Superior Pharyngeal Constrictor

What is the Superior Pharyngeal Constrictor

The superior pharyngeal constrictor is a thin quadrilateral muscle in the oropharynx region. It is the highest of the three circular constrictor muscles of the pharynx, which acts on the oropharynx to help with swallowing food. 

Anatomy

Location and Attachments

Origin	The pterygoid hamulus of the sphenoid, pterygomandibular raphe, back of the mylohyoid line of the mandible, and the tongue
Insertion	Median pharyngeal raphe

The muscle is divided into four parts, based on its points of origin.

Origin

• Pterygopharyngeal part: The lower one-third of the posterior border of the medial pterygoid process of the sphenoid, mainly the pterygoid hamulus.
• Buccopharyngeal part: The pterygomandibular raphe, which is a tendinous extension of the buccopharyngeal fascia.
• Mylopharyngeal part: The posterior part of the mylohyoid line of the mandible.
• Glossopharyngeal part: Consists of only a few fibers, arising from the sides of the tongue.

Insertion

After originating from these separate points, the muscle fibers blend and course posteriorly and medially to meet the fibers from the contralateral side. As they come together, they insert along the median pharyngeal raphe. The raphe itself inserts into the pharyngeal tubercle on the occipital bone’s basilar part.

Relations With Surrounding Muscles and Structures

Anterior and Posterior Relations

The superior constrictor lies anterior to the prevertebral muscles and posterior to the buccinator, one of the primary muscles in the cheek. The pterygomandibular raphe, where the muscle inserts, also separates it from the buccinator muscle. 

The buccopharyngeal fascia covers the posterior surface of the muscle, forming a wall between this muscle and the retropharyngeal space, an open space behind the pharynx and esophagus, that provides space for swallowing.

Superior Relations

The gap between the muscle’s upper border and the base of the skull is enclosed by the pharyngeal aponeurosis, forming the sinus of Morgagni. Through this region pass the levator veli palatini muscle, the Eustachian (auditory) tube, and a superior projection of the pharyngobasilar fascia.

The most important neurovascular relation in this region is the pharyngeal artery that courses across the upper border of the muscle.

Inferior Relations

A narrow interval separates the inferior border of the superior constrictor from the middle constrictor. The two muscles overlap at the back, with the lower margin of the superior constrictor lying deep to the upper border of the middle constrictor.

The space between the two transmits the stylopharyngeus muscle, stylohyoid ligament, as well as the glossopharyngeal and lingual nerves.

Lateral Relations

The tonsillar artery penetrates the lateral side of the superior constrictor near the upper border of the styloglossus, a vital extrinsic muscle forming the tongue. 

The muscle also creates the medial wall of the parapharyngeal space. Together with the buccopharyngeal fascia, it forms the lateral wall of the peritonsillar space surrounding the palatine tonsil.

Function

Action

Constricting the upper portion of the pharynx to help propel the bolus down during swallowing

It plays a central role in the early phase of swallowing. As the chewed food, or bolus, enters the pharynx, the suprapharyngeal muscles relax, allowing the pharynx to descend back to its resting position. The superior constrictor then contracts to narrow the upper pharyngeal cavity, guiding the bolus downward. Working in sequence with the middle and inferior constrictors, it helps generate a coordinated, wave-like movement that propels the bolus from the oropharynx toward the esophagus.

Antagonists

It doesn’t have an antagonist because it is involved in swallowing, where the muscles work in a coordinated sequence rather than in opposing pairs.

Innervation

Nerve

Pharyngeal plexus (vagus nerve)

The muscle is innervated by the vagus nerve’s (CN X) pharyngeal branch, through the pharyngeal plexus.

Blood Supply

Artery

The pharyngeal trunk of the ascending pharyngeal artery and the tonsillar artery

Primary blood supply to the muscle comes from the pharyngeal trunk of the ascending pharyngeal artery. The tonsillar artery, a branch of the facial artery, also provides additional blood supply. Both arteries are derived from the external carotid artery.