, or cranial nervethe first

simply CNI, carries the

sensory information for the

. Derived from sense of smell

nasal embryonicthe

, the olfactory nerve placode

is capable of regeneration.

The olfactory nerve is

sensory in nature and

originates on the olfactory

mucosa in the anterosuperior

nasal cavity.

Smell !

Lesions to the olfactory nerve can occur -coupbecause of blunt trauma, such as

damage, meningitis, and tumors coup-contraof the frontal lobe. They often lead to a

reduced ability to taste and smell. However, lesions of the olfactory nerve do not lead to a reduced ability to sense pain from the nasal epithelium. This is because

pain from the nasal epithelium is not carried to the central nervous system by the

olfactory nerve; rather, it is carried to the trigeminal central nervous system by the

nerve(cranial nerve V).

Anosmia, or odorthe inability to perceive |is

in other words a lack of functioning . Anosmia may be olfaction

temporary but traumatic anosmia can be permanent. Anosmia is due

to an inflammation of the nasal mucosa; blockage of nasal passages

or a destruction of one temporal lobe

Damage to this nerve impairs the sense of smell. To test the function

of the olfactory nerve, doctors nostrilsblock one of the patient's (such as pungent odorand place a

essence) under the damp coffeeopen nostril. The test is then

repeated on the other nostril. If the patient can smell the coffee, not necessarily identify what it is, the

patient’s olfactory nerve is functioning.

The optic nerve, also known as cranial nerve II, transmits visual

to the retinainformation from the embryonic. Derived from the brain

, a diverticulum retinal ganglion cell, the diencephalonlocated in the

optic nerve does not regenerate after transection.

Vision !

, as visionDamage to the optic nerve typically causes permanent and potentially severe loss of visual field, which is diagnostically important. The type of pupillary reflexwell as an abnormal

loss will depend on which portions of the optic nerve were damaged. In general:Damage to the optic nerve anterior to the optic chiasm causes loss of vision in the eye on the

same side as the damage.bitemporalthe optic chiasm causes loss of vision laterally in both visual fields (inDamage

.pituitary adenoma). It may occur in large hemianopsiato the chiasm causes loss of vision in the visual field on the posterioroptic tractDamage to the

side opposite to the damage.Leber'sInjury to the optic nerve can be the result of congenital or inheritable problems like

, glaucoma, trauma, toxicity, inflammation, ischemia, infection Hereditary Optic Neuropathy. By far, the three most common injuries aneurysms(very rarely), or compression from tumors or

to the optic nerve are from glaucoma, optic neuritis (especially in those younger than 50 years of age), and anterior ischemic optic neuropathy (usually in those older than 50).

optic neuropathycausing ganglion cellsis a group of diseases involving loss of retinal Glaucoma.loss, initially sparing central visionperipheral visionin a pattern of

is inflammation of the optic nerve. It is associated with a Optic neuritis.multiple sclerosisnumber of diseases, the most notable one being

is a particular type of infarct that affects Anterior Ischemic Optic Neuropathypatients with an anatomical predisposition and cardiovascular risk factors.

is the underdevelopment of the optic nerve causing Optic nerve hypoplasialittle to no vision in the affected eye.can detect and diagnose some optic optometristsand Ophthalmologists

-neurospecialists that are -nerve diseases but, those sub, are often best suited to diagnose and treat diseases of the ophthalmologists

optic nerve.The International Foundation for Optic Nerve Diseases (IFOND) sponsors

research and information on a variety of optic nerve disorders and may provide general direction.

known as the eighth cranial nerve, transmits sound and

equilibrium (balance) information . The brainto the inner earfrom the

vestibulocochlear nerve is derived .placodeoticembryonicfrom the

Balance &

Audition !

Damage to the vestibulocochlear nerve may cause the following symptoms:1- hearing loss

vertigo-23- false sense of motion4- loss of equilibrium (in dark places)

nystagmus-5sicknessmotion -6

.tinnitusevoked -gaze-7