CNS Exam 1 Flashcards
plays a dominant role in coordination, assocation & integration of body responses to internal and external demand
Nervous system
specialization is high
nervous system
little capacity to store oxygen or sugar and it maintains little mitotic capacity
mature nervous tissue
what is the CNS composed of?
Brain (encephalon) & spinal cord (medulla spinalis)
In the PNS how many cranial nerve pairs do we have?
12 cranial nerve pairs
24 nerves
In the PNS how many spinal nerve pairs do we have?
31 spinal nerve pairs
62 nerves
In the PNS how many total nerve trunks are there?
86 total nerve trunks
What does the somatic component innervate?
skeletal musculature
Is somatic voluntary or involuntary?
voluntary
T/F Somatic includes both efference and afferent nerve fibers
True
T/F Somatic involves both CNS and PNS
True
the chemical released by the somatic axon ending (cholingergic) excitatory
Acetylcholine
both preganglionic and postganglionic parasympathetic neurons release ACH
cholinergic system
is autonomic component efference or afferet?
efferent
is autonomic component voluntary or involuntary
involuntary
which nerve fibers receive emphasis?
efferent (motor)
what are the three branches that autonmic innervates?
glands, cardiac, smooth muscle
autonmic component is subdivided into:
parasympathetic and sympathetic
carried away from CNS
parasympathetic
parasympathetic fibers are limited to what cranial nerves?
III, VII, IX, X
3, 7, 9, 10
parasympathetic fibers are limited to what sacral nerves?
2,3,4
the cranial and sacral nerve are known as the____?
craniosacral subdivision
how many efferent neurons are utilized to reach the gland cell or muscle cell involved?
two(not one as in the somatic)
in parasympathetic which is longer?
preganglionic
in parasympathetic which is shorter?
postganglionic
spinal nerves that carry sympathetic efferent fibers are____?
T1-L2
in sympathetic subdivision which is longer?
postganglionic
in sympathetic subdivision which is shorter?
preganglionic
fight or flight
sympathetic
what do preganglionic sympathetic neurons release?
ACH
what do postganglionic sympathetic neurons release?
norepinephrine
preganglionic sympathetic neurons release ACH and postganglionic sympathetic neurons relase norepinephrines what is this sytem called?
adrenergic system
what are the exceptions of the adrenergic system where ACH is released at the target ?
sweat glands, arrector pili muscles
slows heart rate/ speeds peristalsis/ constricts the pupil and respiratory tree. 1:2
parasympathetic
speeds heart rate/ decreases peristalsis/ dilates the pupil and respiratory tree. 1:17
sympathetic
how many nervous systems are there?
one
what is the third subdivision of the autonomic component other than parasympathetic and sympathetic?
enteric
where does the nervous system derive from?
ectoderm
is ectoderm outside or inside?
outside
3 primary brain vesicles
prosencephalon, mesencephalon, rhombencephalon
two flexures:
cervical and cephalic
forebrain
prosencephalon
midbrain
mesencephalon
hindbrain
rhombencephalon
telencephalon and diencehalon come off of the
prosencephalon
metencephalon and myelencephalon come off of the
rhombencephalon
cerebral cortex, basal ganglia and lateral ventricles come from the
telencephalon
thalamus, hypthalamus, pineal gland and the 3rd ventricle come from the
diencephalon
corpora, quadrigemina, cerebral peduncles, cerebral aqueduct come from the
mesencephalon
cerebellum, pons, 4th ventricle come from the
metencephalon
medulla oblongata, 4th ventricle, continuous with the spinal cord come from the
myelencephalon
neural tube gives rise to ?
CNS
neural crest cells give rise to?
PNS
what % of body wt is the brain at birth?
10%
in an adult brain what is the body weight % ?
2-2.5%
in the adult brain what percent of oxygen is used?
20%
neural tube cells give rise to what?
CNS structures
what three things break off of neuroepithelial cells?
neuroblasts, ependymal cells, glioblasts
what comes off neuroblasts
neurons
what comes off glioblasts
astrocytes and oligodendrocytes
what are the functions of a glioblast?
take care of injury, can undergo mitosis & give rise to astrocytes and oligodendrocytes
the glioblasts and its derivations are the _______ of the CNS
functional connective tissue
it is estimated that in total there are __________ as many glioblast derivatives as neurons in the adult human brain.
