Write the main functions of the following :
$(a)$ Sensory neuron
$(b)$ Cranium
$(c)$ Vertebral column
$(d)$ Motor neuron

(N/A) Sensory neuron: It carries sensory impulses from receptors,such as the skin,to the central nervous system.
$(b)$ Cranium: It is the bony case surrounding the brain,which protects it from mechanical injury and shock.
$(c)$ Vertebral column: It is the protective bony covering surrounding the spinal cord. It also provides mechanical support to the body.
$(d)$ Motor neuron: It carries motor impulses from the central nervous system to specific effectors,such as muscle fibers or gland cells.