The Central Nervous System Flashcards
gyri
ridges of outer surface of brain
sulci
depressions between gyri
fissures
deep sulci
gray matter of brain
made of neuron cell bodies, dendrites and unmyelinated axons
cerebral cortex
gray matter on the surface of the cerebrum
cerebral nuclei
regions of gray matter (clusters of cell bodies) found deep in the cerebrum
white matter
myelinated axons
pia mater
innermost layer of meninges that stick to the surface of the brain
thin layer of areolar connective tissue
arachnoid mater (arachnoid membrane)
lie external to the pia mater
made of webs of collagen and elastic fibers
lies deep to dura mater
Subdural hematoma
Subdural space is a potential space to fill with blood if a vein is ruptured
Arachnoid trabeculae
extend to the pia mater through subarachnoid space
subarachnoid space
contain cerebrospinal fluid (CSF)
Dura mater
tough outer membrane
made of dense irregular tissue (2 layers)
Meningeal layer
deep layer of dura
periosteal layer
more superficial layer of dura
forms periosteum on internal surface of cranial bones
dural venous sinuses
where meningeal and periosteal layers separate to drain blood from brain
epidural space of brain
potential space between the dura and the skull the contains arteries and veins
2 lateral ventricles
large cavities in the cerebrum
separated by septum pellucidum
septum pellucidum
medial partition separation 2 lateral ventricles
third ventricle
narrow space in middle of diencephalon
connected to each lateral ventricle by intraventricular foramen
intraventricular foramen
connect each lateral ventricle to the third ventricle
fourth ventricle
sickle shaped space between the pons and cerebellum
connected to third ventricle by cerebral aqueduct
opens to subarachnoid space medially and laterally
narrows before merging with central canal of spinal cord
cerebrospinal fluid (CSF)
clear, colorless liquid that surrounds the CNS
circulate in ventricles and subarachnoid space
provide buoyancy, reducing brains apparent weight by 95%
protect the CNS by providing a liquid cushion
keep CNS environment stable (helps transport nutrients and wastes, protects against chemical fluctuations)
choroid plexus
form CSF
specialized tissue in each ventricle
layer of ependymal cells and blood capillaries
CSF formation
blood plasma filtered through capillary and modified by ependymal cells
ependymal cell secretions and interstitial fluid from the subarachnoid space help make it up
CSF circulation
continuously formed and reabsorbed
begins in choroid plexus of ventricles
flows from lateral ventricles into third
from third ventricle to fourth
passed through apertures, it flows in subarachnoid space and down into central canal of spinal cord
excess CSF flows into arachnoid villi and drains into dural venous sinuses
arachnoid villi
where excess CSF flows into, draining into dural venous sinuses
cerebrum
2 large hemispheres of brain
origin of all complex intellectual functions
center of intelligence and reasoning; thought, memory, judgement, voluntary motor control and special sense interpretation
longitudinal fissure
deep cleft separating hemispheres
corpus callosum
largest white matter tract providing connection between hemispheres
left hemisphere receives sensory signal from
the right side of the body and sends motor signals to the right
the right hemispheres receives sensory signals from
the left side of the body and sends motor signals to the left
how many lobes in each hemisphere?
5 (frontal, parietal, temporal, occipital, and insular)
frontal lobe
anterior part of cerebellum
posterior border is deep central sulcus
precentral gyrus controls voluntary movement
motor control, concentration, verbal communication, decision making, planning, personality
parietal lobe
serves general sensory functions
evaluating shape and texture of objects
temporal lobe
located inferior to lateral sulcus
functions include hearing and smell
occipital lobe
functions in vision and visual memories
insular lobe (insula)
small lobe that can be observed by pulling away temporal lobe
functions in memory and sense of taste
where are motor areas housed?
