Vestibulocochlear Sensory System

Cochlear (Auditory) System

 

  • The receptor cells for the auditory pathway are the hair cells of organ of corti in the scala media inner ear. 


     

 

 

  • First order constituting the cochlear nerve synapse in the cochlear nuclei of the medulla oblongata

  • The cochlear nuclei project to at least one of the following:

    a) Inferior colliculus,
    b    )     Dorsal nucleus of the trapezoid body
    c) Nucleus of the lateral lemniscus

  • Whatever the other relay station(s), the Medial Geniculate Body (MGB) is obligatory.

  • Before the MGB, the pathway is characterized by bilateral projections

  • Thalamocortical projection ends in the superior temporal gyrus (Transverse gyri of Heschl)
 

Vestibular System

 
  • Receptors are the cristae of semi-circular canal and macule of the saccule and utricle.

  • The first order neurons constitute the vestibular nerve which accompanies the cochlear nerve to form the vestibulo-cochlear nerve

  • Some vestibular axons synapse with neurons of fastigio nucleus and flocullo-nodular lobe of the cerebellum

  • Axons from the vestibular nuclei synapse with neurons in:

    a) Cerebellum

    b) Motor neurons of spinal nerves

    c) Motor neurons of cranial nerves (through medial longitudinal fasciculus )