5-10 times
the most numerous cell of the adult central nervous system. maintain some mobility potential.
astrocytes
2 types of astrocytes
protoplasmic and fibrous
found in gray matter-unmyelinated
protoplasmic
found in white matter-myelinated
fibrous
astrocytes are found sandwiched between blood vessel capillaries and neuron cell bodies. those in this position are said to be a part of the _____?
BBB
astrocytes play a dominant role in forming ______tissue following CNS injury. this is where mobility potential may be of use
“scar-like”
fewer in number than the astrocyte but still quite numerous
oligodendrocyte
2 types of oligodendrocyte
perineuroal satellites & interfasicular
found in gray matter; play some nutrient role
perineuronal satellites
found in white matter, responsible for forming myelin in CNS.
interfascicular oligodendrocytes
serve as a leaky barrier betwee CSF and the CNS parenchyma.
ependymal cells
most ependymal cells are classified as________?
simple cuboidal
some highly adapted taller ependymal cells with microvillus borders are preset in all four ventricles. they secrete CSF and form the so-called________ in each ventricle?
choroid plexus
where is CSF found?
in all 4 ventricles
facilitate the transport of things from CSF (in 3rd ventricle) to hypophyseal portal system
tanycytes
most common primary brain tumor
astrocytoma
most lethal brain tumor
glioblastoma
mesodermally derived.
microglia
responsible for clearing dead & damaged tissue and may even wall off damaged areas along with the astrocytes
phagocytic function
mediate immune responses within CNS
HIV: type 1 & 2 productively infected
microglia
neuron classification: shape
anatomical
neuron classification: function
physiological
unipolar are_____
sensory
bipolar are______
special sensory neurons
multipolar are______
motor
do not leave the CNS
internuncial
runs between equivalent structures on opposite sides of the CNS. cross the midline
commissural
begins in one structure and terminates in a different structure of the CNS. may or may not cross the mid-line
projection
type of projection-stays on the same side
ipsilateral
type of projection- crosses to the opposite side
contralateral
the spinal cord that begins and ends at the same cord level within the same segment
intra segmental
the spinal cord that begins at one cord level and terminates at another cord level
inter segmental
what structures meet to form a synapse in the CNS?
axoaxonic
axodendritic
axosomatic
least common form of synapse
axoaxonic
most common form of synapse
axodendritic
when present ________ are found in the dendrites and cell body. they do not appear in the axon or its hillock
nissl bodies aka. tigroid bodies
if a neuron is injured the Nissl bodies respond quickly and appear to dissolve. this process is called_________?
chromatolysis
a fragmentation of the Golgi apparatus under similar injurious conditions
retispersion
3 types of neurofibrils
microtubules, microfilament, neurofilaments
help maintain cell shape and have a diameter between 20-30 nm. largest
microtubules
run longitudinally and circumferentially and are often associated with the axolemma 3-5 nm. smallest
microfilaments
ar moderate diameter filaments 9-10 nm. intermediate
neurofilaments
intracellular movement of such items as protein building blocks for the neurofibrils and mitochondria. speed of flow is directly related to axon length but little energy seems to be required to conduct such flow. will not consume ATP
slow transport
intracellular movement of such items as synaptic vesicles (or precursors), lysosomes, and certain enzymes. consumes ATP
fast transport
most action potential is initiated here
hillock
white matter; neurons do not make______
myelin
myelin covers can be found on both PNS & CNS fibers. no myelin over the ___________________. when myelin is present, it’s only over the long process/fiber/axon/cell.
telodendria, perikaryon or hillock
as a rule myelin seldom forms on neuron fibers which are less than ________micron in diameter in PNS. almost all fibers greater than ____ microns in diameter will be myelinated?
one, two
the _______the myelin the faster an impulse will be conducted along the neuron fiber
thicker
two things that determine conduction veloctiy
myelinaton, fiber diameter
every PNS nerve fiber has such a covering. this does not mean every fiber is myelinated
schwann cell
what does neurilemma mean?
schwann cell
there are unmyelinated PNS nerve fibers. they do have a schwann cell covering but are not myelinted. an example would be a _________?
post-ganglionic sympathetic neuron (long)
where one schwann covering cell meets another, a real, but tiny exposed area is created is called________?
