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'''Jaw Closing Muscles'''
'''Jaw Closing Muscles'''
All jaw closing muscles derivie from the first visceral arch and are innervated by the mandibular branch of the trigeminal nerve (CN V3)
All jaw closing muscles are derived from the first visceral arch and are innervated by the mandibular branch of the trigeminal nerve (CN V3)
*Masseter muscle
*Masseter muscle
==Jaw Articulation==
==Jaw Articulation==
'''Temperomandibular Joint'''
*Articulation between the condylar process of the mandible and the mandibular process of the skull
*Compartmentalised joint for rotational movement and lateral slide (grinding)
*Fibro-cartilagenous disc between bones
*Synovial joint
*Caudal dislocation prevented by a prominent retro-articular process (enlargement of the fossa)
'''Mandibular Symphasis'''
*Rostral end of mandible
*Fibrous joint bewteen the left and right halves of the mandible
*Only in dogs and ruminants
*Precise occlusion
*Mandibular bones can move apart independently by rotation
*Stops jaw breakages (Canid)
==Species Differences==
==Species Differences==
*Canids have a larger digasticus muscle than herbivores (but smaller in comparison with jaw closing muscles)
*Canids have a larger digasticus muscle than herbivores (but smaller in comparison with jaw closing muscles)
*In the dog large forces are needed to shut jaws so the point of articulation of the temporomandibular joint is level with the teeth
*In the horse the muscle insertion site for the masseter is large to snap jaw shut