Anatomy Test #3 Lecture #4 Brain 3 Flashcards
meninges
coverings of the brain and spinal cord
-meninges continue up the spinal cord all the way up and into the brain so it will all be enveloped in the meninges layers
why do we have the meninges?
to protect from mechanical injury
what layer of meninges attach to the gyrus
the Pia mater
name the layers and what is between the layers of the meninges
most deep -> superficial
1. pia mater
- subarachnoid space- true space, filled with cerebral spinal fluid
- arachnoid mater
- subdural space- potential space (can be made, but not naturally there)
- dura mater
do the meninges protect the brain
yes they cover the brain
epidural space in the vertebra
a space around the vertebral column that is filled with vertebral fat and vertebral veins for drainage
epidural space in the skull
a potential space
between the inner table of the bone + periosteum and the dura mater
what can run through the epidural space in the skull
small arteries, like the meningeal artery. But it really has to tunnel through because its not really a space for it
tentorium cerebelli
a sheet of dura mater that covers the posterior cranial fossa and the cerebellum
the tectorial notch
it is a notch in the tentorium cerebelli to allow passing through of the brain stem. If we didn’t have it, our brainstem would stop in the posterior fossa. But since we do it passes through and allows it to continue up
falx cerebri
- a sickle shape double fold of dura mater that has dipped down into the median longitudinal fissure. Runs from frontal lobe back to occipital lobe
- separates your two cerebral hemispheres
- attaches rostrally to Christa Galli
2 types of CNS circulation
anterior circulation
-derived from our carotid arterial system (internal and common carotid). Neck arteries feed the vessels up in the brain
posterior circulation
-derived from your vertebral arterial system; aka your vertebrae arteries. These come off the subclavian artery and go through the transverse foramen to provide blood to posterior brain
anterior and posterior arterial circulations form the
circle of willis (found in inferior brain)
the basilar artery is formed by
the vertebral arteries
the basilar artery as it ascends divides into the
posterior cerebral arteries, which then give off the posterior communicating arteries
The post communicating arteries continue rosturally to join the
internal carotid arteries
Note the subsequent formation of the Circle of Willis with the emergence of the ____ and ____
anterior cerebral arteries and the anterior communicating artery
Posterior inferior cerebellar artery supplies
the lower inferior surface of the cerebellum and the lower brainstem
Anterior inferior cerebellar artery supplies
the upper inferior surface of the cerebellum and the upper brainstem
Superior cerebellar artery supplies
the superior surface of the cerebellum and midbrain (Netter: 139);
Posterior cerebral artery supplies
the cerebral occipital lobes (Netter: 140), Med/Lat and sides of the Occipital Lobe & Inferior Temporal Lobe.
Middle cerebral artery supplies
- the parietal and posterior frontal lobes (upper and lower limbs)
- subcortical structures
- the Lateral side of the brain (frontal, parietal and temporal lobes) and runs through the lateral fissure.
Where do most strokes occur?
Middle cerebral artery
Anterior cerebral artery supplies
the frontal lobe (lower limb only) (Netter: 138-141) Runs in Medial Longitudinal fissure. Supplies Medial cerebral cortex (frontal and parietal lobes.)
common carotid artery divides around your voice box (larynx) into
internal carotid artery (runs posterior)
external carotid artery (runs anterior)
external carotid artery supplies
your face
internal carotid artery does what?
passes through the skull and forms the anterior circulation of the brain
the posterior cerebral artery passes through what to enter the skull and where does it enter the skull?
the 6 cervical transverse processes to enter the skull at the foramen magnum
what does the internal carotid artery enter the skull through?
the carotid canal
the internal carotid artery goes up and into the skull forward and then what happens
it bends back to go into the circle of willis
2 vertebral arteries come up from the subclavian artery, but when they enter the foramen magnum, what happens?
they combine to become a single basilar artery
the basilar artery bifurcates to form
the two posterior cerebral arteries
the posterior cerebral arteries form the
posterior communicating arteries
the posterior communicating arteries plug into
the internal carotid arteries
the internal carotid arteries give off the
middle cerebral arteries
the anterior cerebral artery continues rostrally until it turns into
the anterior communicating artery
arteries of the circle of willis are unique because
if an artery fails, since its all anastomotic, maybe the other side can compensate and keep us running
lenticulostriate arteries
come off of the middle cerebral artery
- supply sub cortical structures. carry motor fibers
i. e., internal capsule, and basal ganglia
calcarine branch
comes off of the posterior cerebral artery. It runs in the calcrine sulcus, which is where your primary visual cortex is
middle cerebral artery arises from which fissure
the Sylvian / lateral fissure
the anterior cerebral artery runs with the
corpus collosum
the anterior spinal artery
- comes from the vertebral arteries
- tiny artery that runs in the median fissure of the spinal cord
posterior inferior cerebellar arteries (PICA
supply the posterior inferior area of the cerebellum AND the lower brainstem, aka the medulla.
