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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.
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.
Contraction of the lateral pterygoid acts to pull the disc and condyle forward within the glenoid fossa and down the articular eminence; thus, the action of this muscle serves to protrude the jaw, it with the assistance of gravity, and the digastricus muscle also opens the jaw. The other three muscles close the mouth; the masseter and the ...
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 ).
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 ]
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.
Oromandibular dystonia (OMD) is an uncommon focal neurological condition affecting the jaws, face, and mouth. [1] Oromandibular dystonia is characterized by involuntary spasms of the tongue, jaw, and mouth muscles that result in bruxism , or grinding of the teeth , and jaw closure.
Now test for stiffness or pain flexing or extending the cervical spine: "bend your neck forwards to try to touch your chin against your chest." "bend your neck back to lift your chin." "open your jaw and move it from side to side" to test for pain free normal temporo-mandibular joint movement.