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Musculoskeletal Anatomy > Head full of blood > Flashcards

Head full of blood Flashcards

0
Q

Brain represents how much of body weight? How much CO does it get? Responsible for how much O2 & glucose consumption?

A
  • 2% of body weight
  • 15% of CO
  • 20% of O2 consumption
  • 25% of glucose consumption
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1
Q

What are the 3 types of fluid in the head?

A
  1. arterial supply
  2. venous drainage
  3. cerebrospinal fluid
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2
Q

What is the venous drainage system good for?

A
  • to decrease likelihood of increased intercranial P

- it is a series of valveless sinuses with collateral channels

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3
Q

What is the CSF good for?

A
  • allows brain to float in the skull

- acts as lymphatic system in brain (?)

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4
Q

What are the meninges? What are the layers?

A
  • CT covering that encloses & protects the brain & spinal cord
  • dura mater, arachnoid mater & pia mater (exterior to interior)
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5
Q

What is the dura mater?

A

-‘tough mother,’ tough fibrous sack that surrounds brain & has firm attachment points to skull & sacrum, creates dural folds & venous sinus system of the brain

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6
Q

What is the arachnoid mater?

A
  • fine, web-like appearance
  • middle layer of meninges
  • CSF flows underneath in the subarachnoid space
  • forms arachnoid villi, responsible for reabsorbing CSF & returning it to the blood stream
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7
Q

What is the pia mater?

A
  • ‘soft mother’
  • very thin
  • adheres to the brain & spinal cord
  • impermeable to fluid
  • covers every surface of the brain except some areas of the ventricular system
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8
Q

What are the 4 dural folds?

A
  1. falx cerebri- located in longitudinal fissure, separates hemispheres of cerebrum
  2. tentorium cerebelli- separates cerebellum from occipital lobe
  3. falx cerebelli- separates cerebral hemispheres in posterior cranial fossa
  4. sellar diaphragm- covers pituitary in it’s fossa
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9
Q

What are the denticulate ligaments?

A
  • specialized structures of the pia mater
  • are thin, ligamentous structures that emerge from the pia of the spinal cord & attach it to the dura mater
  • thought to stabilize motion of the spinal cord
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10
Q

What is the filum terminale?

A

-CT cord, continuous with the pia mater, that extends from the lowest tip of the spinal cord (the conus medullaris) to anchor the spinal cord at the level of the sacrum & coccyx

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11
Q

What does the subarachnoid space contain?

A

CSF

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12
Q

What area do you do lumbar punctures on?

A

-cauda equina area, ALWAYS insert needle below L3 vertebra

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13
Q

What are the properties of CSF?

A
  • small volume: 150 ml
  • low pressure: 10 mmHg
  • choroid plexus produces 450-500 ml/day
  • CSF propelled cranially by brain movements & pulsations of surface arteries
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14
Q

What does the brain ‘float’ in? Why does it float in this? What is the weight of the brain normally vs in CSF?

A
  • CSF
  • 1400 g brain is 45 g when suspended in CSF
  • cranial nerves & blood vessels are not crushed
  • arachnoid trabeculae keep brain in place
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15
Q

What does the CSF move through?

A

-ventricles (intracerebral spaces)

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16
Q

What are the lateral ventricles & how many are there?

A
  • lateral ventricles, 2
  • C-shaped spaces derived from neural tube
  • spaces curve from the medial part of the hemispheres around into the temporal lobes
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17
Q

Where does CSF flow? (order of flow)

A

lateral ventricles—> 3rd ventricle via interventricular foramen (above medulla, lie between halves of thalamus & hypothalamus)—> cerebral aqueduct (through midbrain)—> 4th ventricle (by/right in front of the cerebellum)—> into spinal canal or exit into subarachnoid space

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18
Q

How does CSF enter the subarachnoid space?

A

-exits the 4th through foramina of Luschka & Magendie

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19
Q

After CSF exits into the subarachnoid space what happens to it?

A

-ascends to superior sagittal sinus to be reabsorbed by the arachnoid granulations

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20
Q

What does the choroid plexus do?

A
  • modifies ependymal cells that surround capillaries

- generates CSF in lateral, 3rd & 4th ventricles by filtering blood from capillaries that run through it

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21
Q

What is the blood-CSF barrier?

