1. Spinal Cord
Extends from foramen (base of brain) magnum to second lumbar vertebra
Segmented
Cervical
Thoracic
Lumbar
Sacral
Gives rise to 31 pairs of spinal nerves
Not uniform in diameter throughout length

2. The spinal cord and spinal nerves

3. Cross Section of Spinal Cord
White matter:
Myelinated axons forming nerve tracts
Gray matter:
Neuron cell cell bodies, dendrites, axons
In the spinal cord, the grey matter is found in the center (the butterfly shape) and the white matter surrounds it. The opposite arrangement is found in the cortex of the brain.

4. Spinal Meninges Three membranes surround all of CNS 3) Pia mater
1) Dura mater - "tough mother", strong
2) Arachnoid meninx - spidery looking, carries blood vessels, etc.
Subarachnoid space filled with cerebral spinal fluid (CSF)
3) Pia mater - "delicate mother", adheres tightly to surface of spinal cord
3) Pia mater
2) Arachnoid
1) Dura mater

5. Spinal Cord Anatomy Central canal filled with cerebrospinal fluid
Figure 7.19
Slide 7.53c
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7. Dermatomal Map
Skin area supplied with sensory innervation by spinal nerves

8. spinal cord brain CNS PNS The Organisation of the Nervous System
spinal nerves (31p) cranial nerves (12p)
PNS
sensory motor
motor sensory
Sensory information has to be passed on from the spinal cord to the brain
ascending pathways (red)
Commands from the brain have to be sent out to the PNS
descending pathways (green)

9. Peripheral Nervous System
Nerves and ganglia outside the central nervous system (brain and spinal cord)
Nerve = bundle of neuron fibers
Neuron fibers are bundled by connective tissue
Slide 7.55
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

10. Structure of a Nerve Endoneurium surrounds each fiber
Groups of fibers are bound into fascicles by perineurium
Fascicles are bound together by epineurium
Figure 7.20
Slide 7.56
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

11. Classification of Nerves
Mixed nerves – both sensory and motor fibers
Afferent (sensory) nerves – carry impulses toward the CNS
Efferent (motor) nerves – carry impulses away from the CNS
Slide 7.57
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

12. Spinal Nerves
There is a pair of spinal nerves at the level of each vertebrae for a total of 31 pairs
Slide 7.63
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings