Ventricular System Flashcards

1
Q

What is tela choroidae?

A

Penetrating choroidal artery with invaginating pia mater, vascular bundle and efferent choroidal vein

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2
Q

From what is the choroid plexus formed?

A

Tela choroidae covered by ependymal cells

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3
Q

How does choroid plexus functionally produce CSF?

A

Ependymal cells lining tela choroidea have active secretory Na pumps

Cl follows the Na passively to maintain electroneutrality.

H2O is pulled with it.

Ependymal cells also possess glucose transporters and can transport glucose from blood but these are less effective, therefore CSF [glucose] < [serum glucose]

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4
Q

Rough [csf glucose] : [serum glucose]

A

0.66 : 1

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5
Q

Which substances are transported from csf to the vascular tuft of the tela choroidae?

A

K

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6
Q

What is the name for the distal dilatation of the spinal canal?

A

Terminal ventricle

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7
Q

What is the name of the dilatated subarachnoid space into which foramen luschke open?

A

(Cerebello)Pontine cistern

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8
Q

Into which subarachnoid swelling does the foramen Magendie open?

A

Cerebellomedullary cistern (cisterna magna)

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9
Q

In which portion of the lateral ventricle is the foramen of Monro found?

A

Body of lateral ventricle

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10
Q

How low does the subarachnoid space extend?

A

S2

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11
Q

What are the names of the two layers of dura mater?

A

Periosteal layer

Meningeal layer

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12
Q

What cell type lines dural venous sinsus?

A

Endothelium

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13
Q

What is an arachnoid granulation

A

Macroscopic view of arachnoid mater projecting into dural venous sinuses as arachnoid villi.

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14
Q

How does CSF move through arachnoid villi to venous drainage?

A

Via vesicular channels between endothelial cells

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15
Q

What are the key functions of CSF?

A

Cushion of protection

Buoyancy

Reservoir regulating intracranial contents/pressure

Nourishment

Metabolic waste removal

Hormone transport

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16
Q

What is the weight of brain when suspended in CSF?

A

50g

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17
Q

What is the mechanism through which raised ICP causes projectile vomiting?

A

Traction on vagus nerves

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18
Q

Leptomeninges=

A

Pia and arachnoid mater

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19
Q

Colour of normal CSF

A

Clear

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20
Q

Cellular composition of normal CSF

A

Lymphocytes- <5/mm^3

No RBC

No neutrophils

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21
Q

Glucose in normal CSF

A

[2/3 serum]

As less efficiently transported

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22
Q

Normal level of protein in CSF

A

<0.4g/L

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23
Q

Colour of CSF

in pyogenic bacterial meningitis

A

Yellow/turbid

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24
Q

Colour of CSF

in TB meningitis

A

Turbid +/- fibrin web

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25
Q

Colour of CSF

in viral meningitis

A

Clear

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26
Q

Cell count in

Pyogenic bacterial meningitis

A

High levels of neutrophils

Low lymphocytes (acute rather than chronic inflammation)

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27
Q

Cell profile in TB meningitis

A

Low neutrophils (chronic rather than acute inflammation)

High lymphocytes

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28
Q

Cell profile in viral meningitis

A

Low neutrophils (chronic rather than acute inflammation)

High lymphocytes

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29
Q

Glucose level in pyogenic meningitis

A

[<50% serum]

Bacteria use glucose

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30
Q

Glucose level in TB meningitis

A

[<50% serum]

Bacteria use glucose

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31
Q

Glucose level in viral meningitis

A

[>50% serum glucose]

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32
Q

Protein in pyogenic bacterial meningitis

A

Increased significantly

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33
Q

Protein in TB meningitis

A

Significantly increased

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34
Q

Protein in viral meningitis

A

<=1g/L

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35
Q

Def: Hydrocephalus

A

Excessive CSF within cranial cavity

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36
Q

Causes of hydrocephalus in simple terms

A

Excess production

Abnormal circulation

Impaired drainage

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37
Q

Causes of excessive CSF production?

