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

mastication Chewing or mastication is the process by which food is comminution, crushed and ground by the teeth. It is the first step in the process of digestion, allowing a greater surface area for digestive enzymes to break down the foods. During the mast ...

. It has two heads. It lies superior to the medial pterygoid muscle. It is supplied by pterygoid branches of the

maxillary artery The maxillary artery (eg, internal maxillary artery) supplies deep structures of the face. It branches from the external carotid artery just deep to the neck of the mandible. Structure The maxillary artery, the larger of the two terminal branches ...

, 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 nerves, cranial nerve (CN V). Unlike the other divisions of the trigeminal nerve (ophthalmic nerve, maxillary nerve) which ...

, CN V₃). It depresses and protrudes the

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

. 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 The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the basilar part of occipital bone, basilar part of the occipital bone. The sphenoid bone is one of the seven bon ...

. It inserts onto the

articular disc The articular disc (or disk) is a thin, oval plate of fibrocartilage present in several joints which separates synovial cavities. This separation of the cavity space allows for separate movements to occur in each space. The presence of an articul ...

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 joint, synovial articulation between the temporal bone of the skull above and the condylar process of mandible be ...

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

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 Temporomandibular joint dysfunction (TMD, TMJD) is an umbrella term covering pain and dysfunction of the muscles of mastication (the muscles that move the jaw) and the temporomandibular joints (the joints which connect the Human mandible, mand ...

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