TRIGEMINAL NERVE

ByProf. Laila M. Aboul Mahasen Morsy

Trigeminal Nerve It is the largest cranial nerve and contains both sensory &motor fibers.Origin:

It leaves anterior surfaceof pons by 2 roots :

1 .A small motor root 2 .A large sensory root.

Roots ofTrigeminal N.

Roots of Trigeminal Nerve A. Sensory root fibres :areaxons of cells of the trigeminal

ganglion, enter the pons .Peripheral processes of

these cells form the 3 divisions of trigeminal nerve :

1.Ophthalmic N. 2 .Maxillary N .

3 .Mandibular N .B. Motor root : arises from motor nucleus of trigeminal in

pons , passes below trigeminal ganglion to be distributed with mandibular nerve .

Primary Function of The Trigeminal Nerve (V) It is Mixed (sensory and motor) to face

Ophthalmic branch (sensory) :1.Orbital structures

2 .Nasal cavity3 .Skin of forehead, upper eyelid ,

and eyebrow 4 .Part of nose

Maxillary branch (sensory) :1 .Lower eyelid

2 .Upper lip, gums, and teeth3 .Cheek and nose

4 .Palate and part of pharynx

Mandibular branch ( Mixed ) :Sensory : lower gums, teeth, and lips palate and part of tongue

Motor : Muscles of mastication

Exit from the skull of trigeminal branches N.B. trigeminal ganglion lies at the apex of petrous temporal

bone .The 3 divisions leave the cranial cavity through :

1.Ophthalmic branch :

superior orbital fissure

2.Maxillary branch :

foramen rotundum

3 .Mandibular branch :

foramen ovale .

Ophthalmic N.

Maxillary N.

Mandibular N.

Trigeminal ganglion

Cavernous sinus

Ophthalmic & maxillary nerves lie on lateral wall of cavernous sinus outside the tendinuous ring,

before leaving the cranial cavity

Relations of cranial nerves with cavernous sinus

Ophthalmic NerveIt is the smallest of the three divisions of the trigeminal, and arises from the upper part of the

trigeminal ganglion about 2.5 cm. long, which passes forward along the lateral wall of the

cavernous sinus, below the oculomotor and trochlear nerves ;

just before entering the orbit, through the superior orbital fissure, it divides into 3

branches : lacrimal, frontal, and nasociliary nerves

e

Branches of ophthalmic nerve A-Nasociliary nerve

1.Sensory root of

ciliary ganglion

2.Posterior ethmoidal n.

3 .Long ciliary n.

4 .Infratrochlear n.

5.Anterior ethmoidal n.

B-Lacrimal nerve

C-Frontal nerve

1 .Supratrochlear n.

2 .Supraorbital n.

Lacrimal Nerve— branch of ophthalmic nerve.— Its branches supply the lacrimal gland with sensory fibres.—' It also gives a palpebral branch to the lateral part of the upper eyelid.— It receives a communication from the zygomatic nerve through which secretory fibres pass to the lacrimal gland

Frontal Nerve—The largest branch of ophthalmic nerve-The highest structure in the orbit-Enters the orbit through the superior orbital fissure (outside the common tendinous ring)

— It runs forwards under cover of the periosteum of the roof of the orbit, above the levator palpebrae superioris

— It divides into two branches :1.Supratrochlear N. : is the medial and smaller branch.2. Supraorbital N.: is the lateral and larger branch (continuation of the nerve).

Nasociliary Nerve1.A branch of the ophthalmic nerve

2.Enters the orbit through the superior orbital fissure(inside the common tendinous ring)

3.Crosses above the optic nerve from lateral to medial

4.Runs along the medial wall of the orbit, between the superior oblique and medial rectus muscles

5.Terminates by dividing into :1. Anterior ethmoidal nerve2. Infratrochlear nerve

Branches :1.Sensory root to the ciliary ganglion

2.Long ciliary nerves(carry sympathetic fibers from the plexus around ICA to supply dilator pupillae muscle)

3.Posterior ethmoidal nerve

4.Anterior ethmoidal nerve

5.Infratrochlear nerve

Nasociliary Nerve

Maxillary Nerve

Maxillary Nerve (A pure sensory nerve) One of the 3 divisions of trigeminal nerve . Course:

1.Leaves the cranial cavity through the foramen rotundum into the pterygopalatine fossa

2.Passes through inferior orbital fissure to continue as infraorbital nerve*The infraorbital n. passes through infra-orbital groove and terminates in

the face

Ophthalmic n.

Trigeminalganglion

Maxillary nerve

Mandibular n.

Infraorbital nerve

BranchesFrom the maxillary nerve

From the infraorbital nerve

Branches of maxillary N. & its infraorbital branch

Infraorbital N.