Node of Ranvier
mesodermally derived connective tissue covers
endoneurium, peineurium, epineurium
highly vascular, covers a single neuron
endoneurium
covers a bundle; fasiculi, continuous with the pia and the arachnoid maters
perineurium
outer coat of a nerve, covers a nerve. 25-85%
epineurium
Gullain-Barre Syndrome
PNS
multiple sclerosis; destroys myelin
CNS
single oligodendrocyte covers more than a _______?
schwann cell
loose covering of CNS. thick mother. thickest and outermost of the meninges.
dura mater (pachymeninx)
covers the entire CNS and the roots of the PNS within the vertebral canal and cranial vault.
dura mater (pachymenix)
wthin the cranial vault the dura has two layers:
outer endosteal dura/vascular
inner meningeal dura/fibrous
within the vertebral canal the dura has only one layer:
inner meningeal
slightly more collagenous than its cranial counterpart
inner meningeal
so prominent in the cranial vault, is absent from the vertebral canal
endosteal dura
an actual ________ is created along the vertebral canal. this space is filled with areolar and adipose connective tissue as well as holding a complex internal vertebral venous plexus.
epidural space
slips of dura making attachment into the ligaments of periosteum of the axis, lower cervical and occasionally thoracic vertebrae. these are sometimes called _______ ? (attaches dura to vertebra)
meningovertebral ligaments
its lateral extensions into the IVF’s and sacral foramina give this loose sac _______ of lateral stabilizers.
31 pairs
double layers of meningeal dura extending into a few fissures of the brain. sickle shaped for the most part, therefore called “falx=sickle”
the dural falces
located in the great longitudinal cerebral fissure between the Rt/Lt cerebral hemispheres
falx cerebri
where the meningeal dura dips between the cerebellar hemispheres in the posterior cerebellar notch
falx cerebelli
only bilateral falx; meningeal dura running laterally and forward from its confluence with the falx cerebelli and falx cerebri. this is a paired structure with a right and left extension.
tentorium cerebelli
the openin left in the middle between Lt and Rt. tentorial wings is called the
tentorial hiatus (notch)
are actually located in the transverse (horizontal) cerebral fissure
tentoria
connects the pituitary gland to hypothalamus. meningeal dura that forms a “roof” over the sella turcica (pituitary fossa). it is perforated in the middle by the infundibular stalk (to the pituitary)
diaphragma sellae
these membranes “compartmentalize” the vault and brain. they often serve like “baffles” and add support for the brain’s own internal weight, protecting the brain from blows to the head.
supratentoria/ falx cerebri and infratetorial/ falx cerebelli
the dura and cephalgia
“throbbing” headches
True or False; arachnoid mater has no blood supply
true
non-vascular membrane; transparent and resembles a thin sheet of saran wrap. inner and outer walls are composed of a simple squamous cell lining
arachnoid mater
it is from arachnoid cells that many ___________ arise even though they quickly attach to the dura and appear to be dural tumors
meningiomas
along with the pia mater, form the leptomeninges (or thin membrane)
arachnoid
leptomenigitis
arachnoid & pia
pachymengitis
dura
does not dip into fissures or sulci except where the dura does, follows the path of the dura
arachnoid mater
supply scalp
emissary v
provide passageway
arachnoid vili
supply bone
diploic v
invested by outer pia
artery
potential space
subdural space
located posterior to medulla oblongata and superior to the foramen magnum. largest cranial cistern. the fourth ventricle opens into this cistern via the median foramen (of Magedie)
cerebellomedullary cistern (cistern magna)
deep within the transverse (horizontal) cerebral fissure. some important blood vessels are found on its floor. the pineal gland and the midbrains collicular bodies are found in this region
cistern of the great cerebral vein (superior cistern)
anterior aspect of pons. a pair of openings enter this cistern laterally from the fourth ventricle called the lateral foramina (of Luschka) 1 way in 4 ways out
pontine cistern
region between the cerebral peduncles on the anterior aspect of the midbrain. much of the cerebral arterial circle (of Willis) vascularization is found along the epipia of this cistern
interpeduncular cistern
largest cistern in the body. it extends around the tapering end of the spinal cord (conus medullaris) all the way down to the upper sacral canal L2-S2. fills the so-called lumbar cul-de-sac. place from which CSF is removed during a lumbar spinal tap. needle generally inserted between spinous processes of L4-L5
lumbar cistern
recycle used CSF
arachnoid villi
calcified arachnoid villi
pacchionian body
associate with the lining of dural venous blood sinuses
arachnoid villi
allows used CSF to be removed from the subarachnoi space and carried out of the cranial vault by way of the dural venous sinuses.
