chap 13

1. Major Regions of the Brain and Their Functions

• Cerebrum:

  • Function: Responsible for higher brain functions, including sensation, voluntary movement, reasoning, memory, and learning.

  • Subdivisions:

    • Frontal lobe: Motor control, planning, reasoning, problem-solving, speech (Broca’s area).

    • Parietal lobe: Sensory processing (touch, temperature, pain), spatial awareness.

    • Temporal lobe: Auditory processing, memory, language comprehension (Wernicke’s area).

    • Occipital lobe: Visual processing.

• Diencephalon:

  • Thalamus: Relays sensory information to the cerebral cortex.

  • Hypothalamus: Regulates homeostasis, controls the autonomic nervous system, regulates body temperature, hunger, thirst, and emotional responses.

  • Pineal gland: Produces melatonin, involved in sleep-wake cycles.

• Cerebellum:

  • Function: Coordinates voluntary movements, maintains balance and posture, motor learning.

• Brainstem:

  • Midbrain: Coordinates visual and auditory reflexes, regulates sleep/wake cycles.

  • Pons: Relays information between the cerebrum and cerebellum, controls respiration.

  • Medulla oblongata: Controls autonomic functions such as heart rate, respiration, blood pressure, and reflexes like coughing, swallowing, and vomiting.

2. Major Structures Within Each Region

• Cerebrum:

  • Corpus callosum: Connects the two hemispheres of the brain.

  • Basal nuclei: Involved in motor control, emotion, and learning.

  • Ventricles: Cavities that produce and circulate cerebrospinal fluid (CSF).

• Diencephalon:

  • Thalamus: Gateway for sensory information.

  • Hypothalamus: Regulates endocrine system through the pituitary gland.

• Cerebellum:

  • Cerebellar cortex: Processes information for motor coordination.

• Brainstem:

  • Reticular formation: Controls arousal and consciousness.

3. Motor, Sensory, and Association Areas of the Cerebral Cortex

• Motor Areas:

  • Primary motor cortex (precentral gyrus): Controls voluntary muscle movements.

  • Premotor cortex: Planning and coordination of movements.

  • Broca’s area: Speech production (in the frontal lobe).

• Sensory Areas:

  • Primary somatosensory cortex (postcentral gyrus): Processes sensory input from the body (touch, pain, temperature).

  • Visual cortex: Processes visual information (occipital lobe).

  • Auditory cortex: Processes sound (temporal lobe).

• Association Areas:

  • Integrate sensory information with past experiences for decision-making, language, memory, and learning.

4. Composition and Functions of Cerebrospinal Fluid (CSF)

• Composition:

  • Clear, colorless fluid composed of water, glucose, proteins, and ions.

• Functions:

  • Cushions and protects the brain and spinal cord.

  • Removes metabolic waste.

  • Maintains homeostasis of the CNS by regulating pressure and nutrient exchange.

5. Cranial Nerves and Their Functions

1. Olfactory (I): Smell.

2. Optic (II): Vision.

3. Oculomotor (III): Eye movement, pupil constriction.

4. Trochlear (IV): Eye movement (superior oblique muscle).

5. Trigeminal (V): Sensory input from the face, motor control of chewing.

6. Abducens (VI): Eye movement (lateral rectus muscle).

7. Facial (VII): Facial expression, taste, salivation, lacrimation.

8. Vestibulocochlear (VIII): Hearing, balance.

9. Glossopharyngeal (IX): Taste, swallowing, salivation, monitors blood pressure.

10. Vagus (X): Autonomic functions, heart rate, digestion.

11. Accessory (XI): Shoulder and neck movement.

12. Hypoglossal (XII): Tongue movement.

Principal Sensory and Motor Pathways

• Sensory Pathways:

  • Dorsal column-medial lemniscal pathway: Transmits fine touch, proprioception, and vibration.

  • Spinothalamic pathway: Carries pain and temperature sensations.

• Motor Pathways:

  • Corticospinal tract (direct pathway): Voluntary motor control, especially of the limbs.

  • Extrapyramidal system (indirect pathways): Coordinates posture, balance, and involuntary movements.

7. Brain Integration and Response Coordination

• The brain integrates information by processing sensory input in association areas, linking it with motor areas for appropriate responses.

• The basal nuclei help plan and regulate voluntary movements, and the cerebellum fine-tunes motor actions based on feedback.

8. Major Homeostatic Abnormalities of the Nervous System

• Parkinson’s disease: Degeneration of the basal ganglia, leading to tremors, rigidity, and bradykinesia.

• Multiple sclerosis: Immune-mediated damage to myelin, leading to muscle weakness, vision problems, and sensory disturbances.

• Stroke: Interruption of blood supply to the brain, leading to neurological deficits.

• Alzheimer’s disease: Degeneration of neurons, leading to memory loss, confusion, and cognitive decline.