Examination Damage to this nerve leads to impairment or total loss anosmia of the sense of smell To simply test the function of the<unk> , each nostril is tested with a pungent odor. If the odor is smelled, the<unk>  is likely functioning. On the other hand, the nerve is only one of several reasons that could explain if the odor is not smelled. There are<unk>  testing packets in which strong odors are embedded into cards and the responses of the patient to each odor can be determined. Lesions Lesions to the<unk>  can occur because of "blunt trauma", such as coup-contrecoup damage, meningitis, and tumors of the frontal lobe of the brain. These injuries often lead to a reduced ability to taste and smell. Lesions of the<unk>  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<unk>  - it is carried to the central nervous system by the trigeminal nerve. Aging and smell A decrease in the ability to smell is a normal consequence of human aging, and usually is more pronounced in men than in women. It is often unrecognized in patients except that they may note a decreased ability to taste (much of taste is actually based on reception of food odor). Some of this decrease results from repeated damage to the<unk>  receptors due likely to repeated upper respiratory infections. Patients with Alzheimer's disease almost always have an abnormal sense of smell when tested. Pathway to the brain Some nanoparticles entering the nose are transported to the brain via<unk> . This can be useful for nasal administration of medications. It can be harmful when the particles are soot or magnetite in air pollution. In naegleriasis, "brain-eating" amoeba enter through the<unk>  mucosa of the nasal tissues and follow the<unk>  fibers into the<unk>  bulbs and then the brain.
Olfactory nerve
Olfactory trigone
Olfactory tract
Ciliary ganglion
Oculomotor nerve
Optician
Stellate ganglion
Buccal branches of the facial nerve