Development of CNS Flashcards
Anatomical terminology
What is the sagittal plane?
Divides body into right and left half
What is the coronal plane?
Divides body into anterior and posterior
What does ‘rostral’ mean?
Towards head (nose)
What does ‘caudal’ mean?
Anything towards tail (feet)
What is the cephalic flexure?
the first flexure or bend that forms between the midbrain and hindbrain (bend in CNS)
Different terminology due to bend in CNS
Explanation of different terminology due to bend in CNS
Why can ‘superior’ also be referred to as ‘dorsal’ regarding the forebrain?
Due to this part arising from the dorsal aspect
When referring to the forebrain, what is the ‘superior’ aspect the same as?
The dorsal surface
When referring to the forebrain, what is the ‘caudal’ aspect the same as?
The posterior surface
When referring to the forebrain, what is the ‘rostral’ aspect the same as?
Anterior surface
When referring to the forebrain, what is the ‘ventral’ aspect the same as?
Inferior surface
When does the nervous system start to develop?
In the 3rd week of development
At the end of week two, what appears as a groove in the epiblast layer of the bilaminar disk?
The primitive streak
Cells within the epiblast migrate downward through the primitive streak, giving rise to what three layers?
- Endoderm
- Mesoderm
- Ectoderm
What do these 3 germ layers form?
The trilaminar embryonic disk
What layer is the nervous system derived from?
The ectoderm (outermost layer)
In the third week of development, the notochord appears in the mesoderm. What does the notochord secrete? What is the effect of this?
The notochord secretes growth factors which stimulate the differentiation of the overlying ectoderm into neuroectoderm – forming a thickened structure known as the neural plate.
What then happens to the lateral edges of the neural plate?
They rise to form neural folds
What happens to the neural folds?
he neural folds move towards each other and meet in the midline, fusing to form the neural tube (precusor to the brain and spinal cord).
During fusion of the neural folds, some cells within the folds migrate to form a distinct cell population. What is this called?
Neural crest
What does the neural crest give rise to?
They give rise to a diverse cell lineage – including melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neurons and glia
What is this formation of neural tube known as?
Neurulation
When is neurulation achieved by?
End of 4th week of development
What is the development of the neural plate (thickening of overlying ectoderm) induced by?
Notochord
What is the precursor for the spinal cord and brain (CNS)?
Neural tube (this is a closed structure)
At what end does the neural tube begin to bend?
At the rostral end
In the fifth week of development, what appears at the cranial end of the neural tube? What will these develop into?
3 swellings/vesicles - will develop into brain
What are these 3 vesicles called?
- Prosencephalon
- Mesencephalon
- Rhombencephalon
What is the prosencephalon also known as?
Forebrain
What is the mesencephalon also known as?
Midbrain
What is the rhombencephalon also known as?
Hindbrain
What will everything caudal to the rhombencephalon become?
The spinal cord
Is the neural tube hollow?
Yes (like kitchen roll)
What fluid is found inside the neural tube?
Cerebral spinal fluid
What do these 3 vesicles then develop into?
5 secondary vesicles
What are the 5 secondary vesicles called?
- Telencephalon
- Diencephalon
- Mesencephalon
- Metencephalon
- Myelencephalon
What secondary vesicles does the prosencephalon give rise to?
- Telencephalon
- Diencephalon
What does the telencephalon then give rise to in the mature brain?
Cerebral hemispheres
What does the diencephalon then give rise to in the mature brain?
Thalamus, hypothalamus, and epithalamus
What secondary vesicles does the mesencephalon give rise to?
Continues as the mesencephalon
What will the mesencephalon then give rise to in the mature brain?
Midbrain
What 2ary vesicles does the rhombencephalon give rise to?
- Metencephalon
- Myelencephalon
What will the metencephalon give rise to in the mature brain?
Pons and cerebellum
What will the myelencephalon give rise to in the mature brain?
Medulla
What happens to the lumen of the neural tube after the 5 2ary vesicles?
It remains - beginnings of ventricular system and central canal
Fill in the blanks
What do each of the 5 swellings at the rostral end form?
A subdivision of adult brain
The cavity of the neural tube persists in different degrees of expansion throughout the tube:
- Ventricles
- Connecting channels
- Vestigial
What are each of these?
- Ventricles - expanded cavities within the brain
- Connecting channels - link ventricles
- Vestigial - central canal of spinal cord
What is the central canal of the spinal cord called?
Vestigial
How many are the subdivisions of the CNS are there?
7: Hemispheres, diencephalon, midbrain, medulla, pons, cerebellum and spinal cord