A

Choroid plexus papilloma

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38
Q

Non-communicating hydrocephalus

A

(Obstructive)

CSF from within the ventricular system is not able to communicate with subarachnoid space

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39
Q

Communicating hydrocephalus

A

CSF able to flow from ventricular system to subarachnoid space

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40
Q

Queckenstedt’s Test

A

Test for spinal blockage of CSF using lumbar manometer

With occlusion of IJV manually, there should be increase in CSF pressure.

If there is no increase this indicates blockage of the spinal subarachnoid space

Positive if abnormal- i.e. no increase in CSF pressure with IJV occlusion

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41
Q

What constitutes blood-CSF barrier?

A

Tight junctions between choroidal epithelial cells (in contrast to BBB which is due to tight junctions between endothelial cells)

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42
Q

Macroscopic appearance of ependyma

A

The distinctive, shiny white appearance

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43
Q

Embryological associations of the CSF ventricles

A

Lateral-> telencephalon

Third-> diencephalon

Fourth- rhombencephalon

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44
Q

What is the embryological precursor to the aqueduct of Sylvius?

A

The lumen of the mesencephalon

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45
Q

Def: Frontal horn

A

The portion of the lateral ventricle anterior to the foramen of Monro continuous posteriorly with the body of the lateral ventricle.

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46
Q

If no choroid plexus is seen on entering the lateral ventricle, what is the likely location of the endoscope?

A

Anterior horn as there is no choroid plexus

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47
Q

Location of the body of the lateral ventricle

A

Predominantly in the parietal lobe

Continuous anteriorly with the frontal horn and posteriorly with the atrium

Extends from the foramen of Monro anteriorly to the limit of the septum pellucidum posteriorly

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48
Q

What is the limit of the septum pellucidum posteriorly

A

Where the fornix fuses with the corpus callosum

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49
Q

What divides the caudate from the thalamus in the lateral ventricle?

A

The caudothalamic grooove (striothalamic sulcus)

Contains the stria terminalis and thalamostriate vein

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50
Q

What is the benefit of identifying the choroid plexus when in the lateral ventricle?

A

Following it anteriorly will reliably lead to the foramen of Monro

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51
Q

Comminucations of the atrium (trigone)

A

Anterosuperiorly-> body

Anteroinferiorly-> temporal horn

Posteriorly-> occipital horn

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52
Q

Medial wall of the atrium

A

Superiorly the bulb of the corpus callosum

inferiorly the calcar avis (which overlies the calcarine sulcus)

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53
Q

Lateral wall of the atrium

A

Caudate nucleus and the tapetum of the corpus callosum

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54
Q

Floor of the atrium

A

Collateral trigone, which overlies the collateral sulcus

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55
Q

Roof of the atrium

A

Corpus callosum

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56
Q

Where is the most voluminous colloid plexus in the brain found?

A

In the atrium and is referred to as the choroid glomus which may contain benign, incidental choroid cysts and often becomes calcified with age

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57
Q

Boundaries of the temporal horn

Floor

A

Made up of the hippocampus medially and the collateral eminence laterally

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58
Q

Floor of the third ventricle

A

Bounder anteriorly by the optic chiasm and posteriorly by the opening of the cerebral aqueduct.

From A->P:

Optic chiasma, infundibulum, tuber cinereum, mamillary bodies, posterior perforated substance and mesencephalon.

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59
Q

Recesses of the third ventricle

A

Chiasmatlc recess into the angle formed by the attachment of the chiasm to the anterior wall

Infundibular recess

Bulging or rounding out of these recesses is an early indicator of HCP

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60
Q

What is the surgically important area of the floor of the third

A

Between the hypothalamus and the tuber cinereum

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61
Q

Roof of the third

A

Curves from the foramen of Monro to the suprapineal recess

Most superior layer of the roof is formed by the fornix,

tela choroidea and blood vessels form the inferior layers

62
Q

Tela choroidea

A

Two thin layers of pia mater sandwiching the medial posterior choroidal arteries and the internal cerebral veins in a space called the velum interpositum

63
Q

Anterior wall of the third

A

Foramen of Monro superiorly

Anterior commissure

Lamina terminalis

Optic recess

Optic chiasm

64
Q

Posterior wall of the third

A

Suprapineal recess

The commissure of the habenula

Body of the pineal and its associated recess

Posterior commissure and the mesencephalic opening of the aqueduct.

