There are two types of nerves, which are as follow-
- The nerves grown up to the muscles are called motor or efferent nerves and these nerves provide movement to other organs according to brain’s order.
- The nerves grown up to the skin are called sensory or afferent nerves and these nerves carry impulses from the skin to the spinal cord or brain and the last part of these nerves are very effective.
Both types of nerves remain connected inside the brain and spinal cord as well as inside healthy organs and form an arc, known as reflex arc. For illustration- when a person pricks a needle in his arms or other’s arm, sensory nerves carry its effects to the spinal cord through their nerves. A motor nerves carry impulse (effects) to the arm’s muscles resulting it is left automatically by reflex action and the arm is become free with sudden jerk. The nerves carry these types of impulses with the waves of 100 m/sec to the brain resulting the sensations of heat, pain and cold are felt.
Figure of reflex arc-
The following parts are found in reflex arc-
- The last part of sensory nerves’ fibers.
- Peripheral actions of sensory nerves’ fibers (sensory fibers).
- Sensory cells.
- The central functions of sensory cells.
- Motor nerves’ fiber.
- The last part of the nerves inside muscles.
- Motor nerves’ cells (inside the spinal cord).
- Inter nerves’ cells (inside the spinal cord).
The spinal cord grows from brain root and forwarded through merunali. The mouth of each vertebra is located towards a parshva from where the pair of spinal nerve forms. There are total 31 pairs of these nerves found and each of them is known as lobe. The nerves connect every lobe to each other and also connect the spinal cord with the brain.
The reflex action of the spinal cord can be seen by hammering in the back part of knee. This affect reaches to the spinal cord from where the knees’ muscles get orders for contracting and the legs are spread on knees’ joints.