Lab 2 Flashcards
what does the entire blood supply of the brain depend on?
two sets of branches from the dorsal aorta
where do the vertebral arteries arise from?
the subclavian arteries that supply approximately 20% of the blood supply to the brain
where do the internal carotid arteries arise from?
the common carotid artery
how much of the brain’s blood supply do the internal carotid arteries provide?
80%
what are the two major systems that bring blood to the brain?
common carotid and vertebral arteries
what part of the brain does the common carotid artery supply?
anterior
what side of the brain do the vertebral arteries supply?
posterior
what does the common carotid divide into?
- external carotid
- internal carotid
external carotid function
supplying the face and scalp with blood
what does the internal carotid divide into
- middle cerebral artery
- anterior cerebral artery
- anterior choroidal artery
- posterior communicating artery
middle cerebral artery function and abv.
- supplies the lateral portion of the frontal lobes, occipital lobes, temporal lobes, and parietal lobes as well as medial structures like the insula and globus pallidus
- MCA
anterior cerebral artery function and abv.
- provides blood to the medial part of the frontal lobe and anterior parietal lobes
- connected by the anterior communicating artery
- ACA
anterior choroidal artery function and abv.
- supplies blood to portions of the basal ganglia, amygdala, hippocampus, optic tract, and portions of the thalamus and the internal capsule
- AchA
posterior communicating artery function and abv.
feeds cerebrum, PcomA
what do the vertebral arteries divide into?
- posterior cerebral artery
- basilar artery
- superior cerebellar
- pontline arteries
- anterior inferior cerebelar artery
- posterior inferior cerebellar artery
posterior cerebral artery function and abv.
- provides blood to medial-ventral portions of the temporal lobe, medial occipital lobe, the limbic lobe, and medial structures like the midbrain, thalamus, hippocampus, and corpus callosum
- PCA
basilar artery function
feeds ventral midbrain and pons
superior cerebellar function and abv.
- branches from the basilar artery
- supplies the superior portion of the cerebellum and dorsal midbrain
- SCA
pontine arteries function
feeds brainstem
anterior inferior cerebellar artery function and abv.
- arises from the middle of the basilar artery
- supplies the anterior inferior portion of the cerebellum and a dorsal portion of the pons
- AICA
posterior inferior cerebellar artery function and abv.
- supplies the posterior inferior portion of the cerebellum and a dorsal portion of the medulla
- PICA
what is cerebral circulation normally divided into?
anterior cerebral circulation and posterior cerebral circulation
how are the anterior and posterior cerebral circulations interconnected?
posterior communication arteries from both sides of the brain
benefits of Circle of Willis?
- provides interconnected backup circulation to the brain
- in case one of the supply arteries is occluded, it provides interconnections between the anterior and the posterior cerebral circulation to provide blood to tissues that would otherwise become ischemic/dead
what five arteries is the Circle of Willis composed of?
- anterior cerebral arteries
- anterior communicating artery
- internal carotid arteries
- posterior cerebral arteries
- posterior communicating arteries
the blood brain barrier function
a special cellular barrier that protects the brain and spinal cord from harmful substances from m entering the CNS via the vasculature
- normal blood vessels elsewhere in the body don’t have this level of protection
- allow the passage of water, some gases, and lipid-soluble molecules by passive diffusion through tight junctions, as well as the selective transport of molecules such as oxygen, glucose, and amino acids that are crucial to neural function
what kind of cells is the blood brain barrier made of?
- endothelial cells
- astrocyte end-feet
- pericytes
endothelial cell function in the BBB
form the capillary wall
astrocyte end-feet function
ensheath the capillary
downside to BBB
excludes ~100% of large-molecule therapeutic drugs and >98% of small-molecule drugs
three main functions of cerebrospinal fluid (CSF)
- protection
- buoyancy
- chemical stability
how does CSF protect the brain?
it acts as a cushion for the brain, limiting neural damage in cranial injuries
how does CSF provide buoyancy?
by being immersed in CSF, the net weight of the brain is reduced to ~25 grams, which prevents excessive pressure on the base of the brain
how does CSF provide chemical stability?
creates an environment to allow for proper functioning of the brain, e.g.. maintaining low extracellular K+ for synaptic transmission
what is the path CSF takes to flow through the brain
lateral ventricle —> (Foramen of Monro) —> 3rd ventricle —> cerebral aqueduct —> 4th ventricle —> Foramen of Luschka (lateral aperture), spinal cord central canal, foramen of Magendie (medial aperture) —> cistern magna
nine parts of the ventricular system
- anterior horn of lateral ventricles
- posterior horn of lateral ventricles
- inferior horn of lateral ventricles
- Foramen of Monro
- cerebral aqueduct
- 3rd ventricle
- 4th ventricle
- foramen of magendie
- foramen of luchka
falx cerebri function
divides the two cerebral hemispheres
tentorium cerebelli function
separates the cerebrum from the cerebelli
diaphragma sellae function
surrounds the infundibular stalk
tentorial notch
where the brainstem sits
falx cerebelli function
divides the two cerebellar hemispheres (smaller, underneath the tentorium cerebelli)
what are the dural sinuses?
large venous vessels that take the blood back to the heart
path that blood takes through the sinuses
inferior sagittal sinus —> straight superior occipital —> confluence of the sinuses —> transverse sinus —> sigmoidal sinus —> jugular veins
confluence of sinuses
the midline connnecting point for the superior, straight, and occipital sinuses which then come together at the confluence and drain into the transverse sinuses and then down into the internal jugular veins for return to and recycling in the cardiopulmonary system
