CNS 1 - Meninges and Blood Supply Flashcards
(30 cards)
1
Q
Components of the CNS
A
- brain (inside skull)
- spinal cord (inside vertebrae
2
Q
Components of the PNS
A
- composed of mixed spinal nerves to each level of the spinal cord
- afferents (sensory to the CNS)
- efferents (motor to the body)
- Schwann cells = myelinated, associated with one axon
3
Q
Cells in the CNS
A
- ependymal (brain-CSF barrier)
- astrocytes (blood-brain barrier, composed of lipid)
- neurons (signals)
- microglia (immune)
- oligodendrocytes (myelinated axons)
4
Q
CNS regeneration
A
- limited
- not a lot of recovery
- neurons are postmitotic
- glia inhibit axon growth
5
Q
Cell types
A
- both CNS and PNS have neurons and glial cells
- glial cells = supporting cells, 4 times as many as neurons
6
Q
PNS regeneration
A
- grow encouraged for regeneration (1 mm per day)
- can grow collaterals
- glia produce growth factors
- macrophages remove debris
7
Q
Meninges of the brain
A
- dura mater (fixed to the skull)
- arachnoid mater (fixed to the dura)
- pia mater (covers the brain and cerebral vessels)
- there is a space between the arachnoid and pia = subarachnoid space
8
Q
Meningeal arteries, veins, and nerves
A
- located between the dura and the skull
- leads to grooves on the inside of the skull
9
Q
Division of the skull by meninges
A
- the dura extends inwards to divide the skull into compartments
- falx cerebri = division between left and right hemispheres
- tentorium cerebelli = between cerebellum and cerebrum
- falx cerebellum = divides cerebellar hemispheres
10
Q
Herniation
A
- blood clots can force the brain between compartments
- can arise from a hematoma
11
Q
Coning
A
- if the CSF pressure is decreased, the entire brain can slightly drop down
- falls down into the space above the foramen magnum
12
Q
Meningeal vessels
A
- there is no nerve supply within the brain, only blood supply
- the meninges have a nerve and blood supply
- meningeal artery = derived from the external carotid
13
Q
Trigeminal nerve
A
- CN V
- supplies the sensory information for your face
- three branches = ophthalmic, maxillary, mandibular
- branches of the trigeminal nerve run alongside the meningeal artery
14
Q
Vascular cause of headache
A
- spasm in the meningeal artery
- irritates the trigeminal nerve
15
Q
Blood supply to the brain
A
- arteries come mostly from the bottom of the brain
- the venous drainage occurs at the top
- bridging veins cross the subarachnoid space to get into the venous sinuses
16
Q
Hematomas and CT scans
A
- CT imaging = caudocranial
- epidural = crescent shaped
- subdural = goes throughout the whole area and diffuses through the CSF
- subarachnoid = at the bottom of the brain, spreads out in CSF
17
Q
Epidural hematoma
A
- blunt force to skull
rupture of meningeal vessel - temporal bone is very thin and easy to fracture
18
Q
Subdural hematoma
A
- sudden movement of the head causes the brain to move
- tears the bridging veins (usually where the vein enters the sinus)
- blood in the CSF space
19
Q
Subarachnoid hematoma
A
- congenital weakening of the artery wall (aneurysm)
- rupture of cerebral artery
20
Q
Meninges and the spinal cord
A
- same layers as the brain
- however, the dura is not firmly attached to the vertebral bones
- epidural fat space = easily compressed for movement
21
Q
Ventricles of the brain
A
- lateral ventricles (1 and 2)
- connects to the third ventricle through interventricular foramina
- connects to the fourth ventricle through the cerebral aqueduct
- leads to the central canal (goes down inside the spinal cord)
22
Q
Choroid plexus
A
- tufts of blood vessels
- produces CSF by filtering blood/plasma
- located in the 1st, 2nd, 3rd, and 4th ventricles
- flows down the central canal
- pore in the 4th ventricle allows CSF to flow into the subarachnoid space
23
Q
Drainage of CSF
A
- arachnoid granulations (villi) filter the CSF back to the venous circulatory system
- occurs via the superior sagittal sinus
- this balances the production of CSF
24
Q
Hydrocephalus
A
- water on the brain
- can occur due to a stenosis
- flow of CSF will be altered, leading to dilations in certain areas depending on location stenosis
25
Arterial blood supply to the brain
- subclavian and common carotid (left and right) branch off of the aorta
- early branch of the subclavian (vertebral artery) supplies the brain
- common carotid splits into internal and external
- internal = gives rise to cerebral arteries
- external = gives rise to meningeal arteries
26
Circle of Willis
- vertebral arteries coalesce into the basilar
- basilar gives off posterior cerebral arteries
- internal carotid gives off anterior and middle cerebral arteries
- anterior and posterior communicating arteries lead to an anastamosis
27
Deep arterial blood supply
- deep cerebral arteries supply deeper brain structures
| - eg. limbic system (emotional), basal ganglia (motor movement), thalamus (filter for sensory)
28
Venous drainage
- blood will travel through the bridging veins to the superior sagittal sinus
- lies at the leading edge of the falx cerebri
- divides into left/right transverse sinuses
- lies at the leading edge of the tentorium cerebelli
- drops down to left/right sigmoid sinuses, then to left/right internal jugular veins (adjacent to carotid artery)
29
Hemorrhagic stroke
- hemorrhage
- blood leaks into brain tissue (aneurysm, too many aspirins)
- creates swelling and pressure, damaging cells and tissues
30
Ischemic stroke
- blood clot gets caught in a cerebral artery
- prevention of blood getting supplied to certain areas
- no more oxygen, glucose
