NEUR 255 Unit 1: Organization of the Nervous System

Vocabulary practice flashcards for NEUR 255 Unit 1 covering gross neuroanatomy, cortical lobes, subcortical structures, nervous system divisions, neural development stages, cerebral vascularization, and protective meningeal layers.

Wilder Penfield

The neurosurgeon who founded the Montreal Neurological Institute in 1934 and mapped areas of the cerebral cortex, such as the motor and somatosensory cortices, using an electrical probe on awake surgical patients.

Convolutions

The folds and wrinkles of the cerebral cortex that maximize surface area and cortical brain tissue within a skull size limited by the birth canal.

Gyrus

A ridge or raised fold on the convoluted surface of the cerebral cortex.

Sulcus

A groove or shallow valley located between gyri on the surface of the cerebral cortex.

Fissure

A very large, prominent sulcus that demarcates major anatomical divisions of the brain.

Longitudinal Fissure

The deep midline groove that separates the left cerebral hemisphere from the right cerebral hemisphere.

Lateral Fissure

The prominent cleft separating the temporal lobe below from the frontal and parietal lobes above.

Grey Matter

Brain tissue primarily composed of neuronal cell bodies, giving the outer surface of the cortex its grayish appearance.

White Matter

Brain regions composed predominantly of axon tracts covered in myelin, a fatty substance that produces a white appearance.

Four Lobes of the Cerebral Cortex

The anatomical subdivisions of each cerebral hemisphere named after the overlying skull bones: frontal, parietal, occipital, and temporal.

Frontal Lobe

The anterior lobe involved in planning, organization, impulse control, decision-making, and adjusting behaviour to reward and punishment; it is one of the last brain regions to finish development in the late teens or early twenties.

Precentral Gyrus

The gyrus extending along the anterior bank of the central sulcus that contains the primary motor cortex controlling voluntary movements.

Motor Homunculus

A topographical map of the primary motor cortex showing the relative proportion of cortical tissue dedicated to controlling specific body parts, with disproportionately large areas for the lips and tongue.

Broca's Area

A region in the frontal lobe, typically in the left hemisphere, that governs speech production, grammatical sentence structure, and the movements necessary for vocal articulation.

Broca's Aphasia

Also called expressive aphasia, a disorder resulting from frontal lobe damage where the patient struggles to move mouth and tongue muscles properly, causing severe difficulty producing speech.

Parietal Lobe

The lobe situated superior to the lateral fissure and between the central sulcus and occipital lobe; it contains the primary somatosensory cortex and processes skin sensations and body orientation.

Postcentral Gyrus

The gyrus in the parietal lobe immediately posterior to the central sulcus that houses the primary somatosensory cortex.

Hemineglect

Also termed spatial neglect, a condition often caused by parietal lobe stroke in which patients fail to notice or acknowledge the opposite side of their body or sensory environment.

Temporal Lobe

The inferior cortical lobe containing auditory projection areas, language comprehension centers, and the hippocampus for forming new memories.

Auditory Cortex

The cortical area located on the uppermost gyrus of the temporal lobe, largely within the lateral fissure, responsible for perceiving sound information from the ears.

Wernicke's Area

An association area located in the temporal lobe (typically left hemisphere) responsible for interpreting and comprehending written and spoken language.

Wernicke's Aphasia

Also termed receptive aphasia, a condition resulting from temporal lobe damage characterized by effortless but nonsensical speech production combined with an inability to comprehend spoken or written words.

Occipital Lobe

The posterior lobe of the brain containing the visual cortex and association areas that process visual characteristics including colour, movement, and form.

Corpus Callosum

A major white matter axon tract beneath the cerebral cortex that transfers information and coordinates functions between the left and right cerebral hemispheres.

Corpus Callosotomy

A surgical procedure that severs the corpus callosum to stop epileptic seizures from spreading across hemispheres, creating a 'split-brain' condition.

Lateral Ventricles

The two large fluid-filled upper chambers of the ventricular system situated beneath the corpus callosum that contain cerebrospinal fluid.

Cerebrospinal Fluid (CSF)

Clear fluid circulating through the brain ventricles and subarachnoid space that supplies nutrients from blood vessels, removes waste, and cushions the central nervous system.

