TMJ Muscles

Muscles of Mastication(All attach onto the mandible)

• Temporalis– Contributes to side-to-side grinding (lateral deviation) of mandible.– Tight temporalis may be involved with tension headaches and TMJ dysfunction

• Masseter– Square-shaped muscle, divided into superficial & deep layers.– Prime mover of mandibular elevation at TMJ.– Large parotid glands are superficial to masseter.– Proportional to its size, strongest muscle in body.

• Lateral Pterygoid– Aka external pterygoid.– Lateral deviation is important for grinding and chewing food.– Hypertonicity could excessively pull on TMJ structures causing dysfunction.

• Medial Pterygoid– Aka internal pterygoid– Fairly thick, quadrilateral muscle– Fiber directions are identical to masseter but medial pterygoid is internal to mandible

and masseter is external.

Temporalis

O: Temporal fossa

I: Coronoid process/Ramus of mandible

A: Elevation of Mandible

N: CN V (Trigeminal nerve)

Palpation: page 83

Masseter

O: Inferior margins of both zygomatic bone and zygomatic arch of temporal bone

I: Angle, ramus`, coronoid of a mandible

A: Elevates, protracts and retracts the mandible

N: CN V (Trigeminal Nerve)

Palpation: page 86

Lateral Pterygoid

O: Sphenoid bone

I: Mandible & TMJ

A: Protraction of Mandible

N: CN V (Trigeminal nerve)

Palpation: page 89

Medial Pterygoid

O: Sphenoid bone

I: Internal surface of Mandible

A: Elevates and protracts the mandible

N: CN V (Trigeminal nerve)

Palpation: page 92