Meninges and Ventricular system Flashcards
layers of meninges
Dura matter
Arachnoid mater
Pia mater
connective tissue membranes that invest the brain and the SC
Meninges
most substantial of the meninges
dura mater
dura mater is
mad up of dense CT encloses SC and cauda equina via cont of meningeal layer cont above through foramen magnum ends in filum terminale at lower S2 contains loose areolar CT separated from wall by Extradural space
Spaces in cranial meninges
Epidural ( b/w dura and Calvaria) Subdural (inner most dural layer nera dura arachniod) Sub arachnoid ( CSF filled, enlarged in cisterns)
lerge endothelium lined spaces b/w periosteal and meningeal layer sof dura mater
venous sinuses
Inner surface of the cranium, not continous with the dura mater of SC, comtinuous with periosteum and reaches foramen magnum
Endosteal/ periosteal layer
dense strong fibrous membrane covering the brain that is continuous with the dura mater of SC
Provides tubular sheaths for cranial nerves
meningeal layer
sickle shape fold of dura mater dividing the cerebral hemispheres. From internal frontal crest and Crista galli to internal occipital protuberance and becomes continuous with the tentorium cerebri. Encloses superior sagittal sinus
Falx Cerebri
uon of inferior sagittal sinus and Great cerebral vein of agalen
Straight sinus
crescent shape fold of dura mater that roofs over the posterior cranial fossa covering upper surface of cerebellum and supporting occipital lobes
tentorium crebelli
transverse membrane that attaches posteriorly and laterally (skull at transverse sinus) and anteriorly (petrous portion of temporal bone)
tentorium cerebelli
separates occipital and temporal lobes from cerebellum
tentorium cerebelli
contains the cerebrum; CN 1,2
Supratentorial compartment
contains brainstem and cerebellum; CN 3-12
Infratentorial compartment
large opening that allows passage of the upper brainstem aqueduct and vessels
Incisur tentorii
three sinuses housed by tentorium cerebelli
Straight sinus
Transverse sinus and
Superior petrossal sinus
located b/w the cerebellar hemispheres attatched to internal occipital crest. from the internal occipital protuberance to foramen magnum attached below tentorium cerebelli
Falx Cerebelli
what sinus is housed by the Falx Cerebelli
Occipital sinus
Connects the clinoid attatchments of Tentorium cerebelli and roofs the sella turcica
Diaphragma Sella
Dural nerve supply
CN 5, 10
First three cervical spinal nerves
Branches of sympathetic trunk
Sensory endings of CN 5
referred pain to the area of the skin to the same side of the head
above tentorium cerebelli
referred pain to the neck and back of scalp along dist of greater occipital nerve
Below tentorium cerebelli
Dural arterial Supply
ICA Maxillary A. (branch of ECA) Middle meningeal A Ascending pharyngeal A Occipital a Vertebral a
most important artery that enters the cranial cavity troug foramen magnum
Middle Meningeal A
landmark for middle meningeal A
Pterion
Dural Venous drainage
Meningeal Veins (endosteal layer of Dura)
where does meningeal veins drain into?
Pterygoid venous plexus
Sphenoparietal sinus
recieve blood from brain through the cerebral veins and CSF from sub arachnoid space and ultimately drains to IJV. No valves
Dural Venous Sinus
emergency veins which connects dural venous sinuses with diploic veins of skull ang scalp. No valves
Emissary Veins
weblike membrane of reticular fibers, impermeable and covered with flattened epithelial cells
Arachnoid mater
does the arachnoid mater dips into the sulci?
No
T/F Arachnoid mater fuses with the epinurium
True
Arachnoid mater + Pia Mater
Leptomeninges
T/F Arachnoid mater of the brain is not continuous with the SC
False
separates Arachnoid mater from Dura mater
subdural space
separates Arachnoid mater from pia mater
subarachnoid space
formed when arachnoid mater and pia mater are separated widely
subarachnoid cisternae
Lies b/w the inferiorsurface of the cerebellum and root of 4th ventricle. largerst cranial cistern
Cisterna cerebellomedularis/ Cisterna magna
lies b/w cerebral peuncles
Cisterna interpeduncularis
lies superior to Pituitary glans
suprasella cistern
extension of superior cistern connecting tot he interpeduncular cistern
ambient cistern
surrounds ventral aspect of the pons
Prepontine cistern
Superior cistern contains :
Great v of Galen
Posterior Cerebral A
Superior Cerebral a
extends from conus medularis to level of S2 containing filum terminale and roots of cauda equina
Lumbar cistern
T/F Lumbar puncture is done on the Lumbar cistern
True
major site where CSF diffuses into the blood stream
Arachnoid granulations
groups of arachid villi
pacchonian granulation
small stands of collagenous CT covered with fibroblast like arachnoid cells . suspends brain w/in meninges
Arachnoid Trabeculae
vascular membrane covered with flattened mesothelial cells investing in the gyri and sulci and following its contours in brain
Pia Mater
inner layer of pia mater adhering to underlying nervous tissue that is avascular where cerebral vessels lie on its surface
Intima Pia
superficial layer formed by a meshwork of collagenous fiber cont with arachnoid bundle where BV of SC lie
Epipial Layer
thickened side of nerve root passing laterally to adhere to the arachnoid and dura
