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Introduction to Neuroanatomy

Notes

Introduction to Neuroanatomy

Sections






Central Nervous System

Brain

See: Brain

Cerebrum (Cerebral Hemispheres)

Cerebral cortex

  • The outer, cellular gray matter of the brain.

Subcortical white matter

  • Comprises the underlying axons.

Basal ganglia

  • Most notably involved in motor function.

Thalamus

  • Relays information throughout the cerebrum, most clinically notable is its sensory function.

Hypothalamus

  • The center for autonomic nervous system function.

Brainstem

Brainstem

  • Contains cranial nerve nuclei and other essential neuronal populations and fiber tracts.

From superior to inferior:

Midbrain

Cerebellum

Cerebellum

  • Fundamental for coordination.

Spinal Cord

Spinal Cord

  • Passes information in between the brain and the periphery

Segments of the spinal cord from top to bottom

  • Cervical
  • Thoracic
  • Lumbosacral and coccygeal

Meninges & CSF

Meninges

  • Protects and nourishes the nervous system

Cerebrospinal fluid system

  • Assists the meninges in supporting the nervous system.

Peripheral Nervous System

Nerve Roots

  • Dorsal: sensory
  • Ventral: motor

Peripheral Nerve Plexuses

  • Cervical
  • Brachial
  • Lumbosacral
  • Nerves descend through the lumbar cistern as the cauda equina and exit the spinal canal to form the lumbosacral plexus.

Thoracic Nerves

  • Remain unmixed.
  • Nerve transmissions pass across neuromuscular junctions to stimulate muscle.
  • Peripheral nerve sensory receptors are present to detect sensory impulses from the periphery.

Autonomic Nervous System

Parasympathetic

  • "Rest and Digest"

Sympathetic

  • "Fight-or-Flight"

Clinical Challenge Question

The first step in the evaluation of a patient with a neurological abnormality is to localize the site of the dysfunction within the neuroaxis. Use the following clinical case to test your general understanding of the components of the nervous system.

Localization Question

Full Text

OVERVIEW

  • In this introduction to neuroanatomy we'll learn an organization of the nervous system.
  • Start with a table to keep track of the functions of the various nervous system structures.

BRAIN – SUPERFICIAL STRUCTURES

  • Draw with a coronal section through the brain.
  • Next, outside of the brain, draw another layer and label the intervening space as the meninges.
    • Indicate that it protects and nourishes the nervous system.
  • Next, draw an inner layer of the brain
    • Indicate that it is the outer, cellular gray matter of the brain.
  • Now, draw another layer inside of the cerebral cortex for the subcortical white matter.
    • Indicate that it comprises the underlying axons.

BRAIN – DEEP STRUCTURES

Then, draw the major deep structures within the brain:

  • The basal ganglia
    • Indicate that it is most notably involved in motor function.
  • The thalamus
    • Indicate that it relays information throughout the cerebrum, most clinically notable is its sensory function.
  • The hypothalamus
    • Indicate that it is the center for autonomic nervous system function.
  • Now, draw the cerebrospinal fluid system.
    • Indicate that it assists the meninges in supporting the nervous system.

BRAINSTEM & CEREBELLUM

  • Next, below the brain, draw the brainstem.
  • Show that from superior to inferior, the brainstem comprises the midbrain, pons, and medulla.
    • Indicate that it contains cranial nerve nuclei and other essential neuronal populations and fiber tracts.
  • Now, on the posterior aspect of the brainstem, draw the leafy hemispheres of the cerebellum.
    • Indicate that it is fundamental for coordination.

SPINAL CORD

  • Next, we will draw the spinal cord and peripheral nervous system
  • Draw the spinal cord.
    • Indicate that it passes information in between the brain and the periphery.
  • Label the segments of the spinal cord from top to bottom as: cervical, thoracic, lumbosacral and coccygeal; these segments innervate the superior to inferior periphery, respectively.

NERVE ROOTS

  • Next draw a representative nerve root.
    • Denote that dorsal or posterior nerve roots receive sensory fibers.
    • Whereas ventral or anterior nerve roots emit the motor fibers.

PLEXUSES

  • Now, indicate that the cervical nerves interweave to form cervical and brachial plexuses.
  • Show that the nerves emerge from these plexuses as peripheral nerves and extend through the periphery.
  • Then, show that the lower lumbosacral nerve roots descend through the lumbar cistern as the cauda equina and exit the spinal canal to form the lumbosacral plexus.

NERVES, NEUROMUSCLE JUNCTION, & RECEPTORS

  • Next, show that the majority of thoracic nerves remain unmixed.
  • Then, show that nerve transmissions pass across neuromuscular junctions to stimulate muscle, and indicate that peripheral nerve sensory receptors are present to detect sensory impulses from the periphery.

AUTONOMIC NERVOUS SYSTEM

  • Lastly, include the autonomic nervous system.
  • Draw a parasympathetic ganglion and then a sympathetic paravertebral chain segment.
    • Indicate that the parasympathetic nervous system is active in state's of "rest" whereas the sympathetic nervous system is active in states of "action" — it produces the "fight-or-flight" response.