The Brain

Nervous System Module: The Brain

Key Terms

  • Gyrus: Rounded ridges on the brain's surface.
  • Sulcus: Groove or indentation between gyri.
  • Fissure: A deeper groove that separates large sections of the brain.

Major Parts of the Adult Brain

  • Cerebrum: Largest part of the brain, responsible for higher cognitive functions.
  • Diencephalon: Includes structures such as the thalamus and hypothalamus.
  • Brainstem: Connects the brain to the spinal cord and regulates basic life functions.
  • Cerebellum: Coordinates voluntary movements and balance.

Cerebral Hemispheres & Lobes

Cerebral Hemispheres

  • Divided into left and right hemispheres.

Lobes of the Cerebral Hemispheres

  1. Frontal Lobe:
    • Functions: Rational thought, decision-making, language, personality.
  2. Parietal Lobe:
    • Functions: Sensory information processing (touch).
  3. Temporal Lobe:
    • Functions: Auditory processing.
  4. Occipital Lobe:
    • Functions: Visual processing.
  5. Insula:
    • Functions: Taste interpretation.

Major Landmarks of the Cerebrum

  • Longitudinal Fissure: Separates the two hemispheres.
  • Lateral Sulcus (Sylvian Fissure): Separates the frontal and temporal lobes.
  • Central Sulcus: Separates frontal lobe from parietal lobe.
  • Transverse Fissure: Separates cerebrum from cerebellum.
  • Precentral Gyrus: Located in the frontal lobe, primary motor area.
  • Postcentral Gyrus: Located in the parietal lobe, primary sensory area.

Major Cerebral Regions

  1. Cortex:
    • Gray matter layer; processes higher functions.
  2. White Matter:
    • Myelinated axons that connect different brain regions.
  3. Cerebral Nuclei (Basal Nuclei):
    • Groups of cell bodies involved in movement regulation.

Functional Cortical Areas

  • Primary Motor Cortex: Controls voluntary movements.
  • Primary Somatosensory Cortex: Processes sensory information from the body.
  • Primary Auditory Cortex: Processes sounds.
  • Primary Visual Cortex: Processes visual stimuli.
  • Primary Olfactory Cortex: Processes smells.
  • Primary Gustatory Cortex: Processes taste sensations.

Language Areas

  • Broca's Area:
    • Responsible for speech production. Damage leads to non-fluent aphasia.
  • Wernicke's Area:
    • Responsible for language comprehension. Damage results in fluent aphasia.

Diencephalon Components

  • Thalamus: Relay station for sensory information; processes and distributes signals.
  • Hypothalamus: Controls homeostasis, regulates endocrine system, and influences the autonomic nervous system.
  • Pituitary Gland: Major endocrine gland.
  • Pineal Gland: Secretes melatonin; regulates sleep/wake cycles.

Brainstem Subdivisions

  • Briefly involved in regulating life-sustaining functions (e.g., heart rate, breathing).
  • Controls involuntary actions (coughing, vomiting).

Pons

  • Connects different parts of the brain and regulates functions such as sleep and respiration.

Cerebellum Functions

  • Responsible for coordination of movement and motor learning.
  • Processes proprioceptive information to maintain balance.

Limbic System

  • Collection of structures involved in emotion regulation and memory processing.
  1. Amygdala: Processes fear and emotional responses; recognizes emotional expressions.
  2. Hippocampus: Involved in memory formation and retrieval, connects emotional responses with memories.