Anatomy of the Meninges Flashcards
what fissure divides the 2 cerbral hemispheres
great longitudinal fissure
where is the tranverse fissure located?
between occiptial lobe and cerebellum
what is the termination of the spinal cord called?
what are the extension the spinal nerves below this level referred to as?
spinal cord- brainstem ——> lumabr vertrbae L1
cons medullaris (L1)
Lumbar, scaral and occygeal spinal nerves extend downwards to leave the verebtral colum—–>cauda equina
what are the 3 layers of thje meninges and what is there function?
dura matter
arachnoid matter
pia matter
(DAP)
function- provide framework for cranila and cerebral vasculature
Protective- from mechanical dmaage help from too CSF
Label this diagram
Describe the Dura matter
- tough, fiborous , vascularised
- loos fititng
- double emembrane in the cranium
- outer periosteal layer (con tinuoius with the periostrum of the outer surfave of the skull
- inner meningeal layer (exits skull to cover tehs pinal cord. SC only has one layer.
what is the extra-dural space?
Potential space between the cranium bone and the dura.
Name the Dural Reflections and what is there function
- Falx cereberi- dural extension within great longitudunal fissure
- Tenotrium cerebelli- tranvers fissure
- Falx cerebelli- btetween cerbellar lobes
- diagrahm sellae- hyposeal fossa
Label this
label this
Describe the arachnoid matter
Describe the pai mater
thin
translucent
tirghtly adherent to surfacve of the brain- follows fyri and sulci
Ppathophysiology of the Dura matter?
raised intracanial pressure- brain can herniate under the Falx cerebri
what are the subarachnoid spaces?
true spaces between the pia and arachnoid matter
filled with CSF and blood vessesl
as the pia is atightly adhered to the brain and the arachoid is loose- region sof subarahcnoid spaces - comparatively lareg called Cistern
what holds the arachnoid and pia matter together?
Trabeculae
Label the following…
superiro cistern
chiasmatic cistern
interpeduncular cistern
pontine cistern
cerebelliomedullary cistern
Describe blood supply the the dura
blood supply travels in the outer periosteal layer
4 major arteries
Anteriro meningeal
middle meningeal (main- branch of the maxillary artery from external carotid)
acessory meningeal artery
Posteriro meningeal artery
where does the middle meningeal artery branch from?
branhc of the Maxillary ateyr from external carotid
Where is the Middle meningeal artery?
Describe innervation of the dura?
tirgeminal nerve CNV
what is the clinical relevance of the meninges?
pathohpysiology and treatment/diagnosios
Meningitis- inflaamtion fot the meninges, can be infective and noninfective
Lumbar punction- removal of CSF from the subarachnoid spaxces for analysis (below L1)
form what space do we take CSF from in a lumbar punction
subarachnoid space
why is the Pterion particular site of weaknes? what kind of intercranila haemohrage might we See?
epidural haemorrhage- pterion is particualr weeks site that converges of the skull bones (frontal patielta, occiptal, sphenoid bome)- overlies the middel meningeal artery
in what groups might we see a subdural haemorrhage
occurs generally due to lower impact truama in indivudals with predisposing factors and is often a venous bleed
how might a subarachnoid haemorrhage present in a patient? and the cause
ruputre of an aneurysm- cerbral artery- classic sudden severe- thunderclpa headhace.
is there an epidural space in the spinal meinges?
yes - superificial to the dura/
describe the relationship of the pai matter to the spinal cord and exceptions
tpai matter is tighly adhered to the spinal cord except
Denticulate ligament-–> lateral thickening of pai at the lateral edges of the cord- look for free lateral edge
AND
The filum terminal
thick exentsion of pai matter that arises from the conus medularis and attaches to the top of the coccyX
will apear hite/shiny cord in DR
what are dural sinuses?
dformed between the 2 layers of the dura matter
recieved blood from superficial and deep cerebral veins
non valvues- venous blood can flow in both direction
recive b;ppd from braina nd drian into the interna;l jugual veins
what is this?
