Study Guide: The Central Nervous System – Brain Structure and Function

The Central Nervous System: Brain Structure and Function

Cerebrum

The cerebrum is the largest part of the brain, responsible for higher brain functions such as thought, action, and sensory processing. It is divided into lobes, each with specialized functions.

• Cerebral Cortex: The outer layer of gray matter involved in conscious thought, perception, and voluntary movement.

• Cerebral White Matter: Myelinated axons that connect different parts of the brain.

• Longitudinal Fissure: Deep groove separating the two cerebral hemispheres.

• Central Sulcus: Separates the frontal and parietal lobes.

Lobes of the Cerebrum

Lobe	Main Function(s)	Location/Notes
Frontal lobe	Voluntary movement, planning, reasoning	Anterior portion; underlies frontal bone
Parietal lobe	Somatosensory processing	Underlies parietal bone
Occipital lobe	Vision	Posterior; underlies occipital bone
Temporal lobe	Auditory processing, memory	Lateral; underlies temporal bone
Insula	Visceral sensation, taste, emotion	Deep to other cerebral lobes

Functional Areas of the Cerebral Cortex

Area	Location	Function
Primary somatosensory cortex	Postcentral gyrus	Receives sensory input from skin, muscles, joints
Auditory cortex	Temporal lobe	Processes auditory information
Gustatory cortex	Insula	Taste perception
Olfactory cortex	Temporal lobe	Smell perception
Primary visual cortex	Occipital lobe	Processes visual information
Primary motor cortex	Precentral gyrus	Controls voluntary muscle movement
Premotor cortex	Anterior to precentral gyrus	Plans movements
Prefrontal cortex	Anterior frontal lobe	Higher thought processing, decision making
Broca's area	Usually left hemisphere, frontal lobe	Motor speech production
Wernicke's area	Usually left hemisphere, temporal/parietal lobe	Language comprehension

Diencephalon

The diencephalon is a central brain region that includes the thalamus, hypothalamus, and epithalamus. It acts as a relay and processing center for sensory information and autonomic functions.

• Thalamus: Large, egg-shaped structure; sensory relay station.

• Hypothalamus: Located below the thalamus; regulates homeostasis, produces hormones (e.g., GnRH), controls the pituitary gland.

• Epithalamus: Contains the pineal gland, which secretes melatonin.

Brainstem

The brainstem connects the cerebrum with the spinal cord and controls vital life functions such as breathing, heart rate, and blood pressure. It consists of the midbrain, pons, and medulla oblongata.

Structure	Description/Function
Midbrain	Contains visual and auditory reflex centers
Pons	Relays information between cerebrum and cerebellum; regulates breathing
Medulla oblongata	Controls heart rate, blood pressure, and respiration

Cerebellum

The cerebellum is located under the occipital lobe and is responsible for coordinating voluntary movements, balance, and posture.

• Arbor vitae: White matter tracts in the cerebellum, resembling a tree.

White Matter Tracts

Tract	Description	Function
Commissural fibers	Connect corresponding gray areas of the two hemispheres	Corpus callosum is the largest commissure
Association fibers	Connect different parts of the same hemisphere	Integrate information within a hemisphere
Projection fibers	Connect cerebrum with lower CNS centers	Link cortex with brainstem and spinal cord

Key Terms and Definitions

• Gyri: Elevated ridges of the cerebral cortex.

• Sulci: Shallow grooves between gyri.

• Fissures: Deep grooves separating major brain regions.

Example: Functional Localization

• Damage to the Broca's area results in expressive aphasia (difficulty producing speech).

• Damage to the Wernicke's area results in receptive aphasia (difficulty understanding language).

• The primary motor cortex controls voluntary movements of specific body parts, organized somatotopically (motor homunculus).

Additional info: The notes above expand on the provided tables and lists, adding definitions, context, and examples for clarity and completeness.