Inferior pharyngeal constrictor muscle

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.)
Latin musculus constrictor pharyngis inferior
Gray's subject #244 1142
Origin cricoid and thyroid cartilage
Insertion    pharyngeal raphe
Artery
Nerve Pharyngeal plexus of vagus nerve
Actions Swallowing

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.

Contents

Origin and insertion

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

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

Role in human disease

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.

See also

Additional images

References

  1. ^ LUC icon

External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.


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