External pterygoid muscles

External Pterygoid Muscles

The external pterygoid muscles, also known as the lateral pterygoid muscles, are a pair of muscles of mastication located in the head and neck. These muscles play a crucial role in the movement of the jaw and are essential for chewing and speaking.

Anatomy

The external pterygoid muscles are divided into two distinct heads: the superior head and the inferior head.

Superior Head

The superior head originates from the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone. It inserts into the articular disc and the capsule of the temporomandibular joint (TMJ).

Inferior Head

The inferior head originates from the lateral surface of the lateral pterygoid plate of the sphenoid bone. It inserts into the pterygoid fovea on the neck of the mandible.

Function

The primary function of the external pterygoid muscles is to assist in the opening of the jaw. They also contribute to the protrusion and lateral movement of the mandible. When both muscles contract simultaneously, they help in the depression of the mandible, allowing the mouth to open. When they contract unilaterally, they cause the mandible to move side to side, which is essential for the grinding motion during chewing.

Innervation

The external pterygoid muscles are innervated by the lateral pterygoid nerve, a branch of the mandibular nerve (V3), which is a division of the trigeminal nerve (cranial nerve V).

Blood Supply

The blood supply to the external pterygoid muscles is primarily provided by branches of the maxillary artery, specifically the pterygoid branches.

Clinical Significance

Dysfunction or spasm of the external pterygoid muscles can lead to temporomandibular joint disorder (TMD), which is characterized by pain, difficulty in opening the mouth, and clicking or popping sounds in the jaw. Treatment may involve physical therapy, medication, or in severe cases, surgical intervention.

Related Pages

• Muscles of mastication
• Temporomandibular joint
• Mandibular nerve
• Trigeminal nerve
• Maxillary artery
• Sphenoid bone