ligamentum denticulum
T/F SC is suspended in themiddle of dural sheath
True
cuffs surrounding the arteries formed by invaginatins on Pia mater
Perivascular space / Virchow robin Space
condensation kf Pia mater at the region of Conus medularis
Filum terminale
filum terminale invested by dura mater and continous as
coccygeal ligament
roffs the 3rd and 4th ventricle
Tela Choroidea
Tela choroidea+ ependyma
Choroid plexus
Summary of Cranial meninges
Dura mater: double layered att to calvaria surface
Epidural space: b/w periosteum & calvaria
Arachnoid: att to inner surface of Dura
Pia : Attatched to CNS surface
Summary of Spinal Meninges
Dura mater: single layered sus in vertebral canal
Epidural space:real space
arachnoid: att to inner surface of Dura
Pia: Attached to CNS and elonfates as dentate lgament
communicating system of cavities lined with ependyma and filled with CSF
Ventricular system
occupy lower medial portion of cerebral hemispheres
Lateral ventricles
serves as communication b/w lateral ventricles and 3rd centricles
Lateral foramen of Monro
communicates with 4th ventricle
Cerebral aqueduct of sylvius
Ventricular system extend to the SC as
Central canal
Meningeal artery and vein bursts due to blow to the side of the head. Spread is limited and there is lens shape b/w layers
Epidural Hematoma
tearing of Sup cerebral Veins by blowing of head in front having acute and chronic forms and a crescent shape between dura and arachnoid layers
Subdural Hematoma
Body of Lateral Ventricles
Location: parietal lobe
Roof: Under surface of Corpus Callosum
Medial wall: Posterior portion of septum Pellucidum
Floor:Formix, Choroid plexus, Thalamus, Stria Terminalis, vena Terminalis, caudate nucleus
Anterior/ Frontal Horn of Lateral ventricles
Location:Frontal lobe
Roof: anterior part of corpus callosum
Medial wall: Septum pellucidum ant column of for ix
Floor: Head of caudate nucleusa
Posterior / occipital horn of lateral ventricle
Location: Occipital lobe
Roof and lateral wall: tepetum of corpus callosum
Medial wall:splenium of corpus callosum
Floor: calcar avis by the calcarine sulcus
Inferior / temporal horn of lateral ventricle
Location: temporal lobe
Roof: Tapetum of corpus callosum
Floor: fimbria hippoocampus, collateral eminence
confluence of the three horns of lateral ventricle
Atriun (trigone)
T/F There is choroid plexus in anterior and posterior horns
False
medial aspect of lateral ventricles
Choroid plexus
attachment of plexus to structures
Tela choroidea
3rd ventricle parts
Roof:Tela Choroidea & Choroid Location:
lateral wall: medial surface of two thalami
Floor:hypothalamus ant commissure
Rostral limit: lamina terminalis
T/F Choroid plexus is not present on Cerebral aqueduct of sylvis.
True
tent shaped cavity b/brainstem and cerebellum
4th ventricle
median aperture piercing the roof of 4th ventricle
Foramen of Magendie
lateral aperture that opens the 4th ventricle anteriorly
Foramen of Luschka
4th ventricle
Roof: Cerebellum, choroid plexus
Floor: superior half of medulla and pons
opens superiorly into 4th ventricles expanding into TERMINAL VENTRICLE in conus medularis having no choroid plexus
Central Canal of SC
Cushions and protects CNS against mechanical trauma and possesses inorganic salts
CSF
secretes CSF
choroid plexus
Trace flow of CSF
Choroid Plexus ➡️ Lat ventricle ➡️ interventricular foramen of monro➡️ 3rd ventricle ➡️ cerebral aqueduct of sylvius ➡️ 4th ventricle ➡️ foramen of magendie and lushka ➡️ arachnoid granulations
diverticulum of sub arachnoid space which controls CSF pressure
Arachnoid villi
Isolate brain tissue from blood and CSF
BBB Blood Brain Barrier
Proportionality of BBB in relation to size of molecules and permeability
Inversely
Components of Blood brain barrier
Endothelial cells containing tight junctions
Basement membrane
Foot process of astrocytes
Areas having no BBB
Pineal body Subfornical organs Organum vasculosum Neurohypophysis Area postrema Hypothalamus
Abnormal increase in CSF within skull
Hydrocephalus
Raised CSF pressure is due to
Excessive formation (tumor of choroid plexus) Blockage of circulation (in the ventricles) Diminished absorption (inflammatory exudate, venous thrombosis, obstruction of IJ vein)
When there is inc CSF formation but normal CSF pressure
Compensatory hypoplasia or atrophy of brain
Type of hydrocephalus where there is no obstruction within or to the outflow. CSF freely reaches subarachnoid space
Communicating hydrocephalus
Type of hydrocephalus where there is blockage between formation and exit
Non-communicating hydrocephalus
Free passage of water, gasses, lipid soluble substances however macromolecules would be unable to enter
Blood CSF Barrier
Components of Blood CSF Barrier
Endothelial cells with pseudofenestrations
BM
Scattered flat cells with flat processes
Another BM
Choroidal Epithelial cells and tight junctions
semi permeable barrier that protect the brain and SC from potentially harmful substances
Blood CSF Barrier
T/ FBilirubin freely enter CNS in newborn
TRUE
Breakdown of BBB hence diffusion of large molecules into nervous tissue
Brain trauma
Meninges become more permeable permitting sufficient antibiotic to reach infection
Meningitis
Possess blood vessels that have no BBB allowing spread of these __________
Tumors