The lateral pterygoid muscle (or external pterygoid muscle) is a muscle of

mastication Chewing or mastication is the process by which food is crushed and ground by teeth. It is the first step of digestion, and it increases the surface area of foods to allow a more efficient break down by enzymes. During the mastication process, th ...

. It has two heads. It lies superior to the medial pterygoid muscle. It is supplied by pterygoid branches of the maxillary artery, and the lateral pterygoid nerve (from the

mandibular nerve In neuroanatomy, the mandibular nerve (V) is the largest of the three divisions of the trigeminal nerve, the fifth cranial nerve (CN V). Unlike the other divisions of the trigeminal nerve ( ophthalmic nerve, maxillary nerve) which contain only ...

, CN V₃). It depresses and protrudes the

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bon ...

. When each muscle works independently, they can move the mandible side to side.

Structure

The lateral pterygoid muscle has an upper head and a lower head. * The upper head originates on the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone. It inserts onto the articular disc and fibrous capsule of the

temporomandibular joint In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral synovial articulation between the temporal bone of the skull above and the mandible below; it is from these bones that it ...

. * The lower head originates on the lateral surface of the lateral pterygoid plate. It inserts onto the

pterygoid fovea The pterygoid fovea (occasionally called the pterygoid pit or the pterygoid depression) is located on the mandible. It is a concave surface on the medial side of the neck of the condyloid process of the mandible. It is located posterior to the ...

at the neck of the condyloid process of the

. It lies superior to the medial pterygoid muscle.

Blood supply

The lateral pterygoid muscle is supplied by pterygoid branches of the maxillary artery.

Nerve supply

The lateral pterygoid muscle is supplied by the lateral pterygoid nerve, a branch of the

(CN V₃), itself a branch of the

trigeminal nerve In neuroanatomy, the trigeminal nerve (literal translation, lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for Sense, sensation in the face and motor functions ...

(CN V).

Function

The primary function of the lateral pterygoid muscle is to pull the head of the condyle out of the mandibular fossa along the articular eminence to protrude the

. A concerted effort of the lateral pterygoid muscles helps in lowering the mandible and opening the jaw. Unilateral action of a lateral pterygoid muscle causes contralateral excursion (a form of

), usually performed in concert with the medial pterygoids. When they work independently, they can move the mandible side to side. Unlike the other three muscles of mastication, the lateral pterygoid alone can assist in depressing the mandible (opening the jaw). At the beginning of this action it is assisted by the digastric, mylohyoid and geniohyoid muscles.

Clinical significance

The lateral pterygoid muscle may be involved in temporomandibular joint dysfunction.

Additional images

File:Gray146.png, Sphenoid bone. Anterior and inferior surfaces. File:Gray177.png, Mandible. Inner surface. Side view. File:Gray510.png, Plan of branches of internal maxillary artery. File:Gray778.png, Distribution of the maxillary and mandibular nerves, and the submaxillary ganglion.

References

External links

* () * *
Cross section at tufts.edu
{{Authority control Muscles of the head and neck