Spinal Cord Flashcards
what are the 3 principal planes of reference
- coronal
- sagittal
- horizontal
what are the 3 meningeal layers?
- dura matter
- arachnoid matter
- pia matter
what is the dura mater?
- outermost of the meninges
- completely surrounds brain + spinal cord
what are the characteristics of the dura mater?
- dense
- inelastic membrane
what is the cranial dura mater?
- surrounds the brain
- firmly adhered to inner surface of the skull
what is the extradural/epidural space?
-potential space between dura + skul
what is the subdural space?
-potential space between dura + arachnoid mater
what is the subarachnoid space?
-space below the arachnoid mater
what is an extradural hematoma?
bleeding in the extradural space
how do extradural hematomas form?
- damage to branches of the middle meningeal artery (+ vein)
- form slowly
- due to tight attachment of dura to skull
how can subdural hematomas form?
- form in subdural space
- if bridging veins are torn in head trauma
what is a subarachnoid hemorrhage?
-commonest type of intracranial bleeding
-
how many ventricles are there?
4
what are the 4 ventricles?
- 2 lateral ventricles
- 1 third ventricle
- 1 fourth ventricle
what are the lateral ventricles?
-each follows long C-shaped course through all the lobes
what is the third ventricle?
-occupies most of the midline region of the diencephalon
what is the fourth ventricle?
-sandwiched between the cerebellum posteriorly + the pons + rostral medulla anteriorly
the fourth ventricle is continuous with the ____ via the ______
third ventricle, cerebral aqueduct (aqueduct of sylvius)
the fourth ventricle is also continuous with the ____ via _____
subarachnoid space
through 3 openings and channels
do hematomas have immediate symptoms?
-no, there can be a lucid period + delay
what is the first most noticeable sign of a hematoma?
-extreme headache (due to irritation of dura matter)
what is the most feared event of a hematoma?
- occurs in the transentorial (uncal herniation)
- results in respiratory arrest when medullary structures are compressed
what can cause bleeding into the subarachnoid space?
- hemorrhagic strokes
- ruptured arterial aneurysms
- venous damage
what is the source of CSF?
chroid plexus
what are the qualities of CSF?
- clear, colorless liquid
- low in cells + proteins
- similar to plasma
What are the 2 major functions of CSF?
- CSF in subarachoid space: buoyant function + buffering zone
- regulation of extracellular environment of neurons
where is CSF ultimately returned to?
veins + venous circulation
how does CSF enter the veins?
-through arachnoid villi/arachnoid granulations (tiny vessels)
how is CSF brought back to the heart?
- system of veins:
- dural sinuses
- superficial veins
- deep veins
what can lead to the accumulation of CSF in the ventricular system? (enlargement of ventricles, hydrocephalus)
- overproduction of CSF
- decline of CSF return to venous system
- developmental abnormalities in cerebellomedullary region
- obstruction of intra and extraventricular circulations
how does the brain receive blood supply?
- from 4 arteries
1. two internal carotid arteries (ICA)
2. two vertebral arteries
what are the 4 components of the arch of the aorta?
- right common carotid artery (external + internal)
- left common carotid artery (external + internal)
- right vertebral artery
- left vertebral artery
what do the two vertebral arteries unite to form?
The basilar artery
What does the basilar artery bifurcate into?
two posterior cerebral arteries
what are the 3 principal branches of the internal carotid artery?
- anterior cerebral artery
- middle cerebral artery
- anterior choroidal arter
through the 3 branches of the internal carotid artery, the ICA supplies _______
- cortical
2. subcortical structures of the brain
what does the ICA (internal corotid artery supply)?
- cortical
2. subcortical structures of the brain
what are the other 2 branches of the ICA?
- ophthalmic artery (rise to central artery of retina
2. posterior communication artery
does the occlusion of the ICA have any symptoms?
no
what can the occlusion of the ICA cause?
- transient ischemic attack (TIA) or minor stroke
2. multilobar infarction + serious injury, major stroke
why can the occlusion of the ICA go symptomless?
the Circle of Willis
what is the main function of the Circle of Willis?
-provides opportunities for collateral circulation
how is the Circle of Willis formed?
- posterior communication artery on either side joins
- internal carotid artery
- posterior cerebral artery - an anterior communication artery joins
- two anterior cerebral arteries
what does the Circle of Willis illuminate about blood supply?
-ICA and basilar artery share the blood supply to each hemisphere
where do the opposing streams of the ICA and the basilar artery meet in the circle of willis?
-dead point in Posterior Communication artery
what does the dead point in the Posterior Communication artery result in?
-if one ICA is occluded, collateral circulation from vertebral artery + other ICA can compensate
When can problems arise in the Circle of Willis?
when you have an abnormal Circle of Willis
what is the consequence of blocking the ICA?
massive stroke
what does the anterior cerebral artery supply?
- the paracentral lobule
- containing cortical centers for movement + sensation of lower limbs - ventromedial Prefrontal cortex (short term memory, planning, decision making)