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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).
Pain and tenderness on palpation in the muscles of mastication, or of the joint itself (preauricular pain – pain felt just in front of the ear). Pain is the defining feature of TMD and is usually aggravated by manipulation or function, [ 2 ] such as when chewing, clenching, [ 12 ] or yawning, and is often worse upon waking.
Muscles. There are various muscles that contribute to occlusion of the teeth including the muscles of mastication and other accessory muscles. The temporalis, masseter, medial and lateral pterygoids are the muscles of mastication and these contribute to the elevation, depression, protrusion and retraction of the mandible.
In anatomy, the masseter [help 1] is one of the muscles of mastication. Found only in mammals, it is particularly powerful in herbivores to facilitate chewing of plant matter. [5] The most obvious muscle of mastication is the masseter muscle, since it is the most superficial and one of the strongest.
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.
Trismus may be caused by spasm of the muscles of mastication or a variety of other causes. [3] Temporary trismus occurs much more frequently than permanent trismus. [ 4 ] It is known to interfere with eating, speaking, and maintaining proper oral hygiene.
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 ...