Unit 3 Flashcards
What else is the dura mater called?
thick mother; it is the thickest outer most covering
What does the dura cover?
the entire CNS and roots of PNS in the vertebral canal and cranial vault
Is the dura part of the nervous system?
no it is just an accessory structure
Name the two dural layers in the cranial vault?
endosteal layers and meningeal layer
Describe the endosteal layer
outer highly vascularized layer that serves as a periosteum to cranial bones.
Describe the meningeal layer
inner fibrous layer that is seperated from the endosteal layer only where a falx or dural venous sinus is present
Do both dural layers continue into the cerebral canal?
no, only the meningeal layer which is slightly more collagenous than the cranial meningeal layer
What attaches the dura within the vertebral canal?
meningiovertebral ligaments
Is the dura attached to the foramen magnum?
yes it is fused to it, but for the most part its a loose sac in the canal
At what level does the spinal cord end?
L1-L2 and is named the conus medullaris
What is the lumbar cistern filled with?
cerebrospinal fluid
Describe dural falces
they are double layers of meningeal dural, sickle shaped, and extend into brain fissure
Describe the Falx cereri
located in longitudinal fissure, runs from front to internal occipital protuberance
Describe the falx cerebelli
located between the cerebellar hemispheres
Describe the tentorium cerebelli
runs right and left over the cerebellum and under the occipital lobes
What is the name of the opening between the wings of the tentorium cerebelli?
the tentorial hiatus
Describe the diaphragma sellae
forms a housing over the pituitary gland and has a whole in the middle for the infundibular stalk
Is the dura vascular?
yes
Is the dura innervated?
yes
what nerves innervate the dura?
CN V and VII supratentorially and CN X infratentorially
What artery is attributed for throbbing headaches?
meningeal arteries; commonly middle meningeal arteries
Is the arachnoid vascularized?
no
Describe the arachnoid
transparent and composed of simple squamos epithelium
From what do meningiomas arise?
the arachnoid
True or false, the arachnoid goes into fissures and sulci
false
Describe cranial nerve sheaths
a subarachnoid space that extends with CN II all the way to the eyeball
Describe arachnoid trabeculae
connections between the arachnoid and pia and its avascular
Describe the subarachnoid space
its a real space between the arachnoid and pia thats filled with CSF
Where is a potential space located?
between the dura and arachnoid termed the subdrual space
Describe the Cisterna Magna and its location
Its the largest cranial cistern
its posterior to the M.O. and superior to the foramen magnum
the 4th ventricle opens into it via the median foramen
Describe the superior cistern and its location
some important blood vessels are located on its floor
its in the transverse cerebral fissure
Describe the Pontine Cistern and its location
a pair of openings empty into it from the 4th ventrical via the lateral foramina
its anterior to the pons
Describe the interpeduncular cistern and its location
much of the cerebral arterial circle is found along its periphery
its between the cerebral peduncles on the anterior aspect of the midbrain
Describe the lumbar cistern and its location
it fills the lumbar cul-de-sac
is located from the conus medullaris to the S2 level
Describe Arachnoid villi, its location, and function
Theyre tufted prolongations which dip into dura and associate with dural venous sinuses; mostcommonly along the superior saggital dural venous sinus
they remove CSF from the subarachnoid space
Describe the pia
its the inner most covering
its vascular and follows all fissures and sulci of the brain and cord
Describe the outer portion of the pia
its continuous with the arachnoid trabeculae and also covers blood vessels coming to and from the CNS
What structures do the pia form in the vertebral canal?
the denticulate ligaments which penetrate the aracnoid and fuse with the dura
the pia also forms the fillum terminale internum
Describe the inner portion of the pia
it has fine reticular and elastic fibers which connect with the CNS
it also forms the pial coats and perivascular space
Describe an epidural hematoma
blood between the skull and periosteal dura
what causes an epidural hematoma
commonly a rupture of the middle meningeal artery due to head trauma
what is the result of an epidural hematoma
an increase in intercranial pressure;if it not relieved via surgery death could be a result
describe a subdural hematoma
a collection of blood between the meningeal dura and arachnoid
what causes a subdural hematoma
rupturing to bridging veins due to shearing injury
describe a subarachnoid hemorrhage
a collection of blood in the subarachnoid space
How much blood is perfused through the brain each minute?
800ml
Where is the most commonly reported site to blame for stroke?
the middle cerebral artery
What artery is to blame for chiropractic vascular accidents?
the posterior inferior cerebral artery
What arteries supply 2/3 of the brains blood?
the internal carotid arteries
What artery is the most common anomaly in the brain blood supply?
the anterior communicating artery
What vessel contributes the most blood to the spinal cord?
Segmental arteries
Where do the segmental arteries enter into the cord?
through intervertebral foramina
how much blood is normally present in the brain?
about 75ml
how often does the blood turn over in the brain?
about every 6 seconds
What is the most common type of capillary in the CNS?
continuous capillary
What is the role of astrocytes in the blood brain barrier?
they play some supporting and informing role
What type of substances will cross the BBB and what will not?
lipid soluble will cross and water soluble will not
List some substance that will cross the BBB?
caffeine, B6 and B12, alcohol, nicotine, cocaine
Will veins and venules follow the same course as arteries as they entered,out?
no they wont
After veins have penetrated arachnoid and meningeal dura where do they drains to?
Dural venous sinuses
Where do DVS drain?
internal jugular veins at the jugular foramina
Where does most of the blood in the sinus flow to?
the right transverse DVS
Choroid plexuses are located where?
in brain ventricles?
what do choroid plexuses produce?
CSF
What cells produce CSF in the choroid plexuses?
ependymal cells
