All of the following are concerned with auditory pathway except:
Ans. C Genu of internal capsuleOrgan of Coi is the sense organ of hearing and is situated on the basilar membrane.The actual sensory receptors in the organ of Coi are two specialized types of nerve cells k/a hair cells.Inner hair cells - single layerOuter hair cells - 3 or 4 layersThe nerve fibers stimulated by the hair cells lead to the'spiral ganglion of Coi'which lies in the modiolus (center) of the cochleA.The spiral ganglia has bipolar cells - Its dendrites innervate the hair cells whereas the axons form the cochlear division of CN VIII and end in the dorsal and ventral cochlear nuclei located in the upper pa of medullA.Auditory PathwayAll the fibres from the dorsal and ventral cochlear nuclei synapse (kla Trapezoid body) and the 2deg order neurons pass mainly to the opposite side of the brainstem to terminate in the superior olivary nucleusA few 2deg order fibers pass to the superior olivary nucleus on the same sideFrom the superior olivary nucleus, the auditory pathway passes upward through the lateral lemniscusSome of the fibers terminate in the nucleus of the lateralleminiscus but many bypass this nucleus and travel on to the 'inferior colliculus', where all or almost all fibers do synapse.From there, the pathway passes to the medial geniculate nucleus, where all fibers synapse.Finally the pathway proceeds by way of auditory radiation to auditory coex, located mainly in the superior gyrus of temporal bone. NoteIn sho pathway of hearing is:Organ of Coi|Spiral ganglion|Dorsal/ventral cochlear nuclei|(Trapezoid body)|Superior olivary nucleus|Lateral lemniscus|Inferior colliculus|Medial geniculate body|Auditory coex. Crossing over of the fibers from both sides occurs at 3 places in the brain.At the trapezoid bodyIn the commissure between the 2 nuclei of lateral lemnisciIn the commissure connecting the two inferior colliculi
Trapezoid body
Medial geniculate body
Genu of internal capsule
Lateral lemniscus