08 26 2014 Meninges and Ventricals

Question 1

Cerebral Spinal fluid

Answer 1

Clear, colorless liquid
140mL
Provides buoyancy, and protects against sudden movements.

Some antibacterial properties

Question 2

Cisterns

Answer 2

Enlarged areas of subarachnoid space (around brain stem)

• Perimesencephalic cisterns
• Prepontine cistern
• cisterna magna

Question 3

perimesencephalic cisterns

Answer 3

Interpeduncular cistern (ventral and abovepons)

Quadrigeminal (and ambient) cisterns (between corpus collusum and cerebellum and pons)

Question 4

Prepontine cistern

Answer 4

ventral to pons (aka in front of pons)

Question 5

Cisterna magna

Answer 5

below cerebellum

Question 6

Why do you use a lumbar puncture?

Answer 6

Diagnose subarachnoid hemorrhage and meningitis or introduce drugs.

Adults: L3-L4
Children: L4-L5

Question 7

What is normal pressure of CSF

Answer 7

< 20 cm H2O

Question 8

Layers of Dura in Brain vs. spinal cord?

Answer 8

Brain: 2 layers
-periosteal and meningeal – split to form sinuses

Spinal cord : 1 layer – meningeal (vertebrae have their own periosteum)

Question 9

Layers of Arachnoid in brain vs. spinal cord?

Answer 9

Brain: arachnoid trabecular and many cisterns

Spinal cord: fewer travecule and 1 cistern (lumbar cistern)
- this is where you do lumbar puncture

Question 10

Layers of Pia in brain vs. spinal cord?

Answer 10

Spinal cord: forms denticulate ligaments and filum terminal

Question 11

Denticulate Ligament of spinal cord?

Answer 11

anchor pia to dura (from pia to dura)

Question 12

Filum Terminum of spinal cord?

Answer 12

anchors spinal cord to arachnoid.

Question 13

Coccygeal ligament (filum terminale externum) of spinal cord?

Answer 13

anchors spinal cord to coccyx

Question 14

What are the dural folds?

just name them

Answer 14

Invaginations of inner dural layer. Create the supratentorial and infratentorial spaces (in reference to tentorium)

1. Flax cerebri
2. Falx cerebelli
3. Tentorium cerebelli
4. Diaphragm sellae

Question 15

Falx cerebri

Answer 15

in between cerebral hemispheres (in longitudinal fissure)

Question 16

Falx cerebelli

Answer 16

separates cerebellum in right vs. left

Question 17

Tentorium cerebelli

Answer 17

lies between the posterior cerebral hemispheres and the cerebellum

Question 18

Diaphragm sellae

Answer 18

circular fold beneath the brain that covers the sella turcica.

Question 19

posterior fossa

Answer 19

the cavity formed with occipital bone as base and tentorium cerebella as roof.

Contains cerebellum and brainstem

Question 20

tentorial notch

Answer 20

hole within dural folds where the brainstem can go through

Question 21

Flow of CSF

Answer 21

lateral ventricles — foramen of Monro–> third ventricle (diencephalon) – cerebral aqueduct (midbrain) –> 4th ventricle in pons/medulla— foramen of Magendie and Luschka –> subarachnoid space around brian and spinal cord —> arachnoid granulations —> veinous sinuses

Question 22

Blood - CSF barrier

Answer 22

choroidal capillaries are fenestrated with no tight junctions BUT choroid epithelium (ependymal cells w/tight junctions) has the tight junctions. Therefore the choroid epithelium form the blood-CSF barrier

Question 23

hydrocephales

Answer 23

increase volume of CSF

1. overproduction (rare)
2. Obstruction of flow
3. decrease reabsorption via arachnoid granules

May be chronic in children

Question 24

Communicating hydrocephalus

Answer 24

blockage of CSF reabsorption in arachnoid granules OR obstruction of flow in the subarachnoid space

Question 25

Noncommunicating hydrocephalus

Answer 25

obstruction of flow within ventricular system

Question 26

Symptoms of increased intracranial pressure

Answer 26

1. headache 2. Nausea and vomitting 3. 6th Nerve palsy - eyes appear to look downwards 4. papilledema (swelling of optic papilla) 5. Decreased vision/ diplopia (double vision) 6. Decreased cognition 7. Unsteady gait 8. Cushing's triad: hypertension, bradycardia, and irregular respirations (brainstem)

Question 27

Blood brain barrier

Answer 27

formed by tight junctions of epithelium on capillary. The BBB may be disrupted by infections, tumor or trauma and can cause "vasogenic edema" - shows up as breakdown of epithelium.

Question 28

Circumventricular organs

Answer 28

parts in which the BBB is interrupted. It enables the brain to resound to changes in the blood chemistry - Area postrema: detecting circulating toxins that cause vomiting

Question 29

Epidural Hematoma

Answer 29

Potential space caused by trauma (fracture of the temporal bone) that lesions middle meningeal artery. Rapidly expanding hemorrhage Lens- biconvex shape Increase in pressure causes a herniation

Question 30

Subdural hematoma

Answer 30

Potential space rupture of bridging veins due to a high velocity impact. (acute) Can be a chronic condition in elderly (brain shrinks which puts them at an increased risk of tearing a bridging vein. Cresent shape

Question 31

Subarachnoid hematoma

Answer 31

Real space -- has blood vessels 1. Non-traumatic - WORST HEADACHE OF MY LIFE - aneurysms or Arteriovenus malformations 2. Traumatic - bleeding into CSF from damaged blood vessels associated with cerebral contusions and other traumatic brain injuries

Question 32

What are the two types of Aneurysms?

Answer 32

1. Saccular/ Berry: - balloon like 2. Fusiform -main vessel itself becomes dilated (less likely to rupture and thereofer more likely to compress something) - Posterior communicating arter --> 3rd Nerve palsy

Question 33

where do aneurysms mostly occur? (Saccular)

Answer 33

1. Anterior communicating artery (30%) 2. Posterior communicating artery (25%) 3. Middle cerebral artery (20%) 4. Posterior circulation (15%)

Question 34

Transtentonial Herniation and symptoms

Answer 34

Uncal herniation -- medial temporal lobe herniates through tenurial notch. 1. blown pupil -- ipsilateral dilated, unresponsive pupil (CN 3) 2. Hemiplegia: paralysis of half of the body 3. coma 4. posterior cerebral arteries may be compressed -- infarction in posterior cerebral artery territory.

Question 35

Central herniation

Answer 35

central downward displacement of the brainstem. Mild herniation = traction on abducen's nerve = lateral rectus (unilateral or bilateral)

Question 36

Tonsillar herniation

Answer 36

Cerebellar tonsils move downward through foramen magnum. - compression of medulla - leads to respiratory arrest, blood pressure instability and death

Question 37

Subfalcine herniation

Answer 37

unilateral mass lesions that cause cingulate gyrus (and other structures) to herniate under the flax cerebra from one side of the cranium to the other. - may be symptomatic - may have symptoms of increased cranial pressure