Internal pterygoid

Internal Pterygoid

The Internal Pterygoid or Medial Pterygoid is a thick, quadrilateral muscle of mastication located in the human skull. It is one of the four muscles responsible for the movements of the jaw and plays a crucial role in the process of chewing.

Anatomy

The Internal Pterygoid muscle originates from the medial surface of the lateral pterygoid plate, the pyramidal process of the palatine bone, and the maxillary tuberosity. It inserts into the medial angle of the mandible, a point it shares with the masseter muscle.

Function

The primary function of the Internal Pterygoid is to elevate the mandible, assisting in the closing of the mouth. It also contributes to protrusion of the mandible, moving the lower jaw forward. When only one side contracts, the Internal Pterygoid causes the mandible to move to the opposite side, assisting in side-to-side grinding movements.

Clinical Significance

Dysfunction or damage to the Internal Pterygoid can result in trismus, a condition characterized by an inability to open the mouth fully. This can be caused by trauma, infection, or surgery involving the muscle. Additionally, spasms of the Internal Pterygoid can contribute to temporomandibular joint disorder (TMJ), a condition that can cause pain and difficulty in moving the jaw.

See Also

• External Pterygoid
• Masseter muscle
• Temporalis muscle
• Mastication