Muscles of mastication

Muscles of mastication

The muscles of mastication are a group of muscles responsible for the movement of the mandible (jaw) during the process of mastication (chewing). These muscles are primarily innervated by the mandibular nerve, which is a branch of the trigeminal nerve (cranial nerve V). The primary muscles involved in mastication are the masseter muscle, temporalis muscle, medial pterygoid muscle, and lateral pterygoid muscle.

Masseter Muscle

The masseter muscle is one of the strongest muscles in the human body relative to its size. It is a thick, rectangular muscle that originates from the zygomatic arch and inserts into the angle of the mandible and the lateral surface of the ramus of the mandible. The masseter muscle is primarily responsible for the elevation of the mandible, enabling the mouth to close.

Temporalis Muscle

The temporalis muscle is a broad, fan-shaped muscle located on the side of the head. It originates from the temporal fossa and the temporal fascia, and inserts into the coronoid process of the mandible. The temporalis muscle assists in elevating the mandible and retracting it, which helps in closing the mouth and pulling the jaw backward.

Medial Pterygoid Muscle

The medial pterygoid muscle is a thick, quadrilateral muscle that lies on the inner surface of the mandible. It originates from the medial surface of the lateral pterygoid plate and the pyramidal process of the palatine bone, and inserts into the medial surface of the ramus and the angle of the mandible. This muscle works in conjunction with the masseter muscle to elevate the mandible and also assists in the side-to-side movement of the jaw.

Lateral Pterygoid Muscle

The lateral pterygoid muscle is a short, thick muscle with two heads: the superior head and the inferior head. The superior head originates from the infratemporal surface and the crest of the greater wing of the sphenoid bone, while the inferior head originates from the lateral surface of the lateral pterygoid plate. Both heads insert into the condylar process of the mandible and the articular disc of the temporomandibular joint (TMJ). The lateral pterygoid muscle is primarily responsible for the protrusion of the mandible and assists in the side-to-side movement of the jaw.

Function

The primary function of the muscles of mastication is to facilitate the movement of the mandible during chewing. These muscles work together to perform various movements such as elevation, depression, protrusion, retraction, and lateral (side-to-side) movements of the jaw. Proper functioning of these muscles is essential for effective mastication, speech, and overall oral health.

Clinical Significance

Dysfunction of the muscles of mastication can lead to various conditions such as temporomandibular joint disorder (TMD), bruxism (teeth grinding), and myofascial pain syndrome. These conditions can cause pain, difficulty in chewing, and other complications affecting the oral and maxillofacial region.

See Also

• Mandible
• Trigeminal nerve
• Temporomandibular joint
• Mastication
• Bruxism
• Temporomandibular joint disorder