Study Guide: The Nervous System – Brain Structure and Function

The Nervous System

Cerebrum

The cerebrum is the largest part of the brain, responsible for higher brain functions such as thought, action, and sensory processing.

• White matter vs. Grey matter: White matter consists mainly of myelinated axons, facilitating communication between different brain regions. Grey matter contains neuronal cell bodies and is involved in processing and cognition.

• Ventricles of the brain: The brain contains interconnected cavities called ventricles, filled with cerebrospinal fluid (CSF). The third ventricle connects to the fourth ventricle via the cerebral aqueduct.

• Cerebral hemispheres: The two hemispheres are separated by the longitudinal fissure and connected by the corpus callosum. The transverse cerebral fissure separates the cerebrum from the cerebellum.

• Lobes of the brain: The cerebrum is divided into frontal, parietal, temporal, and occipital lobes. The insula is a lobe not readily visible from the surface.

Cerebral Cortex

The cerebral cortex is the outer layer of the cerebrum, involved in complex functions such as perception, thought, and voluntary movement.

• Motor areas:

  • Primary motor cortex: Controls voluntary movements.

  • Premotor cortex: Plans movements and coordinates learned motor skills.

  • Broca's area: Involved in speech production.

  • Frontal eye field: Controls voluntary eye movements.

• Sensory areas:

  • Primary somatosensory cortex: Receives sensory input from the body; responsible for touch, pressure, pain, and temperature.

  • Gustatory cortex: Processes taste information; located in the insula.

  • Association areas: Integrate information from different sensory modalities for higher-level processing.

  • Limbic association area: Involved in emotion, memory, and motivation.

• Lateralization: Refers to the specialization of functions in each hemisphere. Cerebral dominance is the hemisphere that is dominant for language (usually the left). "Left-handed" individuals may have different patterns of dominance.

Basal Nuclei

The basal nuclei (or basal ganglia) are deep brain structures involved in movement regulation and coordination.

• Striatum: A major component of the basal nuclei, involved in motor and cognitive functions.

• Midbrain connections: The substantia nigra of the midbrain is functionally connected to the basal nuclei and is important in movement control.

• Associated disorders: Parkinson's disease and Huntington's disease are linked to basal nuclei dysfunction.

Diencephalon

The diencephalon is a central brain region containing several important structures.

• Thalamus: Acts as a relay station for sensory information traveling to the cerebral cortex.

• Hypothalamus: Regulates homeostasis, including body temperature, hunger, thirst, and circadian rhythms. It also controls the pituitary gland.

• Mammillary bodies: Involved in memory processing.

• Infundibulum: The stalk connecting the hypothalamus to the pituitary gland.

• Epithalamus: Contains the pineal gland, which secretes melatonin to regulate sleep-wake cycles.

Midbrain

The midbrain is part of the brainstem and is involved in vision, hearing, motor control, sleep/wake, arousal, and temperature regulation.

• Periaqueductal gray matter: Involved in pain modulation.

• Corpora quadrigemina: Consists of four colliculi:

  • Superior colliculi: Visual reflex centers.

  • Inferior colliculi: Auditory relay centers.

• Substantia nigra: Functionally connected to the basal nuclei; involved in movement control.

Pons

The pons is part of the brainstem that relays signals between the cerebrum and cerebellum and regulates vital functions.

• Vital function: The pons helps control breathing.

Medulla Oblongata

The medulla oblongata is the lowest part of the brainstem, controlling vital autonomic functions.

• Fourth ventricle: The medulla contains the fourth ventricle, which houses the choroid plexus (produces CSF).

• Pyramids: Contain motor fibers that cross over (decussate), allowing each hemisphere to control the opposite side of the body.

• Olives: Involved in motor learning and coordination.

• Vital functions: The medulla regulates heart rate, blood pressure, and respiration.

Cerebellum

The cerebellum coordinates voluntary movements and maintains posture, balance, and equilibrium. It communicates with higher brain centers to fine-tune motor activity.

• Function: Ensures smooth, coordinated movements and motor learning.

Additional info: The study guide references material for an exam on the nervous system, focusing on brain anatomy and function, as covered in Chapter 7 of standard Anatomy & Physiology textbooks.