Hearing

This sensory organ of the hearing is situated on the basilar membrane. It is spread like a ribbon along the entire length of basilar membrane.

Explanation : Cortical auditory centers are in the temporal lobe of cerebral cortex. Auditory areas are:
1. Primary auditory area, which includes area 41, area 42 and Wernicke area.
2. Secondary auditory area or auditopsychic area, which includes area 22
Ref : Sembulingam 6th edition (Page- 1014)

Vestibular ganglion is first order neuron of balance or equilibrium

Reference: Guyton 14th; P- 501

Explanation : Receptor organ in semicircular canal is called crista ampullaris and that in otolith organ is called macula. These receptor organs contain the proprioceptors.
Ref : Sembulingam 6th edition (Page- 921)

The sequential steps are as follows:

1.The bipolar cells of the spiral ganglion, which are located in the cochlea’s modiolus, are the first-order neurons of the auditory pathway.
2. The second-order auditory pathway neurons are made up of neurons from the dorsal and ventral cochlear nuclei in the medulla oblongata.
3. Both the superior olivary nuclei and the lateral lemniscus nucleus comprise the third-order neurons.
4.The subcortical auditory centre is formed by the medial geniculate body, where the fibres of third-order neurons terminate.
5.The nerve fibres from the medial geniculate body travel as auditory radiation via the internal capsule to the temporal cortex.
6.In the midbrain, the inferior colliculus of the tectum receives some fibres from the medial geniculate body.
7.The reflex movements in response to auditory stimuli are mediated by the auditory radiation fibres.
8.The temporal lobe of the cerebral cortex houses the cortical auditory centres. The perception of auditory impulses, analysis of sound pitch and intensity, and identification of sound source are all concerns of the cortical auditory centres.

Explanation : Superior semicircular canal gives response to rotation in anteroposterior plane (transverse axis). Horizontal semicircular canal gives response to rotation in horizontal plane (vertical axis). Semicircular canals are concerned with angular (rotatory) acceleration. Otolith organ is concerned with linear acceleration and detects acceleration in both horizontal and vertical planes. Utricle responds during horizontal acceleration and saccule responds during vertical acceleration.
Ref : Sembulingam 6th edition (Page- 924, 926)

Medial geniculate body involve in hearing.

Presbycusis is age related hearing impairment.

Explanation : Neurons of dorsal and ventral cochlear nuclei in the medulla oblongata form the second order neurons of auditory pathway.
Ref : Sembulingum 6th edition (Page- 1013)

Medial geniculate Body is the-
-Relay station for auditory pulse