Corpus: Cricopharyngeus muscle
1. Definition
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. Anatomy
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.
3. Innervation
The cricopharyngeus muscle is innervated by nerve fibers from the pharyngeal plexus.
4. Function
5. Pathology
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.