Lobes of the Brain and Their Functions

Frontal Lobe

Responsible for reasoning, planning, personality, voluntary movement, and speech production.

Parietal Lobe

Processes somatosensory information (touch, pain, temperature) and spatial awareness.

Temporal Lobe

Responsible for hearing, language comprehension (Wernicke's area), smell, and memory formation.

Occipital Lobe

Processes visual information including color, motion, and pattern recognition.

Insula

Deep cortical lobe involved in emotion, autonomic control, pain perception, and memory integration.

Primary Motor Cortex

Located in precentral gyrus; initiates voluntary movement.

Primary Somatosensory Cortex

Located in postcentral gyrus; receives sensory input from skin, muscles, and joints.

Primary Visual Cortex

Located in occipital lobe; first cortical area receiving visual signals.

Primary Auditory Cortex

Located in temporal lobe; first cortical area receiving auditory signals.

Broca's Area

Motor speech production; damage causes nonfluent aphasia.

Wernicke's Area

Language comprehension; damage causes fluent but meaningless speech.

Hippocampus

Consolidates new memories and supports spatial navigation; requires sleep for optimal function.

Amygdala

Processes fear, anger, love, and emotional memory; determines which memories are stored.

Limbic Cortex

Regulates motivation, emotional behavior, and reward/punishment.

Basal Nuclei

Initiate and terminate movement, regulate muscle tone, and inhibit unnecessary movements.

Parkinson's Disease

Caused by degeneration of dopaminergic neurons; symptoms include bradykinesia, rigidity, and resting tremor.

Cerebellum Functions

Coordinates movement, balance, posture, fine motor control, and motor learning.

Ataxia

Loss of coordinated movement due to cerebellar damage.

Intention Tremor

Tremor during purposeful movement caused by cerebellar dysfunction.

Thalamus

Relay station for all sensory input except smell; sorts and sends signals to cortex.

Hypothalamus

Controls homeostasis, autonomic function, endocrine system, and circadian rhythms.

Epithalamus

Contains pineal gland; produces melatonin for sleep regulation.

Midbrain

Controls visual and auditory reflexes; relays sensory input to thalamus.

Pons

Connects cerebellum to cerebrum; regulates breathing; initiates REM sleep.

Medulla Oblongata

Controls vital autonomic functions including heart rate, blood pressure, and respiration.

Lateral Ventricles

Largest ventricles; produce CSF via choroid plexus.

Third Ventricle

Midline ventricle bordered by thalamus and hypothalamus.

Cerebral Aqueduct

Connects 3rd to 4th ventricle; narrow passageway.

Fourth Ventricle

Located between pons and cerebellum.

CSF Production

Made by ependymal cells in choroid plexus from blood plasma.

CSF Flow

Lateral → 3rd → aqueduct → 4th → subarachnoid space → dural sinuses → jugular vein.

CSF Functions

Cushioning, buoyancy, nutrient transport, waste removal.

Dura Mater

Tough outer layer with periosteal and meningeal layers; forms dural sinuses.

Arachnoid Mater

Middle layer; contains subarachnoid space with CSF.

Pia Mater

Thin inner layer adhered to brain; highly vascular.

Epidural Space

Space between skull and dura.

Subdural Space

Space between dura and arachnoid; site of subdural hematoma.

Subarachnoid Space

Space between arachnoid and pia; contains CSF.

Epidural Hematoma

Arterial bleed between skull and dura; rapid onset.

Subdural Hematoma

Venous bleed between dura and arachnoid; slower onset.

Subarachnoid Hemorrhage

Bleeding into subarachnoid space.

Hydrocephalus

Excess CSF due to obstruction or impaired absorption.

Blood-Brain Barrier

Protects brain from toxins; allows water, glucose, oxygen, CO₂, alcohol, nicotine, anesthetics.

TIA

Temporary blockage of blood flow; symptoms resolve within 24 hours.

Thrombotic Stroke

Clot forms in cerebral artery.

Embolic Stroke

Clot travels from elsewhere and lodges in brain.

Hemorrhagic Stroke

Vessel rupture causing bleeding.

Gray Matter

Butterfly-shaped center of spinal cord containing neuron cell bodies.

White Matter

Myelinated axons arranged into ascending and descending tracts.

Posterior Horn

Contains sensory neurons.

Anterior Horn

Contains motor neurons.

Lateral Horn

Contains sympathetic neurons (thoracic/lumbar).

Dorsal Root

Carries sensory input into spinal cord.

Ventral Root

Carries motor output out of spinal cord.

Dorsal Root Ganglion

Contains sensory neuron cell bodies.

Association Fibers

Connect areas within the same hemisphere.

Commissural Fibers

Connect right and left hemispheres (e.g., corpus callosum).

Projection Fibers

Connect cortex with lower CNS structures.

Nerves

Bundles of axons in the PNS.

Tracts

Bundles of axons in the CNS.

Circadian Rhythms

24-hour biological cycles regulated by hypothalamus.

REM Sleep

Dreaming, muscle atonia, increased ACh, active limbic system.

Non-REM Sleep

Stages 1-4; deep restorative sleep.

Stage 1

Light sleep with theta waves.

Stage 2

Sleep spindles; memory consolidation.

Stages 3-4

Deep sleep with delta waves; tissue repair.

Beta Waves

Alert, active thinking.

Alpha Waves

Relaxed wakefulness.

Theta Waves

Early sleep or emotional stress.

Delta Waves

Deep sleep.

EEG

Measures synchronized EPSPs in cortical neurons; used for diagnosing epilepsy and sleep disorders.

Histamine

Promotes wakefulness; inhibited during sleep.

GABA

Inhibits arousal centers; promotes NREM sleep.

Glycine

Inhibits motor neurons; contributes to REM atonia.

Acetylcholine

High during REM; supports dreaming.

Norepinephrine

Promotes wakefulness; decreases during sleep.

Serotonin

Regulates wakefulness and muscle tone.

Sensory Memory

Immediate impressions lasting milliseconds.

Short-Term Memory

Seconds to minutes; limited capacity.

Working Memory

Active manipulation of information.

Long-Term Memory

Structural changes; unlimited capacity.

Memory Consolidation

Process of converting short-term to long-term memory; requires sleep.

Declarative Memory

Facts and events.

Nondeclarative Memory

Skills and habits.

Anterograde Amnesia

Inability to form new memories.

Retrograde Amnesia

Inability to recall past memories.

Chunking

Grouping information into meaningful units.

Chaining

Creating a story linking items together.

ALS

Degeneration of motor neurons causing progressive paralysis.