mandibular nerve

Human Anatomy

Mandibular nerve

This is the largest division of the trigeminal nerve and is the only one to contain motor as well as sensory fibers. Developmentally, it is the nerve of the first branchial arch and is thus responsible for supplying structures derived from it . its sensory fibers supply the:
• mandibular teeth and their supporting structures,
• the mucosa of the anterior two-thirds of the tongue
• and the floor of the mouth,
• the skin of the lower part of the face (including the lower lip)
• and parts of the temporal region and auricle.
Its motor fibers supply the four muscles of mastication and the mylohyoid, anterior belly of digastric, tensor veli palatine and tensor tympani muscles.





The mandibular nerve is formed in the infratemporal fossa by the union of the sensory and motor roots immediately after they leave the skull at the foramen ovale, within the foramen ovale the motor root (or roots) lie posteromedially to the sensory root and these root are accompanied by emissary veins , the lesser petrosal nerve (from the glossopharyngeal nerve) going to the otic ganglion and by the accessory meningeal artery . as the mandibular nerve leaves the foramen ovale, it lies on the lateral pterygoid muscle (slightly anterior to the neck of the mandible). After a short course, the nerve divides into a smaller anterior trunk and a larger posterior trunk. Before this division , the main trunk gives off two branches – the meningeal branch and the nerve to medial pterygoid. The anterior trunk of the mandibular nerve is mainly motor , the posterior trunk mainly sensory.

Branches

Meningeal branch ( nervus spinosus)
Nerve to medial pterygoid
Anterior trunk:
Masseteric nerve
Nerve to lateral pterygoid
Buccal nerve
posterior trunk:
Auriculotemporal nerve
Lingual nerve
Inferior alveolar nerve

Meningeal branch of the mandibular nerve ( nervus spinosus):

This arises from the main trunk of the mandibular nerve. It is a ' recurrent nerve' as it rubs back into the middle craniam through the foramen spinosum. It supplies the dura mater lining the middle and anterior cranial fossae and the mucosa of the mastoid antrum and mastoid air cells.

Nerve to the medial pterygiod muscle:

This enters the deep surface of the muscle and also gives slender branches that pass uninterrupted through the otic ganglion to supply the tympani and tensor veli palatine muscles.

Masseteric nerve (Anterior trunk)

This is usually the first branch of the anterior trunk of the mandibular nerve. It passes above the upper border of the lateral pterygoid muscle ( accompanying the posterior deep temporal nerve ) and then crosses the mandibular notch ( between the condylar and coronoid processes) to be distributed into the masseter muscle. It also gives an articular branches. The larger, lower trunk innervates the more superficial layers of the masseter muscle .

deep temporal nerve

These nerve also pass above the lateral pterygoid muscle.
nerve to the lateral pterygiod muscle
This may arise separately or may run with the buccal nerve before entering the deep surface of the lateral pterygoid muscle .





Buccal branch of the mandibular nerve
This is the only sensory branch of the anterior trunk of the mandibular nerve. On emerging between the upper and lower heads of the lateral pterygoid muscle it passes downwards and forwards across the lower head to contact the medial surface of the temporalis muscle as it inserts onto the coronoid process of the mandible. It then clears the ramus of the mandible to lie on the lateral surface of the buccinator muscle gives branches to the skin of the cheek before piercing the buccinator to supply its lining mucosa, the buccal sulcus and the buccal gingiva related to the mandibular molar and in the buccal mucosa , these being post-ganglionic fibres from the otic ganglion.
The buccal branch of the mandibular nerve may be seen to 'anastomose' with the buccal branches of the facial nerve.

