CNS Flashcards
major parts of the brain
- cerebrum
- diencephalon (thalamus and hypothalamus)
- cerebellum
- brain stem (midbrain, pons, medulla oblongata)
white matter
- bright pearly white color due to myelin around its nerve fibers
- in most of the brain it is deep to gray matter (opposite of spinal cord)
- composed of tracts (bundles of axons)
gray matter
- little myelin, duller white color
- forms the cortex and deeper masses called nuclei
cranial meninges
- dura mater, arachnoid, pia mater
- connective tissue membranes
- cover and protect the CNS, protect blood vessels, enclose venous sinuses, contain CSF, partition the brain
dura mater
- layer of meninges pressed closely against the cranial bone
- two layers which are separated in some places by dural sinuses
superior sagittal sinus
dural sinus found just under the cranium along the median line
transverse sinus
dural sinus that runs horizontally from the rear of the head toward each ear
jugular veins
the place where the sinuses empty into
falx cerebri
extension of the dura mater into the longitudinal fissure as a wall between the cerebral hemispheres
tentorium cerebelli
extension of the dura mater is like a roof over the posterior cranial fossa and separates the cerebellum from the cerebrum
falx cerebelli
extension of the dura mater that partially separates the right and left halves of the cerebellum
arachnoid mater
transparent membrane over the brain surface
ventricles
four internal chambers of the brain that are filled with cerebrospinal fluid, continuous with each other and the central canal of the spinal fluid, and lined with ependymal cells
lateral ventricles
the largest ventricles, which form an arc in each cerebral hemisphere; separated by the septum pellucidum; interventricular foramen allow CSF to flow into third ventricle
third ventricle
ventricle in the diencephalon; CSF flows through cerebral aqueduct into fourth ventricle
fourth ventricle
triangular chamber between the pons and cerebellum in the brain stem; lateral apertures allow CSF to flow into subarachnoid space
choroid plexus
a mass of blood capillaries on the floor or wall
ependyma
a type of neuroglia that resembles cuboidal epithelium; lines ventricles and canals, covers the choroid plexuses, and produces CSF
blood-cerebrospinal fluid
made up of ependymal cells, which permit certain substances to enter the fluid but excludes others and protects the brain and spinal cord from harmful elements
cerebrospinal fluid (CSF)
a clear, colorless liquid that protects the brain and spinal cord against chemical and physical injuries and carries oxygen, glucose, and other needed chemicals from the blood to neurons and neuroglia
three ways the CSF contributes to homeostasis
1) Buoyancy
2) Protection
3) Chemical stability
blood vessels that deliver blood to the brain
internal carotid arteries and basilar artery
areas blood is drained into in the brain
dural sinuses and then into jugular veins
blood-brain barrier (BBB)
protects brain cells from harmful substances and pathogens by serving as a selective barrier to prevent passage of many substances from the blood to the brain
stroke
caused by decreased blood supply
- occlusion of cerebral blood vessel
- hemorrhage (brain bleed) from cerebral blood vessel
brain bleed of epidural space
rapid bleeding
brain bleed of subdural space
slower bleeding
cerebrum
- the center of intelligence and personality
- two hemispheres
- cortex and medulla
cortex
superficial layer of the cerebrum
medulla
deeper layer of the cerebrum
gyrus
a thick fold of the cerebrum
sulcus
a shallow groove of the cerebrum
longitudinal fissue
separates the right and left hemispheres
transverse cerebral fissure
separates the hemispheres from the cerebellum
corpus callosum
a bundle of transverse white fibers that allows communication between the hemispheres
left hemisphere functional differences
- right-handed control
- spoken and written language
- numerical and scientific skills
right hemisphere functional differences
- left-handed control
- musical and artistic awareness
- space and pattern perception
- insight/intuition
- emotion, imagination, generating mental images of sight, sound, touch, taste, smell
functions of the cerebrum
- interpreting impulses
- initiating voluntary movements
- storing information as memory
- retrieving stored information
- reasoning
- intelligence and personality
frontal lobe
- primary motor cortex (precentral gyrus)
- voluntary motor functions
- higher mental functions
- Broca area (speech production, left hemisphere only)
- anterior association area (cognition, mood, intelligence, social skills)
parietal lobe
- primary somatosensory corex
- taste
primary somatosensory cortex
- allows spatial discrimination and the ability to detect the location of stimulation
- touch, pressure, pain, stretch, movement, heat, cold, pain
- sensory homunculus
primary gustatory cortex
in parietal lobe, receives taste signals
temporal lobe
- interprets hearing, smell, language
- primary auditory cortex
- auditory association area
- primary olfactory cortex
- Wernicke area (language recognition, left hemisphere only)
occipital lobe
- interprets vision
- primary visual cortex
insula
- deep to the other lobes
- language, taste, integrating visceral sensory information
cerebral medulla
- white matter beneath the cortex
- glia and myelinated nerve fibers
- communication between cerebral areas and the cerebral cortex and lower CNS centers
