The pterygoid muscles are two of the four muscles of mastication, located in the infratemporal fossa of the skull. These muscles are: lateral pterygoid and medial pterygoid.
The primary function of the pterygoid muscles is to produce movements of the mandible at the temporomandibular joint. Both muscles are innervated by branches of the mandibular division of the trigeminal nerve (CN V3), and receive their blood supply from branches of the maxillary artery.
This article will introduce you to the anatomy and function of the pterygoid muscles.
|Definition and function||Muscles of mastication that produce movements of the jaw.|
|Muscles||Lateral pterygoid, medial pterygoid|
|Innervation||Branches of the mandibular division of the trigeminal nerve (CN V3)|
|Blood supply||Pterygoid branches of the maxillary artery|
Lateral pterygoid: Protrusion, depression, medial movement of mandible.
Medial pterygoid: Protrusion, elevation, medial movement of mandible
Lateral pterygoid muscle
The lateral pterygoid is a short, two-headed muscle, located in the infratemporal fossa of the skull. The smaller superior head arises from the infratemporal crest of the greater wing of sphenoid bone, while the larger inferior head arises from the lateral surface of the lateral pterygoid plate. The fibres of both muscle heads merge and insert on the pterygoid fovea on the neck of the mandible. Some fibres from the superior head insert on the capsule of the temporomandibular joint and its articular disc.
The lateral pterygoid muscle is innervated by the nerve to the lateral pterygoid muscle, which is a branch of the mandibular division of the trigeminal nerve (CN V3). It receives blood supply from the pterygoid branches of the maxillary artery and the ascending palatine branch of the facial artery.
The function of the lateral pterygoid muscle is to protrude and depress the mandible when contraction is bilateral. In unilateral contraction, the lateral pterygoid muscle moves the mandible medially.
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Medial pterygoid muscle
The medial pterygoid muscle is a thick quadrilateral muscle that arises by two heads, a superficial and a deep head. The smaller superficial head originates from the maxillary tuberosity and pyramidal process of palatine bone. The larger deep head originates from the medial surface of the lateral plate of the pterygoid process and the pyramidal process of the palatine bone. From their origin, the muscle fibers run posteroinferiorly and laterally, surrounding the lower fibers of the lateral pterygoid muscle. Together, the two heads of the medial pterygoid muscle insert onto the triangular impression located on the medial surface of the mandible.
The medial pterygoid muscle is innervated by the medial pterygoid branch of the mandibular division of the trigeminal nerve (CN V3). It receives blood supply from the pterygoid branches of the maxillary artery.
The bilateral contraction of this muscle elevates the mandible and closes the mouth. Furthermore, because of the directions of its muscle fibers, this muscle pulls the mandible forward and produces the movement also known as protrusion. In contrast, the unilateral contraction of the medial pterygoid, together with lateral pterygoid, causes the swinging of the mandible to the opposite side. These movements are crucial for the act of chewing.
The in-depth anatomy of the medial pterygoid is waiting for you here.
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