Medial pterygoid muscle

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Medial pterygoid
Musculuspterygoideusmedialis.png
The Pterygoidei; the zygomatic arch and a portion of the ramus of the mandible have been removed. (Internus is visible at center bottom.)
Gray783.png
The otic ganglion and its branches. (Pterygoideus internus labeled at bottom right.)
Latin musculus pterygoideus medialis, musculus pterygoideus internus
Gray's p.387
Origin deep head: medial side of lateral pterygoid plate behind the upper teeth
superficial head: pyramidal process of palatine bone and maxillary tuberosity
Insertion medial angle of the mandible
Artery pterygoid branches of maxillary artery
Nerve mandibular nerve via nerve to medial pterygoid
Actions elevates mandible, closes jaw, helps lateral pterygoids in moving the jaw from side to side
MeSH Pterygoid+Muscles
Anatomical terms of muscle

The medial pterygoid (or internal pterygoid muscle), is a thick, quadrilateral muscle of mastication.

The mandibular branch of the fifth cranial nerve, the trigeminal nerve, innervates the medial pterygoid muscle.

Origin and insertion

It consists of two heads.

Its fibers pass downward, lateral, and posterior, and are inserted, by a strong tendinous lamina, into the lower and back part of the medial surface of the ramus and angle of the mandible, as high as the mandibular foramen. The insertion joins the masseter muscle to form a common tendinous sling which allows the medial pterygoid and masseter to be powerful elevators of the jaw.

Innervation

Unlike the lateral pterygoid and all other muscles of mastication which are innervated by the anterior division of the mandibular branch of the trigeminal nerve, the medial pterygoid is innervated by the main trunk of the mandibular branch of the trigeminal nerve (V), before the division.

Actions

Given that the origin is on the medial side of the lateral pterygoid plate and the insertion is from the internal surface of the ramus of the mandible down to the angle of the mandible, its functions include:

  • Elevation of the mandible (closes the jaw)
  • Minor contribution to protrusion of the mandible
  • Assistance in mastication
  • Excursion of the mandible; contralateral excursion occurs with unilateral contraction.

Additional images

External links

This article incorporates text from a public domain edition of Gray's Anatomy.








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