1. Central Nervous System
Plus Spinal and Cranial Nerves

2. Central Nervous System
Consists of Brain and Spinal Cord

3. Spinal Cord Protection and Covering
Vertebral Colum
Ring of bone formed by vertebral foramina protect the spinal cord

4. Spinal Cord Protection and Covering
Meninges – connective tissue covering that protect the spinal cord. They are found in 3 layers

5. Meninges Dura Mater – outer layer of meninges
Composed of tough connective tissue

6. Meninges Arachnoid Mater – middle layer of meninges
Composed of collagen and elastic fibers that resemble a spider’s web

7. Meninges Pia Mater – inner layer of meninges
Composed of transparent collagen and elastic fibers that adhere to the spinal cord and brain

8. Subarachnoid Space
Area between the arachnoid mater and pia mater containing CSF
Spinal Tap (lumbar puncture) – a long needle is inserted into the subarachnoid space (generally between L3 & L4 or L4 & L5) to withdraw CSF for diagnostic purposes or to introduce medication.

10. External Structure
The adult spinal cord is only about inches long…it ends around L2

11. Cauda Equina
Nerves on the lower portion of the cord angled downward through the vertebral canal.

12. Enlargements
Cervical Enlargement – contains nerves that supply the upper limbs
Lumbar Enlargement – contains nerves that supply the lower limbs

13. Indentations/divisions
Anterior Median Fissure &
Posterior Median Sulcus – divide the cord into right and left halves

14. Central Canal
Space down the center of the spinal cord containing CSF

15. Internal Structure Gray Matter
Anterior Horns – contain cell bodies of somatic motor neurons
Posterior Horns – contain cell bodies of somatic and autonomic sensory neurons
Lateral Gray Horns – present only in lower portion of the spinal cord. Contains cell bodies of autonomic nervous system

16. Ventral Horn
Lateral Horn
Dorsal Horn

17. Posterior White Column
White Matter
Organized into columns containing myelinated and unmyelinated axons of sensory and motor neurons
Posterior White Column
Lateral White Column
Anterior White Column

18. White Matter
Tracts – bundles of axons having a common origin or destination carrying similar information
Sensory (ascending) tracts – consist of axons that conduct nerve impulses toward the brain
Motor (descending) tracts – consists of axons that carry nerve impulses down the spinal cord

19. Tracts

20. Spinal Nerves
Paths of communication between the spinal cord and the nerves that serve the specific regions of the body

21. Roots Connect each spinal nerve segment to the spinal cord
Posterior (dorsal) root – contains only sensory axons
Dorsal Root Ganglion – swollen area containing sensory cell bodies
Anterior (ventral) root – contains both somatic motor and autonomic motor neurons

23. Spinal Reflexes
A fast, involuntary sequence of actions that occurs in response to a particular stimulus in which integration takes place in the gray matter of the spinal cord

24. Reflex Arc Sensory Receptor Sensory Neuron Integrating Center
Motor Neuron
Effector