Summary Cranial nerves,

Cranial nerves
The cranial nerves form part of the peripheral nervous system and
originate from the brain.


Olfactory (I)
Function Smell

Test

Identify a familiar odour

Abnormal signs

Partial or total loss of smell Altered or increased sense of smell



Optic (II)
Function Sight

Test

Visual acuity: read with one eye covered

Peripheral vision: detect objects or movement from the corner of the
eye with the other eye covered

Abnormal signs
Visual fields defects, loss of visual acuity, colour-blind
Oculomotor (III)
Function

Movement of eyelid and eyeball, constriction of pupil, lens
accommodation

, Test

Follow the examiner’s finger, which moves up and down and side to
side, keeping the head in mid-position

Abnormal signs

Squint, ptosis, diplopia, pupil dilation


Trochlear (IV)
Function

Movement of eyeball upwards

Test

As for oculomotor

Abnormal signs
Diplopia, squint


Trigeminal (V)
Function

Mastication, sensation for eye, face, sinuses and teeth

Test

Test fascial sensation ,Clench teeth

Abnormal signs

Trigeminal neuralgia, loss of mastication and sensation in eye, face,
sinuses and teeth