frontal lobe
primary motor cortex (somatic motor area)
located in precentral gyrus
control skeletal muscle activity on opposite side of body
motor homunculus
controlled body regions map
distorted proportions of the body reflect amount of motor cortex dedicated to each part
hands are large on homunculus bc large area of brain controls precise movements
motor speech area
located in inferolateral portion of left frontal lobe
controls movements for vocalization
frontal eye field
superior surface of middle frontal gyrus
regulates eye movements needed for reading and binocular vision
premotor cortex (somatic motor association area)
located anterior to primary motor cortex
coordinates learned. skilled activities
primary somatosensory cortex
located in postcentral gyrus of parietal lobes
receives somatic sensory info from touch, pressure, pain, temperature, proprioceptors
sensory homunculus
areas of body sending input mapped
large regions for lips, fingers and genitals
somatosensory association area
immediately posterior to postcentral gyrus (parietal lobe)
integrates touch info, letting us identify objects by feel
primary visual cortex
located in occipital lobe
visual association area
surrounds primary visual cortex
integrates color, form, memory to allow us to identify things we see (faces)
primary auditory cortex
located in temporal lobe
auditory association area
located in temporal lobe
interpret sound; stores/retrieves memories of sounds
primary olfactory cortex
located in temporal lobe
provides conscious awareness of smells
no association area-individual experiences
primary gustatory cortex
located in insula
involved in processing taste info
no distinct association area
prefrontal cortex
located closer to front of head (rostral) to premotor cortex in frontal lobe
complex thought, judgement, personality, planning and deciding
still developing in adolescence
Wernicke area
typically located in left hemisphere of temporal lobe
involved in language comprehension
gnostic are (common integrative area)
integrates info from variety of sensory association areas
sights, smells, sounds converge and brain becomes aware of situation (lunch time)
association tracts
connect regions of cerebral cortex within same hemisphere
arcuate fibers
short tracts connecting neighboring gyri
longitudinal fasciculi
longer tracts connecting gyri in different lobes
commissures
connect regions in different hemispheres from right to left
includes corpus callosum, anterior and posterior commissure
projection tracts
link cerebral cortex to inferior brain regions and spinal cord
corticospinal tracts carry signal from cerebral cortex to spinal cord
internal capsule
when the projection tract passes between the thalamus and cerebral nuclei
cerebral lateralization (hemisphere specialization)
2 sides of cerebrum exhibit differences in higher order functions
develops in early childhood (5-6 years)
correlated with handedness (right handed, left hemisphere is categorical, speech dominant)
categorical hemisphere
usually left hemisphere
specialized for language abilities, functions in categorization and analysis
contains Wernicke’s area and motor speech area
representational hemisphere
usually right hemisphere
concerned with visuospatial relationships, imagination, comparison of senses
diencephalon
includes epithalamus, thalamus and hypothalamus
provides relays and switching centers for sensory, motor, visceral pathways
epithalamus
forms posterior part of roof of diencephalon
covers third ventricle
pineal gland
endocrine gland secreting melatonin
helps regulate day-night cycles (circadian rhythm)
thalamus
oval masses of gray matter on lateral sides of third ventricle
composed of about a dozen thalamic nuclei
receives signals from all conscious areas
thalamic nuclei
axons from a given nucleus project to a particular region of cortex
hypothalamus
anteroinferior region of diencephalon
infundibulum
stalk of pituitary that extends from hypothalamus
functions of hypothalamus
controls autonomic nervous system (heart rate, blood pressure)
controls endocrine system (secretes hormones that control normal activities in anterior pituitary gland, produce ADH and oxytocin)
regulated body temp
emotional behavior (part of limbic system that controls emotional responses)
food intake
water intake
sleep-wake rhythms
brainstem connects
cerebrum, diencephalon and cerebellum to spinal cord
the brainstem contains tracts and tracts
ascending
descending
the brainstem contains , nuclei of , and
