Buccopharyngeal part of superior pharyngeal constrictor

The buccopharyngeal part of superior pharyngeal constrictor is the intermediate portion of the superior pharyngeal constrictor muscle. It forms the lateral wall of the oropharynx region. This part plays an important role in coordinating the oral and pharyngeal phases of swallowing, linking the actions of the buccinator in the mouth with those of the pharyngeal constrictors.

Origin

• Arises from the pterygomandibular raphe, a fibrous band extending from the pterygoid hamulus (of the sphenoid bone) to the posterior end of the mylohyoid line of the mandible.

• The buccinator muscle arises from the anterior aspect of the same raphe, while the buccopharyngeal part of the superior constrictor arises from the posterior aspect — providing a direct anatomical and functional continuity between the oral and pharyngeal musculature.

Insertion

• Fibres pass posteriorly and medially to join the median pharyngeal raphe.

• They blend superiorly with the pterygopharyngeal part and inferiorly with the mylopharyngeal part of the superior constrictor.

Innervation

• Supplied by the pharyngeal branch of the vagus nerve (cranial nerve X) via the pharyngeal plexus, which carries motor fibres from the cranial part of the accessory nerve (CN XI).

Action

• Constriction of the oropharyngeal wall during the early phase of swallowing.

• Coordinates the transition from oral propulsion (by the buccinator) to pharyngeal constriction, ensuring smooth passage of the bolus from the oral cavity to the pharynx.

Clinical Relevance

• The pterygomandibular raphe, shared by the buccinator and the buccopharyngeal part, serves as an important intraoral landmark for dental anesthesia — particularly the inferior alveolar nerve block.

• Disruption of coordination between these muscles may contribute to oropharyngeal dysphagia.