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Pharynx

Last updated: January 9, 2022

Summarytoggle arrow icon

The pharynx is a musculomembranous cavity that connects the oral and nasal cavities to the larynx and esophagus. It is divided into the nasopharynx (extending approx. from the base of the skull to the soft palate), the oropharynx (extending approx. from the uvula to the level of the hyoid bone), and the laryngopharynx (extending approx. from C4 to C6). The pharynx plays a role in deglutition, vocalization, and air conduction. The arterial supply is derived from branches of the external carotid artery, the ascending palatine and tonsillar branches of the facial artery, the maxillary artery, and the dorsal lingual branches of the lingual artery. The pharyngeal veins drain into the internal jugular vein. The lymphatics drain directly into the deep cervical nodes, either directly or through the retropharyngeal or paratracheal nodes. Motor and sensory innervation are mainly via branches of the vagus and glossopharyngeal nerves. The pharyngeal mucosa is lined by both stratified squamous epithelium and ciliated pseudostratified epithelium with goblet cells. Diseases that may affect the pharynx include infections (pharyngitis, tonsillitis, diphtheria, infectious mononucleosis), sleep apnea, dysphagia, and pharyngeal cancer.

Overview

Functions

Regions of the pharyngeal cavity

Pharyngeal regions
Region Location Contents Function
Nasopharynx
  • Air conduction
Oropharynx
  • Air conduction and food passage
Laryngopharynx

Pharyngeal muscles

  • The muscles of the pharynx can be divided into two groups:
    • Pharyngeal constrictors (outer circular layer of muscles): contract sequentially to move the bolus of food through the pharynx into the esophagus
    • Pharyngeal elevators (inner longitudinal layer of muscles): elevate the pharyngeal wall to protect the airway as well as widen and shorten the pharynx to move the bolus of food through the pharynx into the esophagus

Pharyngeal constrictors

Constrictor muscles of the pharynx

Muscle Origin Insertion Function Innervation
Superior pharyngeal constrictor (oropharynx)
  • Pharyngeal raphe
  • Constricts the upper part of the pharynx
  • Prevents passage of food into the nose while eating
Middle pharyngeal constrictor (laryngopharynx)
  • Constricts the middle part of the pharynx
  • Transfer of food to the esophagus.
Inferior pharyngeal constrictor (laryngopharynx)

Thyropharyngeus (superior component)

  • Constricts the lower part of the pharynx

Crico­pharyngeus (inferior component)

  • Main component of the upper esophageal sphincter
  • Transfer of food to the esophagus.
  • Prevents passage of food into the trachea while eating
  • Prevents tracheobronchial aspiration and pharyngeal reflux of the gastric contents that pass through the esophagus

Pharyngeal elevators

The three longitudinal muscles are named according to their origins.

Longitudinal muscles of the pharynx

Muscle Origin Insertion Function Innervation
Stylopharyngeus
  • The styloid process
  • Elevates the pharynx and larynx
Palatopharyngeus
  • Elevation of the pharynx
Salpingopharyngeus

Vasculature

Innervation

Innervation of the pharynx
Region Sensory Motor
Nasopharynx
Oropharynx
Laryngopharynx
  • CN X (internal branch)

References: [1][2]

Unlike the rest of the digestive tract, the pharynx has no muscularis mucosae!

References: [3]

Development of the pharyngeal apparatus begins at the 4th week of gestation.

Overview of pharyngeal embryology
Brachial apparatus Structures
First pharyngeal arch
Second pharyngeal arch
Third pharyngeal arch
Fourth pharyngeal arch
  • Remaining constrictor and longitudinal muscle groups
Sixth pharyngeal arch
Second pharyngeal pouch
  • Epithelial crypts of palatine tonsil
  • Supratonsillar fossa

For more details on the embryology of the pharynx, see “Branchial apparatus” in “Embryogenesis.”

  1. Standring S. Gray's Anatomy: The Anatomical Basis of Clinical Practice. Elsevier Health Sciences ; 2016
  2. Drake R. Gray's Anatomy for Students. Elsevier ; 2019
  3. Ross MH, Pawlina W. Histology. Lippincott Williams & Wilkins ; 2006