Changes

All jaw closing muscles are derived from the first visceral arch and are innervated by the '''mandibular''' branch of the '''trigeminal''' nerve ([[Cranial Nerves - Anatomy & Physiology|CN V3]]).

All jaw closing muscles are derived from the first visceral arch and are innervated by the '''mandibular''' branch of the '''trigeminal''' nerve ([[Cranial Nerves - Anatomy & Physiology|CN V3]]).

The '''masseter muscle''' originates from the  [[Skull and Facial Muscles - Anatomy & Physiology#Maxilla|maxilliary]] region of the skull and the zygomatic arch. It inserts on the wide area on the caudal side of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]]. It has several divisions and causes '''unilateral''' and '''bilateral''' contraction. It also protrudes the jaw.

The '''masseter muscle''' originates from the  [[Skull and Facial Muscles - Anatomy & Physiology#Maxilla|maxillary]] region of the skull and the zygomatic arch. It inserts on the wide area on the caudal side of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]]. It has several divisions and causes '''unilateral''' and '''bilateral''' contraction. It also protrudes the jaw.

The '''lateral pterygoid muscle''' originates from the [[Skull and Facial Muscles - Anatomy & Physiology#Pterygoid Bone (os pterygoideum)|pterygopalatine]] region of the skull. It inserts on the lateral aspect of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]]. It also protrudes the jaw (one-sided contraction).

The '''lateral pterygoid muscle''' originates from the [[Skull and Facial Muscles - Anatomy & Physiology#Pterygoid Bone (os pterygoideum)|pterygopalatine]] region of the skull. It inserts on the lateral aspect of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]]. It also protrudes the jaw (one-sided contraction).

The articulation between the condylar process of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]] and the mandibular process of the skull. It is a compartmentalised joint for rotational movement and lateral slide (grinding). It is a '''synovial joint'''. Caudal dislocation is prevented by a prominent retro-articular process (enlargement of the fossa).

The articulation between the condylar process of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]] and the mandibular process of the skull. It is a compartmentalised joint for rotational movement and lateral slide (grinding). It is a '''synovial joint'''. Caudal dislocation is prevented by a prominent retro-articular process (enlargement of the fossa).

===Mandibular Symphasis===

===Mandibular Symphysis===

Located at the rostral end of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]]. It is a '''fibrous joint''' between the left and right halves of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]]. It is only found in dogs and ruminants. It has a precise occlusion and the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|Mandibular]] bones can move apart independently by rotation. It stops jaw breakages (Canid).

Located at the rostral end of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]]. It is a secondary cartilaginous joint between the left and right halves of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]]. It is only found in dogs and ruminants. It has a precise occlusion and the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|Mandibular]] bones can move apart independently by rotation. It stops jaw breakages (Canid).

==Species Differences==

==Species Differences==

===Hebivores===

===Hebivores===

Herbivores have large '''masseter''' and '''pterygoid''' muscles for extensive chewing. Herbiverous species have a limited '''digastricus''' muscle. In the horse, the muscle insertion site for the '''masseter''' is large to snap jaw shut.

Herbivores have large '''masseter''' and '''pterygoid''' muscles for extensive chewing. Herbivorous species have a limited '''digastricus''' muscle. In the horse, the muscle insertion site for the '''masseter''' is large to snap jaw shut.

===Carnivores===

===Carnivores===

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[[Category:Teeth - Anatomy & Physiology]]

[[Category:Teeth - Anatomy & Physiology]]

[[Category:Musculoskeletal System - Anatomy & Physiology]]

[[Category:Musculoskeletal System - Anatomy & Physiology]]

[[Category:Feeding Control]]

[[Category:Feeding Control]]

[[Category:A&P Done]]

[[Category:A&P Done]]