Neuroanatomy of Special Sense Pathways

Question 1

Describe the neuronal pathway of visual input from the optic nerve to the primary visual cortex.

Answer 1

Light -> optic nerve -> optic chiasm -> optic tracts -> lateral geniculate nucleus of the thalamus -> superior colliculi (bilaterally) and separately optic radiations and Meyer’s loop -> primary visual cortex in the occipital lobe

Question 2

Explain the neuronal pathway involved in the afferent pupillary light reflex.

Answer 2

Optic nerve -> optic chiasm -> optic tract -> lateral geniculate nucleus of the thalamus -> superior colliculi bilaterally -> Edinger-Westphal nuclei bilaterally -> constriction of constrictor pupillae via CN III bilaterally

Question 3

Describe the neuronal auditory pathway from hair cells of the inner ear to the primary auditory cortex.

Answer 3

Hair cells release neurotransmitter to spinal ganglion cells -> ipsilateral cochlear nucleus -> superior olivary nuclei bilaterally -> ipsilateral inferior colliculus -> medial geniculate nucleus in the thalamus -> primary auditory cortex