Spinal Cord: Location & Coverings MCQ - Practice Questions with Answers

Spinal Cord: Location & Coverings

• The spinal cord is a part of the central nervous system (CNS). 
• It is situated inside the vertebral canal of the vertebral column. 
• The spinal cord is a continuation of the brainstem. 
• It lies in the neural canal of the vertebral column.
• It extends from the foramen magnum at the base of the skull to the L1/L2 vertebra where it terminates as the Conus medullaris (medullary cone). 
• A thin thread called Filum terminale extends from the tip of the conus medullaris all the way to the 1st coccygeal vertebra (Co1) and anchors the spinal cord in place. 
• Bundle of spinal nerves at the end is Cauda Equina
• Like the vertebral column, the spinal cord is divided into segments: cervical, thoracic, lumbar, sacral, and coccygeal. 
• Each segment of the spinal cord provides several pairs of spinal nerves, which exit from vertebral canal through the intervertebral foramina. 
• There are 8 pairs of cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal pair of spinal nerves (a total of 31 pairs).
• The spinal cord is surrounded by the same three meninges as found in the brain, i.e., a thin innermost piamater, the middle webby arach­noid membrane (arachnoid mater) and the outer tough duramater.
• The subarachnoid space is filled with cerebrospinal fluid. 
• There is an additional space, the epidural space above the Dura mater. 
• The epidural space contains fatty and connective tissues and veins.

Internal Structure of Spinal Cord

The spinal cord is divided into left and right symmetrical halves by the posterior median sulcus and the anterior median fissure.

• The inner butterfly-shaped area is the grey matter of the spinal cord.
• Surrounding the grey matter are bundles of myelinated nerve fibres, called fasciculi or white columns, which together form the white matter of the spinal cord.
• In each segment of the spinal cord a spinal nerve arises from each side of the cord. 
• Each spinal nerve connects with the cord through two nerve roots.
• Anterior or ventral roots transmit motor information, and they originate from the anterior horns of the gray matter and exit the spinal cord through the anterolateral sulcus. 
• The posterior or dorsal nerve root consists of a bundle of sensory axons (carrying incoming signals) whose cell bodies are located in the dorsal root ganglion. 
• These axons extend into the posterior horn of the grey matter, where they often form synapses with other neurons, some of which are called interneurons.
• Interneurons, short neurons confined to the grey matter of the cord, form synapses with other interneurons and motor neurons whose cell bodies are located in the anterior horn of the grey matter.
• Along the white matter of the spinal cord there are two kinds of fasciculi, or bundles of axons:

          - The ascending tracts, which carry sensory impulses to the brain
          - The descending tracts, which carry motor impulses from the brain to the spinal nerves at various levels of the cord