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87 Cards in this Set

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embryological origin of meninges
Endosteal layer of cranial dura
adherent to inner surface of cranium Not continuous w/ dura of spinal cord
Meningeal layer of dura
Continuous w/ dura of spinal cord
Dura mater septa
Septa: inward reflections of dura 4 locations in brain: Falx Cerebri Tentorium cerebelli Falx cerebelli Diaphragma sellae
Falx cerebri
Located in longitudinal fissure b/t cerebral hemispheres Ends just above corpus callosum
Tentorium cerebelli
Horizontal b/t the occipital lobes and cerebellum Attached to falx cerebri olong median plane posteriorly Lateral borders attached to skull Tent-like--> "tent"orium
tentiorium incisure
opening in anterior tentorium cerebelli for midbrain
posterior cranial fossa
space inferior to tentorium cerebelli
supra and infra tentorial lesions
refer to lesions above or below tentorium cerebelli
Falx cerebelli
dural fold between the two hemispheres of the cerebellum
diaphragma sellae
forms roof of hypophyseal fossa, stalk of pituitary passes thru this dural sheath
venous sinuses
endothelium lined blood channels b/t two layers of dura found b/t endosteal and meningeal layers or two meningeal layers
superior sagittal sinus
located within attaced borders of falx cerebri formed b/t endosteal and meningeal layers of dura Receives: branches from the superior cerebral veins on convexity of cerebral hemispheres veins from the meninges, bone, scalp, nose--providing route for infecting CNS site where cerebrospinal fluid is returend to systemic circulation
inferior sagittal sinus
extends along inferior free margin of falx cerebri, formed b/t two meningeal layers of dura drains medial aspect of brain
straight sinus
posterior continuation of the inferior sagittal sinus Empties into transverse (lateral) sinus Formed by great vein of galen and inferior sagittal sinus Supratentorial space-occ lesion can block and impede venous outflow from brain--> perivenous compression hemorrhage
Transverse sinus
Also called lateral sinus continuation of straight sinus around lateral aspect of hemispheres
Arachnoid villi
Protrusions of meningeal dura into venous sinuses; main site of CSF passage into systemic circ.; large numbers of arachnoid villi found in sagital sinus
Arachnoid granulations
macroscopic structures formed by groups of arachnoid villi which often calcify w/ age.
innermost meningeal layer, thin vascular membrane that adheres closely to the surface of brain and spinal cord. Covers ventricals
vasculature of pia
blood vessels in subarachnoid space on surface of pia.vessels pass into brain w/ sleeve of pia and perivascular space
choroid plexus
structure primarily involved in production of CSF; pia is part of it. Telachoroidea + ependyma = choroid plexus.
CSF filled cavities in the brain
thin, one layer of lining epithelium (called cuboidal epithelium b/c of appearance)
vascular tufts of pia invaginated into ventricles
Locations where CSF is found
ventricles, subarachnoid space, cisterns
function of CSF
cushioning of brain in solid vault
CSF protein content
CSF glucose content
40 - 80 mg/100 ml, 2/3 of blood glucose level
CSF cell content
0-5 lymphocytes per mm^3
CSF volume
125-175 ml
ion content of CSF relative to blood
more Na and CL, less glucose and K, very little protein
pink CSF significance
blood in CSF, usually bleeding aneurysm in subarachnoid space
yellow, clotting CSF significance
increased protein content (sometimes b/c tumor), also may be from lysis of red blood cells w/ hemoglobin --> bilirubin
cloudy CSF significance
cloudy white --> bacterial meningitis (neutrophils), increased protein & dec glucose. Slightly Cloudy--> viral meningitis (lymphocytes) near normal protein and glucose
Gram's stains/cultures on normal CSF
Mechanism of CSF secretion
cuboidal cells secrete Na; glucose and protein not very diffusable; low K b/c possible active K transport in opposite direction
brain-CSF barrier
barrier of tight junctions of ependymal cells, but CSF diffuses into parenchyma. Alcohol and other lipid solubles enter brain from CSF. Hangover from toxic effect on meninges and neurons, maybe swelling and stretching of meninges w/ dehydreation
CSF rate of production
continually produced, 500-750 mls/day. 4-5 x Volume at any time (125-175 ml)
Sites of CSF production
formed by choroid plexus primarily in lateral ventricles, also in fourth ventricle
CSF circulation
1) produced in lateral ventricles, passes trhu septum pellucidum (interventricular foramen of Monro) 2) Enter 3rd ventricle, passes posteriorly thru cerebral aqueduct (aqueduct of sylvius) 3) Enters 4th ventricle, thru two lateral foramina of Luschka and medial foramen of Magendie in roof of 4th vent. 4) Enters subarachnoid space, around brain, central canal of spinal cord (small hole in middle of spinal cord) which is continuous w/ 4th ventricle
Return of CSF to circulation
1) thru arachnoid villi which project from the subarachnoid spaces into the dural venous sinuses (primarily the superior saggittal sinus) 2) arachnoid villi contain trabeculae and CSF 3) one way valves for CSF
Subarachnoid hemmorage causes
usually from aneurysm, most common aneurysm is berry (saccular) aneurysm at arterial jx's in circle of willis--often during exertion. Also subarachnoid hemm from trauma, leakage of AVM, angiomas
Symptoms of subarachnoid hemmorhage
sudden headache, stiff neck (nuchal rigidity), altered level of consciousness
nuchal rigidity
stiff neck seen in number of neurological conditions. From irritation of meninges in posterior fossa and cervical canal, stimulating nerve roots resulting in reflex spasm and contraction of posterior neck muscles
Types of hydrocephalous
non-communicating hydrocephalous, communicating hydrocephalous
Non communicating hydrocephalus characteristics
1) fluid flow out of ventricles or 4th ventricle is blocked
most common cause of non-communicating hydrocephalous in adults
blockage of canal of sylvius (from supratentorial space occupying lesion) causes fliuid to build up in lateral and 3rd ventricles
Common cause of non-communicating hydrocephalous in children
aqueductal stenosis in infants whose mothers had mumps or rubella
Dandy Walker malformation
from developmental arrest of hindbrain; cyst develps producing grossly enlarged posterior fossa and hydrocephalou
Arnold Chiari malformation
displacement of brainsten and/or cerebellum into cervical canal closing off foramina in the roof of 4th ventricle
manifestations of brain damage from non-communicating hydrocephalous in infants and adults
infants:head enlarges, may or may not be brain dammage 2) adults brain is flattend against skull w/ brain dammage. Brain herniation and death follow.
