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The muscles responsible for the act of chewing are known as the muscles of mastication. These muscles are involved in the movement of the jaw, or mandible, and help to approximate the teeth. The four main muscles of mastication are the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. These muscles are innervated by the trigeminal nerve and its mandibular branch, which contains both sensory and motor fibres. The muscles of mastication are responsible for the elevation, depression, protrusion, retraction, and side-to-side movement of the mandible, which are essential for grinding food during the process of chewing.
| Characteristics | Values |
|---|---|
| Number of main chewing muscles | 4 |
| Names of the muscles | Temporalis, Medial Pterygoid, Lateral Pterygoid, Masseter |
| Muscle Shape | Fan-shaped, Triangular, Thick rectangular, Quadrangular |
| Muscle Functions | Elevation, Depression, Protrusion, Retraction, Side-to-side movement, Grinding food, Approximation of teeth |
| Innervation | Mandibular nerve (CN V3), a branch of the trigeminal nerve (CN V) |
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What You'll Learn
- The masseter muscle is the strongest muscle involved in mastication
- The temporalis muscle is a fan-shaped muscle that covers the temporal bone
- The medial pterygoid muscle is innervated by the medial pterygoid branch of the mandibular nerve
- The lateral pterygoid muscle is triangular and has two heads
- The four main muscles of mastication attach to the rami of the mandible
The masseter muscle is the strongest muscle involved in mastication
Mastication, or 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 the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles.
The temporalis muscle is a fan-shaped muscle that covers much of the temporal bone on the side of the skull. It functions mainly as an elevator of the mandible. The anterior and mid fibres of the temporalis muscle elevate the mandible, while the posterior fibres retract the mandible. The temporalis muscle also contributes to grinding movements by moving the mandible from side to side.
The medial pterygoid muscle is a thick, rectangular muscle with a superficial head and a deep head. It assists with elevation and protrusion of the mandible, as well as side-to-side mandibular motion to help with the grinding of food. The medial pterygoid forms a tendinous band with the insertion of the masseter called the pterygoid-masseteric sling.
The lateral pterygoid muscle is a triangular muscle with two heads: the upper and lower head. 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 works with the medial pterygoid muscle to produce side-to-side mandibular motion during chewing.
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The temporalis muscle is a fan-shaped muscle that covers the temporal bone
The temporalis muscle, also known as the temporal muscle, is a fan-shaped muscle that covers the temporal bone. It is one of the muscles responsible for mastication (chewing). The temporalis muscle is a powerful muscle of the temporomandibular joint, which is the joint that connects the lower jaw (mandible) to the temporal bone of the skull. This joint allows for movement in all planes, including the side-to-side movement of the jaw during chewing.
The temporalis muscle is a thin, broad muscle that fills the temporal fossa of the skull. The temporal fossa is a broad area of attachment located on each side of the head, superior to the zygomatic arch. The muscle fibres converge towards the deep surface of the zygomatic arch and insert into the coronoid process of the mandible. The origin of the temporalis muscle spans from the temporal fossa to the inferior temporal line of the lateral skull.
The temporalis muscle has a complex structure and can be divided into two functional parts: the anterior portion and the posterior portion. The anterior portion runs vertically and its contraction results in the elevation of the mandible (closing the mouth). The posterior portion has fibres that run horizontally, and their contraction results in the retrusion of the mandible. The middle portion, with fibres running in an oblique direction, is used for both elevation and retraction of the mandible. Additionally, the unilateral contraction of the temporalis muscle contributes to the side-to-side movement of the jaw.
The temporalis muscle receives its blood supply from the deep temporal branches of the maxillary artery and the middle temporal branches of the superficial temporal artery. It is innervated by the deep temporal branches of the mandibular nerve (V3), which is a subdivision of the trigeminal nerve. The auriculotemporal, facial, and zygomaticotemporal nerves also play a role in the temporalis muscle's function.
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The medial pterygoid muscle is innervated by the medial pterygoid branch of the mandibular nerve
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 the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. The medial pterygoid muscle is a thick rectangular muscle with a superficial head and a deep head. The superficial head originates from the maxillary tuberosity of the inferior maxilla, while the deep head is larger than the superficial head and originates from the medial surface of the lateral pterygoid plate of the sphenoid bone.
