CNS Development/Subdivisions

Question 1

What stage and time-line relationship does the nervous system present?

Answer 1

The nervous system develops in the 2-8 weeks during the embryonic stage.

Question 2

What are the temporal stages of neural tube development?

Answer 2

Neural plate, fold, tube.

Question 3

What histological change occurs in the neural plate?

Answer 3

Simple cuboidal to simple columnar

Cuboidal= Ectoderm
Columnar= Neural Plate

Question 4

What sequence does the neural plate undergo?

Answer 4

The plate folds along the anterior/posterior axis forming the neural groove.

Question 5

How is the neural tube finalized?

Answer 5

Opposing edges of the neural folds fuse along anterior/posterior axis.

Separates from the simple cuboidal ectoderm.

Question 6

What days due the cranial and caudal pores finalize themselves.

Answer 6

27 and 30, respectively.

Question 7

What are the primary subdivisions of the Neural Tube? And What is the brain called at this point?

Answer 7

Prosencephalon
Mesencephalon
Rhombencephalon

Tripartite Brain

Question 8

What are the secondary subdivisions of the brain?

And what is the brain called?

Answer 8

Prosencephalon

1. Telencephalon
2. Diencephalon

Mesencephalon

Rhombencephalon

1. Telencephalon
2. Diecephalon

Pentaparite Brain

Question 9

What do the 4 ventricles contain and what is it from?

Answer 9

CFS and it is a dialyate of blood or a derivative.

Question 10

What are the anomalies in the neural tube?

Answer 10

Crainial

1. Anencephaly
2. Holoprosencephaly

Caudal

1. Spina Bifida Occulta=hidden
2. Spina cystica x 3

Question 11

Anencephaly?

Answer 11

Failure of cranial closure.

Question 12

Holoprosencephaly?

Answer 12

Failure of left and right cerebral hemispheres from prosencephalon.

Eye deformations
Proboscis-type nose
Cleft lip/palate.

Question 13

Spina Bifida?

Answer 13

Folate…DNA

Occulta
Failure of inferior neuropore
Spinal cord normal

Cystica X 3
Sac-like cyst at end of spine.
Meninges may be present
Bladder and bowel function impairment

Question 14

SB Meningocele?

Answer 14

Only meninges

Severity various

Question 15

SB Meningomyelocele?

Answer 15

Meninges and spinal cord

Abnormal growth of spinal cord

Lower extremity paralysis

Bowl and bladder dysfunction

Question 16

SB Myeloschisis?

Answer 16

Most severe

Failure of neural folds to close

Question 17

What is Arnold-Chiari Deformity?

Answer 17

Inferior cerebellum and medulla elongate/protrude in vertebral canal

Medulla/Pons deformed

Hydrocephalus

Lower cranial nerves affected 6, 7, 8

1. Deafness
2. Weakness in tongue, face, and lateral eye motions

Question 18

What are the structures of the Telencephalon?

Answer 18

Lumina=Lateral ventricles I,II

Floor
Basal ganglia=voluntary motor action
Olfactory lobes and nerves

Roof
Cerebral hemisphere

Question 19

What are the structures of the Diencephalon?

Answer 19

Lumen
3rd ventricle

Roof
Epithalamus

Wall
Thalamus

Floor
Hypothalamus & infundibulum
…Hormones discussed from last term

Question 20

What are the structures of the Mesencephalon?

Answer 20

Lumen
Cerebral aqueduct

Roof
Superior/inferior colliciuli =vision

Floor
Tegmentum

Question 21

What are the structures of here Metencephalon?

Answer 21

Lumen
Part of 4th ventricle

Roof
Cerebellum

Floor
Pons

Question 22

What the structures of the Myelencephalon?

Answer 22

Lumen
Rest of 4th ventricle

Main
Medulla oblongata

Roof
Posterior choroid plexus

Question 23

What are the functions of the Telencephalon structures?

Answer 23

Olfactory=smelling

BasalGanglia=
subconscious motor control/tone

Cerebral Cortex=gyri and sulci
Hills and valleys

Question 24

What are the functions of the Diencephalon structures?

Answer 24

Thalamus=major relay center for afferent/efferent from/to cerebrum

Epithalamus=Habenular nuclei for emotional/visceral recall. Pineal body

Hypothalamus=
Mammillary bodies for olfactory reflexes and emotional recall

Supraoptic/paraventricular nuclei

Controls ANS

Intermediary for nervous and endocrine

Regulates Temperature

Regulates Extracellular fluid volume

Biorhythms/Oscillation

Question 25

What is the structure and what are the functions of the Cerebellum?

Answer 25

Cortex with Peduncles= Form fiber track connections

1. Inferior to medulla and spinal cord
2. Middle to pons
3. Superior to midbrain

Coordinate biomechanics
Balance/posture/position
Proper firing patterns for synergism

Question 26

What are the functions of the Mesencephalon structures?

Answer 26

Nuclei of CN 3-4

Tectum=roof

1. Superior colliciuli= visual reflexes
2. Inferior colliciuli= auditory & olfactory

Tegmentum

1. Red nucleus
2. Substantial Nigra= Parkinson’s Disease

Question 27

What are the functions of the Metencephalon structures?

Answer 27

Pons

CN 5-8

Pontine nuclei= relay for cerebrum and cerebellum

Center for sleep and respiratory

Cerebellum

Question 28

What are the functions of the Myelencephalon structures?

Answer 28

Medulla

Nuclei for 
Vestibular nuclear complex=balance
Sensory=incoming
Reticular formation=reptilian brain
1. Alert Center=fight or flight

Pyramids
Lateral corticospinal tracts

Olives
Nuclei related to cerebellum

Vital Reflex Centers
Heart, Vasomotor, Respiration

Question 29

What are the 3 objectives for this lecture?

Answer 29

1. Describe development of neural tube.
2. Describe anomalies in neural tube development
3. Neural tube divisions and subunit development with functions.