Introduction to the trigeminal nerve ‫‬dental surgery Ophthalmic nerve dental surgery Maxillary nerve Mandibular nerve

1. Introduction to
The Trigeminal Nerve

2. What are cranial nerves?
• Cranial nerves are nerves that emerge directly
from the brain
• There are 12 pairs of cranial nerves
• Only the first 2 originate from the cerebrum,
the others originate from the brain stem
• Trigeminal nerve is the FIFTH cranial nerve

3. •
•
•
•
The cranial nerves
Ⅰ Olfactory nerve
Ⅱ Optic nerve
Ⅲ Oculomotor nerve
Ⅳ Trochlear nerve
• Ⅴ Trigeminal nerve
•
•
•
•
•
•
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Ⅵ Abducent nerve
Ⅶ Facial nerve
Ⅷ Acoustic nerve
Ⅸ Glossopharyngeal nerve
Ⅹ Vagus nerve
Ⅺ Accessory nerve
Ⅻ Hypoglossal nerve

4. Classification of cranial nerves
• Sensory cranial nerves:
– contain only afferent (sensory) fibers
• Motor cranial nerves:
– contain only efferent (motor) fibers
• Mixed nerves:
– contain both sensory and motor fibers

5. TRIGEMINAL NERVE

6. Trigeminal nerve
• 5th cranial nerve (CN5)
• Largest cranial nerve
• MIXED CRANIAL NERVE
• Sensory to face – 3 dermatomes
• Motor to muscles of mastication

7. View of brain from
below showing
trigeminal ganglion
and trigeminal nerves

8. Nuclei
• Sensory nuclei – largest cranial nerve nuclei
• Sensory nuclei –mid-brain, pons and medulla
• Sensory nuclei – 3 parts
– Mesencephalic nucleus
– Primary/Main sensory (pontine) nucleus
– Spinal trigeminal nucleus
• Motor nucleus – mid-pons

10. Trigeminal ganglion
(semilunar/gasserian /gasser’s ganglion)
• Semilunar in shape
• Situated in Meckel’s cavity /cave on ‘Trigeminal
depression’ present on petrous temporal bone
• Contains the cell bodies of incoming sensory
nerve fibers
• Convex surface below to which the 3 nerve roots
converge:
– Opthalmic division
– Maxillary division
– Mandibular division

11. Trigeminal ganglion - shape
To sensory
nuclei
ro
Motor
5
1
ot
r
luna
i
Sem glion
Gan
2
3
Foramen
ovale
To muscles of
mastication/
swallowing
Foramen
rotundum
Superior
orbital fissure

13. Trigeminal dermatomes
• Areas of cutaneous sensory innervation
• Show very little overlap
• Injection of local anesthesia shows loss of
sensation from very well defined areas
• Knowledge of dermatomes helps in
– Locating site of nerve injury
– Testing result of nerve block

14. V1- OPTHALMIC DIVISION
V2 – MAXILLARY DIVISION
V3 – MANDIBULAR DIVISION

16. Applied anatomy
• Knowledge of dermatomes and their nerve
supply helps locate site of nerve injury
• Also helps in demonstrating effect of nerve
block
• Intracranial causes of trigeminal neuralgia
• Pain control and modulation

18. Stimulus – pin
prick

19. THANK YOU