The pharynx

The pharynx

الدكتور سعد يونس سليمانكلية طب نينوى

Lecture Objectives

Anatomy Divisions of the pharynx The pharyngeal wall .. Killian’s Dehiscence Nerve supply of the pharynx Waldeyer’s ring… Palatine tonsilsRetropharyngeal space ( Space of Gillette) Parapharyngeal Space Functions of the pharynx

Anatomy of The pharynxShape

Irregular conical Fibromuscular tube Length: 12-14 cm

Nasopharynx Oropharynx Laryngopharynx (Hypopharynx)

Anatomy of The pharynxDivisions

Form the upper part of air & food passages Extends from base of skull to inferior border of cricoid cartilage anteriorly and inferior border of C6 posteriorly Widest portion (5cm) at hyoid Narrowest portion (1.5cm) at its caudal end(Pharyngo-oesophageal junction)
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Nasopharynx

Extends from base of the skull to the level of hard palate
communicates anteriorly with the nasal cavity through the posterior nares (choanae) so it has a respiratory function

Three important structures in the nasopharynx

Nasopharyngeal tonsil (adenoid) Openings of the Eustachian tubes Fossa of Rosenmuller

Nasopharynx ( Summary)

Anteriorly; nasal cavityPosterosuperiorly; basisphenoid …adenoidPosteriorly; extend down to the junction of the hard and soft palate in front of C1 (atlas)Inferiorly; the superior surface of the soft palate and opens into the oropharynx.Laterally; openings of the Eustachian tubes Eustachian cushions, fossae of Rosenmuller.

Oropharynx

Behind the oral cavity (in front of 2nd&3rd Cervical vertebrae) from the level of hard palate to the level of hyoid bone( ant. to C2& C3 ). Communicates: Anteriorly with the oral cavity Superiorly with the nasopharynx Inferiorly with the hypopharynx The palatine tonsils lie laterally between the anterior and posterior pillars

Oropharynx (cont.)

The dividing line between the oropharynx and mouth is: junction of hard palate and soft palate above anterior pillar laterally junction of anterior 2/3 and posterior 1/3 of the tongue (circumvallate papillae).

Digestive function Anterior: anterior tonsillar pillar Posterior: superior constrictor Superior: soft palate Inferior: base of tongue, superior epiglottis Laterally: palatoglossal and palatopharyngeal arches

The anterior pillar formed by palatoglossus muscle

The posterior pillar formed By palatopharyngeus m
The tonsils lie between the Two pillars

Hypopharynx

Behind the Larynx (in front of 3rd to 6th Cervical vertebra) from the level of hyoid to the upper end of esophagus at the level of the inferior border of the cricoid cartilage inferiorly Communicates: Anteriorly with the Larynx Superiorly with the oropharynx Inferiorly with the oesophagus

Cricoid cartilage

The hypopharynx does not only lie behind the larynx BUT also Projects laterally on each side of the larynx So it is formed of : Postcricoid region ( behind the larynx) Two pyriform fossa (on each side of the larynx) Posterior pharyngeal wall
Seen from behind
Cross section

The structure of pharyngeal wall 

The wall is formed of 4 layers 1-Mucous membrane 2- Pharyngeal aponeurosis 3-Muscle coat 4-Bucco-pharyngeal fascia
Stratified squamous epithelium except the nasopharynx, it is pseudostratified ciliated columnar epithelium with goblet cells
This is a strong fibrous layer attached superiorly to the base of the skull. It is strengthened posteriorly by strong fibrous band called “median pharyngeal raphe”. This raphe attaches above to the base of the skull, and gives insertion to the constrictor muscles. Circular (outer layer), superior, middle and inferior constrictor muscles Longitudinal ( internal ), Stylopharyngeus Salpingopharyngeus Palatopharyngeus
A thin coat of connective tissue, this fascia is loosely attached posteriorly to the prevertebral fascia and laterally it is connected to the styloid process and the carotid sheath.


Inferior constrictor muscle has two parts: Thyropharyngeus with oblique fibers. Cricopharyngeus with transverse fibers.


Killian’s Dehiscence This is a potential gap between fibers of thyropharyngeus and cricopharyngeus muscles. Normally cricopharyngeus muscle relaxes when food bolus is pushed by the pharynx towards the esophagus. If this does not happen, mucosa will bulge outward forming a pharyngeal pouch.

Nerve Supply

Motor ---► X Except : Stylopharyngeus --►IXTensor palati --► VSensory --►Nasopharynx: VOropharynx: IXLaryngopharynx: X Autonomic:sympathetic: SCGParasympathetic: through VII


Waldeyer’s ring: Definetion: It is a collection of lymphoid tissue in the nasopharynx and oropharynx at the entrance to the airodigestive tract.

It is composed of:

Hypertrophy of the lymphoid tissue of Waldeyer’s ring occurs in the earlier years of childhood, probably in response to URTI. Maximum hypertrophy occurs between 4-10 years, thereafter some regression in size is to be expected, and in old age it atrophies.

Waldeyer’s ring is characterized by:

Palatine tonsils
Two masses of lymphoid tissue situated on each side of oropharynx Its medial surface is pitted by a number of crypts. Laterally the tonsil is enclosed by a dense fibrous capsule separating the tonsil from the superior constrictor (tonsillar bed) plane for dissection of the tonsil during tonsillectomy.

Blood supply of the tonsil

From the External Carotid Artery & its branches 1- Tonsillar artery (from Facial Artery) 2-Ascending palatine artery (from Facial Artery) 3-Ascending pharyngeal Artery (from external carotid) 4-Descending palatine artery ( from Maxillary artery. 5-Dorsalis lingulae artery (from Lingual artery)

Venous drainage

To the paratonsillar veins which drains to the pharyngeal plexus. The plexus drain to the internal jugular veins.

Retropharyngeal space ( Space of Gillette)

It is a potential space that lies between the pre vertebral fascia posteriorly and the buccopharyngeal fascia anteriorly. It extend from the base of the skull to the superior mediastenum. It contains retropharyngeal lymph nodes of Rouviere: few lymph nodes that disappear spontaneously during the 3rd or 4th year of life.

Prevertebral space

Retropharyngeal space
Parapharyngeal space
Bucco-pharyngeal fascia
Prevertebral fascia

Parapharyngeal Space

lateral to the pharynx and connects posteriorly with the retropharyngeal space. It extends from the base of the skull to the hyoid bone (i.e. it is lateral to the nasopharynx and oropharynx ).


Boundaries of parapharyngeal space
Medially: superior constrictor muscle laterally: medial ptrygoid muscle, mandible and deep lobe of parotid gland. Posteriorly: the prevertebral muscle and fascia.

Contents of parapharyngeal space

Deep cervical lymph nodes. Last 4 cranial nerve and cervical sympathetic trunk. Great vessels of the neck; common carotid artery and internal jugular vein.

Functions of the pharynx

Food and air inlet. Play an important role in speech through vocal resonance and articulation. The immunologic function of Waldeyer's ring. Deglutition; which is divided into three stage; Oral stage ( voluntary ) Pharyngeal stage ( involuntary ) Eosophageal stage ( involuntary )

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