The muscles the mastication are linked with movements of the jaw (temporomandibular joint). They are one of the significant muscle teams in the head – the various other being the muscle of facial expression. Over there are 4 muscles:

MasseterTemporalisMedial pterygoidLateral pterygoid

The muscles of mastication develop from the first pharyngeal arch. Thus, they are innervated by a branch the the trigeminal nerve (CN V), the mandibular nerve.

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In this article, we shall look at the anatomy of the muscles of mastication – their attachments, actions, and also innervation.

(NB: it is crucial to keep in mind that all the muscle mentioned right here are bilateral structures).

Masseter

The masseter muscle is the most an effective muscle the mastication. That is quadrangular in shape and has two parts: deep and also superficial.

The whole of the muscle lies superficially come the pterygoids and also temporalis, spanning them.

Actions: Elevates the mandible, close up door the mouth.Innervation: Mandibular nerve (V3).
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Fig 1 – The masseter muscle. Only the superficial head is visible


Temporalis

The temporalis muscle originates native the temporal fossa – a shallow depression top top the lateral facet of the skull. The muscle is covered by challenging fascia which have the right to be harvested surgically and also used to fix a perforated tympanic membrane (an operation known as a myringoplasty).

Attachments: Originates from the temporal fossa. The condenses right into a tendon, i beg your pardon inserts top top the coronoid procedure of the mandible.Actions: Elevates the mandible, closing the mouth. Likewise retracts the mandible, pulling the jaw posteriorly.Innervation: Mandibular nerve (V3).
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Fig 2 – The temporalis muscle.


Medial Pterygoid

The medial pterygoid muscle has a quadrangular form with 2 heads: deep and also superficial. It is situated inferiorly to the lateral pterygoid.

Attachments:The superficial head originates indigenous the maxillary tuberosity and the pyramidal procedure of palatine bone.The deep head originates native the medial facet of the lateral pterygoid bowl of the sphenoid bone.Both heads attach to the ramus of the mandible close to the edge of mandible.Actions: Elevates the mandible, closing the mouth.Innervation: Mandibular nerve (V3).

Lateral Pterygoid

The lateral pterygoid muscle has actually a triangular shape with 2 heads: superior and inferior. It has actually horizontally orientated muscle fibres, and thus is the significant protractor of the mandible.

Attachments:The premium head originates native the greater wing of the sphenoid.The worse head originates from the lateral pterygoid bowl of the sphenoid.The 2 heads converge right into a tendon i m sorry attaches come the neck of the mandible.Actions: acting bilaterally, the lateral pterygoids protract the mandible, advertise the jaw forwards. Unilateral activity produces the ‘side come side’ activity of the jaw.Note: contraction of the lateral pterygoid will produce lateral activity on the contralateral side. Because that example, contraction of left lateral pterygoid will deviate the mandible to the right.

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Innervation: Mandibular nerve (V3).