Meninges & Spinal Cord (+Need To Study)

Front 1

What are the primary vesicles of the brain formation?

Back 1

(cervical flexure) Rhombencephalon, (cephalic flexure) mesencephalon, prosencephalon

Front 2

what are the secondary vesicles of the brain?

Back 2

(cervical flexure), myelencephalon, (pountine flexure), metencephalon, mesencephalon, diencephalon, telencephalon

Front 3

when do primary vesicles form?

Back 3

end of 4th week

Front 4

when do secondary vesicles form?

Back 4

end of 6th week

Front 5

what is the myelencepahlon?

Back 5

medulla & 4th ventrile, central canal

Front 6

what is the metecephalon?

Back 6

pons, cerebellum, 4th ventricle

Front 7

what is the mesencephalon

Back 7

midbrain, cerebral aqueduct

Front 8

what is the diencephalon?

Back 8

thalamus, hypothalamus, retina, 3rd ventricle

Front 9

what is the telencephalon

Back 9

cerebral hemi, lateral ventricles

Front 10

what are the meninges made of?

Back 10

collagen fibrils & fibroblasts

Front 11

what are the layers of the meninges?

Back 11

Dura mater (outer), arachnoid mater (middle), pia mater (closet to brain)

*pia+arachnoid=leptomeninges

* differences between meninges covering brain and spinal cord

Front 12

explain the dura mater

Back 12

-tough & fibrous, lots of collagen fibrils

-2 layers which are fused except where dural venous sinuses located (1. periosteal layer 2. meningeal layer)

Front 13

explain the periosteal layer

Back 13

-external layer dura

-adhered to skull

-vascular and pain sensitive

-stops at foramen magnum

-cranial epidural space is pathological=can be filled with fluid

Front 14

whats an epidural hematoma?

Back 14

-usually trauma

-life threatening: usually arterial rupture (periosteal is vasular!)

-drainage by burr hole or craniotomy

-frequently OT after

Front 15

explain the meningeal layer

Back 15

-internal layer of dura

-smooth and avascular

-joins the spinal dura mater at foramen magnum and continues down spinal cord

Front 16

what are septa or dural reflections?

Back 16

-sheet-like processes that extend from the meningeal layer of dura deep into cranial cavitys forming compartments

-fx: reduce brain displacement when head moves

1) falx cerebri (separating cerebral hemis)

2) tentorium cerebelli (attached dorsal to falx cerebri & occipital bone= separates cerbelllum and occipital

3) falx cerebelli (cerebellar hemispheres)

Front 17

what's a subdural hematoma (SDH)?

Back 17

-collection blood under dura (between meningeal & arachnoid)

-more common than epidural hemmorrhages

-broken vein (TBI, shaken baby, shearing injury, cerebral atrophy)

-TX: small=let heal; large= craniotomy w/evacuation of hematoma

* OT residual deficits caused by brain damage

Front 18

explain the arachnoid mater

Back 18

-middle layer

-delicate, avascular

-surrounds brain loosely not in sulci

structures: subarachnoid space, arachnoid trabeculae (cobwebs connecting arachnoid to pia/suspend brain), subarachnoid cisterns (: enlargements of subarachnoid space, cisterna magna/cerebellomedullary cistern-largest), arachnoid granulations or villi (small tufts tissue projecting into dural sinuses)

Front 19

explain the arachnoid granulations or villi

Back 19

1st is larger

-consist of spongy tissue with small tubules that fx as one-way valves allowing CSF to flow into blood in dural sinuses but the blood cannot flow into the subaracnoid space

Front 20

explain a subarachnoid hemorrhage

Back 20

-bleeding into subarachnoid space (form of stroke)

-usually caused by aneurysm or arteriovenous malformation (AVM) & TBI

-severe headache, vomiting, altered level of consciousness (LOC)

-TX: surgical clipping, coiling, medication to control vasospasms, craniotomies, OT/therapy

Front 21

explain the pia mater

Back 21

-innermost layer

-thin follows contours of cortex

-highly vascular/not pain

Front 22

what are the 2 major differences of meninges in spinal cord?

Back 22

1) spinal dura single-layer (lacks periosteal)

-begins at foramen & ends at second sacral vertebra

2) spinal epidural space (actual space-epidural anesthesia)

Front 23

whats important about a lumbar cistern?

Back 23

-wides area of subarachnoid space around spinal cord

-next to 2nd sacral vertebra

-site for lumbar puncture (spinal tap) for removal CSF (L3-L4 adults, L4-L5 children)

Front 24

whats the purpose of a lumbar puncture?

Back 24

collect CSF for diagnositc, measure CSF pressure, insert anesthetics or dye in CSF, lower pressure in brain if too much CSF

* OT implications: typically patient bedrest 1-4 hrs & persistent headache that doesn't go away after 1-2 days may be CSF leak

Front 25

meningocele

Back 25

:protrusion of meninges outside vetebral column

-typically lumbar & sacral

-little evidence of motor/sensory deficits but maybe certebral column defects

Front 26

what do the ventricles do?

Back 26

spaces in brain cavities where CSF is produced and found

Front 27

what is the flow of CSF?

Back 27

lateral ventricles->interventricular foramina -> 3rd ventricle -> cerebral aqueduct -> (4th ventricle)->lateral ventricular foramina & median ventricular foramen -> subarachnoid space

-> (4th ventricle) -> central canal

Front 28

what are the mechanisms of CSF flow?

Back 28

1) mechanical- pulsate by arteries

2) pressure gradient system- pressure higher in subarachnoid space than dural venous sinuses

Front 29

what is the fx of CSF?

Back 29

1) provide environment for brain and spinal cord to be suspended, buoyancy reduces traction on nerves/blood vessels

2) cushioning/impact protection for CNS

3) remove unwanted substances

4) provide stable ionic enivornment for CNS

Front 30

what is the choroid plexus?

Back 30

-invagination/pouch of vascular pia mater

-formed from specialized epithelial cells

-produces CSF & provides BBB in ventricles

-present in ea ventricle so CSF flows through system, more is made

Front 31

what is the Blood-Brain Barrier (BBB)?

Back 31

-tight junctions exist between capillary walls and brain tissue so large molecules cannot pass from the blood into the brain tissue

-benefits: bloodborne foreign substances cannot enter brain

-cons: medication cannot

-exceptions to BBB: 7 structures called circumventricular organs lack BBB to allow hormones to teach target areas of brain

Front 32

what is Arnold-Chiari malformation?

Back 32

cerebellum and parts of medulla are displaced through the foramen magnum into cervical vertebral canal

- CSF blocked so hydrocephalus is common

Front 33

what is hydrocephalus?

Back 33

-dilation of ventricles, occuring when circulation of CSF is blocked or absorptio impeded (cogential due to fetal viral/prematurity with interventiruclar hemorrhage) or acquired

-pressure on brain can cause associated problems

Front 34

what are the 2 types of hydrocephalus?

Back 34

1. non-communicating (obstructive): CSF blocked usually cerebral aqueduct or foramina in 4th)

2. communicating (non-obstructive): CSF not reabsorbed into arachnoid villi. Subtype: normal pressure hydrocephalus (NPH): isn't "normal" but increase very gradual (wet, wobbly, weird)

Front 35

treatment of hydrocephalus?

Back 35

1) address cause (remove tumor) and shunting (reroute CSF from ventricles to abdomen

2) hole in floor of 3rd ventricle