Corpus: Medial pterygoid muscle
from ancient Greek: πτέρυξ ("pteryx") - wing
Synonym: internal pterygoid muscle
1. Definition
The medial pterygoid muscle is a skeletal muscle that is part of the muscles of mastication (chewing).
2. Course
The medial pterygoid muscle originates from the pterygoid fossa of the sphenoid bone, the lateral lamina of the pterygoid process, and the maxillary tuberosity. It then runs along the inside of the mandible to attach at the pterygoid tuberosity.
3. Innervation
The medial pterygoid muscle is innervated by the medial pterygoid nerve, a branch of the mandibular nerve (cranial nerve V3).
4. Function
The primary function of the medial pterygoid muscle is to elevate the mandible (adduction), closing the jaw and contributing to mouth closure. When contracted unilaterally, it assists in protrusion of the mandible, facilitating forward movement of the lower jaw, which is important for grinding food. The medial pterygoid works in synergy with the masseter muscle to achieve these functions.
Together, the medial pterygoid and masseter muscles form a strong muscle loop along the jawline. The strength of this muscle loop exceeds that of the temporalis muscle, which is the strongest individual muscle involved in jaw closure.