2. Efferent or motor neurons: Nerve conduction from the central nervous system to the effector organs.
3. Association neurons or interneurons: They lie between motor and sensory neuron, mostly confined within the central nervous system.

Physiology of Nerve.
The two main properties of nervous tissue are excitability and conductivity. Excitability is the ability of nerve cell and nerve fibres to enter into state of excitation in response to stimulus. The transmission of excitation in a particular direction is called conductivity. The initiation and conduction of nerve impulse is shown in Figure 13.3.

Figure 13.3 : Initiation and conduction of nerve impulse.