Nervous Tissue I: Functional Organization, Spinal Cord and Spinal Nerves

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Nervous Tissue IFunctional Organization, Spinal
Cord and Spinal Nerves

• Lecture 12

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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
• Tract

Fig. 14.1
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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
• Cervical
• Thoracic
• Lumbar
• Sacral
• Gives rise to 31 pairs of spinal nerves
• Not uniform in diameter throughout length

Fig. 16.1
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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
• Neuron cell bodies, dendrites, axons
• Three horns

Fig. 16.3
Fig. 16.4
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Spinal NervesCervical 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.
• Radial
• Median
• Phrenic
• Femoral
• 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?