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The human face has about 20 facial muscles that help with chewing and making facial expressions. The muscles of mastication (chewing food) are the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. The lateral pterygoid muscle is the sole muscle that causes depression of the mandible, or lowering of the jaw, and is therefore the muscle responsible for lowering the jaw.
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What You'll Learn
- The lateral pterygoid muscle is the primary muscle that lowers the jaw
- The medial pterygoid muscle also assists in lowering the jaw
- The temporalis muscle moves the jaw from side to side
- The masseter muscle is a strong, quadrangular muscle that covers the mandible
- The platysma muscle assists with depression of the mandible
The lateral pterygoid muscle is the primary muscle that lowers the jaw
The human face has about 20 facial muscles, which are essential for chewing and making facial expressions. The lateral pterygoid muscle is a thick, triangular muscle with two heads: the upper and lower head. The upper head arises from the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone, which forms the roof of the infratemporal fossa. The lower head originates from the lateral surface of the lateral pterygoid plate of the sphenoid bone.
The medial pterygoid muscle, which is situated in the infratemporal fossa, also plays a role in the movement of the jaw. It is composed of two heads with distinct origins. The deep head arises from the medial surface of the lateral pterygoid plate of the sphenoid bone, while the superficial head originates from the tuberosity of the maxilla. The medial pterygoid muscle functions in the elevation of the mandible and side-to-side movements during grinding and chewing.
The temporalis muscle is another muscle that contributes to the movement of the jaw. It aids in grinding movements by moving the mandible from side to side. Additionally, the masseter muscle, a strong quadrangular muscle that covers the lateral aspect of the mandible, is involved in the elevation of the mandible.
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The medial pterygoid muscle also assists in lowering the jaw
The human face has about 20 facial muscles, which are essential for chewing and making facial expressions. The medial pterygoid muscle is one of the four main muscles of mastication (chewing food), along with the temporalis, lateral pterygoid, and masseter muscles. These muscles attach to the rami of the mandible and function to move the jaw.
The medial pterygoid muscle is a quadrangular muscle situated in the infratemporal fossa. It has two heads with distinct origins. The larger, deep head arises from the medial surface of the lateral pterygoid plate of the sphenoid bone and the adjacent pyramidal process of the palatine bone. The smaller, superficial head originates from the tuberosity of the maxilla. Both heads encircle the lower fibres of the lateral pterygoid muscle.
From their points of origin, the muscle heads converge and run posterolaterally in an oblique fashion to insert onto the medial surface of the mandibular ramus, close to the angle of the mandible. The medial pterygoid muscle is innervated by the medial pterygoid branch of the mandibular nerve. Its primary blood supply comes from the pterygoid branches of the maxillary artery.
The major functions of the medial pterygoid muscle include elevating the mandible and enabling side-to-side movements during grinding and chewing. In addition to these primary roles, the medial pterygoid muscle also assists in lowering the jaw. This muscle works in conjunction with other muscles of mastication to ensure smooth and coordinated jaw movements during essential activities such as chewing and speaking.
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The temporalis muscle moves the jaw from side to side
The human face has about 20 facial muscles that are essential for chewing and making facial expressions. These muscles are part of the skeletal system and are flat, attaching to different places on the skull. They originate from bone or fascia and insert into the skin.
The temporalis muscle is one of the four primary muscles of mastication (chewing food). The other three are the medial pterygoid, lateral pterygoid, and masseter muscles. These muscles attach to the rami of the mandible and function to move the jaw. The temporalis muscle specifically contributes to grinding movements by moving the mandible from side to side.
The mandible, or jawbone, is capable of several movements, including elevation, depression, protrusion, retraction, and side-to-side movement. The lateral pterygoid muscle, which has two parts, is the primary muscle responsible for depression of the mandible, or lowering of the jaw. However, the temporalis muscle assists in the side-to-side movement of the mandible, which is essential for grinding food during the process of eating.
The medial pterygoid muscle, which is situated in the infratemporal fossa, also plays a role in side-to-side jaw movements during grinding and chewing. It has two heads with distinct origins and encircles the lower fibers of the lateral pterygoid muscle. The masseter muscle, another muscle of mastication, is strong and quadrangular, covering the lateral aspect of the ramus of the mandible. It is composed of two layers with slightly different attachments.
In summary, the temporalis muscle is one of the key muscles involved in moving the jaw from side to side, along with the medial pterygoid, lateral pterygoid, and masseter muscles, which collectively enable the various movements of the mandible during chewing and grinding food.
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The masseter muscle is a strong, quadrangular muscle that covers the mandible
The human face has about 20 facial muscles, which are essential for chewing and making facial expressions. The primary muscles that enable mastication (chewing food) are the temporalis, medial pterygoid, lateral pterygoid, and masseter muscles. These four main muscles of mastication attach to the rami of the mandible and function to move the jaw.
The masseter muscle is one of the muscles responsible for the elevation of the mandible, along with the medial pterygoid muscle. The medial pterygoid muscle is also quadrangular and is situated in the infratemporal fossa. It is composed of two heads that have two sets of origins. The larger deep head arises from the medial surface of the lateral pterygoid plate of the sphenoid bone and the adjacent pyramidal process of the palatine bone. The smaller superficial head originates from the tuberosity of the maxilla.
The lateral pterygoid muscle is the primary muscle responsible for the depression of the mandible. It is a short, thick muscle with two heads: an upper and a lower head. The upper head arises from the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone, while the lower head arises from the lateral surface of the lateral pterygoid plate of the sphenoid bone. The lateral pterygoid muscle fibres converge inferiorly, forming a tendon that inserts into a depression in the neck of the condylar process of the mandible.
The masseter muscle, along with the other muscles of mastication, plays a crucial role in chewing and grinding food by enabling the movement of the jaw.
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The platysma muscle assists with depression of the mandible
The human face has about 20 facial muscles that are essential for chewing and making facial expressions. These muscles are part of the facial skeletal system, also known as the musculoskeletal system. They originate from bone or fascia and insert into the skin.
The platysma muscle is a facial muscle that assists with depression of the mandible, or the lowering of the jaw. It is a superficial muscle of the neck, and it also helps with opening the mouth and lowering the corners of the mouth and lower lip.
The platysma is not the only muscle that contributes to the movement of the mandible. The lateral pterygoid muscle, for example, is the primary muscle responsible for the depression of the mandible. It has two parts: an upper head and a lower head. The upper head arises from the infratemporal surface of the greater wing of the sphenoid bone, while the lower head originates from the lateral surface of the lateral pterygoid plate of the same bone. The medial pterygoid muscle, on the other hand, is responsible for the elevation of the mandible.
The mandible, or jawbone, is capable of several movements, including elevation, depression, protrusion, retraction, and side-to-side motion. These movements are essential for chewing and grinding food. The muscles of mastication, or chewing, also function to approximate or bring together the teeth.
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Frequently asked questions
The lateral pterygoid muscle is the primary muscle responsible for lowering the jaw (depressing the mandible).
The lateral pterygoid muscle is a short, thick muscle with two heads: the upper and lower head. The upper head arises from the infratemporal surface and crest of the greater wing of the sphenoid bone, while the lower head originates from the lateral surface of the lateral pterygoid plate of the sphenoid bone.
The medial pterygoid, temporalis, and masseter muscles are also involved in jaw movement, along with the lateral pterygoid muscle.
The medial pterygoid muscle is responsible for elevating the mandible and facilitating side-to-side movements during grinding and chewing.
The cardinal mandibular movements include elevation, depression, protrusion, retraction, and side-to-side movement.
