Point 17 Motor V Sensory V Mes V Corn. Refl. Summary Overview Problems Contents Anatomy

Damage to the C.N. V results in problems with the CORNEAL REFLEX. This reflex involves C.N. V (on the sensory side) and CN VII (on the motor side). Stimulation of the cornea of one eye results in the closing of BOTH eyelids. The pathways involved are (1) touch fibers in the ophthalmic division of C.N. V (innervate cornea) that pass into the chief sensory nucleus V, some pain fibers probably pass into spinal tract V, but lets concentrate on the touch fibers to the CHIEF. Cells in the CHIEF project BILATERALLY to motor VII (we can not identify these axons in our sections). The result is closing of BOTH eyelids upon stimulation of ONE cornea. The response on the side that is stimulated is called the DIRECT corneal reflex while that on the opposite side is called the CONSENSUAL corneal reflex. Go over the diagram and think about the results of lesions of the various components.