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, ...
. It has two heads. It lies superior to the
medial pterygoid muscle
The medial pterygoid muscle (or internal pterygoid muscle), is a thick, quadrilateral muscle of the face. It is supplied by the mandibular branch of the trigeminal nerve (V). It is important in mastication (chewing).
Structure
The medial pteryg ...
. It is supplied by
pterygoid branches of the
maxillary artery
The 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 of the external carotid 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 V
3). 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 bone ...
. 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 the occipital bone. The sphenoid bone is one of the seven bones that articulate to form the o ...
. It inserts onto the
articular disc
The articular disk (or disc) 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 articula ...
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
The pterygoid processes of the sphenoid (from Greek ''pteryx'', ''pterygos'', "wing"), one on either side, descend perpendicularly from the regions where the body and the greater wings of the sphenoid bone unite.
Each process consists of a me ...
. It inserts onto the
pterygoid fovea at the neck of the
condyloid process
The condyloid process or condylar process is the process on the human and other mammalian species' mandibles that ends in a condyle, the mandibular condyle. It is thicker than the coronoid process of the mandible and consists of two portions: the ...
of 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 bone ...
.
It lies superior to the
medial pterygoid muscle
The medial pterygoid muscle (or internal pterygoid muscle), is a thick, quadrilateral muscle of the face. It is supplied by the mandibular branch of the trigeminal nerve (V). It is important in mastication (chewing).
Structure
The medial pteryg ...
.
Blood supply
The lateral pterygoid muscle is supplied by
pterygoid branches of the
maxillary artery
The 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 of the external carotid artery, ...
.
Nerve supply
The lateral pterygoid muscle is supplied by the
lateral pterygoid nerve, a branch of 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 V
3), itself a branch of the
trigeminal nerve
In neuroanatomy, the trigeminal nerve ( lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and che ...
(CN V).
Function
The primary function of the lateral pterygoid muscle is to pull the head of the condyle out of the
mandibular fossa
The mandibular fossa, also known as the glenoid fossa in some dental literature, is the depression in the temporal bone that articulates with the mandible.
Structure
In the temporal bone, the mandibular fossa is bounded anteriorly by the art ...
along the articular eminence to protrude 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 bone ...
.
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
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, ...
), 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
The geniohyoid muscle is a narrow muscle situated superior to the medial border of the mylohyoid muscle. It is named for its passage from the chin ("genio-" is a standard prefix for "chin") to the hyoid bone.
Structure
It arises from the infe ...
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
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Muscles of the head and neck