65
Q

Lateral wall of the third

A

Made up of the thalamus and hypothalamus which are demarcated by the hypothalamic sulcus

66
Q

What is the prevalence of the massa intermedia?

A

Absent in up to 25%

67
Q

Vertical divisions of the floor of the fourth

A

Divided into two lateral halves by the median sulcus

Sulcus limitans is lateral to median sulcus and the medial eminences run between these

68
Q

Three triangles of the lower part of the fourth

A

Hypoglossal triangle

Vagal triangle

Area postrema

69
Q

Location of the vestibular area in the floor of the fourth?

A

Lateral to medial eminence

70
Q

What demarcates the superior and inferior triangles in the floor of the fourth?

A

Striae medullares which contains cochlear fibres

71
Q

What makes up the cranial portion of the roof of the fourth?

A

Superior cerebellar peduncles and their interconnecting superior medullary velum

72
Q

What makes up the caudal roof of the fourth ventricle?

A

Consists of ependymal and non-neural inferior medullary velum with a layer of tela choroidea

73
Q

Use of anterior transcallosal approach

A

The anterior portion of the lateral ventricle

Access to third ventricle

74
Q

Advantages of the anterior transcallosal approach

A

Avoids cortical incision

Reduces risk of seizures and cortical deficit

Feasible even with small or normal ventricles

Allows access to both ventricles

75
Q

Disadvantages of anterior transcallosal approach

A

Potential injury to falcine bridging veins

Relatively narrow working corridor

Disconnection-type syndromes are extremely rare

76
Q

Beta-transferrin

A

Transferrin isomer found in CSF and inner ear perilymph

Positive in CSF leak (though may also suggest perilymph leak if otorrhoea)

77
Q

Ions in CSF compared to plasma

A

Same Na, osmolarity

Increased Cl

Reduced K, Ca, uric acid and glucose

78
Q

Froin’s Syndrome

A

CSF xanthochromia

High protein

Coagulation (due to presence of fibrinogen)

Occurs when CSF loculated, usually in the lumbar thecal sac

Can be caused by dural irritation, blockage of CSF flow by tumour or abscess

79
Q

Normal CSF glucose

A

2/3rds of serum

normal CSF glucose levels lie between 2.5 and 4.4 mmol/L

80
Q

CSF specific gravity

A

1.007

81
Q

CSF pH

A

7.33-7.35

82
Q

Traumatic tap cell count

A

700 RBCs per 1 WBC

83
Q

Sites of CSF production

A

70% choroid plexus

18% ultrafiltrate

12% H2O production from metabolism

84
Q

Control of CSF production

A

Raphe nuclei send axons (5HT) to the periependymal vessels

85
Q

Factors causing decreased CSF production

A

Carbonic anhydrase inhibitors

Noradrenaline

86
Q

Factors causing increased CSF production

A

Volatile anaesthetics

Increased CO2

87
Q

CSF volume within ventricles

A

25mL

88
Q

Location of choroid plexus

A

Roof of fourth

Inferior medullary velum and lateral recess to the foramen of Luschka

Posterior roof of third

Floors of the bodies and roofs of the temporal horns of the lateral ventricles

89
Q

CSF production ml/min

A

0.3-0.37

90
Q

Normal ICP in adults

A

5-15mmHg

91
Q

Normal ICP in younger children

A

3-8mmHg

92
Q

Normal ICP in infants

A

1.5-6mmHg

93
Q

Constituents of BBB

A

Capillary endothelial tight junctions

Pinocytic activity in endothelial cells

Astrocytic foot processes

94
Q

Mechanisms of molecular movement across the BBB

A

Diffusion

Carrier-mediated transport

Active transport

95
Q

BBB highly permeable to which substances?

A

H2O

CO2

O2

Lipid-soluble drugs e.g. ETOH, barbiturates, heroin, anaesthetics

96
Q

BBB slightly permeable to which substances

A

Ions

Na, Cl, K

97
Q

BBB Impermeable to which substances?