arachnoidvilli
tender mother
pia mater
innermost meninx- vascular transparent membrane and is lumped with the arachnoid as par of the leptomeninx
pia mater
does dip into all fissures and sulci of the brain and cord.
pia mater
outer portion or pia, blood vessels going to or coming from the CNS structures within are generally conducted in this outer pia covering.
epipial
in the vertebral canal are formed by the pia. these penetrate the arachnoid and fuse with the dura
denticulate ligaments
formed primarily by this outer pial layer
the filum terminale internum
the pia forms a “cuff”, the ________
pial coat
pry dura away from bone, collection of blood between the skull and the periosteal dura. most commonly due to a rupture of the middle meningeal artery due to head trauma.
epidural hematoma
MMA=trauma
middle meningeal artery
potential space. collection of blood between the meningial dura and arachnoid. most commonly due to a rupture of “bridging veins” due to a “shear injury”. chronic usually seen in older patients. acute usually seen with severe trauma resulting in other head injuries
subdural hematoma
collection of blood in subarachnoid space. (where CSF is supposed to be). associated with cerebral contusions.(traumatic) usually associated with a ruptured aneurysm or A-V malformation. usually presents as “worst headache of my life”
subarachnoid hemorrhage
the mature brain weight is about _________ of our body weight
2-2.5%
20% oxygen.
10% of baby brain
60% oxygen
the brain is responsibe for nearly ________of the body’s total metabolic activity
15%
perfusion of the brain with arterial blood is most complex and significant. approx. _______ of blood is perfused through the brain each minute
800 ml. -75 ml each milisecond
3 caus of death in the U.S. of adults
Stroke (CVA)
leading cause of death of in males and females over 25 years old having high blood pressure or arteriosclerosis or both. many of these “accidents” result in arterial hemorrhage. a rupture of an aneurysm is a particulary dangerous, but rare, type of hemorrhage. most are due to arterial blockage. in about 85% of the cases the patients have already reported signs of TIA’s (transient ishemic attacks) to primary health care providers
stroke (CVA)
TIA (transient ischemic attacks
first signal of stroke
the __________ and its branches are the most common reported sites for strokes. these vessels carry more blood than others and supply area of great clinical importance.
the middle cerebral artery. MCA=stroke
chiropracic cervical manipulation may, in rare incidences, contribute to _________
vascular accidents
the ________supply the majority of blood to the brain (2/3rds)
internal carotid arteries
deviations from the normal are common:
anomalies
the most common anomalies involve the ________
anterior communicating artery
the most stable side of the cerebral arterial circle is that formed on the left by the ___________
left internal carotid
travels through the transverse foramen
vertebral artery
most common place for anomalies to occur for people who don’t look like the text
anterior communicating
major contributing vessels to the cord.
spinal cord blood supply
this small artery sends nearly 200 branches into the ventral aspect of the cord
anteromedial longitudinal artery trunk (AMLAT) or “anterior spinal artery”
anteromedial longitudinal artery trunk (AMLAT) or “anterior spinal artery”. posterolateral longitudinal artery trunks (PLLAT) or “posterior spinal arteries” segmental artery contributions
spinal cord blood supply
only a few areas of the cord are particulary vulnerable due to minimal anastomoses between vessels. these areas include the posterior surface of ________ and the anterior surface near _________
T1-T3 —-T4 and L1
penetrated the dura and arachnoid sheaths, and are generally conducted for varying distances along the outer pial layer. these vessels must eventually reach the white and gray matter of the CNS. they penetrate inward from the pia mater with a slight cuff of pia called the pial coat. the space between the blood vessel and the pia is designated the perviavascular space or virchow robin space. this space contains a mix of CSF and intersitiual fluid. the pial coat is lost as the vessels reach the arteriole stages. only glial cells associate with the surfaces of arterioles, capillaries and venules. in general arteries and veins of the cerebrum have thinner walls than similar vessels in other areas of the body. in specific, internal elastic membranes are reduced or absent and most major branches show considerable thinning at branching sites. VEINS LACK VALVES with the exception of some spinal veins.
brain/cord blood vessels
blood vessels that supply the blood vessels themselves
vasa vasorum are missing
extremely dense capillary beds are found in the _______
gray matter (synaptic activity)
less dense capillary beds exist in
white matter
how much blood is normally present in the brain?