The medial pterygoid muscle fibres converge inferiorly, forming a tendon that inserts on the medial ramus of the mandible. The medial pterygoid muscle functions to assist with elevation and protrusion of the mandible. It also assists the lateral pterygoid muscle with side-to-side mandibular motion to help with the grinding of food. The medial pterygoid muscle is innervated by the medial pterygoid branch of the mandibular nerve. The mandibular nerve is the largest and inferior-most division of the trigeminal nerve. It contains both sensory and motor fibres and is the only division of the trigeminal nerve that carries motor fibres.
The medial pterygoid muscle is susceptible to injury during inferior alveolar nerve block procedures due to its proximity to the nerve. If the anaesthetic needle is placed too medially, it can accidentally inject into the muscle, causing postoperative trismus and pain when attempting to open the mouth.
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The lateral pterygoid muscle is triangular and has two heads
The act of chewing involves adduction and lateral motion of the jaw bone, which is controlled by four bilateral muscles in the face. The four main muscles of mastication are the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. These muscles originate from the surface of the skull and attach onto the rami of the mandible at the temporomandibular joint (TMJ). The temporomandibular joint allows movement in all planes.
The lateral pterygoid muscle is located deep to the temporalis and masseter muscles, spanning between the sphenoid bone and temporomandibular joint. It is one of the four masticatory muscles and acts upon the temporomandibular joint to enable chewing and biting. The muscle is innervated by the nerve to the lateral pterygoid muscle, 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.
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The four main muscles of mastication attach to the rami of the mandible
The muscles of mastication are a group of muscles responsible for the movement of the mandible at the temporomandibular joint (TMJ). They enhance the process of eating by assisting in grinding food and also function to approximate the teeth. The four main muscles of mastication are the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. These muscles originate from the surface of the skull and attach onto the rami of the mandible at the TMJ.
The temporalis muscle is a fan-shaped muscle that arises from the temporal fossa to the inferior temporal line of the lateral skull. Its 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 function to retract the mandible. The temporalis muscle also contributes to side-to-side grinding movements.
The medial pterygoid muscle is a thick rectangular muscle with a superficial head and a deep head. The deep head of the medial pterygoid is larger than the superficial head. The fibres of the medial pterygoid converge inferiorly, forming a tendon that inserts on the medial ramus of the mandible. The medial pterygoid functions to assist with elevation and protrusion of the mandible, as well as side-to-side mandibular motion to help with the grinding of food.
The lateral pterygoid muscle is triangular in shape and has two heads: the upper and lower head. It is the major protractor (opener) of the jaw. The lateral pterygoids work together to protract the jaw and independently to produce lateral movement. The lateral pterygoid fibres converge inferiorly, forming a tendon that inserts on the pterygoid fovea of the neck of the condylar process of the mandible. The lateral pterygoid functions as the sole muscle of mastication that causes depression of the mandible, as well as assisting with protrusion and side-to-side movement of the mandible.
The masseter muscle is a strong, quadrangular muscle with three layers: superficial, deep, and intermediate. The origin of the masseter muscle is the inferior zygomatic arch and the anterior two-thirds of the zygomatic arch, with a connection to the posterior aspect of the zygomatic bone. The masseter muscle fibres converge inferiorly, forming a tendon that inserts on the outer surface of the mandibular ramus and the coronoid process of the mandible. The major function of the masseter muscle is to elevate the mandible, approximate the teeth, and contribute to the protrusion of the mandible.
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Frequently asked questions
The muscles of mastication are the main chewing muscles. There are four main muscles: the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles.
The muscles of mastication are responsible for the movement of the jaw (mandible). They help with grinding food and approximating the teeth.
The four main muscles of mastication originate from the surface of the skull and attach onto the rami of the mandible at the temporomandibular joint.
The temporalis muscle has anterior, mid and posterior fibres. The anterior and mid fibres have a vertical and oblique orientation, respectively, while the posterior fibres are horizontal.
