The Central Nervous System

Comprehensive vocabulary flashcards covering the Central Nervous System, including the cerebral cortex, diencephalon, brain stem, cerebellum, spinal cord, and meningeal protections.

Left Cerebral Hemisphere

The hemisphere of the cerebrum specialized in analytical thinking, language processing, cognition, and metacognition, which controls the right side of the body due to crossing fiber tracts.

Right Cerebral Hemisphere

The hemisphere of the cerebrum that controls the left side of the body and specializes in spatial orientation, visual-spatial processing, face and music recognition, and emotional prosody (tone of voice).

Corpus Callosum

The largest white matter structure in the human brain, shaped like a white 'C' in the midline, which connects the left and right cerebral hemispheres to share motor, sensory, and cognitive information.

Gyri (Gyrus)

Elevated ridges of cortical tissue that work alongside sulci to increase the surface area of the cerebral cortex, bringing brain regions closer together to speed up neural communication.

Sulci (Sulcus)

Shallow grooves or furrows on the brain's surface that divide each cerebral hemisphere into distinct lobes and work with gyri to expand cortical surface area.

Fissures

Deeper grooves or indentations that separate large anatomical regions of the brain, such as the longitudinal fissure dividing the cerebral hemispheres.

Cerebral Cortex

The superficial outermost layer of gray matter in the cerebrum composed of unmyelinated cell bodies and dendrites; responsible for sensory interpretation, consciousness, memory, and voluntary skeletal muscle control.

Primary Motor Area

Cortical area located on the precentral gyrus anterior to the central sulcus in the frontal lobe that consciously controls skeletal muscles, providing fine motor control to the face, mouth, and hands.

Pyramidal (Corticospinal) Tract

The major voluntary motor tract formed by descending axons of primary motor cortex neurons that cross over before reaching the spinal cord, representing the body upside-down.

Broca's Area

A motor speech area located at the base of the precentral gyrus in the frontal lobe that directs muscles involved in vocalization; damage impairs the ability to speak words despite knowing what to say.

Anterior Association Area

A region in the anterior frontal lobe that associates motor and sensory areas, responsible for higher intellectual reasoning, socially acceptable behavior, judgment, problem-solving, and working memory.

Premotor Area

A motor functional area located anterior to the primary motor cortex that is responsible for planning and coordinating complex movements.

Primary Somatic Sensory Area

An area located in the postcentral gyrus of the parietal lobe that interprets incoming impulses from cutaneous sense organs and proprioceptors, allowing recognition of pain, temperature differences, and light touch.

Sensory Homunculus

A spatial map of the primary somatic sensory cortex showing an upside-down representation of the human body, wherein body regions with the most sensory receptors (lips, fingertips) occupy disproportionately large areas.

Gustatory Area

The cortical area located in the cerebral cortex responsible for interpreting the sense of taste.

Auditory Area

The sensory area of the cortex located in the temporal lobe bordering the lateral sulcus, responsible for hearing perception.

Wernicke's Area (Speech/Language Area)

An area situated at the junction of the temporal, parietal, and occipital lobes that enables language comprehension and sentence formation; damage causes the utterance of meaningless strings of words.

Olfactory Area

The sensory area located deep within the temporal lobe that is responsible for the conscious interpretation of smell.

Visual Area

The sensory area located in the posterior part of the occipital lobe responsible for processing visual information; blunt trauma to this region can trigger blackout vision.

Posterior Association Area

A cortical region encompassing parts of the parietal, temporal, and occipital lobes that blends visual, auditory, and somatosensory inputs to provide holistic scene recognition, pattern recognition, and face recognition.

Cerebral White Matter

The internal substance of the cerebral hemispheres made of myelinated nerve fiber tracts that transport impulses to, from, or within the cerebral cortex and link the brain to the spinal cord.

Commissural Fibers

Tracts of myelinated nerve fibers that connect corresponding cortical regions of the left and right cerebral hemispheres, exemplified by the corpus callosum.

Association Fibers

Fiber tracts within the cerebral white matter that connect different anatomical areas within the same cerebral hemisphere.

Projection Fibers

Nerve fibers that connect the cerebral hemispheres with lower CNS structures such as the brainstem and spinal cord, undergoing decussation at the brainstem level.

