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In humans, the mandible, or lower jaw, is connected to the temporal bone of the skull via the temporomandibular joint. This is an extremely complex joint which permits movement in all planes. The muscles of mastication originate on the skull and insert into the mandible, thereby allowing for jaw movements during contraction.
The mylohyoid muscle or diaphragma oris is a paired muscle of the neck. It runs from the mandible to the hyoid bone, forming the floor of the oral cavity of the mouth. [1] It is named after its two attachments near the molar teeth. It forms the floor of the submental triangle.
The orbicularis oris is not a simple sphincter muscle like the orbicularis oculi; it consists of numerous strata of muscular fibers surrounding the orifice of the mouth, but having different direction. It consists partly of fibers derived from the other facial muscles which are inserted into the lips, and partly of fibers proper to the lips.
The facial muscles are just under the skin (subcutaneous) muscles that control facial expression. They generally originate from the surface of the skull bone (rarely the fascia), and insert on the skin of the face. When they contract, the skin moves. These muscles also cause wrinkles at right angles to the muscles’ action line. [2]
Muscle Action Risorius: Smirk Buccinator: Aids chewing by holding cheeks flat Levator labii superioris: Elevates upper lip Levator labii superioris alaeque nasi muscle: Snarl Levator anguli oris: Soft smile Nasalis: Flare nostrils Orbicularis oris muscle: Purse Lips Depressor septi nasi: Depresses nasal septum Procerus: Moves skin of forehead
These may include the thick muscle in the cheek that closes the jaw (masseter muscle) and the broad muscle that draws back the lower jaw and closes the mouth (temporalis muscle). Some patients may also experience involuntary contractions of the wide muscle at the side of the neck (platysmal muscle). This muscle draws down the corner of the ...
The lateral pterygoid muscle (or external pterygoid muscle) is a muscle of mastication. It has two heads. It lies superior to the medial pterygoid muscle. It is supplied by pterygoid branches of the maxillary artery, and the lateral pterygoid nerve (from the mandibular nerve, CN V 3). It depresses and protrudes the mandible. When each muscle ...
In anatomy, the temporalis muscle, also known as the temporal muscle, is one of the muscles of mastication (chewing). It is a broad, fan-shaped convergent muscle on each side of the head that fills the temporal fossa , superior to the zygomatic arch so it covers much of the temporal bone . [ 1 ]