association fibers
fibers between gyri in the same hemisphere
commissural fibers
fibers from one hemisphere to the other
- most pass through the corpus callosum, which forms the floor of the longitudinal fissure
projection fibers
fibers that form ascending and descending tracts and connect the cerebral cortex to the lower brain or cord centers
basal nuclei
- masses of cerebral gray matter buried in the white matter, lateral to the thalamus
- help program habitual or automatic sequences and set an appropriate level of muscle tone
- determine the onset and cessation of intentional movements, walking, and highly practiced learned behaviors (typing, tying shoes)
limbic system
- ring of structures on medial side of cerebral hemispheres, encircling corpus callosum and thalamus
- “emotional brain,” functions in emotional aspects of behavior and memory
- associates smells with emotions and memories
diencephalon
- lies medial to the cerebral hemispheres and superior to the brainstem
- surrounds the third ventricle and includes thalamus, hypothalamus, and epithalamus (pineal gland)
thalamus
- mediates sensation, motor activities, cortical arousal, learning, and memory
- contains nuclei that serve as relay stations for all sensory impulses except smell to the cerebral cortex for interpretation
lateral geniculate nucleus
in thalamus; gateway for visual signals, sends them to occipital lobe
ventral lateral nuclei
motor integration (cerebellum, basal nuclei, projects to motor cortex)
mammillary body
contains three to four mammillary nuclei that relay signals from the limbic system to the thalamus
hypothalamus
- control center of the body
- regulates ANS activity
- initiates physical responses to emotions
- regulates body temperature, food intake, water balance, thirst, sleep-wake cycles, and endocrine function
- links nervous and endocrine systems
epithalamus
- superior and posterior to thalamus
- contains pineal gland
pineal gland
secretes melatonin to influence diurnal cycles in conjunction with the hypothalamus
brain stem
- produces programmed automatic behaviors
- provides a passageway for fiber tracts running between the cerebrum and spinal cord
- provides innervation of the face and head through cranial nerves III-XII
medulla oblongata
- continuous with upper spinal cord
- contains portions of both motor and sensory tracts
- major portion of reticular formation runs through it
- nuclei that are reflex centers for regulation of heart rate, respiratory rate, vasoconstriction, swallowing, coughing, vomiting, sneezing, and hiccupping
pons
- connects spinal cord with brain
- relays nerve impulses related to voluntary skeletal movements from the cerebral cortex to the cerebellum
- pneumotaxic and apneustic areas help control rate and depth of breathing along with respiratory center in the medulla
midbrain
- conveys motor impulses from the cerebrum to the cerebellum and spinal cord
- sends sensory impulses from spinal cord to thalamus
- regulates auditory and visual reflexes
superior colliculi
in midbrain; control vision and eye-related functions (visual tracking, blinking, focusing, etc)
inferior colliculi
in midbrain; receive signals from inner ear and relays them to other parts of the brain, especially the thalamus
reticular formation
complex network of nerve fibers scattered throughout the brain stem that consists of small areas of gray matter interspersed among fibers of white matter
- sensory and motor functions
reticular activating system (RAS)
- alerts cortex to incoming sensory signals
- responsible for maintaining consciousness and awakening from sleep
- filters sensory information and arouses cerebral cortex into wakefulness, dampening familiar or weak sensory input
- waking up to the alarm clock but not the train going by
four aspects of cerebellar function
- monitoring intent for movement
- monitoring actual movement
- comparing intent with actual performance
- sending out corrective signals
functions of the spinal cord
- conduction pathway (receptor to sensory to inter to motor to effector)
- processes reflexes
- neural integration
meningitis
inflammation of the meninges
gray matter of spinal cord
- cell bodies and neuroglia and unmyelinated axons and dendrites of association and motor neurons
- dorsal, ventral, and lateral horns
dorsal (posterior) horn
afferent nuclei of interneurons
ventral (anterior) horn
efferent nuclei of somatic lower motor neurons
lateral horn
autonomic nervous system preganglionic nuclei
ascending pathways
conduct sensory impulses upward through a chain of three neurons (first-, second-, third-order neurons)
first-order fibers
touch, pressure, proprioception
- large, myelinated, and fast
heat and cold
- small, unmyelinated or lightly myelinated, slower
first-order neurons
detect stimulus and conduct impulses to CNS
second-order neurons
in the brain, collect information from first-order neurons and end in the contralateral thalamus
third-order neurons
complete route to the cerebrum
fasciculus gracilis and cuneatus
touch, pressure, vibration, visceral pain, proprioception of limbs and chest
(ascending tract)
lateral spinothalamic tract
pain, cold, warmth
(ascending tract)
anterior (ventral) tract
tickle, itch, crude touch, pressure
(ascending tract)
corticospinal tract
voluntary, precise, finely coordinated movements of the limbs and trunk
(descending tract)
reticulospinal tract
automatic movements for tone, posture, and balance
(descending tract)
