Anatomy of Pharynx

BY DR. FAUZIA SIRAJ

ISRA UNI ISB. CAMPUS

LO’s

• Learning Outcomes:
• Differentiate extent, anatomical features, vascular supply, nerve supply of three parts of pharynx on anatomical basis
• List muscles of pharynx with nerve supply and action
• Name structures passing through the spaces between muscles of pharynx
• Trace origin of pharyngobasilar fascia on base of skull.
• Correlate anatomical knowledge of pharayngobasilar fascia with patency of nasopharynx
• Justify role of Eustachian tube in equalizing middle ear pressure, age related obliquity
• Describe anatomical route of spread of infections from nasopharynx to middle ear.
• Relate boundaries of tonsillar fossa and tonsillar bed with significant structures that must be protected during tonsillectomy.
• (9) Define Kilian’s dehiscence

Define

• is a muscular tube
• the superior expanded part of the alimentary system
• The pharynx is situated behind the nasal cavities, the mouth, and the larynx and may be divided into nasal, oral, and laryngeal parts.

Shape & Anatomical position

• The pharynx is funnel shaped, its upper, wider end lying under the skull and its lower, narrow.
• The pharynx is widest (approximately 5 cm) opposite the hyoid and narrowest (approximately 1.5 cm) at its inferior end, where it is continuous with the esophagus.
• The pharynx extends from the cranial base to the inferior border of the cricoid cartilage anteriorly and the inferior border of the C6 vertebra posteriorly.
• The flat posterior wall of the pharynx lies against the prevertebral layer of deep cervical fascia.

Trace origin of pharyngobasilar fascia on base of skull.

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The pharyngeal constrictors have a strong internal fascial lining, the pharyngobasilar fascia, and a thin external fascial lining, the buccopharyngeal fascia

Shape

• The pharynx has a musculomembranous wall, which is deficient anteriorly.
• Here, it is replaced by the posterior openings into the nose (choanae), the opening into the mouth, and the inlet of the larynx.
• By means of the auditory tube, the mucous membrane is also continuous with that of the tympanic cavity.

Eustachian tube, also known as the auditory tube or pharyngotympanic tube, is a tube that links the nasopharynx to the middle ear. 

Muscles of the Pharynx

• Differ from rest of GIT
• Skeletal in nature
• Longitudinal are placed inside
• Circular r incomplete anteriorly & arranged in 3 layers overlapping each other
• Circular/ constrictor muscles= fibers run in a somewhat circular direction
• superior,
• middle, & inferior constrictor muscles,
• Longitudinal

stylopharyngeus

palatopharyngeus

& salpingopharyngeus muscles, whose fibers run in a somewhat longitudinal direction.

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Longitudinal muscles

Name structures passing through the spaces between muscles of pharynx

• There are several gaps that exist between the folds of the pharyngeal constrictor muscles which allow structures to enter and exit the pharynx.
• Between the superior constrictor muscle and the skull , the levator palatini muscle, the auditory tube and the ascending palatine artery pass through.
• Between the superior and middle pharyngeal constrictor muscles, the stylopharyngeus muscle, the glossopharyngeal nerve and the stylohyoid muscle pass through.
• Between the middle and inferior pharyngeal constrictor muscles, the internal laryngeal nerve and the superior laryngeal artery and vein pass through.
• Lastly, below the inferior pharyngeal constrictor muscle, the recurrent laryngeal nerve and the inferior laryngeal artery pass through.

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The fibers of the cricopharyngeus pass horizontally around the lowest

and narrowest part of the pharynx and act as a sphincter.

Killian’s dehiscence is the area on the posterior pharyngeal wall

between the upper propulsive part of the inferior constrictor and the lower sphincteric part,

the cricopharyngeus.

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• Killian's dehiscence (also known as Killian's triangle) is a triangular area in the wall of the pharynx between the cricopharyngeus and thyropharyngeus which are the two parts of the inferior constrictors(also see Pharyngeal pouch).

• dehiscence =separation of the edges

Interior of the Pharynx�

• The pharynx is divided into three parts:
• the nasal pharynx,
• the oral pharynx,
• and the laryngeal pharynx.

Nasal Pharynx�

• This lies above the soft palate and behind the nasal cavities.
• In the submucosa of the roof is a collection of lymphoid tissue called the pharyngeal tonsil/adenoids(if it enlarged).
• The pharyngeal isthmus is the opening in the floor between the soft palate and the posterior pharyngeal wall.
• On the lateral wall is the opening of the auditory tube, the elevated ridge of which is called the tubal elevation.
• The pharyngeal recess is a depression in the pharyngeal wall behind the tubal elevation. The salpingopharyngeal fold is a vertical fold of mucous membrane covering the salpingopharyngeus muscle.