A

Plasma proteins

Protein bound molecules

Large organic molecules

L-glucose

98
Q

Def: Circumventricular organ

A

Midline ventricular system structures of specialised tissues with absent BBB due to fenestrated capillaries

99
Q

Circumventricular organs from rostral->caudal

A

Organum vasculosum (lamina terminalis)

Neurohypophysis

Median eminence of hypothalamus

Subfornical organ

Subcommisural organ

Pineal gland

Area postrema

100
Q

Function:

Organum vasculosum

A

Outlet for hypothalamic peptides

Detects peptides, amino acids and proteins in blood

101
Q

Function:

Neurohypophysis

A

Outlet for hypothalamic hormones (vasopressin and oxytoxin)

102
Q

Function:

Median eminence of hypothalamus

A

Release hypothalamic releasing factors

103
Q

Function:

Subfornical organ

A

May be involved in body fluid regulation

Located between the foramina of Monro

Connected to choroid plexus

104
Q

Function;

Pineal gland

A

Melatonin production

Role in circadian rhythm

105
Q

Function:

Subcommissural organ

A

Unknown

Only circumventricular organ with intact BBB

106
Q

Function:

Area postrema

A

Chemoreceptor that induces emesis when stimulated by digitalis or apomorphine

Floor of fourth ventricle

Only paired circumventricular organ

107
Q

Taenia choroidea

A

2 narrow bands of WM one on either side, which complete the lower part of the roof of the fourth ventricle.

Each consists of a vertical and a horizontal part.

The vertical part is continuous below the obex with the gracile nucleus, to which it is adherent by its lateral border.

The horizontal portion extends transversely across the inferior peduncle, below the striæ medullares, and roofs in the lower and posterior part of the lateral recess

Attached by its lower margin to the inferior peduncle, and partly encloses the choroid plexus, which, however, projects beyond it like a cluster of grapes; and hence this part of the tænia has been termed the cornucopia.

108
Q

CSF xanthochromia

High protein

Coagulation (due to presence of fibrinogen)

Occurs when CSF loculated, usually in the lumbar thecal sac

Can be caused by dural irritation, blockage of CSF flow by tumour or abscess

A

Froin’s Syndrome

109
Q

Boundaries of the frontal horn of the lateral ventricle

Anterior wall

A

Anterior wall: genu of the corpus callosum

110
Q

Boundaries of the frontal horn of the lateral ventricle

Floor

A

Rostrum of corpus callosum

111
Q

Boundaries of the frontal horn of the lateral ventricle

Roof

A

Genu of corpus callosum

112
Q

Boundaries of the frontal horn of the lateral ventricle

Lateral wall

A

Head of caudate nucleus

113
Q

Boundaries of the frontal horn of the lateral ventricle

Medial wall

A

Septum pellucidum

114
Q

Border of body of lateral ventricle

Roof

A

Body of the corpus callosum

115
Q

Borders of the body of lateral ventricle

Medial wall

A

Continuation of the septum pellucidum in upper part and fornix in the lower

116
Q

Borders of the body of lateral ventricle

Floor

A

Sloping from lateral to medial:

Body of caudate

Thalamus

Choroid plexus

Body of fornix

117
Q

Borders of the body of lateral ventricle

Lateral wall

A

Caudate nucleus

118
Q

Boundaries of the temporal horn

Roof

A

Lateral roof formed by tapetum

Medial roof is the inferior thalamus, caudate tail and intervening caudothalamic groove

119
Q

Boundaries of the temporal horn
Lateral wall

A

Tapetum

120
Q

Boundaries of the temporal horn

Medial

A

Choroidal fissure

121
Q

Boundaries of the temporal horn

Anterior

A

Amygdaloid nucleus

122
Q

Location of crural cistern

A

Between uncus and crus cerebri at ventrolateral aspect of midbrain

123
Q

Contents of crural cistern

A

Anterior choroidal artery

Medial posterior choroidal artery

Basal vein of Rosenthal

124
Q

Contents of cisterna magna

A

VA and PICA origin

9/10/11/12

Choroid plexus

125
Q

Prepontine cistern contents

A

BA

AICA origin

SCA origin

CN6

126
Q

CP cistern contents

A

5

7/8

AICA

Petrosal vein

127
Q

Communication of interpeduncular cistern

A

With Ambient

With PComm cistern

Prepontine and cerebellopontine cisterns

128
Q

Division of the interpeduncular cistern

A

BA bifurcation divides cistern into deep and superficial portions

Superficial portion adjoins CN3 and deep communicates with ambient cistersn

Deep subdivided by posterior perforated membrane- anterior and posterior areas

129
Q

Contents of interpeduncular cistern

A

Arteries:

