Blood Supply To The Brain Flashcards
Two arterial systems supply the brain:
Internal carotid arteries (80%) Vertebral arteries (20%)
What does the internal carotid arteries supply
Most of telencephalon and diencephalon
What does the vertebral arteries supply
- brainstem
- cerebellum
- parts of diencephalon
- spinal cord
- occipital and temporal lobes
Has a cervical and intracranial part and ascends through side of the neck until it reaches the temporal bone, where it veers anteriorly
Internal carotid artery
In the carotid canal, the internal carotid gives this small branch
Ramus caroticotimpanicus
How does the internal carotid artery enter the skull
Traverses the temporal bone, entering the skull through the carotid canal
What is the first branch of the internal carotid artery
Ophthalmic artery
How does the internal carotid artery run through skull
Passes through the cavernous sinus and he subarachnoid space at the base of the brain
How does the ophthalmic branch of internal carotid artery leave skull
Through the superior optic foramen
What artery does the ophthalmic artery give rise to
Central retinal artery
As the internal carotid artery proceeds alongside the optic chiasm, what other branches does it give off?
The anterior choroidal artery and the posterior communicating artery
What does the internal carotid turn into and continue as?
MCA
What is the first branch off of the MCA
ACA
How does the ACA run
Medically, superior to the optic nerve and enters the longitudinal fissure
How are the two ACA connected
Near their entrance into the longitudinal fissure, are connected by the anterior communicating artery
What happens to the ACA after the connection with the anterior communicating artery
Enters the longitudinal fissure and curves around the corpus callosum
What does ACA supply
Medial parts of the frontal and parietal lobes
What does ACA branch into
- callosomarginal artery follows the cingulate sulcus
- continues as the pericallosal artery which stays immediately adjacent to the corpus callosum
Occlusion of ACA
Causes restricted contralateral motor and somatosensory deficits affecting the leg more than other parts of the body
MCA after the cavernous sinus
Proceeds posteriorly in the lateral sulcus, divides into a number of branches that supply the insula, emerges from the lateral sulcus and spread out to supply most of the lateral surface of the cerebral hemisphere
Occlusion of MCA
Causes major motor and somatosensory deficit especially in upper body and hand
The segments of the MCA and what occlusions mean there
The lower the number, the more proximally the artery gets occluded and more serious the consequences
How many branches does the MCA give rise to
12 that supply deep structures of the diencephalon and telencephalon
What are the branches of the MCA that supply the deep structures of the diencephalon and the telencephalon
Lenticulostriate arteries
Where are perforating arteries (lenticulostriate) numerous
Adjacent to optic chiasm and in area between the cerebral peduncles. These areas areas are called the anterior and posterior perforated substances
How do the vertebral basilar arteries run
- Rostral (up) through the foramina of the lateral processes of the spinal vertebrae
- enter the skull cavity through the foramen magnum
- fuse between the medulla and pons to form basilar artery
What foramen does vertebral arteries run through
Magnum
Branches of the vertebral arteries
- posterior spinal artery
- anterior spinal artery
- posterior interfering cerebrally artery (PICA)
Runs caudally along the posteriolateral aspect of the spinal cord and supplies the posterior third of that half of the cord
Posterior spinal artery
Joins its counterpart from the opposite side, forming a single anterior spinal artery that runs caudally along the anterior midline of the spinal cord supplying the anterior two third of the cord
Anterior spinal artery
Branches of the basilar artery
- numerous unnamed branches
- anterior inferior cerebellar artery (AICA)
- superior cerebellar artery (SCA)
At the level of the midbrain, what does the basilar artery bifurcate into
The two posterior cerebral arteries (PCA)
What supplies the thalami
Perforating branches of the posterior cerebral artery
What supplies the choroid plexus of the third and the lateral ventricle
Choroidal branches of the posterior cerebral artery
What are the cortical branches of the posterior cerebral artery
- anterior temporal
- posterior temporal
- lateral occipital
- medial occipital
What supplies the visual cortex
The medial occipital branch of the posterior cerebral artery
What does the lateral artery of the posterior cerebral artery branch into
Anterior, middle, and posterior inferior temporal arteries
What does the circle of willis connect
The internal carotid and the vertebral basilar systems
What completes the arteries life polygon known as the circle of willis
The posterior cerebral artery is connected to the internal carotid by the posterior communicating artery
Communicating arteries and alternate routes
The communicating arteries vary in size and more often are not sufficient to ensure functional anastomoses
How does the circle of willis look in different people
Asymmetries are common
Venous drainage of the brain
Between inner and outer layers of the dura mater
- receive blood from brain as wells as CSF from subarachnoid space
- collected by dural venous sinuses
- these drain into internal jugular
Valves in CNS veins
None
Process where cerebral blood vessels act to maintain constant flow
Autoregulation
Cerebral angiogram
- dye
- catheter into femoral artery, threading it up to aorta, to artery of choice
- rapid series of X ray pics
