions metastasize to cervical lymph

nodes, and in the case of the posterior pharyngeal wall, bilateral metastasis is the rule rather than the exception; 40% of posterior pharyngeal wall

lesions and probably an equal number of upper pyriform sinus lesions metastasize to t he retropharyngeal nodes; in those patients with c linically

negative necks, the incidence of occult metastasis is substantial; and between 20% and 30% of pyriform sinus lesions, and probably an equal number

of posterior pharyngeal wall lesions, are associated with distant metastasis. Even in the lesser-stage hypopharyngeal lesions, the high rate of

regional metast ases requires inclusion of the neck(s) in all management plans.

HISTOLOGY

From outside to inside, the pharyngeal wall is formed by the buccopharyngeal fascia, muscular layer, fibrous layer, and mucosa.

The buccopharyngeal fascia is a thin layer covering the epimysium and, for all practical purpose s, corresponds to the externa l part of the epimysium.

The muscular layer (superior, middle, and inferior constrictor muscles) and its fibrous network is described previously in connection with the several parts of the

pharynx.

The fibrous layer supports the mucosa that rests on it.

The mucosa of the pharynx may be divided into three pa rts. The anterior portion consists of ciliated and pseudostratified epithelium. The trans itional layer is

columnar epithelium. The posterior layer is non-keratinized stratified squamous epithelium. Several mucous g lands are present.

PHYSIOLOGY

Coordinated movements of the palatal and pharyngeal muscles take place during both swallowing and speech. As previously mentioned the velum (soft

palate and uvula) is instrumental in c losing the nasopharynx during speech.

Certain sounds, such as fricatives, require closure of the nasopharynx by the velum. Closure of the velopharyngeal port (sphincter) is a very complex

sequence of rapid muscle actions. The soft palate elevates toward the posterior pharynx with the levator veli palatini. The muscles of the uvula draw it

upward and forward. The palatoglossus, which forms the anterior tonsillar pillar, narrows the caudal nasopharynx and draws the soft palate down.

Swallowing is a very complex sequence of involuntary events, starting with velopharyngeal closure to prevent reflux. In the first phase of swallowing, the

food bolus enters the mouth and the soft palate tenses and elevates. It is then drawn downward to strip the bolus from the valleculae. The tongue

projects the bolus from the oropharynx into the laryngopharynx.

The three paired constrictor muscles (Figs. 13-18, 13-28) are important in the second phase of swallowing (pharyngeal phase). This is an involuntary phase

that involves the serial contraction of the pharyngeal constrictor muscles in a superior-to-inferior direction to propel a bolus inferiorly.

The cricopharyngeus muscles, unlike the remaining portions of the constrictor muscles, have a tonic level of contraction, allowing them to function as the

upper esophageal sphincter. Relaxation of the cricopharyngeus muscle is necessary to allow the passage of a bolus from the pharynx to the esophagus.

Failure of the cricopharyngeus muscle to relax results in dysphagia. This may be the result of a neuromuscular disease such as amyotrophic lateral sclerosis

polymyositis, myasthenia gravis, multiple sclerosis, Parkinson's disease, or cerebrovascular accidents. Cricopharyngeal achalasia, which may be idiopathic or

the result of gastroesophageal reflux or other etiologies, is failure of the cricopharyngeus muscle to relax.

In the pharyngeal phase of swallowing, the larynx also elevates and moves forward under the base of tongue to aid in protection against aspiration. The

epiglottic folds also move caudal and backward and strip the epiglottic

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Chapter 13 Pharynx