Inferior pharyngeal constrictor muscle

The inferior pharyngeal constrictor muscle is one of the three pharyngeal constrictor muscles that form the muscular wall of the pharynx. It plays a crucial role in the process of swallowing by constricting the pharyngeal cavity and propelling the bolus of food from the oropharynx to the esophagus.

Anatomy

The inferior pharyngeal constrictor muscle is the thickest of the pharyngeal constrictors and is located in the lower part of the pharynx. It is composed of two parts:

• The thyropharyngeal part, which originates from the oblique line of the thyroid cartilage.
• The cricopharyngeal part, which originates from the lateral aspect of the cricoid cartilage.

Both parts insert into the pharyngeal raphe, a fibrous seam that runs along the posterior midline of the pharynx.

Function

The primary function of the inferior pharyngeal constrictor muscle is to facilitate swallowing. During the act of swallowing, the muscle contracts sequentially with the other pharyngeal constrictors to constrict the pharyngeal cavity, pushing the food bolus downward into the esophagus. The cricopharyngeal part acts as a sphincter at the top of the esophagus, preventing air from entering the esophagus during breathing and preventing reflux of esophageal contents.

Innervation

The inferior pharyngeal constrictor muscle is innervated by the pharyngeal plexus, which is primarily composed of fibers from the vagus nerve (cranial nerve X). The cricopharyngeal part also receives some innervation from the recurrent laryngeal nerve, a branch of the vagus nerve.

Blood Supply

The blood supply to the inferior pharyngeal constrictor muscle is primarily from the ascending pharyngeal artery, a branch of the external carotid artery.

Clinical Significance

Dysfunction of the inferior pharyngeal constrictor muscle, particularly the cricopharyngeal part, can lead to swallowing disorders such as dysphagia. Cricopharyngeal achalasia, a condition where the cricopharyngeal muscle fails to relax properly, can cause difficulty in swallowing and may require medical or surgical intervention.

Also see

• Pharyngeal constrictor muscles
• Swallowing
• Vagus nerve
• Dysphagia

Gallery

• 
  Muscles of the pharynx, viewed from behind, together with the associated vessels and nerves.
• 
  Sagittal section of the pharynx, showing the pharyngeal constrictor muscles.
• 
  Lateral view of the pharynx, highlighting the inferior pharyngeal constrictor muscle.