Mandibular nerve

By:

Mohamed saber

It is the 3rd division of the trigeminal nerve.Origin:It is a mixed nerve formed of 2 roots.a)Sensory root :arises from the trigeminal ganglion& runs forward& laterally toward foramen ovale.b) Motor root: a smaller root which arises from the trigeminal motor nucleus in the pons & runs deep to the trigeminal ganglion to join the sensory root in the foramen ovale

Course& relations

1)The 2 roots unite together in the foramen ovale to form the main trunk mandibularn.(mixed).

2)The main trunk descends through the f. ovaleto reach the infra temporal fossa where it is related :laterally to lat. Pterygoid m.

madially to otic ganglion& tensor palatim.

posterolaterally to middle meningeal art.

3)The main n. trunk gives 2 branches then divides into 2 divisions (small ant.& large post.) about 1\2cm below the f. ovale.

Branches of the mand. nerve

A)Branches of the main nerve trunk.

B)Branches from the anterior division.

C)Branches from the posterior division.

Branches of the main nerve trunk

2 branches (one motor &one sensory):

(11)Nervous spinosus (sensory): it enters the cranial

cavity through the foramen spinosum to supply the

dura of the middle cranial fossa .

2) Nerve to medial pterygoid (motor): supplies this muscle through its deep surface.

It also gives a branch which traverse the oticganglion without relay to supply the tensor palati & tensor tympani muscles.

Branches of the anterior

division3motor&1 sensory:

1)Masseteric n. :passes laterally above the upper border of the lat. Pterygoid m. then through mand. Notch to enter the deep surface of the masseter m.

2) N. to lat. Pterygoid m: enter the deep surface of lat.pterygoid m.

3) 2 deep temporal nerves pass laterally above the upper border of the lat. Pterygoid to enter the deep surface of the temporalis m.

4) Buccul n.(sensory):

Passes bet. The 2 heads of the lat. Pterygoid m.

Then it descends superficial to the lower head of lat. Pterygoid & medial to the coronoid process of the mandible, to appear bet. Masseter & buccinatormuscles.

It supplies:

The skin covering the buccinator muscle.

The mucous membrane of the cheeck & gum oppsite to the molar teeth.

c)Brancnes from the posterior

division3 sensory & 1 motor:

(1Auriculo-temporal n. (sensory)

Arises by 2 roots which surround the middle meningeal a.

Passes backwards medial to the neck of the mandible,then behind the tmj,ascends deep to the parotid gland to appear at its upper pole behind the superficial temporal vessels.

It supplies:

The tempromandibular joint.

Sensory fibers to the parenchyma of the parotid gland

Skin of the upper 2\3 of outer surface of the auricle +scalp above it(temporal region).

Skin lining the external auditory meatus, tragus of ear+ outer surface of the ear drum.

It caries symp.& parasymp. Secretoryfibers from the otic ganglion to the parotid gland.

Lingual nerve (sensory)

Origin: post. Div. of mand. N.Course & relations:It lies deep to the lat. Pterygoid m. ,here it is joined by the chorda tympani n. (br. Of facial n. carrying taste &parasympathaticfibers)It emerges from the undercover of the lower border of the lat. Pterygoid m. ,infront of the inferior alveolar n.Then it descends bet. The ramus of the mand.(superficially)& the med. Pterygoidm. (deeply)

It passes along a groove on the inner surface of the socket of the last molar tooth just undercover the mucosa of the gum (dangerous area during tooth extractin).Then it runs superficial to the styloglossusm.Then it crosses superficial to the hyoglossus m. Here the nerve lies deep to the submandibular salivary gland& submandibular ganglion hangs from it.Finally it passes deep to the mylohyoidm.& ascends superficial to genioglossusm.

Here the lingual n. has a tripple relation with the submandibular duct :1st it passes lat. To the duct,Then it curves below the duct,Finally it ascends med. To the ductBooth the nerve & the duct pass forward & upward bet. Genioglossus m. & subling. Salivary gl. To reach the tongue.Termination: it ends by dividing into terminal branches which enter the side of the tongue under its mucous membrane.

Distribution:

It carries general& taste sensations from

the ant. 2\3 of the tongue.

It carries general sensations from the

floor of the mouth& gums.

It carries secretomotor parasympathatic

fibers from chorda tympani to the

submand. & subling. Glands (relaying

1st in the submandibular ganglion)

Inferior alveolar nerve

It is the largest branch of the post. Division of mandibular nerve.Course & relations:It begins deep to the lateral pterygoid m. then emerges from undercover of its lower border where the lingual n. lies infront of itIt descends bet. The ramus of the mand. (laterally) & med. Pterygoid m. medially.It enters the mandibular foramen infront of the inf. Alveolar art. & runs in the mandibular canal suppling the molar& premolar teeth

It ends opposite to the mental foramen

by dividing into 2 branches:

Mental n : comes out of mental foramen

& it is sensory to the chin .

Incisive n. : continues inside the

mandible to supply the lower canine &

incisor teeth.

Nerve to mylohyoid(motor)

It contains all the motor fibers of the

post. Division of mandibular n.

It arises as a branch of inf. Alv. N.

before it enters the mandibular

foramen.

It runs in the mylohyoid groove on the

inner surface of ramus of mandible.

It ends by supplying the mylohyoid m. +

anterior belly of digastric m.