Thalamus

The central relay station of the brain situated below the lateral ventricles that directs sensory information (with the exception of smell) to corresponding areas of the cortex.

Hypothalamus

A small forebrain structure inferior to the thalamus that regulates emotion, motivated behaviors (eating, drinking, sex), and the endocrine system via the pituitary.

Pituitary

A master endocrine structure composed half of glandular tissue and half of nervous tissue that releases vital systemic hormones like corticosterone, estrogen, and testosterone.

Inferior Colliculus

A midbrain nucleus that aids in hearing by determining the directional source of sounds.

Substantia Nigra

A midbrain nucleus ('black substance') containing dopamine-producing neurons critical for initiating smooth, controlled movements, which degenerates in Parkinson's disease.

Pons

A hindbrain structure within the brainstem containing the reticular formation that regulates sleep, arousal, and wakefulness.

Medulla

The lowest region of the hindbrain connecting to the spinal cord, responsible for essential life-support functions like breathing and heart rate.

Cerebellum

A convoluted hindbrain structure perched on the back of the brainstem ('little brain') that refines motor accuracy, speed, and direction, and coordinates complex learned movements.

Central Nervous System (CNS)

The core division of the nervous system made up exclusively of the brain and the spinal cord.

Peripheral Nervous System (PNS)

The nervous system division comprising all nerves extending outside the brain and spinal cord, including spinal nerves and twelve cranial nerves.

Somatic Nervous System

The subdivision of the PNS under conscious control, made up of motor neurons governing skeletal muscles and sensory neurons transmitting environmental input.

Autonomic Nervous System

The involuntary division of the PNS that regulates internal physiology, including blood pressure, heart rate, glandular secretions, and digestion.

Sympathetic Nervous System

The activating branch of the autonomic nervous system that readies the body for fight-or-flight emergencies by increasing heart rate, dilating airways, sweating, and halting digestion.

Parasympathetic Nervous System

The calming branch of the autonomic nervous system that operates at rest to conserve energy, slow heart rate, constrict airways, and promote digestion.

Neural Tube

The hollow embryonic structure formed when neural grooves fold together, which later develops into the cerebral ventricles, spinal canal, forebrain, midbrain, hindbrain, and spinal cord.

Cell Proliferation

The initial phase of neural development occurring in the ventricular zone, where progenitor cells rapidly divide at a rate of 250,000 new cells every minute.

Cell Migration

The second developmental stage where newborn neurons travel outward from the ventricular zone to their final positions guided by radial glial scaffolding.

Growth Cone

A motile sensory structure at the tip of an extending axon that detects chemical cues to navigate toward synaptic targets during circuit formation.

Circuit Pruning

The final stage of brain development characterized by programmed cell death of neurons that fail to reach targets, followed by elimination of excessive, unrefined synapses.

Fetal Alcohol Syndrome (FAS)

A developmental disorder caused by prenatal alcohol exposure, resulting in cognitive impairment and characteristic facial features due to failure of migrating neurons to arrange into proper cortical columns.

Middle Cerebral Artery

The largest branch of the internal carotid artery network that vascularizes large portions of the frontal, parietal, and temporal lobes, frequently becoming a bottleneck site for ischemic strokes.

Blood-Brain Barrier

A specialized protective barrier constructed of capillary endothelial tight junctions and surrounding glial end feet that blocks pathogens and large toxins from entering neural tissue.

Meninges

The three protective membranes (dura mater, arachnoid mater, and pia mater) enclosing the brain and spinal cord, between which cerebrospinal fluid circulates.

Dura Mater

The outermost, thick, and durable layer of the meninges adjacent to the interior of the skull ('tough mother').

Arachnoid Mater

The web-like middle membrane of the meninges separated from the pia mater by the subarachnoid space.

Pia Mater

The delicate, innermost membrane of the meninges adhering closely to the brain's gyri and sulci ('soft mother').

Subarachnoid Space

The interval between the arachnoid mater and the pia mater filled with cerebrospinal fluid, allowing the brain to float and reducing its effective weight from 1400 grams to 100 grams.