Embryology of the brain

Question 1

When does the CNS appear and what does it appear as?

Also state the location.

Answer 1

CNS appears in 3rd week as
slipper-shaped plate of 
ectoderm thickening = Neural 
Plate, located in front of 
primitive pit.

Question 2

How is the neural tube formed?

Answer 2

Lateral edges are elevated to
form neural folds, which finally
fuse = Neural Tube.

Question 3

Where does the fusion begin and proceed?

Answer 3

Fusion begins in the cervical region
& proceeds in cephalic and
caudal directions.

Question 4

List the 3 dilations[brain vesicles].

Answer 4

(i) Prosencephalon (Forebrain)
(ii) Mesencephalon (Midbrain)
(iii) Rhombencephalon (Hindbrain)

Question 5

Prosencephalon (Forebrain) →

Answer 5

Telencephalon : Lateral ventricle

Diencephalon : 3rd Ventricle

Question 6

Rhombencephalon (Hindbrain)→

Answer 6

Metencephalon : Upper part of 4th
ventricle
Mylencephalon : Lower part of 4th
Ventricle

Question 7

Cervical flexure :

Answer 7

At the junction of the hindbrain & spinal

cord

Question 8

Cephalic Flexure:

Answer 8

In midbrain region

Question 9

The prosencephalon consists of 2 parts :

Answer 9

Telencephalon and diencephalon

Question 10

TELENCEPHALON :

Answer 10

formed by midpoint & 2
lateral outpocketings: cerebral
hemispheres

Question 11

DIENCEPHALON :

Answer 11

characterized by outgrowth:

optic vesicles

Question 12

Mesencephalon :

Answer 12

forms the

Midbrain

Question 13

Rhombencephalon

Consists of 2 parts:

Answer 13

• Metencephalon

* Myelencephalon

Question 14

Metencephalon:

Answer 14

Pons &

Cerebellum

Question 15

Myelencephalon:

Answer 15

Medulla

oblongata & Spinal Cord

Question 16

Between these 2 portions:

Answer 16

pontine flexure

Question 17

Neural Tube Defect :

Answer 17

Spina Bifida

Question 18

Cleft vertebral column :

Answer 18

Rachischisis

Question 19

Defect in dura & cranium with associated extra cranial herniation, related to
abnormal closure of the neural tube:

Answer 19

Cephalocele

Question 20

Herniation of meninges with CSF:

Answer 20

Meningocele

Question 21

Herniation of brain &meninges :

Answer 21

Encephalocele

Question 22

Failure of the brain and skull development :

Answer 22

Anencephaly

Question 23

Failure to separate into hemispheres :

Answer 23

Holoprosencephalies

Question 24

Defective development of roof of fourth ventricle :

Answer 24

Dandy Walker\