Spinal Cord-
Spinal cord (42 to 45 cm long) extends from the medulla oblongata and is continuous to the level of second lumbar vertebra. It conducts impulses to and from the brain and controls most of the reflex activities and provides a means of communication between spinal nerves and the brain. It is formed of two types of neural tissue: internal grey matter and outer white matter. The area within
the vertebral column below the second lumbar vertebra contains spinal nerves that are collectively called, the cauda equina. The spinal cord ends as the conus
medullaris from which a fine connective tissue filament called filum terminale arises that anchors spinal cord within the vertebral column.
Functions
Spinal cord performs two main functions:
1. The stimuli are passed from and to the brain through the spinal cord.
2. It is the centre of spinal reflex action.
REFLEX ACTION
Reflex action (Marshal Hall, 1833) is an immediate involuntary action of any organ or part of the body in response to a particular stimulus.
The nervous pathway taken by nerve impulses in a reflex action is called reflex arc. The components that mediate
a reflex, usually includes a receptor, afferent pathway, integrating centre, efferent pathway and effector. Hence,
the entire impulse circuit of a reflex response.
