Cranial Nerves III,IV & VI

Ufaq Raool

Cranial Nerves

Nerves of the brain which emerge from or enter the cranium as opposed to the spinal nerves which emerge from the vertebral columnThey are 12 in number

Cranial Nerve IIIOculomotor Nerve

The Oculomotor Nerve Is entirely motor Supplies all the extrinsic

muscles of the eye except superior oblique and lateral rectus

Have two nuclei1. Main Oculomotor

nucleus2. Accessory

parasympathetic nucleus

Nuclie lie in the mid brain at the level of superior colliculus

Preganglionic parasympathetic fibers from the accessory nucleus join the main oculomotor nerve

The nerve traverses the middle cranial fossa and exits the cranial cavity through the superior orbital fissure

Preganglionic fibers synapse in the ciliary ganglion

Post ganglionic fibers from here supply the contactor pupillae and ciliary muscles of the eye

Cranial Nerve IV TROCHLEAR NERVE

Trochlear nerve Is entirely motor nerve Arises in the midbrain Leaves the midbrain from

its posterior surface Runs through the middle

cranial fossa Leaves the cranial cavity

through superior orbital fissue

Supplies the superior oblique muscle of the eye

Cranial Nerve VIAbducent Nerve

Abducent nerve Is entirely motor nerve Supplies lateral rectus

muscle of the eye Arises in the pons Leaves the brainstem at

the junction of medulla and pons

Leaves the cranial cavity through the superior orbital fissure

Examination of III, IV & VI Cramial Nerves

Examination of these nerves involves Checking for ptosis Squint Checking the extra ocular movements Pupillary reflex