Inferior pharyngeal constrictor muscle

The inferior pharyngeal constrictor muscle is a muscle of the throat that assists in swallowing by constricting the pharynx when contracted. It is the lowest of the three pharyngeal constrictor muscles that coordinate the downward movement of food through the pharynx to the esophagus in a swallowing motion.

The inferior pharyngeal constrictor is composed of two parts, the cricopharyngeus and the thyropharyngeus, which connect the pharynx to the cricoid cartilage and the thyroid cartilage respectively.

Origin
The inferior pharyngeal constrictor muscle originates from the cricoid and thyroid cartilage.

Cricopharyngeus
The cricopharyngeus, the lower part of the inferior pharyngeal constrictor, originates from the lateral aspect of the arch of the cricoid cartilage.

Thyropharyngeus
The thyropharyngeus, the upper part of the inferior pharyngeal constrictor, originates from the oblique laminar line of the thyroid cartilage and the fibrous cricothyroid arch.

Insertion
The inferior pharyngeal constrictor muscle inserts at the lower pharyngeal raphe.

The cricopharyngeus does not have a definite insertion because the left and right cricopharyngeus connect to each other behind the pharynx, forming essentially a single muscle. The thyropharyngeus inserts at the lower pharyngeal raphe.

Action
In addition to the main function as part of the swallowing motion, the lower part of the inferior pharyngeal constrictor, the cricopharyngeus, acts as a sphincter around the esophagus.