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The four classical muscles of mastication elevate the mandible (closing the jaw) and move it forward/backward and laterally, facilitating biting and chewing. Other muscles are responsible for opening the jaw, namely the geniohyoid , mylohyoid , and digastric muscles (the lateral pterygoid may play a role).
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 ).
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 ...
This also supplies the tensor tympani muscle and the tensor veli palatini muscle. The medial pterygoid nerve is a main trunk from the mandibular nerve, before the division of the trigeminal nerve - this is unlike the lateral pterygoid muscle, and all other muscles of mastication which are supplied by the anterior division of the mandibular nerve.
This action causes the muscle to keep food pushed back on the occlusal surface of the posterior teeth, as when a person chews. By keeping the food in the correct position when chewing, the buccinator assists the muscles of mastication. [4] It aids whistling and smiling, and in neonates it is used to suckle.
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 muscle which can 'cancel' or to some degree reverse the action of the muscle. Muscle synergies are noted in parentheses when relevant. O (Occurrences) Number of times that the named muscle row occurs in a standard human body. Here it may also be denoted when a given muscles only occurs in a male or a female body.
Receives sensation from the face, mouth and nasal cavity, and innervates the muscles of mastication. VI Abducens: Mainly motor Nuclei lying under the floor of the fourth ventricle Pons. Located in the superior orbital fissure. Innervates the lateral rectus, which abducts the eye. VII Facial: Both sensory and motor Pons (cerebellopontine angle ...