Transcript Functional Organization of Nervous Tissue

Lecture 12
Nervous Tissue I:
Functional Organization, Spinal
Cord and Spinal Nerves
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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
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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
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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
Fig. 14.1
• Tract
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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
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Spinal Cord
• Extends from foramen
magnum to second
lumbar vertebra
• Segmented
–
–
–
–
Fig. 16.1
Cervical
Thoracic
Lumbar
Sacral
• Gives rise to 31 pairs
of spinal nerves
• Not uniform in
diameter throughout
length
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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
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Cross Section of Spinal Cord
• White matter
– Myelinated axons
forming tracts
– Three funiculi (columns)
• Gray matter
Fig. 16.3
– Neuron cell bodies,
dendrites, axons
– Three horns
Fig. 16.4
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Spinal Nerves
Cervical Plexus
• C1-C4
• Phrenic nerve
– from C3-C5 (cervical
and brachial plexus)
– innervates diaphragm
Fig. 16.8
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Brachial Plexus
• C5-T1
• Major nerves
– Radial
– Ulnar
– Median
Fig. 16.9
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Lumbar Plexus
Fig. 16.10
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Sacral Plexus
Fig. 16.11
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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
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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
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Questions?
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