Collect information on the actions controlled by spinal cord by using reference books from your school library. (AS4)

The spinal cord is a posterior part of the central nervous system which runs mid dorsally within the vertebral column. It lies in the neural canal of the vertebral column. The spinal cord extends from the medulla oblongata. In an adult, the spinal cord is from 42-45 cm long. By adulthood, the area within the vertebral column below the second lumbar vertebra contains spinal nerves that branch from the spinal cord at higher levels. In each segment of the spinal cord, a spinal nerve arises from each side of the cord. Spinal cord performs two major functions: the stimuli are passed to and from the brain through the spinal cord and it is the center of spinal reflex actions. The spinal nerves are formed by the union of the dorsal and ventral roots shortly after they leave the spinal cord. All spinal nerves are mixed nerves as they carry both sensory and motor impulses. Spinal nerves join to form the following plexuses :

i. cervical plexus - it innervates the neck and diaphragm.

ii. Brachial plexus - it connects the chest and arm.

iii. Lumbar plexus - it innervates the legs.

iv. Sacral plexus - it connects the pelvic region.

v. Coccygeal plexus - it also innervates the pelvic region.

Hence, the spinal nerves show connections with various above organs and body parts.

Maximum reflex actions are controlled by spinal cord and are called spinal reflex actions.

For example,

a) closing of eyes when strong light is flashed across them.

b) withdrawal of limbs when they are touched by hot things.

c) watering of mouth on seeing favorite food.

d) opening of mouth on hearing a loud sound.

e) typing, riding a bicycle, knitting, etc.