Superior pharyngeal constrictor
Superior pharyngeal constrictor muscle is one of three pharyngeal constrictor muscles whose main function is to facilitate the process of deglutition. This muscle has a complex morphology, as it consists of four parts;
- Pterygopharyngeal part
- Buccopharyngeal part
- Mylopharyngeal part
- Glossopharyngeal part
Apart from its role in deglutition, the superior pharyngeal constrictor muscle is an important anatomical landmark bounding some of the main compartments of the neck, such as peritonsillar and parapharyngeal space.
This article will discuss the anatomy and function of the superior pharyngeal constrictor muscle.
|Origin||Pterygoid hamulus, pterygomandibular raphe, posterior end of mylohyoid line of mandible, the tongue|
|Insertion||Pharyngeal tubercle on basilar part of occipital bone|
|Action||Constricts wall of pharynx during swallowing|
|Innervation||Branches of pharyngeal plexus (CN X)|
|Blood supply||Pharyngeal branch of ascending pharyngeal artery, tonsillar branch of facial artery|
Origin and insertion
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.
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 pharyngotympanic 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.
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.
Superior pharyngeal constrictor receives innervation from the pharyngeal branch of vagus nerve, via the pharyngeal plexus.
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.
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.
Tonsillectomy is a surgical procedure in which the tonsils get removed. It is a common procedure usually performed to prevent the complications of inflamed tonsils. One of the most serious complications is the formation of peritonsillar abscess, a collection of pus that is usually located between the superior pharyngeal constrictor muscle and the tonsils.
The rich innervation of the tonsils allows for this procedure to be performed under local anesthesia, which is usually achieved by blockage of the glossopharyngeal nerve through the fibers of superior pharyngeal constrictor muscle.