75 ml
how much blood passes thru the brain in one minute?
800 ml
most common capillary type
continuous capillary
important role in BBB. lacks holes and windows. does not have fenestrae. (windows) it does have thin wall construction expected of a capillary. junctions between cells are tight and the basement membranes are thick. specialized areas of CNS do have other capillary types, including some with fenestrae, holes, or actually large leaky sinusoids.
ex: pineal body, infundibular stalk
capillaries of the CNS
lets fat soluble in not water. most of this is due to the continuous capillary that is not excessively permeable. the presence of the astrocyte on up to 85% of the capillary surface. (astrocyte supports) lipid soluble substance will cross while water soluble substances will not.
BBB
________ substances will cross the BBB
lipid soluble
__________substances will not cross the BBB
water soluble
L. dopa caffeine cocaine alcohol nicotine B12 & B6 vitamins
can cross BBB
botox and dopamine
do not cross the BBB
_____ and _____ of the CNS usually do not follow back the same course the arteries and arterioles followed inward
venules and veins
penetrate the arachnoid mater and meningeal dura to drain into the dural venous sinuses
cerebral veins
many dural venous sinuses receive blood from the ______. (via emissary veins) and surrounding bone (via diploic veins) as well as the CNS.
scalp
scalp, nasal, and mastoid air cell infections can spread into the venous sinuses through these routes
dural venous sinuses
vault drainage of dural venous sinus blood is into the Rt./ or Lt. internal jugular veins at the ____________
jugular foramina
longest. to the right. runs along attached border of the falx cerebri from foramen cecum to confluence of the sinuses.
superior sagittal dural venous sinus
most blood in this sinus flows into the right transverse dural venous sinus after passing through the _____________. (everything else to the left)
confluence of the sinuses
inferior enter into the _______ not confluence
straight
begin when the transverse sinus leaves the tentorium cerebelli. continuous with the internal jugular vein (end goal)
sigmoid dural venous sinuses
only way out
inferior petrosal DVS
go in and come out
superior petrosal DVS
in each of the four brain ventricles, CSF is produced in specialzed ependymal structures called:
choroid plexus
each lateral ventricle is totally separate from the other. a glial membrane called the ______helps separate them anteriorly
septum pellucidum
how many interventricular foramina do we have?
2
anterior (frontal) horn ventricular body collateral trigone (atrium) inferior (temporal) horn posterior (occipital) horn
5 basic parts of R/L lateral ventricles
is extensive and is located along the roof of the inferior horn, through the atrium and along the floor of the body. continues down through the interventricular formaina (of monro), spreading onto the roof of the third ventricle.
choroid plexus
a narrow opening in the substance of the diencephalon
3rd ventricle
continuous with the cerebral aqueduct of the mesencephalon
3rd ventricle
cerebral aqueduct
3rd & 4th (only way in)
central canal
4th to spinal cord
median foramen
4th to cerebellum mengillary cistern
cerebral aqueduct central canal median foramen R. lateral foramena L. lateral foramena
5 openings into or out of 4th ventricle
first forms during the 5th-6th month of fetal development. higher than blood plasma in NA+, Cl-, Mg+++ions. quite different from blood plasma, but it does have a closer similarity to brain intersitial fluid.
CSF
will secrete CSF from blood plasma
choroid plexus
functions of CSF
shock absorber
bouancy
70-80% of CSF is secreted by choroid plexus the rest is secreted by ____________ and enters the ventricles through the ependymal cells.
brain capillaries
Frontal & top along the longitudinal fissure & the anterior aspect of the parietal lobe
Anterior cerebral
Occipital & medial temporal lobe
Posterior cerebral
Lateral aspect of all 4 lobes
Middle cerebral
