Special sense I – VISION

Visual pathway

Lesion in optic nerve leads to loss of vision on the same side of lesion optic tract: *Left optic tract is responsible for vision in nasal half of left visual field and temporal half of right visual field *right optic tract is responsible for vision in nasal half of right visual field and temporal half of left visual field

II- HEARING

Auditory pathway

External ear: collect sounds & direct it to tympanic membrane Middle ear: sounds vibrate the tympanic membrane then transmitted to auditory ossicles Types of conduction: 1- ossicular conduction 2- air conduction 3- bone conduction Austachian tube: responsible for equalizing pressure on either side of tympanic membrane

III- TASTE

Taste buds situation

Taste pathway

Taste sensation

IV- SMELL

Smell pathway

VisionHearingSmellTaste Receptor Rods & consHair cell in organ of corti Olfactory receptorTaste buds Site In retinaInner earNoseTongue Nerve Optic nerveAuditory nerve “vestibulocochlear “ Olfactory nerve*Anterior 2/3 of tongue: fibers of facial nerve *Posteior 1/3 of tongue: glossopharyngeal nerve *Vagal fibers from other regions Relay in thalamus RelayNot relay in thalamus Relay Cerebral cortex Occipital roleTemporal lobeOlfactory cortex includes structures which form apart of limbic system Parietal lobe