The spinal cord is a cylindrical bundle of nerve fibers and associated tissue, enclosed within the spine, and connects nearly all parts of the body to the brain.

Gross Structure

1. Location and Extent

   • Origin: Begins at the foramen magnum of the skull, continuous with the medulla oblongata.

   • Termination: Extends down to the level of the first or second lumbar vertebra (L1 or L2) where it tapers into the conus medullaris.

   • Length: Approximately 45 cm in males and 42 cm in females.

2. Enlargements

   • Cervical Enlargement (C4-T1): Supplies nerves to the upper limbs.

   • Lumbosacral Enlargement (T11-S1): Supplies nerves to the lower limbs.

3. Meningeal Coverings

   • Dura Mater: Tough outer layer.

   • Arachnoid Mater: Web-like middle layer.

   • Pia Mater: Delicate inner layer adhering to the spinal cord.

   • Spaces Between Layers:

     • Epidural Space: Contains fat and venous plexus.

     • Subdural Space: Potential space.

     • Subarachnoid Space: Contains cerebrospinal fluid (CSF).

4. Filum Terminale and Cauda Equina

   • Filum Terminale: A delicate filament of pia mater extending from the conus medullaris to anchor the spinal cord to the coccyx.

   • Cauda Equina: Bundle of spinal nerves and nerve roots resembling a "horse's tail" extending beyond the conus medullaris.

Internal Structure

1. Gray Matter

   • Shaped like a butterfly or letter "H" in cross-section.

   • Horns:

     • Anterior (Ventral) Horns: Contain motor neurons affecting skeletal muscles.

     • Posterior (Dorsal) Horns: Contain sensory neurons receiving information from the body.

     • Lateral Horns: Present in thoracic and upper lumbar segments, contain neurons of the sympathetic nervous system.

   • Central Canal: Filled with CSF, runs the length of the spinal cord.

2. White Matter

   • Surrounds gray matter.

   • Organized into funiculi:

     • Anterior Funiculus

     • Lateral Funiculus

     • Posterior Funiculus

   • Contains ascending (sensory) tracts and descending (motor) tracts.