Development of the Nervous System

Question 1

Which embryonic layer does the nervous system develop from?

Answer 1

Ectoderm

Question 2

Main insulators of the peripheral nervous system.

Answer 2

Schwann cells

Question 3

Neurulation

Answer 3

The formation and closure of the neural tube

Question 4

The main events of neuralation (in order):

Answer 4

(1) The NOTOCORD induces the overlying ectoderm to differentiate into neuroectoderm and form the neural plate.
(2) The neural plate folds to give rise to the NEURAL TUBE, which is open at both ends at the anterior and posterior neuropores.
(3) As the neural plate folds, some cells differentiate into NEURAL CREST CELLS and form a column of cells along both sides of the neural tube.

Question 5

What does the notochord directly become in an adult?

Answer 5

The nucleus pulposus

Question 6

The rostral part of the neural tube becomes the adult…

Answer 6

Brain

Question 7

The caudal part of the neural tube becomes the adult…

Answer 7

Spinal Cord

Question 8

The lumen of the neural tube gives rise to the…

Answer 8

Ventricular system of the brain and central canal of the spinal cord.

Question 9

What is the origin and general fate of neural crest cells?

Answer 9

They differentiate from the NEUROECTODERM of the neural tube and Forms column of cells along both sides of the neural tube.

Neural crest cells undergo a prolific migration throughout the embryo (both the CRANIAL and TRUNK region), and ultimately differentiate into a wide array of adult cells and structures.

Question 10

What are the 5 secondary brain vesicles? When do they develop?

Answer 10

(1) Telencephalon
(2) Diencephalon
(3) Mesencephalon
(4) Metencephalon
(5) Rhombencepalon

Develop during week 6 and form various adult derivatives of the brain

Question 11

What does the telencephalon form?

Answer 11

Cerebral cortex, basal ganglia, hippocampus , amygdala

Question 12

What does the Diencephalon form?

Answer 12

Thalamus, hypothalamus, choroid plexus, pineal body

Question 13

What does the Metencephalon form?

Answer 13

Pons, cerebellum

Question 14

The spinal cord develops from the…

Answer 14

Neural tube

Question 15

Alar plate

Answer 15

Sensory

Question 16

Basal plate

Answer 16

Motor

Question 17

Sulcus Limitans

Answer 17

Longitudinal groove in lateral wall of the neural tube which separates the alar and basal plates.

Question 18

Caudal Eminence

Answer 18

Gives rise to sacral and coccygeal segments of the spinal cord. Arises from the primitive streak and blends with the neural tube.

Question 19

Rhombic Lip

Answer 19

The cerebellum develops from this. It is a metencephalic thickening at the rostral border of the fourth ventricle.

Question 20

White mater and gray mater locations (brain vs spinal cord)

Answer 20

In brain white mater is deep to the more superficial gray mater.

In spinal cord the white mater forms superficial to the gray mater

Question 21

Spina Bifida

Answer 21

Occurs when the bony vertebral arches fail to form properly, thereby creating a vertebral defect usually in the lumbosacral region. Often can be avoided with folic acid supplements for mom.

Question 22

A 7 day old infant was evaluated because of intermittent vomiting that began a day after birth. A barium enema demonstrated contraction of the colon near the rectum and a length of colon proximal to the contraction was severely distended. Biopsy revealed an absence of autonomic ganglia cells in the colon. The most likely cause of this disorder was:

Answer 22

A defective formation or migration of neural crest cells.

Question 23

In the development of the medulla, how does location of cells effect future functioning?

Answer 23

Future motor components are found in the middle of the MYELENCEPHALON.

Future sensory components are found in the lateral sections.

Question 24

As the brainstem develops, it expands laterally, forming the…

Answer 24

4th ventricle.

Question 25

What foramen is associated with the lateral aperture?

Answer 25

Foramen of Luschka (2 of them)

Question 26

What foramen is associated with the median aperture?

Answer 26

Formamen of Magendie (1 of them)

Question 27

The 3 regions of the midbrain

Answer 27

• Tectal (Dorsal)
• Tegmentum (Intermediate)
• Peduncular (Ventral)

Question 28

How do the lateral ventricles communicate with the 3rd ventricle?

Answer 28

Via the interventricular foramen of Monro

Question 29

General role of the hippocampus

Answer 29

Constant sampling of what is going on in the brain

Question 30

3 main types of Spina Bifida

Answer 30

SB Occulta (Least servere- multiple dimples in the back of infant. May or may not be accompanied by tufts of hair)
SB Cystica (Worse)
SB Rachischisis (worst- paralysis from the level of defect)

Question 31

Menigo- cele

Answer 31

Ossification defects in the bones of the skull which can lead to this breed of cranial defect.

Question 32

Exencephaly

Answer 32

Characterized by failure of the cephalic neural tube to close. Results in failure of the skull to form, leaving the malformed brain exposed. Tissue typically becomes necrotic, leading to ANENCEPHALY.

Question 33

Hydrocephalus

Answer 33

Abnormal accumulation of CSF within the ventricular system due to blockage or narrowing of the aqueduct of Sylvius. Fluid build-up causes developing skull to press out and skull to expand and become very large and thin.

Question 34

Arnold-Chiari malformation

Answer 34

Caudal displacement and herniation of the posterior cranial fossa structures, namely the cerebellum, through the foramen magnum.

Question 35

Microcephaly

Answer 35

Cranial vault which is smaller than normal, normally due to lack of brain development. Impaired mental development is associated with more than 50% of these cases.

Question 36

What does the mesencephalon form?

Answer 36

Midbrain