In: Anatomy and Physiology
what does the pupillary reflex tell you about the afferent nerve pathway?
Which division of the ANS causes the pupils to constrict? Which division of the ANS causes the pupils to dilate?
If you shine light into the eyes of an individual who has suffered a blow to the head, what could happen and why?
Pupillary reflex is used to check the function of brain stem. Pupillary light reflex controls the diameter of pupil in response to intensity of light. Optic nerve sends impulses to brain for image processing and image recognition. This is called as pupillary light reflex afferent pathway. Afferent pathway has nerve fibres running in optic nerve (CN II) which carries sensory input to brain.
Autonomic Nervous System (ANS) has two divisions: Sympathetic nervous system and Parasympathetic nervous system. Parasympathetic nervous system causes pupils to constrict. Sympathetic nervous system causes pupils to dilate.
If one shines light into the eyes of an individual who has suffered a blow to the head and if the individuals pupil constricts then it indicates that brain function is normal but if the pupil does not constrict then it indicates brain is not functioning properly. The light shone in one eye will cause both pupil to constrict if brain is working properly.