SPINAL CORD- HEALTH EDUCATION

Definition :

The spinal cord is the lowe,, elongated, cylindrical part of the central nervous system, which occupies the upper two thirds of the vertebral canal. 

Extension :

The spinal cord is continuous above with the medulla oblongata and extends from the upper border of atlas to the lower border of the first lumber vertebra, the lower end is conical and is called the conus medullaris. 

Gross anatomy :

1. Length :45 cm (adult male) 

2. The spinal cord has two major thickenings or enlargements :

- A cervical enlargement occurs in the region associated with the origin of spinal nerves C5 to T1 that innervate the upper limbs. 

- A lumbosacral enlargement occurs in the region associated with the origins of spinal nerves L1 to S3, which innervate the lower limbs. 

3. Thirty - one pairs of spinal nerve roots are attached to the spinal cord.

4. The external surface of the spinal cord is marked by -

- anterior median fissure. 

- posterior median sulcus. 

- posterolateral sulcus.       

Cross - sectional anatomy : 

Internally the cord has a small central canal surrounded by grey matter and white matter : 

1. In cross section, the grey matter has a characteristic H- shaped appearance, having two posterior, two anterior and two lateral columns. 

2. The white matter surrounds the grey matter and is rich in nerve cell processes, which form tracts. The tracts are separated into three regions - anterior, posterior and lateral. 

Functions of the spinal cord : 

1. The spinal cord is the conduit for signals from the periphery of the body to the brain or in the opposite direction from the brain back to the body. 

2. Neuronal circuits in the spinal cord can cause. 

- walking movement. 

- Reflexes that withdraw protions of the body form objects. 

- Reflexes that stiffen the legs to support the body against gravity. 

- Reflexes that control local blood vessels, gastrointestinal movements.