Overview
This lecture covers the basic structures, functions, and organization of the cerebrum, the largest and most advanced region of the brain.
Cerebrum Structure
- The cerebrum consists of two cerebral hemispheres separated by the longitudinal fissure, with the falx cerebri inside.
- Each hemisphere appears similar anatomically but has some functional differences.
- Hemispheres operate contralaterally, meaning each side controls the opposite side of the body.
Lobes and Major Cortical Areas
- The cerebrum is divided into lobes: frontal, parietal, occipital, temporal, and insula (insular lobe).
- Frontal lobe: contains the primary motor cortex (precentral gyrus) responsible for initiating voluntary skeletal muscle movement.
- Parietal lobe: contains the primary sensory cortex (postcentral gyrus) for processing touch, pain, temperature, and taste.
- Occipital lobe: houses the visual cortex for processing visual stimuli.
- Temporal lobe: processes auditory (hearing) and olfactory (smell) information.
- Insula: located beneath the lateral sulcus, processes taste (gustatory cortex).
Association Areas and Specialized Functions
- Association areas help interpret information and plan responses by integrating sensory and motor data.
- The prefrontal cortex (front of frontal lobe) manages reasoning, judgment, emotions, personality, and decision-making.
- Broca’s area (frontal lobe) is necessary for speech production; Wernicke’s area (temporal lobe) is needed for speech comprehension.
- Sensory and motor experiences are given context through nearby association areas.
Hemispheric Specialization and Communication
- The left hemisphere excels in language, speech, and math; the right in touch and spatial visualization.
- Association fibers connect regions within a hemisphere; commissural fibers (e.g., corpus callosum) connect the two hemispheres.
- Projection fibers link the cerebrum to lower brain regions and the spinal cord.
Gray and White Matter
- Gray matter includes the cerebral cortex and basal nuclei (islands of gray matter deep within the cerebrum).
- White matter consists of myelinated axons (fibers) transmitting information between brain regions.
Basal Nuclei Function
- Basal nuclei provide subconscious control of skeletal muscle tone and help coordinate learned movement patterns.
Key Terms & Definitions
- Cerebrum — largest brain region, responsible for higher functions.
- Longitudinal fissure — deep groove dividing left and right hemispheres.
- Gyri (gyrus) — raised ridges on the brain surface.
- Sulci (sulcus) — shallow grooves between gyri.
- Association area — cortex region integrating and interpreting sensory/motor information.
- Prefrontal cortex — region for intellect, reasoning, personality, and emotions.
- Corpus callosum — main commissural fiber connecting both hemispheres.
- Basal nuclei — clusters of gray matter within the cerebrum controlling movement.
Action Items / Next Steps
- Review diagrams of the cerebrum and label the lobes and key cortical areas.
- Read about the history and function of the prefrontal cortex (optional).
- Prepare for next lecture on the cerebellum and brainstem.