nuclei
cranial nerves
reflex centers
the brainstem is made up of the
midbrain (highest) pons (middle) and medulla oblongata (lowest)
functions of midbrain
several tracts and bands of axons carry impulses to and from other portions of CNS
reticular formation-alertness
cerebral peduncles-motor tracts
components of midbrain
cerebral aqueduct (aqueduct of Sylvius) that connects third and fourth ventricles
houses nuclei of CN III (oculomotor) and IV (trochlear)
tectum (posterior part of midbrain)
contains 4 mounds making a tectal plate (corpora quadrigemmina)
Corpora quadrigemmina (Tectal plate)
pair of superior colliculi that control visual reflexes and tracking
pair of inferior colliculi that control auditory reflexes
Pons
bulging region on anterior brainstem
includes sensory and motor tracts connecting brain to spinal cord
cranial nerve nuclei (sensory and motor) nuclei for CN V to CN VIII: trigeminal, abducens, facial, and vestibulocochlear nerves
medulla oblongata
medulla: inferior portion of brainstem
continuous with spinal cord inferiorly
includes sensory and motor tracts connecting brain to spinal cord
autonomic nuclei of medulla
cardiac center, vasomotor center and medullary respiratory center
cardiac center
regulates heart output
vasomotor center
regulates blood vessel diameter
strong influence on blood pressure
medullary respiratory center
controls respiratory rate
communicates with pontine respiratory center
cranial nerve nuclei of medulla
nuclei for vestibulocochlear, glossopharyngeal, vagus, accessory, and hypoglossal nerves
cerebellum
second largest brain area (after cerebrum)
cerebellar cortex: convoluted surface with folia
left and right cerebellar hemispheres
vermis
arbor vitae
folia
folds in cerebellar cortex
vermis
narrow band of cortex between left and right lobes of cerebellum
receives sensory signals regarding torso position and balance
arbor vitae
internal region of white matter in cerebellum
three thick nerve tracts connecting cerebellum to brainstem are
superior cerebellar peduncles
middle cerebellar peduncles
inferior cerebellar peduncles
superior cerebellar peduncles
connect cerebellum to midbrain
middle cerebellar peduncles
connect cerebellum to pons
inferior cerebellar peduncles
connect cerebellum to medulla oblongata
functions of cerebellum
coordinates and “fine tunes” movements
ensures muscle activity follows correct pattern
adjusts movements initiated by cerebrum, ensuring smoothness
helps maintain equilibrium and posture
receives proprioceptive information from muscles and joints
spinal cord
extends inferiorly from brains medulla through vertebral canal
ends at L1 vertebrae with conus medullaris
2 widened regions with greater number of neurons (cervical and lumbosacral enlargements)
conus medullaris
terminal end of spinal cord
cervical enlargement
contains neurons innervating upper limbs
lumbosacral enlargement
contains neurons innervating lower limbs
spinal cord regions top to bottom
cervical part (8 pairs of cervical spinal nerves)
thoracic part (12 pairs of thoracic spinal nerves)
lumbar part (5 pairs of lumbar spinal nerves
sacral part (5 pairs of sacral spinal nerves)
coccygeal part (1 pair of coccygeal spinal nerves)
cauda equina
roots from parts L2 and below extending inferiorly
filum terminale
thin strand of pia attaching conus medullaris to coccyx
anterior median fissure
groove on front of spinal cord
posterior median fissure
groove on back of spinal cord
subdural space of spinal cord
between dura and arachnoid
epidural space of spinal cord
between dura and vertebrae
houses adipose, areolar connective tissue, blood vessels
gray matter of spinal cord
made of neuron cell bodies, dendrites, unmyelinated axons, and glial cells
anterior horns
house cell bodies of somatic motor neurons
lateral horns
house cell bodies of autonomic motor neurons
only present in T1-L2
posterior horns
house axons of sensory neurons and cell bodies of interneurons
gray commissure
horizontal band of gray matter surrpunding the central canal
contains unmyelinated axons connecting left and right gray matter
nuclei
groups of cell bodies
sensory nuclei
in posterior horn, contain interneurons
somatic sensory nuclei
receive signals from skin, muscle, joints
visceral sensory nuclei
receive signals from blood vessels, viscera
motor nuclei
in anterior and lateral horns contain motor neurons
somatic motor nuclei
anterior
innervate skeletal muscle
autonomic motor nuclei
lateral
innervates smooth muscle, heart, glands