Trigeminal nerve

PRESENTATION LAYOUT
>INTRODUCTION
> NUCLEI
>FUNCTIONAL COMPONENT [ SENSORY & MOTOR]
>DISTRIBUTION OFTHE NERVE
> DIVISIONS

1. Trigeminal Nerve Tariq Al Fayad M

2. PRESENTATION LAYOUT INTRODUCTION NUCLEI FUNCTIONAL COMPONENT [ SENSORY & MOTOR] DISTRIBUTION OF THE NERVE DIVISIONS

3. INTRODUCTION It is the Largest cranial Nerve Contains both the Sensory and motor fibres. It is sensory from the head, but motor to the jaw muscles.

4. The term trigeminal was given by Winslow on account of its three divisions. The part of parasympathetic craniosacral outflow. It is a mixed nerve ( sensory and motor ) Contains 1,70,000 sensory fibres 7,700 motor fibres The 3 divisions have approx. Ophthalmic 26,000 Maxillary 50,000 Mandibular 78,000

5. NUCLEI The trigeminal nerve has four nuclei: The main sensory nucleus, The spinal nucleus, The mesencephalic nucleus, and The motor nucleus.

6. SENSORY NUCLEUS It lies in the upper part of pons lateral to the motor nucleus. It is continuous below with the spinal nucleus and above with the mesencephalic nucleus.

7. SPINAL NUCLEUS It descends from the main sensory nucleus in the pons, through the whole length of medulla oblongata And into the upper two segments of the spinal cord.

8. MESENCEPHALIC NUCLEUS This nucleus is situated in the lateral part of the central grey matter of the midbrain. It extends down in the pons up to the main sensory nucleus.

9. MOTOR NUCLEUS This is situated in the upper part of the pons medial to the main sensory nucleus.

10. FUCTIONAL COMPONENT – SENSORY COMPONENT [GENERAL SOMATIC AFFERENT] AND CONNECTIONS OF THE SENSORY NUCLEI Sensation from the eyeball, lacrimal gland, conjunctiva, face, oral and nasal cavities are carried along the sensory component of the serve and relayed as below

11. Pain,temp,light touch touch , pressure proprioception (relay) trigeminal gang. Bypasses trigem gang. main sensory nucleus descending fibres ascending fibres

12. descending fibres ascending fibres Spinal nuc . Principal sen nuc . Mesencephalic T rigeminal Leminiscus Thalmus P ost C entral G yrus C erebral C ortex (areas 3,2,1.)

13. THE TRIGEMINAL GANGLION :- Also known as  Gasserian ganglion, or semilunar ganglion, is a sensory ganglion of the trigeminal nerve  that occupies a cavity (Meckel's cave) in the dura mater, covering the trigeminal impression near the apex of the petrous part of the temporal bone.

14. It is somewhat crescentic or semilunarin shape, with its convexity directed anteriomedialy . The three divisions of the trigeminal nerve emerges from this convexity.

15. RELATIONS:- MEDIALY - Internal carotid artery & posterior part of cavernous sinus LATERALY -Middle meningeal artery SUPERIORLY - Uncus And temporal lobe INFERIORLY -Motor root of trigeminal nerve, greater petrosal nerve , apex of the petrous temporal bone, foramen lacerum .

16. DIVISINS OF 5 TH CRANIAL NERVE Trigeminal nerve Ophthalmic (sensory) Maxillary (sensory) Mandibular (mixed)

17. OPHTHALMIC NERVE [V1] It is the smallest of 3 division. It lies in the Cavernous sinus where the oculomotor and trochlear nerves are superior to it and maxillary division is inferior to it.

18. Before entering the orbit by the superior orbital fissure it divides into Lacrimal Nasociliary Frontal (smallest) (intermediate) (largest) Internal External Supra Supra nasal nasal Troclear Orbital Long Infra Posterior ciliary Trochlear Ethmoidal

19. Lacrimal nerve: Smallest of main ophthalmic branches Enters the orbit through the lateral part of the superior orbital fissure Runs along the upper border of the rectus lateralis with the lacrimal artery Receives a communication from the zygomaticotemporal branch of maxillary nerve.which contains lacrimal secretomotor fibres

20. FRONTAL NERVE: Largest branch of the ophthalmic division. Enters the orbit by the superior orbital fissure . Divides midway between the apex and the base of the orbit into two branches: Supratrochlear Supra orbital (small) (large)

21. SUPRATROCHLEAR BRANCH: Runs anteromedially , passing above the troclear . Supplies a descending filament to the infratrochlear branch of naso ciliary nerve. Then it emerges between the trochlea and the supraorbital foramen and supplies - conjunctiva - skin of the upper eyelid - skin of the lower forehead near the midline

22. SUPRA ORBITAl BRANCH: Emerges from orbit through supraorbital notch or foramen. It supplies, - Conjuctiva -Central part of the upper eyelid, -Frontal air sinus -Skin of the forehead -scalp up to the vertex or even upto the lambdoid suture.

23. Nasociliary nerve: Begins in lateral wall of the anterior part of cavernous sinus. Enters the orbit through middle part of superior orbital fissure. Crosses above the optic nerve from lateral to medial side.

24. Branches as follows: Communication branch to the ciliary ganglion from sensory root of the ganglion. It is mixed with sympathetic root. Long ciliary nerves run on the medial side of the optic nerve. Supply sensory nerves to cornea, iris ciliary body. Posterior ethmoidal nerve passes through posterior ethmoidal foramen Supplies ethmoidal and sphenoidal air sinuses.

25. Infratrochlear nerve is smallest terminal branch of Nasocilliary nerve. Emerges from orbit below the trochlea and appears on the face above the medial angle of the eye. Supplies -Conjunctiva -Lacrimal sac -Caruncle -Medial ends of the eyelids.

26. Anterior ethmoidal nerve is the largest terminal of nasociliary nerve. Passes through anterior ethmoidal foramen. Appears for short distance, in the anterior cranial fossa then it descends into the nose through a slit at the side of anterior part of the crista galli .

27. Maxillary Nerve [v2] After arising from the ganglion passes through the foramen rotundum and reaches the pterygopalatine fossa. It has 5 Branches: Middle meningeal nerve Pterygopalatine nerve Posterior superior alveolar nerves Zygomatic nerve

28. Mandibular Nerve [V3] It is formed by union of tensor trunks, large sensory trunk with motor root of the trigeminal. The motor root supplies the muscles of mastication, tensor tympani, tensor veli palatine , mylohyoid and the anterior belly of the digastric muscle.

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