Question

(a).label that two parts labelled 1 and 2 in the diagram
(b). suggest a suitable caption heading for this diagram

Answer 1

(a) Label 1: Central canal (or spinal cord if pointing to the outward region).
Label 2: Effector muscle (where the motor nerve fibres relay or send some particular electrical impulses or messages to the motor impulses from the CNS or central nervous system to the Effector organs, making a reaction towards the stimuli).

Suitable caption or a heading?
》 Reflex Action or Reflex arc