CSF, Ventricles and Meninges

Question 1

Ventricles lined with

Answer 1

Ependyma

Question 2

Ependyma

Answer 2

Modified epithelium that produces CSF

Question 3

The ventricular system is filled with

Answer 3

CSF

Question 4

Ventricular system empties into

Answer 4

Subarachnoid space

Question 5

CSF functions = 3

Answer 5

1) immune
2) autoregulation of cerebral blood flow
3) allow brain to float and reduce weight (1500 - 50g)

Question 6

CSF produced by

Answer 6

60% choroid plexus
30% capillary seepage
10% water from metabolism

Question 7

CSF = 7 points

Answer 7

1) It is an ultrafiltrate of plasma that diffuses passively through the ependyma-glial membrane lining the ventricles, passing through the extracellular spaces of the hemispheres, bathing neurons and neuroglia to diffuse out through the pia-glial membrane on the surface, and into the subarachnoid space
2) It ‘rinses’ the metabolic waste from the central nervous system through the blood–brain barrier
3) Its composition is similar to extracellular fluid - inorganic salts, 280-300 mosm/kg H2O; glucose, 50-80mg/dL; trace protein, 15-40mg/dL
4) Its total volume is 150ml, but its daily output is 550ml, therefore if circulation is blocked, pressure builds up rapidly
5) At any one time there is 30ml of CSF in the ventricular system and 100ml in the subarachnoid space
6) It accounts for 15% of brain volume
7) Cerebrospinal fluid also circulates through the ventricular system and the subarachnoid space before passing through the arachnoid villi, into the dural venous sinuses

Question 8

Choroid plexus

Answer 8

network of blood capillary invaginated into ventricle, and site of CSF production

Question 9

Layers of choroid plexus

Answer 9

capillary, pia and ependyma

Question 10

Location of choroid plexus in each ventricle

Answer 10

These capillaries invaginate through the choroid fissure for the lateral ventricles, through the posterior wall of the 3rd ventricle and through the foramina of Luschka of the 4th ventricle

Question 11

Each cerebral hemisphere contains

Answer 11

a lateral ventricle

Question 12

Each lateral ventricle resembles

Answer 12

a C-shaped structure that begins at an inferior horn in the temporal lobe, travels through a body in the parietal lobe and frontal lobe, and ultimately terminates at the interventricular foramina where each lateral ventricle connects to the central third ventricle

Question 13

Lat ventricle pos and ant horns

Answer 13

a posterior horn extends backward into the occipital lobe, and an anterior horn extends farther into the frontal lobe

Question 14

A single midline 3rd ventricle is located

Answer 14

between the subcortical nuclei (in the diencephalon)

Question 15

A single midline 4th ventricle

Answer 15

is located in the brain stem

Question 16

Connecting the lateral ventricles with the 3rd ventricle are two

Answer 16

interventricular foramina (of Monro)

Question 17

Between the 3rd & 4th ventricles runs

Answer 17

the aqueduct of Sylvius (passing through the midbrain)

Question 18

Linking the 4th ventricle to the subarachnoid space are

Answer 18

two lateral foramina (of Luschka) and one median foramen (of Magendie)

Question 19

3rd ventricle location and contents

Answer 19

This is a slit-like central chamber between thalami and hypotahalami of each hemisphere
Its contents are CSF and the choroid plexus

Question 20

3rd ventricle roof

Answer 20

fornix

Question 21

3rd ventricle floor

Answer 21

tuber cinereum, mamillary bodies and upper midbrain

Question 22

3rd ventricle ant boundary

Answer 22

anterior commissure, lamina terminalis and optic chiasma

Question 23

3rd ventricle pos boundary

Answer 23

pineal gland and posterior commissure

Question 24

4 protrusions on 3rd ventricle

Answer 24

ant sup = supraoptic recess
ant inf = infundibular recess
pos sup = suprapineal recess
pos inf = pineal recess

Question 25

4th ventricle relations

Answer 25

This is a tent-shaped space between the pons and medulla anteriorly, and the cerebellum posteriorly. It communicates inferiorly with the central canal of the medulla oblongata It communicates superiorly with the aqueduct of Sylvius. The ‘floor’ (anterior wall) of the 4th ventricle has many cranial nerve nuclei near it

Question 26

4th ventricle foramen

Answer 26

Its foramina of Luschka and Magendie are the exit foramina for circulation of CSF between the ventricular system and the subarachnoid space

Question 27

Meninges layers and function

Answer 27

From superficial to deep they are: dura mater, arachnoid mater and pia mater These layers have different functions; physical support, shock protection, CSF circulation and watertightness The blood vessels which supply the brain run between these layers