Maxillary N.

Branches of maxillary nerve in infratemporal fossa: l. Meningeal branch : before leaving the skull.2. Two roots to the sphenopalatine ganglion in the pterygopalatine fossa.3. Zygomatic nerve : arises in the infratemporal fossa and enters the orbit

through the inferior orbital fissure where it divides into : Zygomaticotemporal and Zygomaticofacial nerves.

4. Posterior superior alveolar nerve : arises in the infratemporal fossa and divides into anterior and posterior branches which enter the maxilla to supply the premolar and molar teeth.

*The anterior branch may be described as middle superior alveolar nerve.

5. Infraorbital nerve is the terminal branch, gives many branches:

1. Nerve supply to the mucosa of the maxillary air sinus .2. Anterior superior alveolar nerve : which supplies the incisor and canine

teeth.3. Terminal branches in the face :a) Palpebral : to the lower eyelid.b) Nasal : to the side of the nose.c) Labial : to the upper lip.

Maxillary N. & sphenopalatine ganglion

Vidian N.N. Of pterygoid

canal

Greater superficialPetrosal N. Facial N.

Deeppetrosal

Sphenopalatineganglion

Zygomatic Nerve 1. Branch of the maxillary nerve of the second division of trigeminal

n.2. Enters the orbit through the inferior orbital fissure3. Divides into : zygomatico-temporal and zygomatico-facial nerves

4. Zygomatico-temporal nerve carries parasympathetic secretory fibers from the sphenopalatine ganglion to the lacrimal gland (via its communication with the lacrimal nerve)

1 .The largest division of the trigeminal nerve2 .It is a mixed nerve has a sensory root and a motor root

3 .It leaves the skull through the Foramen Ovale4 .Below foramen ovale, the 2 roots unite to form the trunk of the nerve

5 .Then , it divides into anterior & posterior divisions

*The anterior is mainly motor

The posterior is mainly sensory

Mandibular Nerve

Branches of the mandibular nerve Branches of the trunk: 1.Nerve to medial pterygoid

2 .Nervus spinosus

Branches of Anterior Division1 .Deep temporal nerves

2 .Nerve to masseter 3 .Nerve to lateral pterygoid

4 .Buccal N. ( sensory) Branches of Posterior

Division: 1 .Auriculotemporal (sensory)

2 .Lingual nerve (sensory)3 .Inferior alveolar nerve

(mixed)

Branches from the trunk:1.Nerve to medial

pterygoid (motor):supply the tensor palati and tensor tympani ms

&medial pterygoid

2 .Nervus spinosus (sensory) , Passes

through Foramen spinosum into the cranial cavity to supply meninges

Trigeminal Nerve

Anterior Division :

A.3 motor branches for muscles of mastication

1.Deep temporal nerves (temporalis ms)

2.Nerve to masseter

3.Nerve to lateral pterygoid

B.one sensory branchBuccal nerve (sensory): supplies skin over the buccinator, and mucosal lining of buccinator m.

Deep temporalnerves

Buccal nerve

Lingualnerve

Inferior alveolarnerve

Auriculotemporalnerve

Posterior division :sensory branches Auriculotemporal nervearises by 2 roots (which embrace the middle meningeal artery) and passes backwards deep to the neck of the mandiblesupplies the scalpsensory the parotid gland and carries postganglionic parasympathetic to the

parotid gland

Deep temporalnerves

Buccal nerve

Lingualnerve

Inferior alveolarnerve

Auriculotemporalnerve

2 .Lingual nerve1.Joined by the chorda tympani

2.Carries general sensations from the anterior 2/3 of the tongue

& by joining chorda tympani , it carries taste sensations from the anterior 2/3 of the tongue and preganglionic parasympathetic fibres to the submandibular and sublingual glands

3 .Inferior alveolar nerve1.Runs behind the lingual nerve to reach mandibular foramen

2 .It continues through mandibular canal and exits from the mental canal as mental nerve.

Lingual nerveInferior alveolarnerve

Mylohoid nerve &vessels Mylohoid m.

Inferior alveolar nerve

Mental N.

Incisive N.N. To mylohyoid

Branches of inferior alveolar nerve Branches : It supplies the teeth and gums of the

lower jaw.1.Mylohyoid branch : arise from the nerve before

enter the mandibular foramen . It supplies the mylohyoid and anterior belly of diagastric muscle

2. Incisive nerve which continues forwards . It supplies the canine and incisor teeth of the lower jaw.

3-Mental nerve which comes out of the mental foramen. It supplies the skin of the chin and skin and mucous membrane of the lower lip.

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