A
  • tight junctions b/w choroidal epithelial cells
  • prevents passage of large molecules
  • O2, CO2, glucose can go in freely
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22
Q

What is the brain-CSF barrier?

A

-minimal restriction between ventricles & brain interstitium b/c needs to be getting metabolites, O2, glucose, etc through CSF

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23
Q

What are ependymal (glial) cells?

A
  • line the interior of ventricles
  • not connected by TJs
  • fluid passes freely b/w brain interstitium & ventricles
  • metabolites of neurotransmitters can move from brain to ventricles & be detected in spinal taps (catecholamines are lower in CSF of Parkinson’s)
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24
Q

What are arachnoid villi/arachnoid granulations?

A
  • membranous filters that allow CSF to pass into venous blood of the superior sagittal sinus
  • protrusions into dura created by the villi
  • cerebral veins also drain into dural sinuses
25
Q

What branches off the aorta to supply blood to the head? What are the branches afterwards?

A

Arch of aorta–>common carotid artery–>vertebral artery–>middle cerebral artery

26
Q

Where does the internal carotid artery come from? What do they split into? What do they supply?

A
  • ascends from brachiocephalic artery or arch of aorta
  • internal carotid splits from external carotid at carotid sinus
  • IC then splits into anterior & middle cerebral arteries
  • supply most of cerebral hemispheres
27
Q

Where does the vertebral artery come from?

A
  • ascends from subclavian artery
  • passes through transverse foramina of vertebrae C1-6
  • penetrates atlanto-occipital membrane and dura
28
Q

What does the basilar-vertebral system supply? What are the 2 arteries?

A
  • spinal cord, brain stem, inner ear, cerebellum, occipital & temporal lobes
  • vertebral arteries: unite to form the basilar artery on ventral medulla, spinal arteries & posterior inferior cerebellar arteries branch from here
  • basilar artery: ascends on ventral surface of brainstem, anterior inferior cerebellar, pontine, superior cerebellar & posterior cerebral arteries all branch off of basilar artery
29
Q

What are spinal arteries?

A
  • vertebral artery: anterior (1, runs medially down the spine) & posterior spinal arteries (2, dorsal, run on either side)
  • radicular branches of intercostal arteries
30
Q

Symptoms of Occlusion (SOs) for anterior/posterior spinal arteries:

A

-loss of spinal cord fxn at level of occlusions (paralysis, loss of sensation)

31
Q

SOs for posterior inferior cerebellar artery (PICA):

A

-wallenberg syndrome= loss of pain & temp sensation on contralateral side of body/torso &ipsilateral side of face

32
Q

SOs for anterior inferior cerebellar artery (AICA):

A

lateral pontine syndrome= sudden onset of vomiting/vertigo, ipsilateral loss of sensation to face & ipsilateral facial paralysis

33
Q

SOs for superior cerebellar artery:

A

ipsilateral limb dysmetria (lose ability to make smooth movements), contralateral loss of sensation

34
Q

SOs for pontine artery:

A

-contralateral paralysis & loss of sensation, often results in death, several outcomes possible depending on size of infarct

35
Q

SOs for labyrinthins artery:

A

ipsilateral hearing loss & vertigo

36
Q

What is the circle of Willis?

A
  • communicating branches from anastomoses b/w cerebral arteries
  • anterior communicating: connects anterior cerebral arteries
  • posterior communicating: connects middle to posterior cerebral arteries
37
Q

Where is the middle cerebral artery?

A
  • heads out laterally from internal carotid

- along lateral fissure & lateral surface of cerebral cortex

38
Q

What are the two branches of the middle cerebral artery? What happens with occlusion (stroke) to each?

A
  • cortical branches to lateral surface of cortex; paralysis & sensory loss to contralateral side, damage to dominal side usually results in aphasia (difficulty speaking)
  • lateral striate arteries to internal capsule & basal ganglia (hemiplegia)
39
Q

Where is the anterior cerebral artery? What does occlusion cause? What is abulia?

