Corpus: Cricopharyngeus muscle

The cricopharyngeus muscle is a component of the pharyngeal musculature. It can be considered part of the inferior pharyngeal constrictor muscle (constrictor pharyngis inferior) but is also often regarded as an independent muscle.

2.1. Classification

Anatomically, the cricopharyngeus muscle can be divided into two parts:

• the oblique part
• the fundiform part (also known as Killian's sling muscle)

2.2. Origin

The cricopharyngeus muscle originates laterally on the cricoid cartilage.

2.3. Attachment

The cranial part of the cricopharyngeus muscle, the oblique part, extends obliquely upward toward the pharyngeal raphe and intermingles with fibers from the opposite side in the posterior pharyngeal wall. The caudal part, the fundiform part, runs horizontally and similarly intermingles with fibers from the opposite side.

2.4. Peculiarities

Between these two parts of the muscle, the posterior pharyngeal wall has a weak point that is sparsely interspersed with muscle fibers, known as Killian's triangle. Below the fundiform part lies another anatomical weak spot called Laimer's triangle.

The cricopharyngeus muscle is innervated by nerve fibers from the pharyngeal plexus.

The cricopharyngeus muscle functions to constrict the laryngeal part of the pharynx, aiding in the process of swallowing by pushing food toward the esophagus. The fundiform part relaxes during swallowing to allow food to pass into the esophagus.

If the tone of the fundiform part is too high or there is a lack of coordination during swallowing, the increased pressure on Killian's triangle can cause it to give way, leading to the formation of a Zenker's diverticulum.