Pterygoideus lateralis muscle

The pterygoideus lateralis muscle is located under the base of the skull, rostro medially to the temporomandibular joint.

Conformation: It is a short, thick, conoid muscle, almost entirely fleshy. Its base is attached to the sphenoid region and its apex ends at the neck of the mandible. In humans, it is initially divided into two distinct bundles between which the maxillary artery usually passes. It is simple in all domestic animals; it is particularly low in ruminants.

Insertions: It originates on the ventral surface of the sphenoid bone and on the lateral side of the pterygoid process. It ends at the pterygoid fovea of ​​the neck of the mandible and the adjacent part of the temporomandibular joint capsule.

Functions: Bilateral contraction pulls the lower jaw in a rostral direction. When the contraction is unilateral, the protraction is accompanied by a movement of the rostral end of the jaw towards the side opposite to that occupied by the muscle; the latter is therefore adductor for the corresponding mandible and abductor for the opposite. The alternating functioning of the right then left pterygoid muscles is particularly visible during mastication in large ungulates.

Vessels and nerves: This muscle is vascularized by the collateral arteries of the maxilla: pterygoid, buccal, inferior alveolar. Innervation is provided by a small branch of the maxillary nerve.

Variations: In equines, the lateral pterygoid muscle is thick, conoid, clearly distinct from the medial pterygoid muscle. It has an orientation almost parallel to the base of the skull and its termination occupies a relatively large pterygoid fovea.