Fourth Ventricle

Question 1

Definition and site

Answer 1

Cavity of hindbrain lying between pons and upper part medulla (in front) and cerebellum (behind)

Question 2

Shape and angles

Answer 2

Diamond shaped
4 angles
1. Upper angle
2. Lower angle
3. Lateral angle

Question 3

Upper angle

Answer 3

Continuous with sylvius aqueduct

Question 4

Lower angle

Answer 4

Continuous with central canal closed medulla

Question 5

Lateral angle

Answer 5

2 lateral angles
Each at meeting of SCP and ICP of its own side

Question 6

Boundaries

Answer 6

1. Roof
2. Floor
3. 2 lateral borders

Question 7

Lateral borders

Answer 7

1. Above
2. In middle
3. Below

Question 8

Lateral borders: above

Answer 8

SCP

Question 9

Lateral borders: in middle

Answer 9

Lateral angle forming lateral recess

Question 10

Lateral borders: below

Answer 10

1. Gracile tubercle
2. Cuneate tubercle
3. ICP

Question 11

Floor

Answer 11

Divided by median longitudinal sulcus into 2 similar halves
It is also divided by transverse nerve bundles (medullary stria) into:
1. Upper pontine part
2. Lower medullary part

Question 12

Upper pontine part

Answer 12

Dorsal (tegmental) surface pons

Question 13

Dorsal surface pons

Answer 13

Forms upper 1/2 of 4th ventricle floor separated from back of open medulla by medullary stria and bounded lateral by SCP

Question 14

Dorsal surface pons features

Answer 14

1. Medial eminence and facial colliculus
2. Sulcus limitans
3. Upper vestibular area

Question 15

Medial eminence and facial colliculus

Answer 15

(At medial eminence lower end produced by abducent nucleus and encircling facial nerve fibers

Question 16

Sulcus limitans

Answer 16

Lateral to medial eminence and its lower part lies lateral to facial colliculus and called superior fovea

Question 17

Upper vestibular area

Answer 17

Overlies superior and lateral vestibular nuclei

Question 18

Dorsal surface of medulla upper 1/2 (open medulla)

Answer 18

Forms lower 1/2 of 4th ventricle floor separated from pons back by medullary stria and bounded lateral by ICP

Question 19

Open medulla transversed by

Answer 19

1. Vertical median sulcus
2. Lateral to it inverted v shaped depression (inferior fovea)
3. On each side, inferior fovea divides medullary part in 3 triangular areas

Question 20

Medullary part of open medulla is divided into 3 parts from medial to lateral

Answer 20

1. Hypoglossal trigone
2. Vagal trigone
3. Lower vestibular area

Question 21

Hypoglossal trigone

Answer 21

Overlies hypoglossal nerve nucleus

Question 22

Vagal trigone

Answer 22

Overlies vagus nerve dorsal nucleus

Question 23

Lower vestibular area

Answer 23

Overlies inferior and medial vestibular nuclei

Question 24

Area postrema

Answer 24

1. Vomiting center
2. Protruberence at 4th ventricle inferoposterior limit

Question 25

Superior roof

Answer 25

Superior medullary velum (thin sheet of white matter connecting 2 SCP)

Question 26

Inferior roof: upper area

Answer 26

Cerebellum nodule and inferior medullary velum (connecting 2 ICP)

Question 27

Inferior roof: lower area

Answer 27

Tela choroidea of 4th ventricle (where choroid plexus invaginates 4th ventricle and where pia mater comes in contact with ependyma).

Question 28

Recesses

Answer 28

1. Median recess 2. 2 lateral recesses

Question 29

Median recess

Answer 29

4th ventricle roof is drawn backwards towards cerebellum forming median recess with upper wall formed by superior medullary velum and lower wall formed by cerebellum

Question 30

2 lateral recesses

Answer 30

1. At 4th ventricle lateral angles 2. Each runs forward around medulla to open anterior into subarachnoid space by lateral aperture (foramen luschka)

Question 31

Communication

Answer 31

1. Upper angle 2. Lower angle 3. With subarachnoid space

Question 32

Communication: upper angle

Answer 32

Communicates with 3rd ventricle through sylvius aqueduct

Question 33

Communication: lower angle

Answer 33

Communicates with central canal of medulla

Question 34

Communication: subarachnoid space

Answer 34

By median (foramen of magendie which opens in cisterna magna) and 2 lateral apertures (foramina of luschka which open into ponto-medullary cistern)

Question 35

Choroid plexus

Answer 35

1. Invaginates lowermost area of 4th ventricle roof above median aperture of magendie 2. T shaped with median stem and 2 arms extending to lateral recesses 3. Blood supply is posterior inferior cerebellar arteries