Palatopharyngeus muscle

Origin and insertion

Palatopharyngeus muscle originates from the posterior border of hard palate and palatine aponeurosis. The originating fibers are divided by the levator veli palatini muscle into anterior and posterior fascicles or layers, which converge into a compact muscle belly at the posterolateral border of soft palate. 

The muscle then descends posterolaterally along the pharyngeal wall, forming a notable projection posteriorly to the pharyngeal and anteriorly to the palatine tonsil, called the palatopharyngeal arch. In the oropharynx, the muscle fibers gradually diverge into a fan-shaped insertion, with most of the fibers inserting to the posterior border of thyroid cartilage, while some cross the midline and blend with the contralateral palatopharyngeus muscle.

Relations

The palatopharyngeus muscle lies directly beneath the pharyngeal mucosa within the palatopharyngeal arch. At the point where the anterior and posterior fascicles fuse, the salpingopharyngeus muscle inserts into the palatopharyngeus by fusing with its fibers.

Anteromedially to palatopharyngeus is the stylopharyngeus muscle. The two muscles maintain a close relationship as they course towards their insertion at the posterior border of thyroid cartilage.

Medially to the muscle’s origin is the musculus uvulae, the muscle that controls the shape of the uvula, while the levator veli palatini muscle is in the forceps between the anterior and posterior palatopharyngeus muscle fascicles.

Innervation

Palatopharyngeus muscle is innervated by branches of pharyngeal plexus, which in turn receives input from the vagus nerve (CN X).

Blood supply

The muscle is supplied by the ascending palatine branch of facial artery, greater palatine branch of maxillary artery and the pharyngeal branch of ascending pharyngeal artery.

Function

Palatopharyngeus muscle assists deglutition as it shortens the pharynx by elevating it superiorly, anteriorly and medially. This action closes the laryngeal airway and prevents aspiration of food. 

According to some authors the posterior fascicle of palatopharyngeus contributes to forming the palatopharyngeal sphincter (Passavant’s muscle) along with the superior pharyngeal constrictor muscle, while others list the salpingopharyngeus and soft palate muscles as additional contributors. Some even consider it a distinct muscle. Regardless of its controversial anatomy, it is known that when this sphincter contracts, it forms a notable Passavant’s ridge along the nasopharyngeal isthmus at the level of the C1 vertebra (atlas). The function of this sphincter is to seal the nasopharynx during swallowing, thus preventing food from passing from oropharynx into it.