vestibulocochlear pathway
Pathway of hearing
Sound waves travel through the external auditory canal, causing vibration in the tympanic membrane, then the bony ossicles in middle ear untill they stimulate the receptors in inner ear.
Sensation carried by cochlear nerve (CN VIII) to cochlear nuclei located at the junction between medulla and pons.
cochlear nuclei project to superior olivary nucleus in both sides and from there to inferior colliculus in midbrain.
Inferior colliculus projects to medial geniculate body in thalamus and from there to superior temporal gyrus where auditory and auditory assicated area are located.
Injury of hearing pathway from any part of the ear until the cochlear nuclei causes ipsilateral deafness
Injury of the pathway from the superior olivary nucleus until the temporal lobe causes bilateral decrease in hearing.
Vestibular pathway
Vestibular nuclei project to different parts of CNS to ensure coordination of body moevement and balance. This includes:
1- Cerebrum (Temporal lobe)
2. Cerebellum (Floccuolnodular lobe)
3. Cranial nerve nuclei of nerves that supply extraocular muscles (occulomotor, trochlear and abducens or CN III, IV and VI).
4. Spinal cord to coordinate the movement of muscles of trunk, neck and extremities.