Victor Forge
The muscles responsible for the act of chewing, or mastication, are known as the muscles of mastication. They are a group of four muscles that attach to the mandible (the lower jaw) and facilitate its movement at the temporomandibular joint (TMJ). These muscles are the temporalis, masseter, medial pterygoid, and lateral pterygoid. The muscles of mastication enable essential functions such as chewing and grinding food through movements including protrusion, retraction, elevation, depression, and side-to-side motion.
| Characteristics | Values |
|---|---|
| Number of muscles | 4 |
| Muscle names | Temporalis, Masseter, Medial Pterygoid, Lateral Pterygoid |
| Muscle shape | Fan-shaped, Rectangular, Triangular, Quadrangular |
| Muscle parts | Deep and superficial |
| Muscle origin | Skull, Zygomatic bone, Sphenoid bone, Maxillary tuberosity, Palatine bone |
| Muscle attachment | Mandible, Coronoid process of the mandible, Ramus of the mandible |
| Muscle function | Elevation, depression, protrusion, retraction, side-to-side movement, grinding, chewing |
| Innervation | Trigeminal nerve, Mandibular nerve, Lateral pterygoid nerve, Medial pterygoid nerve, Masseteric nerve |
| Blood supply | Masseteric artery, Maxillary artery, Pterygoid branches of the maxillary artery |
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What You'll Learn
- The masseter muscle is the most powerful muscle of mastication
- The temporalis muscle is fan-shaped and covers much of the temporal bone
- The medial pterygoid muscle has two heads: deep and superficial
- The lateral pterygoid muscle has two heads: superior and inferior
- The mandibular nerve is the largest division of the trigeminal nerve
The masseter muscle is the most powerful muscle of mastication
The muscles of mastication are a group of muscles responsible for the chewing movement of the mandible at the temporomandibular joint (TMJ). They enhance the process of eating, assist in grinding food, and function to approximate the teeth. The four main muscles of mastication are the temporalis, masseter, medial pterygoid, and lateral pterygoid muscles.
The temporalis muscle is fan-shaped and covers much of the temporal bone on the side of the skull. It originates from the temporal fossa to the inferior temporal line of the lateral skull. The fibres of the temporalis muscle converge inferiorly, forming a tendon that exits the temporal fossa, passing underneath the zygomatic arch, and inserting on the coronoid process of the mandible. The function of the anterior and mid fibres of the temporalis muscle is to elevate the mandible, while the posterior fibres function to retract the mandible.
The medial pterygoid muscle is a thick rectangular muscle with a superficial head and a deep head. The deep head is larger than the superficial head. The superficial head originates from the front of the skull, while the deep head attaches to the skull adjacent to the eye socket. Both heads attach to the jaw. The medial pterygoid muscle functions to elevate the jaw and assist in the production of lateral movement.
The lateral pterygoid muscle has a triangular shape with two heads: superior and inferior. It is the major protractor (opener) of the jaw. Both heads originate adjacent to the eye socket and converge into a tendon that attaches to the jaw. The lateral pterygoid muscle functions to protrude and depress the mandible. Unilateral contraction on one side moves the mandible to the opposite side, allowing for alternating side-to-side movements during chewing.
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The temporalis muscle is fan-shaped and covers much of the temporal bone
The act of chewing involves adduction and lateral motion of the jaw bone. It is controlled by four bilateral muscles in the face. These muscles are known as the muscles of mastication. They include the temporalis, masseter, medial pterygoid, and lateral pterygoid muscles. The temporalis muscle is a fan-shaped muscle that covers much of the temporal bone. It fills the temporal fossa, with anterior fibres that have a vertical orientation, mid fibres that have an oblique orientation, and posterior fibres that have a horizontal orientation. The origin of the temporalis muscle spans from the temporal fossa to the inferior temporal line of the lateral skull. The temporalis muscle fibres converge inferiorly, forming a tendon that exits the temporal fossa, passing underneath the zygomatic arch, and inserting on the coronoid process of the mandible. The function of the anterior and mid fibres of the temporalis muscle is to elevate the mandible, while the posterior fibres retract the mandible. The temporalis muscle receives innervation by deep temporal branches of the mandibular nerve.
The masseter muscle is the most powerful muscle of mastication. It is quadrangular in shape and is split into two regions: deep and superficial. It covers the other muscles of mastication. The superficial region originates from the skull below the eye socket, while the deep part originates from the skull above the jaw. Both parts attach to the jaw. The masseter muscle is responsible for elevating the jaw.
The medial pterygoid muscle is a thick rectangular muscle with a superficial head and a deep head. The deep head is larger than the superficial head. The superficial head originates from the maxillary tuberosity of the inferior maxilla, while the deep head originates from the medial aspect of the lateral pterygoid plate of the sphenoid bone. Both heads attach to the ramus of the mandible. The medial pterygoid muscle functions to elevate the mandible and assist in the production of lateral movement.
