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Medial pterygoid muscle

  (Redirected from Pterygoideus internus)

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

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.)
Details
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
Identifiers
Latin musculus pterygoideus medialis, musculus pterygoideus internus
MeSH D011626
TA A04.1.04.009
FMA 49011
Anatomical terms of muscle

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

Contents

StructureEdit

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.

InnervationEdit

Medial pterygoid is innervated by nerve to medial pterygoid (a branch of the mandibular nerve), which also innervates tensor tympani and tensor veli palatini.

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.

FunctionEdit

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 imagesEdit

ReferencesEdit

This article incorporates text in the public domain from page 387 of the 20th edition of Gray's Anatomy (1918)

External linksEdit

  • MedicalMnemonics.com: 70
  • "Anatomy diagram: 25420.000-1". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2014-01-01.