1. Spinal Cord

2. 42 cm long (17 inches) and 1.8 cm thick 42 cm long (17 inches) and 1.8 cm thick Provides two way conduction pathway to and from the brain (white matter) Provides two way conduction pathway to and from the brain (white matter) Major reflex center (gray matter) Major reflex center (gray matter) Enclosed within vertebral column Enclosed within vertebral column Extends from skull to the last rib (L1) Extends from skull to the last rib (L1) Protected by bone, cerebrospinal fluid and meninges Protected by bone, cerebrospinal fluid and meninges

3. Spinal Cord The cord does not extend the entire length of the vertebral column The cord does not extend the entire length of the vertebral column A group of nerves leaves the inferior spinal cord and extend downward A group of nerves leaves the inferior spinal cord and extend downward Resembles a horses tail and is called the cauda equina. Resembles a horses tail and is called the cauda equina.

4. Spinal Cord 31 pairs of spinal nerves arise from the vertebral column 31 pairs of spinal nerves arise from the vertebral column

5. Cross Section of Spinal Cord The gray matter in the center surrounds the central core The gray matter in the center surrounds the central core Looks like a butterfly Looks like a butterfly

6. Cross section of Spinal Cord Two posterior projections Two posterior projections Posterior/Dorsal horns Posterior/Dorsal horns Two anterior projections Two anterior projections Anterior/Ventral horns Anterior/Ventral horns

7. Cross section of Spinal Cord Neurons with specific functions can be found in the gray matter Neurons with specific functions can be found in the gray matter Dorsal horns contain interneurons and cell bodies Dorsal horns contain interneurons and cell bodies Sensory neurons enter through dorsal root ganglion Sensory neurons enter through dorsal root ganglion Motor neurons send their signals through the ventral root Motor neurons send their signals through the ventral root

8. White matter in the spinal cord runs in three directions depending on function White matter in the spinal cord runs in three directions depending on function Ascending, descending, and across Ascending, descending, and across Myelinated nerve fibers Myelinated nerve fibers Made up of tracts – axons with the same direction and functions Made up of tracts – axons with the same direction and functions Cross section of Spinal Cord