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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 mandible is moved primarily by the four muscles of mastication: the masseter, medial pterygoid, lateral pterygoid and the temporalis. These four muscles, all innervated by V 3, or the mandibular division of the trigeminal nerve, work in different groups to move the mandible in different directions. Contraction of the lateral pterygoid acts ...
The digastric muscle (also digastricus) (named digastric as it has two 'bellies') is a bilaterally paired suprahyoid muscle located under the jaw.Its posterior belly is attached to the mastoid notch of temporal bone, and its anterior belly is attached to the digastric fossa of mandible; the two bellies are united by an intermediate tendon which is held in a loop that attaches to the hyoid bone.
The styloid process gives attachments to several muscles, and ligaments. [1] It serves as an anchor point for several muscles associated with the tongue and larynx. [citation needed] stylohyoid ligament [citation needed] stylomandibular ligament [citation needed] styloglossus muscle (innervated by the hypoglossal nerve) [citation needed]
The mylohyoid muscle originates from the anterior (front) part of the mylohyoid line. [1] Rarely, the mylohyoid muscle may originate partially from other surfaces of the mandible. [ 2 ] The posterior (back) part of this line, near the alveolar margin , gives attachment to a small part of the superior pharyngeal constrictor muscle , and to the ...
The temporalis muscle is covered by the temporal fascia, also known as the temporal aponeurosis. This fascia is commonly used in tympanoplasty, or surgical reconstruction of the eardrum. The temporalis muscle is accessible on the temples, and can be seen and felt contracting while the jaw is clenching and unclenching.
The action of the muscle during bilateral contraction of the entire muscle is to elevate the mandible, raising the lower jaw. Elevation of the mandible occurs during the closing of the jaws. The masseter parallels the medial pterygoid muscle, but it is stronger and superficial fibres can cause protrusion.
A mental spine is a small projection of bone on the posterior aspect of the mandible in the midline. There are usually four mental spines: two superior and two inferior. Collectively they are also known as the genial tubercle, [1] genial apophysis and the Latin name spinae ment