Medial pterygoid muscle
From Wikipedia, the free encyclopedia
| Medial pterygoid | |
|---|---|
| The Pterygoidei; the zygomatic arch and a portion of the ramus of the mandible have been removed. (Internus is visible at center bottom.) | |
| 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 | A02.633.567.600.700 |
| Dorlands /Elsevier | m_22/12550302 |
| TA | A04.1.04.009 |
| FMA | 49011 |
| Anatomical terms of muscle | |
The medial pterygoid (or internal pterygoid muscle), is a thick, quadrilateral muscle ofmastication.
The mandibular branch of the fifth cranial nerve, the trigeminal nerve, innervates the medial pterygoid muscle.
Structure[edit]
It consists of two heads.
- The bulk of the muscle arises as a deep head from just above the medial surface of the lateral pterygoid plate.
- The smaller, superficial head originates from the maxillary tuberosity and the pyramidal process of the palatine bone.
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 themandibular 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[edit]
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.
Function[edit]
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[edit]
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 the maxillary and mandibular nerves, and the submaxillary ganglion.
Mandibular division of trifacial nerve, seen from the middle line.
Muscles of the pharynx, viewed from behind, together with the associated vessels and nerves.
PTERYGOID MEDIAL MUSCLEDeep dissection.Anterior view.
Medial pterygoid muscle
Medial pterygoid muscle
Medial pterygoid muscle
Medial pterygoid muscle
Medial pterygoid muscle
Infratemporal fossa. Lingual and inferior alveolar nerve. Deep dissection. Anterolateral view
References[edit]
This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)
External links[edit]
| 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 2014-01-01.
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Lateral pterygoid muscle
From Wikipedia, the free encyclopedia
| Lateral pterygoid muscle | |
|---|---|
| The Pterygoidei; the zygomatic arch and a portion of the ramus of the mandible have been removed (labeled as "pterygoideus externus", visible in pink at center) | |
| Sagittal section of the temporomandibular joint(labeled as "pterygoideus externus", visible in gray at bottom right) | |
| Details | |
| Origin | Great wing of sphenoid andpterygoid plate |
| Insertion | Condyloid process of the mandible |
| Artery | Pterygoid branches of maxillary artery |
| Nerve | Lateral pterygoid nerve from themandibular nerve |
| Actions | depresses mandible, protrude mandible, side to side movement of mandible |
| Identifiers | |
| Latin | Musculus pterygoideus lateralis, musculus pterygoideus externus |
| MeSH | A02.633.567.600.700 |
| Dorlands /Elsevier | m_22/12550292 |
| TA | A04.1.04.006 |
| FMA | 49015 |
| Anatomical terms of muscle | |
The lateral pterygoid or external pterygoid is a muscle of mastication with two heads. It lies superiorly to the medial pterygoid.
Origin and insertion[edit]
The upper/superior head originates on the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone, and the lower/inferior head on the lateral surface of the lateral pterygoid plate.
Inferior head inserts onto the neck of condyloid process of the mandible; upper/superior head inserts onto the articular disc and fibrous capsule of the temporomandibular joint.
Innervation[edit]
The mandibular branch of the fifth cranial nerve, the trigeminal nerve, specifically the lateral pterygoid nerve, innervates the lateral pterygoid muscle.
Function[edit]
The primary function of the lateral pterygoid muscle is to pull the head of the condyle out of themandibular fossa along the articular eminence to protrude the mandible. A concerted effort of the lateral pterygoid muscles helps in lowering the mandible and open the jaw whereas unilateral action of a lateral pterygoid produces contralateral excursion (a form of mastication), usually performed in concert with the medial pterygoids.
Unlike the other three muscles of mastication, the lateral pterygoid is the only muscle of mastication that assists in depressing the mandible (opening the jaw). At the beginning of this action it is assisted by the digastric, mylohyoid and geniohyoid muscles.
Additional images[edit]
Sphenoid bone. Anterior and inferior surfaces.
Mandible. Inner surface. Side view.
Plan of branches of internal maxillary artery.
Distribution of the maxillary and mandibular nerves, and the submaxillary ganglion.
External links[edit]
- lesson4 at The Anatomy Lesson by Wesley Norman (Georgetown University) (musclesofmastication2)
- MedicalMnemonics.com: 70
- "Anatomy diagram: 25420.000-1". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2014-01-01.
- Cross section at tufts.edu
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| Soft palate | |||||||||||||||||
| Tongue |
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The human medial pterygoid muscle: Attachments and distribution of muscle spindles:
Abstract
Introduction Published descriptions about the sites of origin of the human medial pterygoid muscle vary and there are few reports on the distribution and density of muscle spindles in this muscle. We aimed to: 1) determine the extent of anatomical variability in the origins and insertions of the superficial and deep heads of the human medial pterygoid muscle, and 2) determine the extent of variation in the distribution of spindles in the two heads of the muscle.
Materials and methods Thirty-nine human cadaver hemi-heads were dissected and the attachments of the medial pterygoid muscle examined. The whole muscle was removed, weighed, cut into segments and embedded in wax for light microscopy. Sections were stained with Weigert-Van Gieson stain and scanned into digital images. Spindles were manually counted.
Results In seven specimens, the deep head of the muscle arose from the medial surface of the lateral pterygoid plate and the pterygoid fossa. In 28 specimens, the origin extended onto the lateral surface of the medial pterygoid plate.
There were abundant muscle spindles in the middle of the muscle, slightly fewer 1cm toward the insertion, significantly fewer 1cm toward the origin, and few or no spindles near the origins of the superficial and deep heads or near their insertion.
Conclusion Firstly, this study shows that in 72% of the specimens examined, the origin of the medial pterygoid is wider than conventionally described in anatomical textbooks. Secondly, the segmental distribution of muscle spindles is described for the first time. This article is protected by copyright. All rights reserved.
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Medicine by Alexandros G. Sfakianakis,Anapafseos 5 Agios Nikolaos 72100 Crete Greece,00302841026182,00306932607174,alsfakia@gmail.com,