Auriculotemporal nerve (posterior trunk)

This is the first branch of the posterior trunk of the mandibular nerve . it is essentially sensory but also distributes autonomic fibers to the parotid gland derived from the otic ganglion. It usually arises as two roots(approx.. 75% of cases ) that encircle the middle meningeal artery and unite behind the artery. The nerve then runs backwards under the lateral pterygoid muscle to lie beneath the mandibular condyle(between the condyle and the sphenomandibular ligament).
On entering the parotid region , it turns to emerge superficially between the temporomandibular joint and the external acoustic meatus. From the upper surface of the parotid gland , the auriculotemporal ascends on the side of the head with the superficial temporal vessels , passing over the posterior part of the zygomatic arch, it gives several branches along its course:

Ganglionic branches which communicate with the otic ganglion.

Articular branches which enter the posterior part of the temporomandibular joint; these carry proprioceptive information important in mastication.
Parotid branches which convey parasympathetic secretomotor fibers and sympathetic fibers to the auriculotemporal nerve supply the gland (with the exception of the capsule , which is innervated by the great auricular nerve).
Auricular branches ( usually two) which supply the tragus and crus of the helix of the auricle , part of the external acoustic meatus , and the outer ( lateral ) surface of the tympanic membrane .
Superficial temporal branches which are cutaneous nerve supplying part of the skin of the temple.

lingual nerve .

This is second branch of the posterior trunk of the mandibular nerve. It is essentially a sensory nerve but , following union with the chorda tympani branch of the facial nerve , it also contains parasympathetic fibers. chorda tympani joines the posterior surface of the lingual nerve . emerging from the inferior border of the lateral pterygoid muscle , the lingual nerve curves downwards and forwards in the space between the ramus of the mandible and the medial pterygoid muscle .At this level, it lies anterior to , and slightly deeper than , the inferior alveolar nerve . the lingual nerve then leaves the infratemporal fossa, passing downwards and forwards to lie close to the lingual alveolar plate of The mandibular third molar.

.before curving forwards into the tongue, the nerve is found above the origin of the mylohyoid muscle and lateral to the hyoglossus muscle. The close relationship of the lingual nerve to the third molar tooth makes the nerve susceptible to damage during removal of the tooth. In addition , in about one in seven cases , the lingual is actually located above the lingual bony plate in the third molar region and is liable to damage during surgery .




The lingual nerve supplies the mucosa covering the anterior two-thirds of the dorsum of the tongue, the ventral surface of the tongue, the floor of the mouth and the lingual gingivae of two types: sensory and parasympathetic. The sensory fibers are associated with taste for the anterior two- thirds of the dorsum of the tongue. The parasympathetic fibers are preganglionic fibers that pass to the submandibular ganglion . postganglionic fibers are distributed to the submandibular and sublingual salivary glands.

The chorda tympani branch of the facial nerve

This is distributed through the lingual nerve and has two types of fibers. Sensory fibers are associated with taste to the anterior two-thirds of the tongue. Parasympathetic fibers are preganglionic to submandibular ganglion postganglionic fibers are secretomotor to the submandibular and sublingual glands.

The inferior alveolar nerve

This is the largest branch of the mandibular division of the trigeminal nerve . it is the third branch of the posterior trunk of the mandibular nerve. Although it is essentially a sensory nerve , it also carries motor fibers which are given off as the mylohyoid nerve . indeed the mylohyoid nerve contains all the motor fibers of the posterior trunk of the mandibular nerve .the inferior alveolar nerve descends deep to the lateral pterygoid muscle , posterior to the lingual nerve in the pterygoid hiatus . here, it is crossed by the maxillary artery . on emerging at inferior border of the mandible to enter the mandibular foramen. It is accompanied in its course by inferior alveolar blood vessels .






The mylohyoid nerve is given off just before the mandibular foramen. It pierces the sphenomandibular ligament and runs in agroove ( the mylohyoid groove) which lies immediately below the mandibular foramen . the mylohyoid nerve may also contain sensory fibers that supply the skin of the chin and medial parts of the submandibular triangle in the suprahyoid region.
The main distribution of the inferior alveolar nerve is to the mandibular teeth and their supporting structures , there being molar and incisive branches, the mental nerve is a cutaneous branch that supplies the skin of the chin and the lower lip . it arises within the mandible in the premolar region, but soon exits onto the face via the mental foramen.

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