Spinal cord is a long and thin structures comprising of millions of nervous tissues. The spinal cord starts from the medulla ablongata, end of brainstem. This is near the occipital bone (bone at the back) of the skull. It ends at the lumbar region of the backbone or vertebral column.
The backbone or vertebral column protects the spinal column. Cerebrospinal fluid extends from the brain and is found in the center portion of the spinal column. There are 31 pairs of spinal nerves. Based on the location where they branch out, the nerves are grouped as cervical (8), thoracic (12), lumbar(5), sacral (5) or coccygeal (1) nerves.
Along the spinal cord, clusters of nerves are formed from which the groups of nerves divide into sensory or motor nerves supplying to the various parts of the body. These clusters of nerves are called nerve networks or plexuses. There are 4 pairs of plexuses along the spinal cord.
- Cervical plexus: Nerves that supply the neck and shoulder regions are group together in the cervical plexus. Eight pairs of cervical nerves branch out from cervical plexus to supply to the neck muscles, diaphragm, shoulder muscles, arm, elbow, wrist and finger muscles.
- Brachial plexus: Continuing from the lower cervical nerves, 12 pairs of thoracic nerves branch out to supply the organs and muscles of the upper back, shoulder and abdomen.
- Lumbar plexus: Five pairs of lumbar nerves branch out from the lumbar plexus to supply the hip joint, flexion and extension of the thigh, knees, foot and toes.
- Sacral plexus: Sacral nerves, which are also five pairs, supply to the hip, foot and toes flexion movement. One pair of coccygeal nerve also originates from this plexus.
- Injury to the spinal cord: Spinal cord injury is possible with trauma, stretching or applying pressure, infections, etc. Depending on the nerve near which the injury has occurred and the extent of the injury, the individual may suffer symptoms varying from mild loss of sensations to paralysis of the limbs.
- Nerve compression: The joint between consequent bones of the vertebral column comprises of an air space and a lubricating fluid bag, so that the nerves passing do not get compressed or pinched. When there is any disturbance in the joint, the nerve gets pinched and the corresponding limb or muscle pain is experienced by the individual.
- Tumours: Spinal tumours may occur on the inside or outside of the dura mater (covering of the cerebrospinal fluid) which may compress the adjacent nerves and disturb the cerebrospinal fluid.
- Lumbar puncture: The cerebrospinal fluid is extracted by performing lumbar puncture at the level of L1-L2 vertebral bones, as a treatment to avoid damage to the spinal cord.