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FNS: Lab
Neuro Lab Handout: Blood Supply
Question | Answer |
---|---|
What is an ischemic stroke? | blood clots that block an artery |
What percentage of all strokes are ischemic? | 80% |
What is a hemorrhagic stroke? | a break in the wall of an artery |
What percentage of all strokes are hemorrhagic? | 20% |
Where does the blood supply to the brain come from (in the neck)? | internal carotid and vertebral arteries |
What are the terminal branches of the internal carotid arteries? | anterior and middle cerebral aa |
Where do the middle cerebral arteries run? | laterally to the insular lobes |
Which artery connects the anterior cerebral aa? | anterior communicating artery |
Where do the vertebral aa come from? | subclavian aa |
Where do the vertebral aa unite? What do they form? | At the pons-medullary junction, basilar artery |
What does the basilar artery divide into? Where? | two posterior cerebral aa, pons-midbrain junction |
Where do the posterior communicating aa arise from? | proximal portions of the posterior cerebral aa |
Where do the posterior communicating aa connect to? | internal carotid aa |
What all is in the Circle of Willis? Which aa? | anterior communicating, anterior cerebrals, internal carotids, posterior communicating, and posterior cerebrals |
Which of the two terminal branches of the internal carotid is thicker? | MCA |
Where do the lenticulostriate aa supply? | striatum and posterior limb of internal capsule |
Strokes involved with the posterior limb of the internal capsule involve which arteries? | lenticulostriate |
What are symptoms of a stroke involving the posterior limb of the internal capsule? | contralateral weakness and UMN signs (corticobulbar, corticospinal tracts), and contralateral loss of discriminatory aspects of sensation (2 point localization, joint position) |
After giving off lenticulostriate aa, where does the MCA go? | Continues laterally to insula |
Name the 5 key areas supplied by insular branches of the MCA. | 1. lateral prefrontal c, 2. frontal eye fields on middle frontal gyrus, 3. primary motor c (precentral gyrus- only head/UE portions), 4. primary somatosensory c (postcentral gyrus- only head/UE), 5. posterior parietal c. |
Which areas are supplied by insular branches of the MCA on the dominant hemisphere only? | Broca’s motor speech area, and Wernicke’s speech area |
Strokes involving this main artery are most common types | MCA (can involved it or its branches) |
What are the most common S+S of unilateral MCA stroke? | [weakness, UMN signs, AND somatosensory deficits] on the contralateral arm and lower face |
Strokes involving the posterior parietal cortex on the non-dominant hemisphere produce which S+S? | contralateral neglect |
Strokes involving the posterior parietal cortex on the dominant hemisphere produce which S+S? | difficulty reading, writing, arithmetic and distinguishing right from left |
What is Gerstmann Syndrome? | trouble distinguishing right from left |
What areas does the ACA supply (in general)? | branches to the medial aspects of the frontal and parietal lobes (not occipital) |
What are the key areas supplied by the ACA (specifically)? | 1. medial prefrontal c, 2. primary motor c (on paracentral lobule), 3. primary somatosensory c (on paracentral lobule) |
What are the primary motor and somatosensory cortices medial continuations of? | precentral and postcentral gyri |
Which portions of the homuncululi are represented on the paracentral lobule? | lower limb and anogenital areas |
What are the most common S+S of unilateral ACA stroke? | weakness and other UMN signs involving contralateral leg; and somatosensory deficits of contralateral leg |
What do the PCAs mainly supply? | the inferior temporal lobe and most of occipital lobe- including primary visual cortex along calcarine sulcus |
What is the most obvious sign of a unilateral stroke involving cortical branches of the PCA? | contralateral homonomous hemianopsia |
Where is Broca’s area? | right above the most anterior part of the lateral sulcus (on the outer surface of the cortex) |
Where is Wernicke’s area? | right above the superior temporal sulcus, below the lateral sulcus (at the posterior portions of these sulci) |
Which arteries (main) supply the brainstem and cerebellum? | vertebral and basilar aa |
Which artery supplies the medial medulla? | anterior spinal artery |
Where does the anterior spinal artery come from? | branches of each vertebral artery |
Strokes of the anterior spinal artery result in infarction of which tissues? | hypoglossal nucleus and nerve, and corticospinal tract (in medullary pyramids) |
T/F Usually a stroke of the anterior spinal arteries affects both sides | False- it usually involves a branch on one side |
What S+S would be observed with a stroke involving branches from the anterior spinal artery? | 1. ipsilateral weakness/paralysis of tongue (CN XII), contralateral weakness/paralysis of body (corticospinal tract) |
Where do the PICA come from? What does it stand for? | vertebral aa- posterior inferior cerebellar arteries |
What do the PICAs supply? | lateral medulla and cerebellum |
What S+S would result from a PICA stroke? | 1. contralateral pain+temperature loss of body (LST) and 2. ipsilateral pain+temperature loss of face (spinal trigeminal nucleus/tract) |
What is telling of the level of the lesion (stroke) in the brainstem? | cranial nerve signs |
What is telling of whether the lesion (stroke) is medial or lateral in the brainstem? | signs related to tracts |
What supplies the pons? | branches of the basilar artery |
Where does the medial pons receive its blood supply from? | pontine branches of the basilar a |
Where does the lateral CAUDAL pontine zone receive its blood supply from? | AICA (anterior inferior cerebellar aa) |
Where does the lateral ROSTRAL pontine zone receive its blood supply from? | SCA (superior cerebellar aa) |
Which branch of the basilar artery is usually the first branch? | AICAs |
Which branch of the basilar artery is usually the second to last? | SCA |
Which arteries surround the oculomotor nerve? Which is rostral, which is caudal? | posterior cerebral is rostral, SCA is caudal |
Strokes involving the caudal part of the medial pons typically involve which two structures? What are the associated S+S? | 1. ipsilateral weakness/paralysis of LR muscle (CN VI) and 2. contralateral weakness/paralysis of body medullary pyramids |
Where does the midbrain get its blood from? | branches of the proximal part of PCA |
Strokes involving the medial parts of the PCA typically involve which structures? What are associated S+S? | 1., CN III (ipsilateral eye weakness/paralysis) and 2. cerebral peduncles (contralateral weakness/paralysis of body, face, tongue) |
Which 3 arteries supply the SC? How far down do they go? | anterior spinal a, and 2 posterior spinal aa- they run the length of the SC |
When do the posterior spinal aa arise from the vertebral aa? (in the picture, they arise from PICA, shortly after it comes from vertebral) | as they pass through the foramen magnum |
How far down the spinal aa does blood go from the vertebral junction? | only about C4- there are other spinal medullary aa further caudal that supply SC |
Can you see the posterior medullary arteries on the specimens in lab? Where? | no (would run with the dorsal roots) |
Can you see the anterior medullary arteries on the specimens in lab? Where? | if you’re lucky, at the cervical and lumbar enlargements (run with ventral roots) |
Do most veins associated with the brain follow the arteries’ courses? How about the SC? | no- some, but not most; SC do follow the aa |
Where does venous blood flow from the brain go? | adjacent dural venous sinuses |
Where does venous blood flow from the SC go? | parallel the arteries and eventually drain into epidural venous plexus |
What is the other name for the epidural venous plexus? | internal vertebral venous plexus of Batson |
Study atlas pictures of functional areas |