Chewing muscles
Last reviewed: 23.04.2024
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Chewing muscles develop on the basis of the first visceral (mandibular) arch. These muscles originate on the bones of the skull and attach to the lower jaw - the only movable bone, providing a variety of its movements in humans in the temporomandibular joint.
The masticatory muscle (m.masseter) is quadrangular in shape, divided into a superficial and a deep part.
The superficial part begins with a thick tendon on the zygomatic process of the upper jaw and the anterior two-thirds of the zygomatic arch. The bundles pass down and back and attach to the chewing tuberosity of the lower jaw. The deep part of the muscle is partially covered with superficial, begins on the posterior third of the lower edge and the entire inner surface of the zygomatic arch. The bundles of this part extend almost vertically from top to bottom and are attached from the lateral surface of the coronoid process of the lower jaw to its base.
Function: lifts the lower jaw, developing great strength. The superficial part of the muscle also participates in the extension of the lower jaw forward.
Innervation: trigeminal nerve (V).
Blood supply: chewing and transverse arteries.
The temporal muscle (m.temporalis) is fan-shaped, occupying the same area (temporal fossa) on the lateral surface of the skull. This muscle begins on the entire surface of the temporal fossa and the inner surface of the temporal fascia. The muscle bundles, converging downwards, continue into the thick tendon, which is attached to the coronoid process of the lower jaw.
Function; lifts the lower jaw, acts mainly on the front teeth ("biting muscle"). The posterior fascicles pull the lower jaw forwardward.
Innervation: trigeminal nerve (V).
Blood supply: deep and superficial temporal arteries.
The medial pterygoid muscle (m pterygoideus medialis) is thick, quadrangular. The muscle begins in the pterygoid fossa of the same spine of the sphenoid bone. The muscle bundles pass downward, laterally and posteriorly, continuing into the strongly developed tendon plate, which attaches to the pterygoid tuberosity on the inner surface of the angle of the lower jaw. The direction of the fibers of this muscle corresponds to the direction of the fibers of the masticatory muscle.
Function: lifts the lower jaw, pushes the lower jaw forward.
Innervation: trigeminal nerve (V).
Blood supply: pterygoid branches of the maxillary artery.
The lateral pterygoid muscle (m.pterygoideus lateralis) - a thick, short muscle, begins with two heads - the upper and lower. The upper head begins on the maxillary surface and the transverse crest of the large wing of the sphenoid bone, the lower head - on the outer surface of the lateral plate of the pterygoid process of the same bone. The bunches of the two muscle heads, converging, are guided posteriorly and laterally and are attached to the anterior surface of the neck of the lower jaw, to the joint capsule of the temporomandibular joint and to the intraarticular disk.
Function: with bilateral contraction of the muscle, the lower jaw extends forward, pulls forward the joint capsule and the intraarticular disk of the temporomandibular joint. With one-sided cutting, shifts the lower jaw in the opposite direction.
Innervation: trigeminal nerve (V).
Blood supply: pterygoid branches of the maxillary artery.
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