Study Guide: The Nervous System – Brain Structure and Function

Chapter 12: The Nervous System – Brain Structure and Function

Cerebrum

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

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

• Ventricles of the Brain: - The third ventricle is connected to the fourth ventricle via the cerebral aqueduct.

• Cerebral Hemispheres: - Longitudinal fissure divides the two hemispheres. - Transverse cerebral fissure separates the cerebrum from the cerebellum. - Gyri are the ridges, and sulci are the grooves on the brain surface.

• Cerebral Cortex Functional Areas: - Primary motor cortex: Controls voluntary movements. - Premotor cortex: Plans movements. - Broca's area: Controls speech production. - Frontal eye field: Controls voluntary eye movements.

• Sensory Areas: - Primary somatosensory cortex: Responsible for processing tactile information. - Association areas integrate and interpret sensory input. - Motor areas initiate and control voluntary movements.

• Lateralization: - Cerebral lateralization refers to the specialization of functions in each hemisphere (e.g., language in the left hemisphere).

Basal Nuclei

The basal nuclei are deep gray matter structures involved in regulating voluntary motor activities.

• Striatum: The main input center of the basal nuclei, consisting of the caudate nucleus and putamen.

• Globus pallidus: Functionally connected to the basal nuclei and involved in movement regulation.

• Associated Nuclei: Other nuclei involved in basal nuclei function include the subthalamic nucleus and substantia nigra.

Diencephalon

The diencephalon is a central brain region that includes the thalamus, hypothalamus, and epithalamus.

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

• Hypothalamus: Regulates homeostasis, including temperature, hunger, thirst, and endocrine functions.

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

Brainstem

The brainstem connects the cerebrum and cerebellum to the spinal cord and controls vital functions.

• Midbrain: - Periaqueductal gray matter: Involved in pain modulation. - Corpora quadrigemina: Contains superior colliculi (visual reflex center) and inferior colliculi (auditory reflex center). - Substantia nigra: Functionally connected to the basal nuclei and involved in movement control.

• Pons: - Relays information between the cerebrum and cerebellum. - Controls functions such as breathing and sleep.

• Medulla Oblongata: - Contains the fourth ventricle and the choroid plexus (produces cerebrospinal fluid). - Pyramids: Contain motor fibers that cross over (decussate) to the opposite side. - Regulates vital functions such as heart rate, blood pressure, and respiration.

Cerebellum

The cerebellum coordinates voluntary movements and maintains balance and posture.

• Communicates with higher brain centers to refine motor activity.

• Receives input from sensory systems and other parts of the brain.

Table: Major Brain Regions and Their Functions

Region	Main Function	Key Structures
Cerebrum	Higher cognitive functions, sensory and motor processing	Cerebral cortex, white/gray matter, gyri/sulci
Basal Nuclei	Regulation of movement	Striatum, globus pallidus
Diencephalon	Sensory relay, homeostasis, endocrine regulation	Thalamus, hypothalamus, epithalamus
Brainstem	Vital functions, reflexes	Midbrain, pons, medulla oblongata
Cerebellum	Coordination, balance	Cerebellar cortex, arbor vitae

Key Terms and Definitions

• Melatonin: A hormone produced by the pineal gland that regulates sleep-wake cycles.

• Choroid plexus: A network of cells that produces cerebrospinal fluid in the ventricles of the brain.

• Pyramids: Motor tracts in the medulla where fibers cross to the opposite side of the body.

• Association areas: Regions of the cerebral cortex that integrate information from different modalities.

Additional info:

• Understanding the anatomical and functional organization of the brain is essential for interpreting neurological disorders and their effects on behavior and physiology.

• Further details on each brain region's specific nuclei and pathways may be covered in lecture or lab.