VPB 121: Veterinary Physiology - II (2+1)

NYSTAGMUS

• It is the movement of the eye in relation to the movement in the head of the animal.
• It consists of rhythmic movements of the eyes in a dorsoventral, lateromedial, or oblique directions.
• It is characterized by the slow movement of the eye in one direction and then quick return to its original starting position.
• These movements are continued till the rotatory acceleration is maintained.
• The receptor organs of the nystagmus are the cristae of the semicircular canals. 
• The afferent neurons for the nystagmus are present within the VIII cranial nerve.
• These fibers synapse with internuncial neurons within the vestibular nuclear complex of the medulla and pons.
• The motor activity is relayed to the extrinsic muscles ot the eye via the brainstem reticular formation.