MOST COMMON ARTERY FOR BRAINSTEM STROKES
the anterior inferior cerebellar arteries
supply the anterior inferior cerebellum AND the middle portion of the brainstem
the labyrinthine arteries
- comes off just rostral to the anterior inferior cerebellar artery
- enters the temporal bone through internal acoustic meatus and supplies the inner ear with blood
pontine arteries
supply the basis pontis of the brainstem
superior cerebellar arteries
supply the superior region of the cerebellum AND your upper brainstem
Blood is returned from the cranial cavity and brain via the
dural venous sinuses
the dural venous sinuses receive blood from the
superficial cerebral veins
The venous sinuses converge in the occipital region to eventually drain bilaterally into the
internal jugular vein
Superficial Cerebral Veins:
pierce the arachnoid mater (so run in the subarachnoid space) and attach to superior the sagittal sinus in the subdural space.
-Injury here may result in a Subdural Hematoma
Subdural Hematoma
venous bleed and is thus very slow, so that symptoms or signs may take several days to develop. An example of subdural hematoma occurs in babies with head trauma.
the superficial anastomotic vein
a superficial cerebral vein that runs with the central sulcus
the superficial middle cerebral vein
a superficial cerebral vein that runs the Sylvian fissure
superficial cerebral veins drain into the
superior sagittal sinus. Once they are in here they are in the subdural space
the superior sagittal sinus runs over the
falx cerebri, which runs from the frontal lobe to occipital lobe
what runs under the falx cerebri
the inferior sagittal sinus
the inferior saggital sinus eventually joins with
the great cerebral vein (Galen)- drains deep subcortical structures (basal gangla, thalamus, etc)
great cerebral vein drains what? and it is going to merge with inferior saggital sinus to form the
drains the diencephalic area
forms the straight sinus
occipital sinus
- found in the falx cerebelli
- venous return from the cerebellum
confluence of sinuses
in the occipital region where the dural veins come together
- the superior sagittal sinus
- the straight sinus
- the occipital sinus
superior sagittal sinus turns into the
transverse sinuses
transverse sinuses dive deep into the posterior cranial fossa, and then make an s shape (sigmoid sinus), which drains into the ___ ____ ____ at the ____ ____
internal jugular vein at the jugular foramen
the cavernous sinus
venous “pool” lying on either side of the body of the sphenoid - receives venous drainage from the ophthalmic veins (superior and inferior). The cavernous sinus drains into the pterygoid plexus of veins, and into the greater and lesser petrosal sinuses
superior opthalmic vein
comes out of orbit and drains into SSS
sphenoparietal sinuses
drains the lateral aspects of your skull
Note the course of the petrosal sinuses as they course to terminate in the
sigmoid sinus
to get blood out of the cavernous sinus we need
the greater petrosal sinus and the lesser petrosal sinus
the sigmoid sinus
the s shape sinus that drains into the internal jugular vein
pterygoid plexus of veins
- found right inside your cheeks
- receive drainage from emissary veins from inferior ophthalmic veins and cavernnous veins
- drains into the internal jugular vein and external jugular vein
the downside to the pterygoid plexus of veins
its an easy infection route. the pterygoid plexus flows in and out. Can lead to meningitis (infection of meninges) or encephalitis (infection of the brain)
cerebral spinal fluid is produced in
cavities called the ventricles of the brain
How many ventricles does the brain have
4!
2 lateral ventricles
3rd ventricle
and the 4th ventricle
why do we have cerebrospinal fluid?
NUTRITION! Lots of sugar and glucose. AND MECHANICAL SUPPORT!
CSF is produced by
Choroid plexus found in the ventricles
CSF is absorbed by
arachnoid villi
too much CSF in the brain is called
hydrocephalus- it increases the pressure in the brain
What actually is a choroid plexus? Yes it produces CSF, but what is it?
a capillary tuft found in all of the ventricles
2 lateral ventricles are found where? And what do they have?
one in the cerebral cortex on one side(hemisphere left), one on the cerebral cortex on the other side(hemisphere right))
they both have their own anterior, posterior and inferior horn
To get CSF from the lateral ventricle into the third ventricle you have to pass through the
interventricular foramen of monroe
to get CSF from the 3rd ventricle to the 4th ventricle, you have to pass through the ___ ____ in the midbrain
the cerebral aqueduct of sylvius
the 4th ventricle has the dorsomedian aperture (FORAMEN OF MEGINDIE). What does it do?
it is THE MAIN HOLE that allows CSF to escape the 4th ventricle and end up in the subarachnoid space
the lateral foramina (the lateral foramina of luschka)
1 on either side of the 4th ventricle. Help allow CSF to escape the 4th ventricle and enter the subarachnoid space
Hydrocephalis
increased cranial pressure because you still produce CSF but the foramen of megindie won’t drain.
CSF absorption occurs at arachnoid villa through
granulations
the CSF absorbed by arachnoid villi goes into venous blood in the
superior sagittal sinus
arachnoid villa can become hard and granular as people age. These are then called pacchonian bodies. Effects of pacchonian bodies =
could result in increased cranial pressure and hydrocephalus
