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1. 11-1
Nervous Tissue I:
Functional Organization, Spinal
Cord and Spinal Nerves
Lecture 12

2. 11-2
Nervous Tissue
• Found in brain, spinal cord and nerves
• Property
– Ability to produce action potentials (electric
signals)
• Cells
– Nerve cells or neurons
– Neuroglia or support cells
– Oligodendrocytes and Schwann cells

3. 11-3
The Nervous System
• Subdivisions
– Central nervous system (CNS)
– Peripheral nervous system (PNS)
• Sensory receptor
– Receptor of sensory information
• Nerve
– Made up of a bundle of axons
• Ganglion
– Collection of cell bodies of neurons
• Plexus
– Network of spinal nerves

4. 11-4
Central Nervous System
• Consists of
– Brain
• Located in cranial
vault of skull
– Spinal cord
• Located in vertebral
canal
• Brain and spinal cord
– Continuous with each
other at foramen
magnum
• Tract
Fig. 14.1

5. 11-5
Peripheral Nervous System
• Two subcategories
– Sensory or afferent
– Motor or efferent
• Divisions
– Somatic nervous
system
– Autonomic nervous
system (ANS)
» Sympathetic
(fight or flight)
» Parasympathetic
(rest and digest)
Fig. 14.2

6. 11-6
Spinal Cord
• Extends from foramen
magnum to second
lumbar vertebra
• Segmented
– Cervical
– Thoracic
– Lumbar
– Sacral
• Gives rise to 31 pairs
of spinal nerves
• Not uniform in
diameter throughout
length
Fig. 16.1

7. 11-7
Meninges
• Connective tissue
membranes surrounding
spinal cord and brain
– Dura mater
– Arachnoid mater
– Pia mater
• Spaces
– Epidural: Anesthesia
injected
– Subdural: Serous fluid
– Subarachnoid:
cerebrospinal fluid (CSF)
Fig. 16.2

8. 11-8
Cross Section of Spinal Cord
• White matter
– Myelinated axons
forming tracts
– Three funiculi (columns)
• Gray matter
– Neuron cell bodies,
dendrites, axons
– Three horns
Fig. 16.3
Fig. 16.4

9. 11-9
Spinal Nerves
Cervical Plexus
• C1-C4
• Phrenic nerve
– from C3-C5 (cervical
and brachial plexus)
– innervates diaphragm
Fig. 16.8

10. 11-10
Brachial Plexus
• C5-T1
• Major nerves
– Radial
– Ulnar
– Median
Fig. 16.9

11. 11-11
Lumbar Plexus
Fig. 16.10

12. 11-12
Sacral Plexus
Fig. 16.11

13. 11-13
Review Question
Compression of the ________ nerve against the
medial epicondyle of the humerus will produce
strong tingling sensations along the forearm and
hand.
(a) Radial
(b)Median
(c) Phrenic
(d)Femoral
(e) Ulnar

14. 11-14
Points to Remember
• Nervous system consists of central nervous system
(brain and spinal cord) and peripheral nervous
system (all nervous tissue outside of central
nervous system)
• Sensory (afferent) neurons carry sensory
information to brain and spinal cord
• Motor (efferent) neurons carry motor away from
brain and spinal cord to spinal nerves and cranial
nerves
• Spinal nerves have a dorsal root (sensory neurons)
and a ventral root (motor neurons)
• Names of nerves in plexuses generally describe
the body region they travel

15. 11-15
Questions?