Basal Nuclei (Basal Ganglia)

Islands of gray matter embedded deep within the cerebral white matter that help regulate voluntary motor activities by modifying instructions (specifically starting and stopping movements) sent by the primary motor cortex.

Internal Capsule

A tight, prominent band of projection fibers that passes between the thalamus and the basal nuclei.

Diencephalon

The cup-like 'interbrain' that sits atop the brain stem and is enclosed by the cerebral hemispheres, containing the thalamus, hypothalamus, and epithalamus.

Hypothalamus

A pearl-sized structure forming the floor of the diencephalon below the thalamus; serves as the chief autonomic integration center maintaining homeostasis (temperature, water balance, appetite) and limbic system drives.

Pituitary Gland

An endocrine organ dangling from the hypothalamus that operates under hypothalamic regulation to produce hormones including ADH and oxytocin.

Mammillary Bodies

Paired reflex centers involved in the sense of olfaction that bulge outward from the inferior floor of the hypothalamus.

Thalamus

A large mass of gray matter enclosing the third ventricle that serves as the principal relay station for ascending sensory impulses directed to the sensory cortex, crude recognition of pleasant/unpleasant stimuli, and memory.

Epithalamus

The dorsal-most region of the diencephalon that forms the roof of the third ventricle and houses the pineal gland and choroid plexus.

Pineal Gland

A structure of the epithalamus sensitive to sunlight that secretes melatonin to govern circadian rhythms and sleep-wake cycles.

Choroid Plexus

Knots of capillaries located within each of the brain's four ventricles that, together with ependymal cells, produce cerebrospinal fluid (CSF).

Limbic System

A functional neural network consisting of cerebral and diencephalic structures that mediates emotional responses, survival drives, and memory processing.

Brain Stem

A stalk-like structure at the base of the brain comprising the midbrain, pons, and medulla oblongata that connects the cerebrum to the spinal cord and manages autonomic survival functions.

Midbrain

The topmost division of the brain stem directly connected to the diencephalon; coordinates subcortical motor actions, processes visual and auditory reflexes, and contains nuclei for cranial nerves III and IV.

Cerebral Peduncles

Bulging fiber tracts of the midbrain ('little feet of the cerebrum') that convey ascending and descending nerve impulses between higher and lower brain centers.

Corpora Quadrigemina

Four rounded dorsal protrusions of the midbrain that serve as visual and auditory reflex centers.

Cerebral Aqueduct

A slender canal traversing the midbrain that connects the third ventricle of the diencephalon to the fourth ventricle.

Pons

The bridge-like middle segment of the brain stem composed of fiber tracts; contains nuclei for cranial nerves V–VII and coordinates breathing depth/rate, facial movement, and REM sleep.

Medulla Oblongata

The lowest part of the brain stem merging into the spinal cord; contains the decussation of the pyramids, cranial nerve nuclei VIII–XII, and centers controlling heart rate, blood pressure, swallowing, and vomiting.

Reticular Formation

A diffuse column of gray matter extending through the brainstem that filters repetitive sensory stimuli and regulates cerebral alertness; damage causes prolonged coma.

Ascending Reticular Activating System (ARAS)

A functional division of the reticular formation projecting to the thalamus and cortex to maintain wakefulness, alertness, and conscious perception.

Cerebellum

The cauliflower-like 'little brain' located dorsal to the brain stem that acts as an autopilot, processing motor instructions and sensory inputs to ensure smooth, coordinated muscle movements and balance.

Vermis

A narrow, worm-like midline white-matter-lined structure connecting the left and right cerebellar hemispheres, crucial for coordinating whole-body posture, balance, and smooth eye movements.

Arbor Vitae

The branching, fern-like tree of white matter inside the cerebellum made of myelinated axons that rapidly transmits impulses between the cerebellar cortex and other CNS centers.

Cauda Equina

A collection of spinal nerve roots at the inferior end of the vertebral canal resembling a horse's tail, resulting from the vertebral column growing faster than the spinal cord.

Meninges

Three connective tissue protective membranes encasing the CNS: the tough outer dura mater, web-like middle arachnoid mater, and delicate inner pia mater.

Cerebrospinal Fluid (CSF)

A watery plasma-like fluid ($150\,\text{ml}$ total volume) formed by the choroid plexuses that circulates through ventricles and the subarachnoid space to cushion and float the brain.