A
  • along medial surface of cerebral cortex, including cingulate gyrus (part of limbic system)
  • paralysis & sensory loss in contralateral leg & foot
  • abulia: lack of will or initiative, pronounced passivity, reduced social interactions, reduced emotional responsiveness, reduced spontaneous motions
40
Q

Where does the posterior cerebral artery project to? What can occlusions cause?

A
  • projects to the occipital & temporal lobes
  • occlusions can cause: visual field defects, prosopagnosia (face blindness), contralateral deficits of the facial, vagus & hypoglossal n. & ipsilateral deficits of the occulomotor n.
41
Q

Where do the veins drain in the brain?

A
  • blood from cerebral hemispheres & brain stem drain outwardly into surface veins
  • cerebral veins drain venous blood into dural sinuses
42
Q

What are dural sinuses?

A
  • compartments w/in dura mater
  • spaces b/w periosteal & meningeal dural layers convey venous blood (meningeal dural layers from falx cerebri & tentorium cerebelli)
  • located at junction of dural folds or b/w bone & dura
43
Q

Where is the superior sagittal sinus?

A

-where falx attaches to interior of frontal, parietal & occipital bones

44
Q

Where is the inferior sagittal sinus located?

A

-on the free edge of the falx

45
Q

What are straight sinuses for & where are they?

A

-connect inferior sagittal sinus w/the confluens along the intersection of falx cerebri & tentorium cerebelli

46
Q

What are the dural sinuses associated with?

A

-tentorium cerebelli & anterior cranial base

47
Q

Where are the confluens?

A

-on the inside of the occipital bone, at the intersection of falx cerebri & tentorium cerebelli

48
Q

Where does the transverse sinus extend to?

A

-extends outward from the confluens along the intersection of the tentorium cerebelli & interior surface of the occipital bone

49
Q

What is the sigmoid sinus an extension of?

A

-extension of transverse sinus that drops down into the jugular foramen & becomes the internal jugular vein

50
Q

Dural sinuses associated with the anterior cranial base?

A

-cavernosus sinus & inferior & superior petrosal sinuses

51
Q

Where are the cavernous sinuses, what do they do & what do they contain?

A
  • on either side of the body of the sphenoid bone
  • receives blood from local sinuses, orbital veins–> RELATIONSHIP= BAC CAN SPREAD TO BRAIN
  • communicates w/pterygoid plexus in lateral pterygoid muscle
  • surrounds pituitary gland
  • several structures pass through from inferior of the neurocranium, through meingeal dural layer, through sinus & then through posterior dural layer to exit through foramina in cranial base (internal carotid artery, CN: III, IV, V, VI)
  • infections entering sinus can affect those structures
52
Q

Where are the inferior & superior petrosal sinuses from & what do they do?

A

-drain blood from cavernous sinus posteriorly & into the transverse sinus

53
Q

What are the spinal veins?

A
  • anterior & posterior longitudinal sinuses

- basivertebral vein

54
Q

What are the anterior & posterior longitudinal sinuses?

A
  • valveless veins around dura

- blood flows up or down vertebral column

55
Q

What are the basivertebral veins?

A
  • drains vertebral body

* *how prostate cancer metastasizes into vertebrae

56
Q

What are the emissary veins good for?

A
  • venous blood can flow freely b/w scalp & dural sinuses
  • thermoregulation: brain needs to be at constant temp
  • during hyperthermia, cooler blood from surface travels internally through emissary veins to cool the brain
57
Q

What is the BBB?

A
  • consists of endothelium, pericytes, astrocyte feet & basal lamina
  • prevents passage of large, water soluble molecules (ex. proteins) into brain
  • capillary endothelial cells sealed by high resistance TJs
  • BBB TJs maintained and induced by astrocyte feet
  • peripheral endothelial cells more permeable to solutes
58
Q

What gets taken in through the BBB and how?

A
  • glucose & a.a.s penetrate endothelial cells via transporters
  • gases (O2, CO2) penetrate directly through lipid membranes
59
Q

Where does the BBB not exist in the brain? What does this allow?

A
  • hypothalamus, area postrema & other periventricular regions
  • capillaries permit passage of larger molecules
  • hormones contact hypothalamic cell receptors
  • digested poisons stimulate area postrema’s pathway to vomiting center

Musculoskeletal Anatomy (9 decks)

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