Dural venous sinus
Label this
superiro sagital sinus
inferiro sagital sinus
strasight sinus
confluence of sinuses
sigmoid sinus
tranver sinus
internal jugualr
what is the cavenrous sinus?
paired plexus of veins conntected by the intercavernous sinuses
drain into the sigmoid sinus or IJV via superiro petrosal sinus
Label this
label this
why is the cavernous sinuses area of veins an area that could potential cause problems?- Infection
the veins have no valves- infection can come form oral cavity
nasopharynx
orbiut paranasal sinus
what is subdrual empyema?
pus between the dura and arachnoid
what is the image showing?
Thrombus formation in the superiro sagital sinus.
Clinical relevance of the dural venous sinuses
infecition risk- infections can trigger- compresion of structures within resulting in CN palsy (CNIII) blood vessels
lots of structures pass through (nerves)- O TOMCAT
Lateral
Oculomotor (CN III)
Superior
Trochlear (CNIV)
Ophthalmic division-trigeminal (CNV)
Maxillary division-trigeminal (CNV)
Inferior
Carotid artery (internal)
Abducent (CNVI)
(T)represents the level of the C&A e.g in line with the trochlear nerve
dural venous sinuses
formed with — layers?
does it have valves?
can blood flow bidirectionally?
how does no valves and bllod flow create potential riks of?
formed between the 2 dural layers
the sinuses have no valves
blood flow can be bi-directional
Potential risk of intracrnail infection and thrombus
Label? and what is the ventricular system?
Ventricular system- cavities within the brian- repsonsible for the production and transport and removal of CSF
name the connections between the ventricles
interventricular formen- between 2 lateral lateral and 3rd
Cerebal aqueduct between third and forth
Describe production of the CSF
Choriod plexus
vascular potion of the pia mater (tele choroidea)- folds into the vcavity of the ventricle then covered by ependymal cells.. extensive folding gives large surface area
choriod epithelial cells (modified epednymal cells) cuodi or simple columnar- secvete CDF
mostly in the lateral ventricles (alos in 3rd,4th)
describe the flow of CSF
- produced/secret choriod plexus lateral ventricle
- fllow through interventriucalr foramina)- 3rd ventricle
- CSF produced secreted by CP in thrid ventricle
- CSf flows down cerebal aqueduct into fourth ventricle
- 4th ventricle
- CSF can flow out of
- Median aperture (magendie)
- right and left lateral (lushka)
- central canal
- CSF can flow out of
- into the subarachnoid spaces
Label the subarachnoid cisterns
posteriro crebellomedullary cistern
Ponto cerebellar cistern
interpeduncualr cistern
chiasmtic cistern
quadriegminal cistern
Describe reabsoption of CSF
once CSf has enter subarachnoid space
will need to be reabsorbe- continual supply of CSF
Arachnoid granulations
- villi projections of arachnoid spaces into the dural venouss sinuses (primarily superior sagital sinus)
- allows CSf to enter venous system
venous pressure within subarachnoif space is higher than that of lumen of sinus and greater colloid osmotic pressure of CSF compared to venous blood.
what is hydrocpehalus
abnromal buildup in the ventricles deep within the brain
this excess fluid causes the ventricle to widne and put pressure on the brain tissues
can be congenital, acquired and norma pressure (older people)
- what are the 2 major types of hydrocephalus
- communicating- occurs when flow of CSf blocked after it exist ventricles- reduced rebasoption
- noncommunicating- CSf flownis blocked along one or more of the narro passages between the centricles
describe the ventriuclar system of the spinal cord?
small , central canal (almost vistigial)
however the subarachnoid space extednds into and around the spoinal cord and therefor bathes the spinal cord
Label this
- Pia matter
- subarachnoid space
- Arachnoid matter
- dura matter
- epiural sapce
remeber- pia matter is tightly adhered to the spinal cord
subarachnodi space between pia and arachnoid
dural matter
then epidural space (above the dura)
