Neural tube
During embryonic development, the CNS first appears as this; extends down the dorsal median plane of the developing embryo's body
Ventricles
Cavities, or chambers, within the brain
Cerebral hemispheres
Most superior part of the brain, this paired structure is a good deal larger than the other three brain regions combined; close and obscure most of the brain stem as they grow
Cerebrum
Largest part of the brain; consists of the right and left cerebral hemispheres
Gyri
Elevated ridges of tissue on the cerebral hemispheres
Sulci
Furrow on the brain; less deep than a fissure, this separates the gyri by forming a shallow groove
Fissures
Deepest depressions or inward folds on the brain; separate the larger regions of the brain
Lobes
Formed by the division of other fissures or sulci; named for the cranial bones that lie over them
Cerebral cortex
Functions to control speech, memory, logical and emotional response, consciousness, interpretation and sensation, and voluntary movement
Primary somatic sensory area
Interprets impulses traveling from the body's sensory receptors; allows us to recognize pain, coldness, or a light touch
Parietal lobe
Lobe so named because it lies on the parietal bone
Central sulcus
Most central furrow on the brain
Sensory homunculus
Spatial map that represents the body in an upside-down manner; "little man
Occipital lobe
The posterior part of this lobe contains the visual area
Temporal lobe
Lobe containing the auditory area; olfactory area is also found deep inside this lobe
Primary motor area
Allows us to consciously control our skeletal muscles; anterior to the central sulcus in the frontal lobe
Frontal lobe
Lobe containing the primary motor area
Corticospinal/pyramidal tract
Major voluntary motor tract formed by the axons of the primary motor area
Motor homunculus
Body map on the motor cortex; includes face, mouth, and hands
Broca's area
Specialized cortical area that is very involved in our ability to speak; found at the base of the precentral gyrus
Speech area
Located at the junction of the temporal, parietal, and occipital lobes, this area allows us to sound out words
Gray matter
Area that contains unmyelinated nerve fibers and nerve cell bodies
Cerebral white matter
Most of the remaining cerebral hemisphere tissue; composed of fiber tracts carrying impulses to, from, or within the cortex
Corpus callosum
Very large fiber tract that connects the cerebral hemispheres; such tracts are called commisures
Basal nuclei/ganglia
Islands of gray matter buried deep within the white matter of the cerebral hemispheres; help regulate voluntary motor activities
Huntington's disease (chorea)
Genetic disease that strikes during middle age and leads to massive degeneration of basal nuclei and later of the cerebral cortex; greek for "dance
Parkinson's disease
An example of basal nuclei problems, this disease typically strikes people in their fifties or sixties that results from a degeneration of the dopamine-releasing neurons of the substantia nigra
Diencephalon/interbrain
Part of the forebrain between the cerebral hemispheres and the midbrain, including the thalamus, third ventricle, and hypothalamus; enclosed by the cerebral hemispheres
Thalamus
Mass of gray matter in the diencephalon of the brain that encloses the third ventricle; relay station for sensory impulses passing upward to the sensory cortex
Hypothalamus
Region of the diencephalon forming the floor of the third ventricle of the brain; regulates body temperature, water balance, and metabolism
Limbic system
Emotional-visceral brain; center for many desires or emotions
Pituitary gland
Neuroendocrine gland located beneath the brain that serves a variety of functions, including regulation of the gonads, thyroid, adrenal cortex, water balance, and lactation
Mammillary bodies
Reflex centers involved in olfaction bulging from the floor of the hypothalamus posterior to the pituitary gland
Epithalamus
Forms the roof of the third ventricle; important parts include the pineal body and choroid plexi
Pineal body
Part of the epithalamus (part of the endocrine system)
Choroid plexus
Knots of capillaries within each ventricle that form the cerebrospinal fluid
Brain stem
Portion of the brain consisting of the medulla oblongata, pons, and midbrain; provides a pathway for ascending/descending tracts
Midbrain
Relatively small part of the brain; extends from the mamillary bodies to the pons inferiorly
Cerebral aqueduct
Slender cavity of the midbrain that connects the third and fourth ventricles
Cerebral peduncles
Two bulging fiber tracts that form the midbrain anteriorly; convey ascending and descending impulses ("little feet of the cerebrum")
Corpora quadrigemina
Four rounded protrusions so called because they reminded some anatomist of two pairs of twins (gemini)
Pons