Question 28

dura mater type, attachment, support, feature

Answer 28

Dense very strong fibrous membrane that is tightly adherent to the endosteum of the skull and vertebral canal. Dura supports the delicate arachnoid mater that is loosely adherent by a capillary layer of fluid, to its inner surface The dura separates from the endosteum in places, to form venous sinuses, to allow passage of arteries, and to send reflections into the fissures of the brain, which stabilize and support the brain

Question 29

3 dural reflections

Answer 29

falx cerebri tentorium cerebelli falx cerebelli

Question 30

falx cerebri

Answer 30

which extends in a saggital arc from the crista galli anteriorly, to the internal occipital protuberance in the posterior fossa, and protects the hemispheres from torsional forces

Question 31

tentorium cerebelli

Answer 31

runs between the transverse sinus laterally and the crest of the petrous part of the temporal bone anteriorly, on each side, leaving a central gap for the brain stem. It supports the weight of the occipital lobes

Question 32

falx cerebelli

Answer 32

extends from the internal occipital protuberance along the occipital crest to the foramen magnum

Question 33

Arachnoid mater = 5 points

Answer 33

1) This is a very delicate membrane between the dura and pia 2) It functions as a ‘CSF-proof’ brain covering, but it needs the dura mater outside it, for support 3) It does not extend into the sulci (but does into the median longitudinal fissure) 4) It is separated from the pia by the subarachnoid space, through which ‘web-like’ (hence arachnoid!) trabeculae pass, to attach to the pia (CSF also circulates through this space and through the ventricles) 5) The cranial nerves pierce the arachnoid as they exit the skull foramina

Question 34

Subdural space

Answer 34

There is a potential space between it and the dura (the subdural space) into which venous blood may leak, with a thin film of lymph occupying it normally

Question 35

Arachnoid villi

Answer 35

1) The arachnoid herniates into the dural venous sinuses in places, as the arachnoid villi 2) Here CSF oozes back into the venous circulation, ‘pushed’ by hydrostatic pressure, and ‘pulled’ by osmotic pressure

Question 36

Subarachnoid cisterns = 5

Answer 36

- - Between the contours of the brain and skull are several larger spaces called subarachnoid cisterns, acting as reservoirs for CSF - - These are the cerebello-medullary cistern (cisterna magna), the pontine cistern, the interpeduncular cistern and the chiasmatic cistern

Question 37

Pia mater = 5 points

Answer 37

1) This is the innermost of the three layers. 2) It is a fibrous layer closely applied to the brain surface. 3) It contains blood vessels which enter and exit the brain. It sends a sleeve to surround blood vessels entering and leaving the brain, that forms part of the blood brain barrier 4) It is prolonged over the exiting cranial nerves and spinal nerve roots to fuse with their fibrous epineurium 5) The pia of the spinal cord projects laterally as the denticulate ligaments which attach to the spinal dura mater

Question 38

supratentorial part of the dura and the upper surface of the tentorium itself innervation

Answer 38

ophthalmic branch of the trigeminal nerve

Question 39

ophthalmic branch of the trigeminal nerve

Answer 39

supratentorial part of the dura and the upper surface of the tentorium itself innervation

Question 40

anterior cranial fossa is also supplied to a lesser degree by the

Answer 40

anterior ethmoidal branch of the opthalmic nerve

Question 41

anterior ethmoidal branch of the opthalmic nerve

Answer 41

anterior cranial fossa is also supplied to a lesser degree by the

Question 42

anterior part of the middle cranial fossa

Answer 42

maxillary nerve

Question 43

maxillary nerve

Answer 43

anterior part of the middle cranial fossa

Question 44

posterior part of the middle cranial fossa

Answer 44

meningeal branch of the mandibular nerve (nervus spinosus)

Question 45

meningeal branch of the mandibular nerve (nervus spinosus)

Answer 45

posterior part of the middle cranial fossa

Question 46

undersurface of tentorium cerebelli

Answer 46

Meningeal branches of the 9th CN (glossopharyngeal)

Question 47

Meningeal branches of the 9th CN (glossopharyngeal)

Answer 47

undersurface of tentorium cerebelli

Question 48

upper part of the bony posterior fossa

Answer 48

Meningeal branches of the 10th cranial nerve - vagus

Question 49

Meningeal branches of the 10th cranial nerve - vagus

Answer 49

upper part of the bony posterior fossa

Question 50

dura around the foramen magnum

Answer 50

upper three spinal nerves

Question 51

major blood supply to the meninges

Answer 51

middle meningeal branch of the maxillary artery that enters the skull through the foramen spinosum

Question 52

meninges also supplied by (blood)

Answer 52

meningeal branches of the ophthalmic, anterior ethmoidal, internal carotid and vertebral arteries, locally