BA bifurcation

PCA

SCA

PCA perforators

PComm

Veins:

Basal vein of Rosenthal

Nerves:

3

130
Q

Contents of chiasmatic cistern

A

Anterior aspect of chiasm and optic nerves

Hypophyseal stalk

ACA origin

131
Q

Contents of carotid cistern

A

ICA

Anterior choroidal

PComm

132
Q

Sylvian cistern contents

A

MCA

Middle cerebral veins

Fronto-orbital veins

Collaterals to vein of Rosenthal

133
Q

Contents of lamina terminalis cistern

A

ACA (A1 and A2)

AComm

Heubner’s

Hypothalamic

Fronto-orbital arteries

134
Q

Quadrigeminal cistern contents

A

Arteries:

The third portion of SCA

Posterior pericallosal

PCA perforators

P3

Medial posterior choroidal

Veins:

VoG

135
Q

Contents of the ambient cistern

A

Supratentorial portion:

Basal vein of Rosenthal

PCA

Infratentorial portion:

SCA

4

136
Q

Anterior border of atrium + occipital horn of lateral ventricle

A

Crus of fornix medially

Pulvinar of thalamus laterally

137
Q

Medial border of atrium + occipital horn of lateral ventricle

A

Forceps major of corpus callosum superiorly

Calcar avis inferiorly

138
Q

Lateral border of atrium + occipital horn of lateral ventricle

A

Caudate nucleus

Fibres of tapetum

139
Q

Inferior border of atrium + occipital horn of lateral ventricle

A

Collateral trigone

140
Q

Blood supply of choroid plexus in the body of lateral ventricle

A

From medial posterior choroidal arteries passing forward through velum interpositum

141
Q

4 layers of tissue between body of lateral ventricle and third

A

fornix, upper layer of tela, velum interpositum (containing medial posterior choroidal arteries, internalcerbral veins), lower layer of tela

142
Q

Which side does Rhoton suggest opening when opening choroidal fissure

A

Forniceal side- allow thalamus and choroid to on other side to reduce traction on thalamus and risk of thalamic venous infarction

143
Q

What are the 5 layers of the roof of the third

A

Neural layer- fornices
2nd: Sup layer of tela choroidea

Velum interpositum
3rd: Vascular ayera: ICV and Post choroidal

4th: inf layer of tela choroidea

5th: choroid plexus of lateral ventricle which extends posterosuperiorly from foramen of monro

144
Q

Attachments of the chorodi plexus of the lateral ventricle

A

Ependymal attachment to the fornix (taenia fornicis) and the thalamus (taenia thalmi)

145
Q

What is the operative significance of the choroid plexus attachments

A

The taenia fornicis is avascular whereas the taenia thalami contains tributaries of the ICV and the medial PChA

Opening the taenia fornicis thus avoids these structures

146
Q

Floor of third from A->P

A

Anterior half: diencephalic
Optic chiasm, infundibular recess, median eminence, tuber cinereum, mamillary podies and posterior perforated substance

Posterior:
Mesencephalic
Tegmentum of the midbrain, aqueduct of sylvius

147
Q

Anterior wall of the third ventricle

A

Columns of fornix, foramina of Monro, Anterior commissure, lamina terminalis, optioc recess and chiasm

148
Q

Posterior wall of. thethird ventricle

A

Suprapineal recess
Habenular commisure
Sylvian aqeuduct

149
Q

What delineates the walls of the thid

A

Hypothalamic sucus- thalamus superiorly and hypothalamus inferiorly

150
Q
A

CP: chorodi plexus
MI: massa intermedia
VI: velum interpositum
HC: habenular commisure
PC: posterior commisure
SC: superior colliculus
MB: mamillary body
OC: chiasm