Middle pharyngeal constrictor

At a glance

English

Middle pharyngeal constrictor

Latin (TA2)

Constrictor medius pharyngis

System

Muscle

Region

Whole body

Side

Paired, left and right

About the middle pharyngeal constrictor

The middle constrictor is the central one of the three curved muscles forming the outer coat of the pharyngeal wall. It is fan-shaped, with a narrow front attachment on the hyoid bone and a broad back edge where it meets its partner. It is smaller than the inferior constrictor and sits at the level of the oral part of the pharynx.

Its origin runs the full length of the upper edge of the hyoid's greater horn, from the lesser horn and from the lower end of the stylohyoid ligament. Two parts are named accordingly: the chondropharyngeal part from the lesser horn and the ceratopharyngeal part from the greater horn. From this narrow origin the fibres spread out widely. The upper ones climb and overlap the superior constrictor, the middle ones run horizontally, and the lowest pass down deep to the inferior constrictor. All end in the pharyngeal raphe in the back midline.

The three constrictors are arranged like stacked flowerpots, each overlapped from outside by the one below. Gaps between them let structures enter the pharynx. Between the middle and superior constrictors pass the stylopharyngeus muscle and the glossopharyngeal nerve, while between the middle and inferior muscles run the internal laryngeal nerve and the superior laryngeal vessels. The lingual artery runs just deep to the front of the muscle.

During swallowing, after the bolus has entered the pharynx, the constrictors contract in a wave from top to bottom that squeezes it down towards the oesophagus. The middle constrictor also influences the shape of the airway and is active in breathing and speech. It is supplied by vagal fibres carried in the pharyngeal plexus and by the ascending pharyngeal artery, with branches of the facial and lingual arteries. Weakness of the constrictors after a stroke or nerve injury leaves food pooling in the throat and raises the risk of choking or aspiration.

Attachments, action and supply

Origin

Upper edge of the hyoid's greater horn, the lesser horn and the stylohyoid ligament.

Insertion

Pharyngeal raphe in the posterior midline, where it meets its partner from the other side.

Action

Constricts the middle pharynx during swallowing, propelling food downwards.

Nerve supply

Pharyngeal plexus (vagus nerve).

Blood supply

Ascending pharyngeal artery, with branches of the facial and lingual arteries.