Chapter 3: Structure of the Nervous System

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Chapter 3 Structure of the Nervous System
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Lecture Overview

• Overview of Brain
• Anatomy Terms
• Blood supply and CSF
• Development of the Brain
• Central Nervous System
• Five divisions
• Peripheral Nervous System
• Somatic Nervous System
• Autonomic Nervous System

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The Two Nervous Systems

• CNS Brain and Spinal Cord
• Conduit for info to and from brain
• PNS Cranial and spinal nerves
• Run to target organs and muscles (efferent)
• Carry sensory info (afferent)

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Neuroanatomy Terms

• CNS
• Nucleus- cluster of cell bodies
• Tract- bundle of axons (nerve fibers)
• PNS
• Ganglion- cluster of cell bodies
• Nerve- bundle of axons (nerve fibers)
• But note exceptions

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Neuroanatomy Terms

• Directional
• Anterior (rostral)
• Posterior (caudal)
• Ventral (inferior)
• Dorsal (superior)
• Location in brain
• Ipsilateral same side of brain
• Contralateral opposite side of brain
• Bilateral both sides
• Unilateral one side

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Anatomical Planes

• Three anatomy planes
• Sagittal
• (mid- vs para-sagittal)
• Coronal (transverse)
• Horizontal

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The Meninges

• Dura mater-outer (thick) layer
• Arachnoid-middle layer
• Overlies the arachnoid space (CSF)
• Blood vessels run through arachnoid layer
• Pia mater- inner layer
• Overlies every detail of the outer brain

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Cerebrospinal Fluid (CSF)

• Brain floats in CSF (1400 g--gt 80 g)
• CSF produced by choroid plexus of the ventricles
• Lateral
• Third
• Fourth
• Ventricles are an access point for drug studies
• Loss of CSF produces headaches
• e.g. spinal cord punctures
• Hydroencephalus

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Overview of the CNS
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Cerebral Cortex

• Grooves in cortex
• Sulci (small)
• Fissures (large)
• Bulges in cortex are termed gyri
• 6 layers of cortical cells

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Cortical Lobes
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Mapping of the Cortex

• Fritsch and Hitzig (1870)
• Penfield (1950s) at Montreal
• Sensory cortex
• Motor cortex
• Homunculus Map of external body region that
  serve various areas of cortex
• Brodmanns areas based on architectural
  features

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Limbic System

• Hippocampus (learning and memory)
• Amygdala (emotion)
• Septum (rage after lesions)
• Fornix
• Mammillary Bodies

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Basal Ganglia

• Ganglia is a misnomer (term refers to
  collections of cell bodies in periphery.
• Basal ganglia consists of
• Globus pallidus
• Caudate nucleus
• Putamen
• Basal ganglia are involved in the control of
  movement.

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The Peripheral Nervous System

• Somatic
• Controls muscle action, gland secretion
• Some afferent info back to CNS
• Autonomic NS
• Parasympathetic Digestion
• Sympathetic Fight or Flight

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Somatic Nervous System

• Spinal Nerves (31 pair)
• Afferents and efferents
• 8 Cervical
• 12 Thoracic
• 5 Lumbar
• 5 Sacral
• 1 Coccygeal
• Cranial Nerves
• Three types Motor only, sensory only, mixed
  function
• On old olympus towering tops, a french-speaking
  German viewed some hops

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The Autonomic Nervous System

• Sympathetic division
• Associated with energy expenditure
• Derives from thoracolumbar sp. cord
• Parasympathetic division
• Associated with energy conservation
• Derives from cranial-sacral sp. cord

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