11-1
Nervous Tissue I:Functional Organization, Spinal
Cord and Spinal Nerves
Lecture 12
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
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
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
• TractFig. 14.1
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
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
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
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
11-9
Spinal NervesCervical Plexus
• C1-C4• Phrenic nerve
– from C3-C5 (cervical and brachial plexus)
– innervates diaphragm
Fig. 16.8
11-10
Brachial Plexus• C5-T1• Major nerves
– Radial– Ulnar– Median
Fig. 16.9
11-11
Lumbar Plexus
Fig. 16.10
11-12
Sacral Plexus
Fig. 16.11
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
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
11-15
Questions?
