Structure and Insertion - Medial pterygoid muscle consists of two heads - Deep head arises above medial surface of lateral pterygoid plate - Superficial head originates from maxillary tuberosity and pyramidal process of palatine bone - Fibers pass downward, lateral, and posterior - Insertion joins masseter muscle to form a common tendinous sling

Nerve Supply - Medial pterygoid muscle is supplied by medial pterygoid nerve - Medial pterygoid nerve is a branch of mandibular nerve, itself a branch of trigeminal nerve (V) - Medial pterygoid nerve also supplies tensor tympani muscle and tensor veli palatini muscle - Medial pterygoid nerve is a main trunk from mandibular nerve, before division of trigeminal nerve - Unlike lateral pterygoid muscle and other muscles of mastication, which are supplied by anterior division of mandibular nerve

Function - Medial pterygoid muscle elevates the mandible (closing the mouth) - Medial pterygoid muscle protrudes the mandible - Medial pterygoid muscle aids in mastication, especially when maxillary teeth and mandibular teeth are close together - Medial pterygoid muscle allows contralateral excursion of the mandible with unilateral contraction

Additional Images - Position of medial pterygoid muscle (red) - Left palatine bone, posterior aspect, enlarged - Mandible, inner surface, side view - Plan of branches of internal maxillary artery - Distribution of maxillary and mandibular nerves, and submaxillary ganglion

References - This article incorporates text in the public domain from page 387 of the 20th edition of Gray's Anatomy (1918) - Wood, W W (1986-05-01). Medial pterygoid muscle activity during chewing and clenching. The Journal of Prosthetic Dentistry. 55 (5): 615–621. doi:10.1016/0022-3913(86)90043-0. ISSN1097-6841. PMID3458914. - Wikimedia Commons has media related to Medial pterygoid muscles - MedicalMnemonics.com: 70 - Anatomy diagram: 25420.000-1. Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2015-02-26.