Muscles of Mastication: A Comprehensive Guide
Mastication, or chewing, is a complex process involving several muscles working in coordination. These muscles are collectively known as the muscles of mastication. They are responsible for opening and closing the jaw, moving it side to side, and grinding food.
Major Muscles Involved in Mastication
1. Temporalis:- Location: Sides of the head, covering the temporal bone.
- Function: Closes the jaw, bringing the upper and lower teeth together.
- Location: Angle of the jaw, connecting the cheekbone to the lower jaw.
- Function: Closes the jaw with great force.
- Location: Inside the lower jaw, near the middle ear.
- Function: Closes the jaw and moves it side to side.
- Location: Also inside the lower jaw, near the middle ear.
- Function: Opens the jaw and moves it side to side.
How the Muscles Work Together
- Opening the jaw: The lateral pterygoid muscles contract, pulling the lower jaw forward and downward.
- Closing the jaw: The temporalis, masseter, and medial pterygoid muscles contract, pulling the lower jaw upward.
- Side-to-side movement: The medial and lateral pterygoid muscles work together to move the jaw from side to side, grinding food.
Note: The muscles of mastication are controlled by the trigeminal nerve (cranial nerve V).
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Disorders Affecting the Muscles of Mastication
- Temporomandibular joint disorder (TMJ): A common condition that affects the joint between the jawbone and the skull. It can cause pain, clicking, and limited jaw movement.
- Myofascial pain syndrome: A condition that causes pain in the muscles and surrounding tissues. It can affect the muscles of mastication, leading to jaw pain and difficulty chewing.
- Muscle atrophy: Wasting of the muscles due to disuse, nerve damage, or other conditions. This can affect the muscles of mastication, making it difficult to chew.
Understanding the muscles of mastication and their functions is important for diagnosing and treating conditions that affect chewing.
