The Muscles of Mastication more commonly known as the muscles of the jaw consist of three muscles the Temporalis, Masseter and Pterygoid Muscles which work together to move the mandible at the Temporomandibular Joint. These three muscles are solely responsible for the chewing action, grinding the teeth, moving our mandible from side to side and also assisting us to speak.
The Temporalis Muscle
The Temporalis muscle is the muscle which assists us to close our mouth, grind our teeth and move our mouth from side to side when we are chewing. The origin point of the Temporalis Muscle is along the entire rim of the Temporal Fossa of the Skull and it’s insertion point is the coronoid process of the mandible.
The Masseter Muscle
The Masseter muscle is a very thick muscle made up in two parts the Outer Masseter muscle and the Inner Masseter muscle. These muscles can be seen when a person clenches their teeth and are primarily the main chewing muscle and combined are one of the strongest muscles in the entire human body. The origin point of the outer Masseter muscle is along the Zygomatic Arch and it’s insertion point is on the surface of the Ramus of the Mandible. The origin point of the inner Masseter muscle is from the rear of the Zygomatic Arch and it’s insertion point is on the upper surface of the Ramus of the Mandible.
The Pterygoid Muscles
The Pterygoid muscles is made up of two muscles the Lateral Pterygoid and the Medial Pterygoid which are located on the inside of the Ramus of the Mandible and work in tandem with the Masseter muscle to assist in the chewing action, jaw rotation, side to side movement of the mouth and the projection of the lower jaw. The Lateral Pterygoid muscle also assist in opening the mouth. These two muscles share the same features with two origin point and as a result both have two heads.
The Upper Head of the Lateral Pterygoid muscle’s origin point is from the lateral plate of the Ethmoid bone and the origin point of the Lower Head is from the Pterygoid Plate. Both heads merge to share the same insertion point which is the articular capsule which covers the condyle of the mandible’s ramus. The Lateral Pterygoid muscle is located higher to the medial Pterygoid muscle.
The Superficial Head of the medial Pterygoid muscle has an origin point from the Pterygoid Plate and the Deep Head of the Medial Pterygoid muscle has an origin point from the Palatine bone. Both heads merge to form a broad insertion point on the inner surface of the Ramus of the Mandible.