Superior pharyngeal constrictor

Origin and insertion

The superior pharyngeal constrictor has a rather complex morphology, consisting of four parts. Each part has its own origin and they all share a unique insertion. The four parts are;

• Pterygopharyngeal part - originates from the pterygoid hamulus of sphenoid bone; 
• Buccopharyngeal part - originates from the pterygomandibular raphe of buccopharyngeal fascia; 
• Mylopharyngeal part - originates from the mylohyoid line of the mandible;
• Glossopharyngeal part - originates from the tongue.

Immediately after originating from these four structures, the muscle fibers converge posteriorly to form the superior lateral wall of the pharynx. 
The muscle fibers eventually meet with the fibers of the opposite side on the median pharyngeal raphe; a strap of connective tissue that extends between the pharyngeal tubercle on the basilar part of the occipital bone across the midsagittal plane.

Relations 

The superior constrictor muscle is located anterior to the prevertebral muscles and posterior to the buccinator muscle, from which it is separated by the pterygomandibular raphe. The slit that contains levator veli palatini muscle, the auditory tube and an upward projection of pharyngobasilar fascia separates the superior border of the superior constrictor muscle from the base of the skull. The inferior part of the muscle is separated from the middle pharyngeal constrictor muscle by a small space that contains stylopharyngeus muscle and the glossopharyngeal nerve.

The pharyngeal artery passes on the superior border of the muscle, while the tonsillar artery penetrates the superior constrictor of the pharynx at the upper border of styloglossus muscle. The superior constrictor is covered by the buccopharyngeal fascia which separates it from the retropharyngeal space located posteriorly. 

The superior pharyngeal constrictor bounds important features of the neck compartment. It makes the medial border of the parapharyngeal space, a potential space above the hyoid bone. Together with the buccopharyngeal fascia, it makes the lateral border of peritonsillar space, a potential space surrounding the palatine tonsils. 

Innervation

The superior pharyngeal constrictor receives innervation from the pharyngeal branch of vagus nerve, via the pharyngeal plexus. 

Blood supply

The majority of the superior pharyngeal constrictor is supplied from the pharyngeal branch of ascending pharyngeal artery, while the smaller part of the muscle receives blood through the tonsillar branch of facial artery. The blood from this region is drained by the pharyngeal venous plexus which ends in the internal jugular vein.

Function

The main function of the superior pharyngeal constrictor is the constriction of the upper part of the pharynx. This action facilitates the act of deglutition by pushing the bolus inferiorly, into the esophagus and stomach. Expand your knowledge with our learning materials about the mucosa and muscles of the pharynx.