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

Tonic labyrinthine reflexes

EXTRACORTICAL REFLEXES - TONIC LABYRINTHINE REFLEXES

Phasic labyrinth reflex

• These reflexes are initiated by receptor organs of the semicircular canal.
• Rotational acceleration of the head stimulates vestibular semicircular canal.
• Maintenance of upright posture on rotation if kept on rotating platform and altering the position of head and body to the opposite of the rotation.
• On stoppage of the rotation, the animal’s head will be turned and animal lean towards the opposite direction.
• Semicircular canals help to maintain the animal’s balance on sudden change in the head’s direction.

Righting reflex(RR)

• This is the involvement of tonic labyrinthic reflex to maintain the position of the head upon the neck.
• If the animal is maintained in a supine position. Further due to the involvement of tonic neck reflex to later the body’s position to an upright position.
• This reflex response to body position is known as righting reflex.
• If a cat is dropped in a space from a supine position, as in the process of dropping, the position of the head is immediately altered to an upright position due to tonic labyrinth reflex. Due to this, other parts of the body of the body position so as to support which is due to tonic neck reflex and assist the animal to land in upright position.