The stylopharyngeus muscle is a muscle in the head. It originates from the

temporal styloid process The temporal styloid process is a slender bony process of the temporal bone extending downward and forward from the undersurface of the temporal bone just below the ear. The styloid process gives attachments to several muscles, and ligaments. Str ...

. Some of its fibres insert onto the thyroid cartilage, while others end by intermingling with proximal structures. It is innervated by the glossopharyngeal nerve (cranial nerve IX). It acts to elevate the larynx and pharynx, and dilate the pharynx, thus facilitating swallowing.

Structure

The stylopharyngeus is a long, slender, tapered pharyngeal muscle. It is cylindrical superiorly, and flattened inferiorly. It passes inferior-ward along the side of the

pharynx The pharynx (: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates ...

between the superior pharyngeal constrictor (situated deep to the stylopharyngeus) and the

middle pharyngeal constrictor The middle pharyngeal constrictor is a fan-shaped muscle located in the neck. It is one of three pharyngeal constrictor muscles. It is smaller than the inferior pharyngeal constrictor muscle. The middle pharyngeal constrictor originates from th ...

(situated superficial to the stylopharyngeus), before spreads out beneath the mucous membrane.

Origin

It arises from (the medial side of the base of) the

. It is the only muscle of the pharynx not to originate in the pharyngeal wall.

Insertion

Some of its fibers are lost in the superior and middle constrictor muscles, some merge with the lateral glossoepiglottic fold, while still others join with those of the palatopharyngeus muscle to insert onto the posterior border of the thyroid cartilage.

Innervation

The stylopharyngeus is the only muscle of the pharynx innervated by the glossopharyngeal nerve (CN IX) (all others being instead innervated by the vagus nerve (CN X)) by special visceral motor neurons with their cell bodies in the rostral part of the nucleus ambiguus.

Blood supply

The stylopharyngeus receives arterial supply from the paryngeal branch of the ascending pharyngeal artery.

Lymphatic drainage

The lymphatic drainage of the region of the stylopharyngeus muscle is mediated by the middle

cervical lymph nodes Cervical lymph nodes are lymph nodes found in the neck. Of the 800 lymph nodes in the human body, 300 are in the neck. Cervical lymph nodes are subject to a number of different pathological conditions including tumours, infection and inflamma ...

that drain into the supraclavicular lymph nodes.

Relations

The stylopharyngeus is the medial-most and most vertical of the three styloid muscles. The muscle is situated in between the external carotid artery and

internal carotid artery The internal carotid artery is an artery in the neck which supplies the anterior cerebral artery, anterior and middle cerebral artery, middle cerebral circulation. In human anatomy, the internal and external carotid artery, external carotid ari ...

. On the lateral pharyngeal wall, it is situated posterior to the superior constrictor muscle, and anterior to the buccopharyngeal fascia. The

glossopharyngeal nerve The glossopharyngeal nerve (), also known as the ninth cranial nerve, cranial nerve IX, or simply CN IX, is a cranial nerve that exits the brainstem from the sides of the upper Medulla oblongata, medulla, just anterior (closer to the nose) to t ...

runs on the lateral side of this muscle, and crosses over it to reach the tongue.

Variation

Supernumerary muscles originating from other nearby regions of the skull may be present, and may be clinically significant.

Development

Embryological origin is the third

pharyngeal arch The pharyngeal arches, also known as visceral arches'','' are transient structures seen in the Animal embryonic development, embryonic development of humans and other vertebrates, that are recognisable precursors for many structures. In fish, t ...

. Its development commences between the 4th and 7th week of gestation.

Function

The stylopharyngeus: *elevates the

larynx The larynx (), commonly called the voice box, is an organ (anatomy), organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The opening of larynx into pharynx known as the laryngeal ...

*elevates the

*dilates the pharynx to permit the passage of a large food bolus, thereby facilitating swallowing

Additional images

File:Epiglotic cartilage.jpg, Stylopharyngeus muscle. File:Gray141.png, Left temporal bone. Inferior surface. File:Gray950.png, The cartilages of the larynx. Posterior view. File:Gray957.png, Side view of the larynx, showing muscular attachments. File:Gray1019.png, Extrinsic muscles of the tongue. Left side. File:Gray1031.png, Muscles of the pharynx, viewed from behind, together with the associated vessels and nerves. File:Slide9aaa.JPG, Stylopharyngeus muscle File:Slide16aaa.JPG, Stylopharyngeus muscle File:Slide3ggg.JPG, Stylopharyngeus muscle File:Slide8hhh.JPG, Stylopharyngeus muscle

References

{{Authority control Muscles of the head and neck