Brain area connecting the medulla with the midbrain, providing linkage between upper and lower levels of the central nervous system; means "bridge", involved in the control of breathing
Medulla oblongata
Most inferior part of the brain stem that merges into the spinal cord below without any obvious change in structure; important fiber tract area that contains nuclei to regulate vital visceral activities
Fourth ventricle
Lies posterior to the pons and medulla and anterior to the cerebellum
Reticular formation
Diffuse gray matter that extends the length of the brain stem; involved in motor control of the visceral organs
Reticular activating system (RAS)
Plays role in consciousness and the awake/sleep cycle; damage to this area can result in permanent unconsciousness (coma)
Cerebellum
Part of the hindbrain; involved in producing smoothly coordinated skeletal muscle activity
Ataxia
If the cerebellum is damaged movements become clumsy and disorganized - forming this condition; victims cannot keep their balance and cannot touch their finger to their nose with their eyes closed
Meninges
Membranes that cover the brain and spinal cord
Dura mater
Outermost and toughest of the three membranes (meninges) covering the brain and spinal cord
Falx cerebri
One of the folds that attaches the brain to the cranial cavity
Tentorium cerebelli
Fold that separates the cerebellum and cerebrum
Arachnoid mater
Weblike middle meningeal layer that looks like a cobweb
Subarachnoid space
Covered by the arachnoid mater, attaching it to the innermost layer of the meninges
Pia mater
Innermost membrane of the meninges that clings tightly to the surface of the brain and spinal cord
Arachnoid villi
Specialized projections that protrude through the dura mater
Meningitis
Inflammation of the meninges of the brain or spinal cord
Encephalitis
Condition of brain inflammation in which bacterial or viral meningitis spreads to the nervous tissue of the CNS
Cerebrospinal fluid (CSF)
Fluid produced by choroid plexi; fills the ventricles and surrounds the central nervous system; watery "broth" similar to blood plasma
Hydrocephalus
Condition in which the cerebrospinal fluid is accumulated and exerted on the brain when something obstructs its drainage; "water on the brain", causes newborn baby heads to enlarge
Blood-brain barrier
Mechanism that inhibits passage of materials from the blood into brain tissues
Concussion
Occurs when a brain injury is slight; victim may be dizzy, "see stars", or lose consciousness briefly, but no permanent brain damage results
Contusion
Result of marked tissue destruction; victim may appear unconscious, but severe cases always result in a coma lasting from hours to a lifetime due to injury to the RAS
Intracranial hemorrhage
Bleeding from ruptured vessels; may result in death after a serious head blow
Cerebral edema
Swelling of the brain due to inflammatory response to injury
Cerebrovascular accidents (CVAs)
Commonly called strokes, which is the third leading cause of death in the Unites States; occur when blood circulation to a brain area is blocked by a clot or ruptured blood vessel and vital brain tissue dies
Alzheimer's disease
Progressive degenerative disease of the brain that ultimately results in dementia
Hemiplegia
Paralysis of one side of the body
Aphasias
Damage to the left cerebral hemisphere where language areas are located
Transient ischemic attack (TIA)
Incomplete stroke; temporary restriction of blood flow to the brain
Spinal cord
Glistening white continuation of the brain stem; major reflex center
Cauda equina
Collection of spinal nerves at the inferior end of the vertebral canal
Dorsal/posterior horns
Two posterior projections on the gray matter of the spinal cord
Ventral/anterior horns
Two anterior projections on the gray matter of the spinal cord
Central canal
Surrounded by the gray matter of the spinal cord, which contains the cerebrospinal fluid
Dorsal root
Cell bodies of sensory neurons have fibers that enter the spinal cord here
Dorsal root ganglion
Enlarged area that contains the dorsal root
Ventral root
Ventral horns of gray matter contain cell bodies of motor neurons of the somatic nervous system, which send their axons out of this in the spinal cord
Spinal nerves
31 pairs of nerves that arise from the spinal cord
Flaccid paralysis
Results from damage to the ventral root; nerves do not reach the muscles affected and thus voluntary movement is impossible; causes muscles to atrophy
Dorsal, lateral, and ventral columns
White matter is divided into these three sections on each side of the spinal cord; each contains fiber tracts made up of axons
Spastic paralysis
Results when the spinal cord is transected (cut cross-wise) or crushed; affected muscles stay healthy because they are still stimulated by reflex arcs, and movement occurs but is involuntary and uncontrollable