Inferior pharyngeal constrictor muscle

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Inferior pharyngeal constrictor muscle
Musculusconstrictorpharyngisinferior.png
Muscles of the pharynx and cheek. (Constrictor pharyngis inferior visible at bottom left.)
Gray1031.png
Muscles of the pharynx, viewed from behind, together with the associated vessels and nerves. (Inf. const. labeled at bottom center.)
Details
Latin musculus constrictor pharyngis inferior
cricoid and thyroid cartilage
pharyngeal raphe
Pharyngeal plexus of vagus nerve
Actions Swallowing
Identifiers
Gray's p.1142
Dorlands
/Elsevier
m_22/12548631
TA A05.3.01.111
FMA FMA:46623
Anatomical terms of muscle

The Inferior pharyngeal constrictor, the thickest of the three constrictors, arises from the sides of the cricoid and thyroid cartilage. Similarly to the superior and middle pharyngeal constrictor muscles, it is innervated by the vagus nerve (cranial nerve X), specifically, by branches from the pharyngeal plexus and by neuronal branches from the recurrent laryngeal nerve.

Origin and insertion[edit]

The muscle is composed of two parts. The first (and more superior) arising from the thyroid cartilage (thyropharyngeal part) and the second arising from the cricoid cartilage (cricopharyngeal part).[1]

  • On the thyroid cartilage it arises from the oblique line on the side of the lamina, from the surface behind this nearly as far as the posterior border and from the inferior cornu.
  • From the cricoid cartilage it arises in the interval between the Cricothyreoideus in front, and the articular facet for the inferior cornu of the thyroid cartilage behind.

From these origins the fibers spread backward and medialward to be inserted with the muscle of the opposite side into the fibrous pharyngeal raphe in the posterior median line of the pharynx.

The inferior fibers are horizontal and continuous with the circular fibers of the esophagus; the rest ascend, increasing in obliquity, and overlap the Constrictor medius.

Action[edit]

As soon as the bolus of food is received in the pharynx, the elevator muscles relax, the pharynx descends, and the constrictors contract upon the bolus, and convey it downward into the esophagus.

Role in human disease[edit]

Uncoordinated contraction, and/or Cricopharyngeal Spasm and/or impaired relaxation of this muscle are currently considered the main factors in development of a Zenker's diverticulum.

Motor incoordination of the cricopharyngeus can cause difficulty swallowing.

Between the two bellies of the inferior constrictor (Thyropharyngeal and Cricopharyngeal) is a small gape called 'Killian's dehiscence'. It is clinically important as a diverticulum can form where a 'balloon' of mucosa becomes trapped outside the pharyngeal boundaries. Food or other materials may reside here, which may lead to infection.

See also[edit]

Additional images[edit]

References[edit]

  1. ^ Origin, insertion and nerve supply of the muscle at Loyola University Chicago Stritch School of Medicine

External links[edit]

This article incorporates text from a public domain edition of Gray's Anatomy.