Notes on Brain Structure and Function

Central Nervous System (CNS)

  • CNS consists of the brain and spinal cord.

Structure of the Brain

  • The brain can be divided into four main parts:
    • Cerebrum:
    • The largest part of the brain.
    • Notable for its squiggly, wrinkled appearance.
    • Diencephalon:
    • Central area of the brain.
    • Cerebellum:
    • Located at the back of the brain.
    • Brain Stem:
    • Stalk-like structure; likened to the stem of lettuce or cabbage.
  • Weight of the Brain: Approximately 3.5 pounds.

Brain Stem Overview

  • In this module, the focus will be on the brain stem, which consists of three key components:
    • Medulla Oblongata:
    • Located at the junction of the spinal cord and brain.
    • Responsible for regulating essential life functions such as:
      • Touch, taste, smell, sight interpretation.
      • Vital signs: heart rate, respiratory rate, and some reflex actions (e.g., swallowing, vomiting).
    • Decussation of Pyramids:
      • Crossing of motor and sensory tracks; right brain affects left body and vice versa.
    • Pons:
    • Connects the medulla and midbrain, aiding in the rhythm of breathing.
    • Midbrain:
    • Contains several important structures:
      • Peduncles:
      • Stalk-like structures that convey information from the brain.
      • Cerebral Aqueduct:
      • Connects the third and fourth ventricles, allowing cerebrospinal fluid to flow.
      • Corpora Quadrigemina:
      • Four bumps on the midbrain.
      • Superior Colliculi: Responsible for visual reflexes (e.g., movement in the periphery triggering a response).
      • Inferior Colliculi: Responsible for auditory reflexes (e.g., turning the head towards sounds).

Important Structures and Their Functions

  • Medulla Oblongata:
    • Key functions include:
    • Heart rate regulation.
    • Regulating breathing.
    • Controls reflex actions: vomiting, hiccuping, and swallowing.
    • Notably protects critical life-support functions.
  • Pons:
    • Works in conjunction with the medulla for breathing regulation.
  • Midbrain:
    • Anatomical features play a role in auditory and visual processing via colliculi.

Summary

  • The brain stem is essential for vital life functions including heart rate and breathing.
  • Key anatomical structures within the brain stem each have specific roles in sensory processing and reflex actions.