NMS

6/28/1999

Pupillary Light Reflex

• Parasympathetic nerve—III, Edengar-Westfall nucleus—Occulomotor –VE (visceral efferent) not under voluntary control—constrict pupil
• The muscles that move the eye that are under the control of CNIII are SE and are under voluntary control—corticobulbar—pyramidal like tract that goes to eye muscles

• Parasympathetic atonia—neurologic lesion
• Sympathetic—come from spinal areas—VE
• If sympathetics do not work the pupils would remain constricted
• If parasympathetics do not work the pupils would remain dilated
• Visceral efferents are the autonomics
• Sclerotome pain is SA-SA
• Dermatome pain is abolishment of nerve and does not fit into this
• Reflex to constrict pupils is VA-VE
• Direct reflex
• Consensual reflex
• Possibilities
• Light into left eye
• Left eye direct intact
• Right eye consensual absent
• What creates this lesion? CNIII coming into that eye
• Light now into the right eye
• Left consensual intact
• Right direct absent
• Accommodation or near vision test—pupils constrict when a person focuses on something close up
• If occulomotor is lesioned, the pupil will never constrict
• Deviation up and out upon following something—lazy eye
• Lesion is distal to Edengar-Westfall nucleus—peripheral neuropathy
• CNIII lesion is parasympathetic atonia
• Horner's syndrome—lesion of sympathetics