Spinal Cord

• The spinal cord is made up of millions of nerve cells and it sends projections up and down the cord and out into other parts of the body that enable us to run, sit, walk and breathe.
• It is the major communication link between the brain and the Peripheral Nervous System (spinal nerves) inferior to the head.

The General Structure

• The spinal cord connects to brain at the level of foramen magnumand extends inferiorly in the vertebral canal to level L1-L2 of the vertebral column.
• It gives rise to 31 pairs of spinal nerves,which exit the vertebral column through intervertebral abd sacral foramina.
• The spinal cord has :

1.  cervical enlargement : spinal nerves supplying the upper limbs originate.
   
2. Lumbosacral enlargement : spinal nerves supplying the lower limbs originate.

• The spinal cord is shorter than the vertebral column. Nerves from the end of the spinal cord form the cauda equina.

Meninges of the Spinal Cord.

• There are three meningeal layers surround the spinal cord.

(superficial)  Dura mater > arachnoid mater > pia mater (deep)

• The epidural space is between the periosteum of the vertebral canal and the dura mater- contains spinal nerve roots,blood vessels,areolar connective tissue and adipose tissue.
• The subdural space is between the dura mater and the arachnoid mater- a very small space containing a small amout of serous fluid.
• The subarachnoid space is between the arachnoid mater and pia mater – contains weblike strands of arachnoid mater,blood vessels and cerebrospinal fluid (CSF)

The Cross Section of Spinal Cord

• The spinal cord consists of peripheral white matter and central gray matter (shaped like butterfly).
• White matter : organized into columns (funiculi) called the ventral , dorsal and lateral columns which are subdivided into tracts (fasciculi or pathways) which consist of ascending  and descending axon.
• Gray matter :

1. consist of neuron cell bodies , dendrites and axons.
2. divided into horns : -The dorsal horns contain sensory axons that synapse with interneurons.
3.  -The ventral horns contain the neuron cell bodies of somatic motor neurons .-The lateral horns contain the neuron cell bodies of autonomic motor neurons.
4. The gray and white commisures connect each half of spinal cord.
5. The dorsal root contains sensory axons, the ventral root has motor axons and the spinal nerves have sensory and motor axons.

 

Here is a video explaining spinal cord anatomy , enjoy your learning 🙂