8: Central Nervous System (CNS)

A comprehensive set of vocabulary flashcards covering the Central Nervous System, including major brain regions, spinal cord anatomy, and functional systems.

Central Nervous System (CNS)

The integration centers of the nervous system consisting of the brain and spinal cord.

Gray matter

Regions of the nervous system containing neuron cell bodies and short nonmyelinated neurons.

White matter

Regions of the nervous system containing mostly myelinated axons with some nonmyelinated axons.

Brain lateralization

The specialization or dominance of each side of the brain for certain functions, such as the left hemisphere's dominance for language and logic.

Corpus Callosum

The largest collection of white matter tracts in the brain that joins the left and right cerebral hemispheres at the midline.

Vermis

The structure that joins the left and right cerebellar hemispheres at the midline.

Neuroplasticity

The brain's ability to change throughout life, involving structural changes in cells and variations in synaptic strength.

Cerebral cortex

The outer superficial layer of gray matter of the cerebrum, approximately $2-4\,mm$ thick, where consciousness is created.

Gyrus

An elevated ridge of tissue or outward fold on the surface of the cerebral cortex.

Sulcus

A shallow groove that separates gyri on the cerebral cortex.

Fissure

A deep groove that typically separates large regions of the brain.

Frontal lobe

The lobe responsible for controlling voluntary movement and processing higher cognitive functions like logic, judgment, and planning.

Parietal lobe

The lobe that processes proprioception and somatosensation, including touch, pressure, and pain.

Temporal lobe

The lobe that processes hearing, vision, memory, and language comprehension.

Occipital lobe

The lobe dedicated to processing visual information.

Insular lobe

A deep brain region within the lateral sulcus that processes visceral information and interoception.

Sensory areas

Functional brain areas that receive and process sensory input for conscious awareness, located in the parietal, occipital, temporal, and insular lobes.

Association areas

Cortical regions where sensory stimuli are integrated and interpreted into meaningful information.

Primary somatosensory cortex

Located on the postcentral gyrus, it receives somatic sensory information and identifies the site of stimulation.

Primary motor cortex

Located on the precentral gyrus, it contains pyramidal neurons that control precise and skilled voluntary skeletal muscle movements.

Broca’s area

A motor speech area typically lateralized to the left cerebral hemisphere that directs muscles involved in speech production.

Somatotopy

The point-for-point correspondence of a body part to a specific point in the Central Nervous System, often visualized as a homunculus.

Projection fibers

Cerebral white matter tracts that relay impulses vertically between the cortex and lower CNS centers like the spinal cord.

Commissural fibers

Tracts that relay impulses between the two hemispheres, such as the Corpus Callosum.

Basal nuclei

Subcortical bundles of cell bodies deep in white matter that regulate the initiation of movement and suppress unwanted movements using dopamine.

Thalamus

The relay station of the diencephalon that sorts and filters all sensory inputs (except olfaction) ascending to the cerebral cortex.

Hypothalamus

The master regulator of whole body homeostasis and main visceral control center, acting as the link between the nervous and endocrine systems.

Pineal gland

A structure in the epithalamus that secretes the sleep-inducing hormone melatonin.

Midbrain

The most superior brainstem region, containing the cerebral aqueduct and corpora quadrigemina.

Pons

The brainstem region that acts as a bridge between higher brain centers and the spinal cord, and contains the pontine respiratory center.

Medulla oblongata

The most inferior brainstem region containing autonomic reflex centers for heart rate, blood pressure, and breathing.

Pyramidal decussation

The crossover point in the medulla where $80-90\%$ of corticospinal fibers cross to the contralateral side of the body.

Arbor vitae

The distinctive branching pattern of white matter within the cerebellum, meaning 'tree of life.'

Reticular Activating System (RAS)

The ascending sensory portion of the reticular formation that filters sensory stimuli and keeps the cerebral cortex alert.

Limbic system

The 'emotional-visceral brain' involved in behavioral and emotional response, learning, and memory formation.

Hippocampus

A limbic system structure critical for memory consolidation and decision-making; the only brain region recognized for adult neurogenesis.

Amygdala

An almond-shaped structure that scans for threats and instructs the hypothalamus to activate the sympathetic nervous system.

Interoception

The perception of physical sensations from inside the body, including internal organ function and autonomic activity related to emotions.

Conus medullaris

The tapered, terminal end of the spinal cord located at the $L1/L2$ vertebral level in adults.

Cauda equina

The collection of nerve roots from $L2$ to $S5$ and the coccygeal nerve that extends past the end of the spinal cord.

Dorsal horns

Sections of spinal cord gray matter where sensory (afferent) axons from the PNS synapse onto interneurons.

Ventral horns

Sections of spinal cord gray matter containing the cell bodies of somatic motor neurons that innervate skeletal muscles.

Lateral horns

Gray matter sections found only in the $T1$ to $L1/2$ spinal segments containing autonomic motor neurons for the sympathetic division.

Nerve plexus

A network where axons from the ventral rami of multiple spinal nerves are sorted and recombined to innervate specific body parts.