Cranial Nerves

Question 1

Name the Nuclei of Occulomotor Nerve.

Answer 1

Origin from ventromedial aspect of Central Gray matter of midbrain at the level of Superior Colliculus.

1. Dorsolateral - to supply inferior rectus
2. Ventromedial- to supply medial rectus
3. Intermediate- to supply inferior oblique
4. Median Raphe- to supply superior rectus
5. Caudal Central- to supply Voluntary part of Levator Palpebrae Superioris
6. Edinger-Westphal- to supply ciliates and sphincter pupillae

Question 2

Functional Components of Occulomor nerve?

Answer 2

1. General somatic efferent- to extraocular muscles
2. General visceral efferent- to ciliaris and sphincter pupillae
3. General somatic afferent - proprioceptive input from eye muscles to Mesencephalic nucleus of Trigeminal (Vth nerve)

Question 3

Signs of occulomotor nerve paralysis?

Answer 3

1. Ptosis
2. Lateral Squint and Proptosis
3. Eyeball depressed
4. Loss of Accomodation and Light Reflex
5. Pupils dilated
6. Diplopia

Question 4

Features of Trochlear nerve paralysis?

Answer 4

• Diplopia on looking below the horizontal plane.

* Loss of depression of adducted eye (due to paralysis of SO)

Question 5

Most common cause of occulomotor nerve damage?

Answer 5

Aneurysm of Posterior Cerebral Artery or Superior Cerebellar Artery as the nerve passes between them.

Question 6

What is the special feature of Trochlear nerve?

Answer 6

Only cranial nerve to emerge from Dorsal aspect of brain stem.

Question 7

Name the orders of neurons in the visual pathway.

Answer 7

1st order- Bipolar cells
2nd order- Ganglion cells
3rd order- Cells of the Lateral geniculate body

Question 8

What are the nuclei and functional components of Trigeminal nerve?

Answer 8

Sensory Nuclei
•Principal Sensory - Upper pons
•Spinal - From the lower end of principal nucleus along the whole length of medulla
•Mesencephalic - midbrain, lateral to cerebral aqueduct

Motor Nucleus - Upper pons, medial to sensory nucleus

Functional Components:

1) General Somatic Afferents - touch and pressure divers end in principal nucleus- pain and temp fibers end in Spinal N- proprioceptive end in mesencephalic N.
2) Special Visceral Efferents - from the motor nucleus —> muscles of mastication and the tensors, mylohyoid, Ant belly of Digastric

Question 9

Maxillary nerve— course, branches, related parasympathetic ganglion?

Answer 9

Origin: Convex distal surface of trigeminal ganglion.
Course: Enters lateral wall of cavernous sinus where it occupies the lowest position —> Leaves the middle cranial Fossa by passing through foramen rotundum—> Crosses upper part of pterygopalatine Fossa (3 branches here)—> Continues as the infraorbital nerve to emerge on the face.

Branches:

1) in middle cranial Fossa - Meningeal branch
2) in pterygopalatine Fossa- Ganglionic, Zygomatic, PSA branch
3) Continues as infraorbital nerve which gives off MSA, ASA nerves and three terminal branches— palpebral, nasal, labial.