Lateral pterygoid muscle
Encyclopedia
The lateral pterygoid is a muscle of mastication
with two heads. It lies superiorly to the medial pterygoid
.
bone, and the lower/inferior head on the lateral surface of the lateral pterygoid plate
.
Inferior head inserts onto the neck of condyle of the mandible; upper/superior head inserts onto the articular disc and fibrous capsule
of the TMJ.
, specifically the V3 branch, innervates the lateral pterygoid muscle.
along the articular eminence to protrude the mandible. A concerted effort of the lateral pterygoid muscles acts in helping lower the mandible and open the jaw whereas unilateral action of a lateral pterygoid produces contralateral excursion (a form of mastication
), usually performed in concert with the medial pterygoids
.
Unlike the other three muscles of mastication, the lateral pterygoid is the only muscle of mastication that assists in depressing the mandible (opening the jaw). At the beginning of this action it is assisted by the digastric, mylohyoid
and geniohyoid muscles.
Mastication
Mastication or chewing 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 more efficient break down by enzymes. During the mastication process, the food is positioned between the teeth for grinding by...
with two heads. It lies superiorly to the medial pterygoid
Medial pterygoid muscle
The medial pterygoid , is a thick, quadrilateral muscle of mastication.The mandibular branch of the fifth cranial nerve, the trigeminal nerve, innervates the medial pterygoid muscle.-Origin and insertion:...
.
Origin and insertion
The upper/superior head originates on the infratemporal surface and infratemporal crest of the greater wing of the sphenoidSphenoid bone
The sphenoid bone is an unpaired bone situated at the base of the skull in front of the temporal bone and basilar part of the occipital bone.The sphenoid bone is one of the seven bones that articulate to form the orbit...
bone, and the lower/inferior head on the lateral surface of the lateral pterygoid plate
Lateral pterygoid plate
The lateral pterygoid plate of the sphenoid is broad, thin, and everted; its lateral surface forms part of the medial wall of the infratemporal fossa, and gives attachment to the lateral pterygoid muscle; its medial surface forms part of the pterygoid fossa, and gives attachment to the medial...
.
Inferior head inserts onto the neck of condyle of the mandible; upper/superior head inserts onto the articular disc and fibrous capsule
Fibrous membrane of articular capsule
The fibrous membrane of articular capsule is attached to the whole circumference of the articular end of each bone entering into the joint, and thus entirely surrounds the articulation....
of the TMJ.
Innervation
The mandibular branch of the fifth cranial nerve, the trigeminal nerveTrigeminal nerve
The trigeminal nerve contains both sensory and motor fibres. It is responsible for sensation in the face and certain motor functions such as biting, chewing, and swallowing. Sensory information from the face and body is processed by parallel pathways in the central nervous system...
, specifically the V3 branch, innervates the lateral pterygoid muscle.
Function
The primary function of the lateral pterygoid muscle is to pull the head of the condyle out of the mandibular fossaMandibular fossa
The mandibular fossa is the depression in the temporal bone that articulates with the mandibular condyle. In the temporal bone, the mandibular fossa is bounded, in front, by the articular tubercle; behind, by the tympanic part of the bone, which separates it from the external acoustic meatus; it is...
along the articular eminence to protrude the mandible. A concerted effort of the lateral pterygoid muscles acts in helping lower the mandible and open the jaw whereas unilateral action of a lateral pterygoid produces contralateral excursion (a form of mastication
Mastication
Mastication or chewing 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 more efficient break down by enzymes. During the mastication process, the food is positioned between the teeth for grinding by...
), usually performed in concert with the medial pterygoids
Medial pterygoid muscle
The medial pterygoid , is a thick, quadrilateral muscle of mastication.The mandibular branch of the fifth cranial nerve, the trigeminal nerve, innervates the medial pterygoid muscle.-Origin and insertion:...
.
Unlike the other three muscles of mastication, the lateral pterygoid is the only muscle of mastication that assists in depressing the mandible (opening the jaw). At the beginning of this action it is assisted by the digastric, mylohyoid
Mylohyoid muscle
The mylohyoid muscle is a muscle running from the mandible to the hyoid bone, forming the floor of the oral cavity. It is named for its two attachments, with the prefix "mylo" coming from the Greek word for "molar". These muscles are mesodermal in origin...
and geniohyoid muscles.