The lateral pterygoid muscle is triangular in shape and has two heads: superior and inferior. It is the major protractor (opener) of the jaw. Both heads originate adjacent to the eye socket and converge into a tendon that attaches to the jaw. The lateral pterygoids work together to protract the jaw and independently to produce lateral movement.
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The medial pterygoid muscle has two heads: deep and superficial
The act of chewing, or mastication, involves adduction and lateral motion of the jaw bone. It is controlled by four bilateral muscles in the face. The lower jaw, or mandible, connects to the temporal bone of the skull via the temporomandibular joint, allowing movement in all planes.
The medial pterygoid muscle is a thick rectangular muscle with a superficial head and a deep head. The deep head is larger than the superficial head. The muscle fibres converge inferiorly, forming a tendon that inserts on the medial ramus of the mandible. The medial pterygoid muscle is located in the infratemporal fossa, lying deep to the masseter and temporalis muscles. The outer surface of the muscle lies against the inner surface of the mandible.
The superficial head of the medial pterygoid originates from the maxillary tuberosity of the inferior maxilla. The deep head originates from the medial surface of the lateral pterygoid plate of the sphenoid bone. The two heads are separated by the inferior head of the lateral pterygoid muscle at their origin. The deep head forms the bulk of the muscle. The medial pterygoid muscle is innervated by the medial pterygoid branch of the mandibular nerve. Its principal blood supply stems from the pterygoid branches of the maxillary artery.
The medial pterygoid muscle is involved in several actions. Unilateral contraction of the medial pterygoid causes a slight medial rotation of the mandible. When this occurs simultaneously with the contraction of the ipsilateral lateral pterygoid, the same-sided part of the mandible swings anteriorly and medially. Bilateral contraction of the medial pterygoid elevates and protrudes the mandible. In synergy with other masticatory muscles, these actions facilitate chewing.
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The lateral pterygoid muscle has two heads: superior and inferior
Chewing, or mastication, involves adduction and lateral motion of the jaw bone. It is controlled by four bilateral muscles in the face. The lower jaw, or mandible, connects to the temporal bone of the skull via the temporomandibular joint, allowing movement in all planes. The muscles of mastication include the temporalis, masseter, medial pterygoid, and lateral pterygoid muscles.
The lateral pterygoid muscle has two heads: the superior head and the inferior head. It is a triangular muscle that lies in the infratemporal fossa, superior to the medial pterygoid muscle. The superior head, or belly, is formed by the most superomedial fibres of the muscle. It is the smaller of the two heads and arises from the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone, which form the roof of the infratemporal fossa. The superior head inserts into the anteromedial part of the articular capsule and articular disc of the temporomandibular joint. The inferior head, or belly, is much wider than the superior one and is three times larger. It originates from the lateral surface of the lateral pterygoid plate of the sphenoid bone. The inferior head inserts onto the pterygoid fovea at the neck of the condyloid process of the mandible. Fibres from both heads merge and run posterolaterally to insert onto a shallow depression on the anterior aspect of the neck of the mandible. The nerve to the superior head and lateral half of the inferior head receives fibres from the buccal nerve, itself a branch of the mandibular nerve. The inferior head acts on the inferior compartment of the temporomandibular joint, facilitating the hinge-like rotation that occurs between the mandibular condyle and the inferior surface of the articular disc.
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The mandibular nerve is the largest division of the trigeminal nerve
The muscles responsible for the act of chewing are known as the muscles of mastication. These muscles consist of the temporalis, masseter, medial pterygoid, and lateral pterygoid. The masseter muscle is the most powerful muscle of mastication. These muscles enable functions such as chewing and grinding, with movements including protrusion, retraction, elevation, depression, and rotation.
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Frequently asked questions
The chewing muscle is known as the muscle of mastication. There are four main muscles of mastication: the temporalis, masseter, medial pterygoid, and lateral pterygoid muscles.
The temporalis muscle is situated in the temporal fossa, the masseter muscle is located in the cheek area, and the medial and lateral pterygoids lie in the infratemporal fossa.
The primary function of the muscles of mastication is to enable chewing and grinding movements of the mandible or lower jaw. They facilitate movements such as protrusion (forward movement), retraction (backward movement), elevation (closing the mouth), depression (opening the mouth), and side-to-side movement.
The muscles of mastication are innervated by the trigeminal nerve, specifically the mandibular branch (V3), which carries both sensory and motor fibres. Each muscle receives innervation from specific branches of the mandibular nerve.
The masseter muscle is quadrangular or rectangular in shape and has two parts: a deep part and a superficial part. It is the most powerful muscle of mastication and is responsible for elevating the mandible.
