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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 depressor anguli oris arises from the lateral surface of the mandible. [1] Its fibers then converge. It is inserted by a narrow fasciculus into the angle of the mouth. [1] At its origin, it is continuous with the platysma muscle, and at its insertion with the orbicularis oris muscle and risorius muscle.
A concerted effort of the lateral pterygoid muscles helps in lowering the mandible and opening the jaw. Unilateral action of a lateral pterygoid muscle causes contralateral excursion (a form of mastication), usually performed in concert with the medial pterygoids. [citation needed] When they work independently, they can move the mandible side ...
The mylohyoid muscle elevates the hyoid bone and the tongue. This is particularly important during swallowing and speaking. Alternatively, if other muscles are used to keep the position of the hyoid bone fixed, then the mylohyoid muscle depresses the mandible. [1] It also functions as reinforcing the floor of mouth. [1]
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.
Depression, in an anatomical term of motion for movement in an inferior direction. ... mandible. Lateral pterygoid muscle; lower lip. Depressor labii inferioris muscle;
Mandible: Underneath skin of lower lip Opening mouth and sliding lower jaw left and right: Lower jaw: Depression, lateral: Depressor angulus oris: Mandible: Underneath skin at corners of mouth Smiling: Corners of mouth: Lateral elevation: Zygomaticus major: Zygomatic bone: Underneath skin at corners of mouth (dimple area), orbicularis oris
The jaw elevator muscles develop the main forces used in mastication. The force generated during routine mastication of food such as carrots or meat is about 70 to 150 newtons (16 to 34 lbf ). The maximum masticatory force in some people may reach up to 500 to 700 newtons (110 to 160 lbf ).