treatment of noncommunicating hydrocephalous
shunt made b/t lateral ventricle and cistern, or lateral ventricle to peritoneal cavity. w/ adults hydrocephalous secondary to another disorder
communicating hydrocephalous
caused by either impaiired return of CSF (i.e. excess protein block arachnoid villi) to circulation or increased CSF
communicating hydrocephalous treatment
medication to reduce CSF production or surgically destroying choroid plexus
cerebral edema definition
swelling of the brain due to increase in fluid
three major types of cerebral edema
1) vasogenic edema, 2) cytotoxic edema 3) interstitial edema
vasogenic edema
cerebral edema caused by increased permeability of brain capillary endothelial cells, causes extracellular volume increase
cytotoxic edema
cerebral edema with increased intracellular fluid volume
interstitial edema
CSF movement from ventricles into surrounding brain tissue due to increased CSF tissue
inflammation of meninges
common symptoms of meningities
high fever, irritability, lethargy, severe headache, vomiting, extreme sensitivity to light (photophobia), nuchal rigidity, and "twitching"
routes of infection of CNS
cardiopulmonary system, nasopharynx and sinuses (including dural venous sinuses), middle ear, skull fracture, scalp and face, and along nerves
Meningeal space involved in meningitis
commonly arachnoid/subarachnoid space/ pia
arachnoid and pia
adhesions (CNS)
adhesion b/t pia and arachnoid, complication of meningitis, interferes w/ circulation of CSF in the subarachnoid space, can impede return of CSF, causes communicating CSF
cause of severe head and neck headache of meningitis
due to inflammation and stretching of dura, which receives trigeminal (supratentorially) and cervical (infratentorially) innervation, results in pain being referred to forehead and face, head and back of neck
encephalitis and ventricular inflamation, west nile virus may cause this
pooling of CSF, may result in arachnoid tearing from trauma
types of brain herniation
tonsillar (tonsil into foramen magnum) and uncal (uncus into tentorial incisure)
signs of uncal herniation
decreased consciousness, dilation of the pupil of the eye on the side of herniation (from compression of parasympathetic fibers w/in CNIII)
signs of tonsillar herniation
may be unconscious (neurons in the medullary reticular formation control conciousness), abnormalities in heart rate and breathing (medullary portion of reticular formation controls vital functions)
hemorrhage involving meninges/sinuses in infants description
tearing of veins as they enter the superior sagittal sinus or from tearing of venous sinuses, rapid compression may tear attachments of falx cerebri from tentorium cerebri
epidural hemorrhage
between the endosteal and menigeal layers of dura, or between bone and endosteal dural if fracture rips dura from bone; side of the head--> middle meningeal artery
brodmann area compressed by hemmorahage of midle meningeal artery
compression of primary motor cortex (area 4), difficulty performing volantery motor movement contralaterally
subdural hemorrhage
bleeding between dura and arachnoid, most commonly from tearing of superior cerebral veins at point of entrance into superior sagittal sinus (bridging veins), usually blow to front or back of head, more comon in elderly
contusion CNS
bruise of surface of brain, usually hemorrhages of variable size
transient disruption of brain function
contents of subarachnoid space
trabeculae, CSF, Blood vessels
Trabeculae of subarachnoid space
bridge arachnoid and pial membranes, resemble spiderweb
fluid which bathes the brain tissue and helps to distribute and equalize pressure w/in the skull
Blood vessels location in meninges
all major blood vessels of brain lie in subarachnoid space before entering brain parenchyma
cistern definition
regions of subarachnoid space where pia and arachnoid are widely separated, contain pools of CSF
major cisterns
1 cerebomedullary cistern (cisterna magna),
2 pontine cistern,
3 interpeduncular cistern,
4 lumbar cistern
cerebellomedullary cistern
cistern which spans the space over the cerebellum and the part of the brainstem called the medulla
pontine cistern
cistern which lies over the pons
interpeduncular cistern
cistern which lies over the interpeduncular fossa (ventral brain surface)
lumbar cistern
extends from vertebral levels L1/L2 to S2