Oral Pharynx

• This lies behind the oral cavity.
• The floor is formed by the posterior one third of the tongue and the interval b/w the tongue and epiglottis.
• In the midline is the median glossoepiglottic fold,
• and on each side the lateral glossoepiglottic fold.
• The depression on each side of the

median glossoepiglottic fold is called the vallecula

• On the lateral wall on each side are the palatoglossal and the palatopharyngeal arches or folds and the palatine tonsils between them

• The palatoglossal arch is a fold of mucous membrane covering the palatoglossus muscle.
• The interval between the two palatoglossal arches is called the oropharyngeal isthmus and marks the boundary between the mouth and pharynx.
• The palatopharyngeal arch is a fold of mucous membrane covering the palatopharyngeus muscle.
• The recess between the palatoglossal and palatopharyngeal arches is occupied by the palatine tonsil.

The Lymphoid Tissue of the Pharynx�

• At the junction of the mouth with the oral part of the pharynx, and
• the nose with the nasal part of the pharynx, are collections of
• lymphoid tissue of considerable clinical importance.
• The palatine tonsils and the nasopharyngeal tonsils are the most important.
• Tonsils and Tonsillitis
• The palatine tonsils reach their maximum normal size in early childhood.
• After puberty, together with other lymphoid tissues in the body, they gradually atrophy.
• The palatine tonsils are a common site of infection, producing the characteristic sore throat
• and pyrexia.
• The deep cervical lymph node situated below and behind the angle of the mandible, which drains lymph from this organ, is usually enlarged and tender. Recurrent attacks of tonsillitis are best treated by tonsillectomy. After tonsillectomy, the external palatine vein, which lies lateral to the tonsil, may be the source of troublesome postoperative bleeding.

Laryngeal Pharynx�

• This lies behind the opening into the larynx .
• The lateral wall is formed by the thyroid cartilage and the thyrohyoid membrane.
• The piriform fossa is a depression in the mucous membrane on each side of the laryngeal inlet

Piriform Fossa and Foreign Bodies�

• The piriform fossa is a recess of mucous membrane situated on either side of the entrance of the larynx.
• It is bounded medially by the aryepiglottic folds and laterally by the thyroid cartilage.
• Clinically, it is important because it is a common site for the lodging of sharp ingested bodies such as fish bones.
• The presence of such a foreign body immediately causes the patient to gag violently.
• Once the object has become jammed, it is difficult for

It is bounded medially by the aryepiglottic folds and laterally by the thyroid cartilage.

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Sensory Nerve Supply of the Pharyngeal�Mucous Membrane�

• Nasal pharynx: The maxillary nerve (V2)
• Oral pharynx: The glossopharyngeal nerve
• Laryngeal pharynx (around the entrance into the larynx): The internal laryngeal branch of the vagus nerve
• Blood Supply of the Pharynx
• Ascending pharyngeal, tonsillar branches of facial arteries, and branches of maxillary and lingual arteries
• Lymph Drainage of the Pharynx
• Directly into the deep cervical lymph nodes or indirectly via the retropharyngeal or paratracheal nodes into the deep cervical nodes

• The pharyngeal plexus is the main nervous plexus that supplies the pharynx. The sensory branches originate from the glossopharyngeal nerve (CN IX) which runs into the plexus. The maxillary nerve (CN V/II) supplies the anterior and superior nasopharynx, while the tonsillar nerves carry fibers from both the glossopharyngeal nerve (CN XI) and the vagus nerve (CN X).
• The motor branches come from the pharyngeal plexus and carry fibers from the vagus nerve (CN X) from the cranial root of the accessory nerve (CN XI) to all the pharyngeal muscles. The inferior constrictor muscles are supplied by the external and recurrent branches of the vagus nerve (CN X).
• All three pharyngeal constrictors are supplied by the pharyngeal plexus of nerves that is formed by pharyngeal branches of the vagus and glossopharyngeal nerves and by sympathetic branches from the superior cervical ganglion (Fig. 8.46A; Table 8.6). The pharyngeal plexus lies on the lateral wall of the pharynx, mainly on the middle pharyngeal constrictor.

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Motor nerve supply

• All muscles are supplied by pharyngeal plexus EXCEPT stylopharyngeus which is supplied by glossopharyngeal

Blood supply�

• The arterial supply of the pharyngeal region comes from the facial artery, which gives the tonsillar artery and supplies the tonsils. Other branches include:
• the ascending pharyngeal artery
• the lingual artery
• the ascending and descending palatine arteries

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Summary