Medial Pterygoid
Mastication · Head & Neck
The medial pterygoid is a deep, quadrilateral muscle of mastication lying on the inner aspect of the mandibular ramus, where it mirrors the more superficial masseter. It arises chiefly from the medial surface of the lateral pterygoid plate, with additional slips from the pyramidal process of the palatine bone and the tuberosity of the maxilla, and it inserts on the medial surface of the ramus and angle of the mandible. Working with the masseter, it elevates the mandible and assists in protraction, and alternating contraction of the two sides produces the side-to-side grinding movements used in chewing. It is supplied by the mandibular division of the trigeminal nerve (CN V3).
Origin, Insertion, Action & Nerve
Origin
Medial surface of lateral pterygoid plate, pyramidal process of palatine bone, tuberosity of maxilla
Insertion
Medial surface of ramus and angle of mandible
Action
Elevates mandible; assists protraction; contralateral grinding movements
Nerve
Mandibular division of trigeminal nerve (CN V3)
Attachments explained
The Medial Pterygoid is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Medial surface of lateral pterygoid plate, pyramidal process of palatine bone, tuberosity of maxilla
Insertion
Medial surface of ramus and angle of mandible
Action & function
When the Medial Pterygoid contracts, it produces the following movements: Elevates mandible; assists protraction; contralateral grinding movements.
As part of the Mastication group of the Head & Neck, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Medial Pterygoid receives its nerve supply from the Mandibular division of trigeminal nerve (CN V3).
Because a muscle can only contract when its nerve is intact, injury to the Mandibular division of trigeminal nerve can weaken or paralyse the Medial Pterygoid, impairing the movements it normally produces (elevates mandible). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Medial Pterygoid (the OIANS method)
Picture the medial pterygoid as the inner counterpart of the masseter, forming a muscular sling that cradles the angle of the mandible between them. Because it attaches to the medial surface of the ramus and angle, its pull elevates the jaw just as the masseter does from the outside; visualising that sling makes both muscles memorable at once.
Fix the grinding action by remembering that the medial pterygoid produces contralateral movement, so contracting one side swings the chin toward the opposite side. Pair this with the lateral pterygoid, which shares the grinding role, and recall that all four muscles of mastication, this one included, are supplied by the mandibular division of the trigeminal nerve (CN V3).
Frequently asked questions
Where is the Medial Pterygoid located?
The Medial Pterygoid is a muscle of the Mastication group, located in the Head & Neck.
What is the origin of the Medial Pterygoid?
Medial surface of lateral pterygoid plate, pyramidal process of palatine bone, tuberosity of maxilla
What is the insertion of the Medial Pterygoid?
Medial surface of ramus and angle of mandible
What movements does the Medial Pterygoid produce?
Elevates mandible; assists protraction; contralateral grinding movements
What nerve supplies the Medial Pterygoid?
Mandibular division of trigeminal nerve (CN V3)
Is the Medial Pterygoid free to study in OIANS?
The Medial Pterygoid is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Head & Neck is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
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