Neuroanatomy Review

Nervous System Divisions Review

• Review of chapter nine, brain (chapter 10), cranial nerves, and senses.
• Reviewing chapter nine lecture to tie everything together.

Divisions of the Nervous System (Chapter 9)

• Main divisions:
  • Central Nervous System (CNS): Brain and spinal cord.
  • Peripheral Nervous System (PNS): Nerves coming out of the spinal cord and 12 cranial nerves.
• Peripheral Nervous System Divisions:
  • Somatic Nervous System:
    • Controls skeletal muscle.
    • Voluntary (conscious control).
  • Autonomic Nervous System:
    • Controls the heart and smooth muscle.
    • Involuntary (happens automatically).

Neuron Structure

• Dendrites: Receivers that direct neurotransmitters to the cell body and nucleus.
• Axon: Transmits signals away from the cell body.
• Myelin Sheath: Fatty coating that insulates the axon, preventing signal leakage.

Neuron Types

• Afferent (Sensory) Neurons (ASB):
  • Carry sensory information to the brain.
• Efferent (Motor) Neurons (EMM or MET):
  • Carry motor commands to muscles.
• Interneurons:
  • Act as switching stations within the central nervous system.
  • Direct signals to appropriate brain regions.

Nerve Structure

• Endoneurium: Connective tissue surrounding a single nerve cell.
• Perineurium: Connective tissue surrounding a bundle of nerve cells, forming a nervous tissue fascicle.
• Epineurium: Connective tissue surrounding a bundle of fascicles, forming an entire nerve.

Neurotransmitters

• Released across synapses to receptors.
• Examples include serotonin (associated with happiness) and acetylcholine (neuromuscular transmitter).

Spinal Cord

• Dorsal Roots: Enter the spinal cord from the rear; carry sensory information (afferent).
• Ventral Roots: Exit the spinal cord from the front; carry motor commands (efferent).
• Plexus: Group of nerves sending signals from a specific body region (e.g., cervical plexus for the neck, brachial plexus for the arm, lumbosacral plexus for the lower back).
• Cauda Equina: Base of the spine where it splits into nerves, including the sciatic nerve.
• Dermatome: Area of skin that receives and sends signals via specific nerves.

Simple Reflex Arc

1. Painful stimulus (e.g., touching a stove).
2. Receptor sends a message up a sensory (afferent) neuron.
3. Signal reaches the dorsal root of the spinal cord.
4. Interneuron redirects the signal to the ventral root.
5. Efferent (motor) neuron carries the signal to the muscle (effector).
6. The muscle contracts.

Autonomic Nervous System Divisions

• Parasympathetic Nervous System: Normal body functions.
• Sympathetic Nervous System: Fight-or-flight response.
• Table 9-2 (page 216) lists the effects of the sympathetic nervous system on different body parts (e.g., pupils dilate, tear production stops).
• Parasympathetic system reverses these effects when the danger is gone.

Medical Procedures

• Lumbar Puncture: Removal of cerebrospinal fluid (CSF) for testing (e.g., to detect meningitis).
• Epidural: Injection of anesthesia into the lumbar spine.

Brain Anatomy (Chapter 10)

• Cerebral Cortex: Divided into lobes, including frontal, parietal, temporal, and occipital.

Brain Divisions

• Cerebrum: The bulk of the brain, mainly referring to the cerebral cortex where higher thinking happens.
• Diencephalon:
  • Thalamus
  • Hypothalamus
• Brain Stem:
  • Connects the brain to the spinal cord.
  • Midbrain
  • Pons
  • Medulla Oblongata
• Cerebellum: Mini-brain located beneath the occipital lobe.

Brain Protection

• From superficial to deep:
  1. Skin with hair
  2. Skull
  3. Meninges (three cushioning layers)
     • Dura Mater (outer layer)
     • Arachnoid Mater (spider-web like middle layer)
     • Pia Mater (inner layer attached to brain tissue)

Subdural Hematoma

• Bleeding under the dura mater, causing pressure on the brain.
• Treated with a craniotomy (drilling a hole in the skull to relieve pressure).

Concussion

• Brain banging against the skull, causing damage.
• Symptoms include blurred vision, disorientation, nausea, and headaches.

Cerebrospinal Fluid (CSF)

• Clear fluid made in the ventricles of the brain.
• Functions:
  • Supports and cushions the brain and spinal cord.
  • Carries nutrients to brain and spinal cord cells.
  • Transports waste products.
• Circulates throughout the meninges, up and down the spine.

Cerebral Cortex Hemispheres and Lobes

• Divided into right and left hemispheres.
• Lobes:
  • Frontal Lobe: Motor control and speech.
  • Parietal Lobe: Somatosensory (touch, pain, temperature).
  • Temporal Lobe: Auditory (hearing), speech comprehension, olfactory (smell).
  • Occipital Lobe: Visual association (vision).

Speech Areas

• Broca's area (frontal lobe): Speech production. Damage leads to difficulty speaking (aphasia).
• Wernicke's area (temporal lobe): Speech comprehension. Damage leads to difficulty understanding speech.