Development of the brain Flashcards
Describe how the CNS becomes a closed system
Following the process of neuralation the neural tube remains opened at the caudal and cranial ends. These openings are known as the caudal and cranial neuropores aka as the posterior and anterior neuropores. These ports have to close before the central nervous system can form. Therefore, the CNS becomes a closed system
what do the cranial and caudal part form?
the cranial part of the neural tube will form the brain, while the caudal part forms the spinal cord.
list and describe the three sections that form in the cranial part of the brain
Two constrictions will form in the cranial part of the neural tube an as a result three dilations/ sections will form.
These three dilations/ sections are known as the primary brain vesicles.
1. Prosencephalon- forebrain (Two optic stalks form on either side of the prosencephalon)
2. Mesencephalon-midbrain
3. Rhombencephalon- hindbrain
what are the two divisions that arises from the optic stalks at the prosencephalon
Cranially: telencephalon
Caudally: diencephalon
does the mesencephalon divide?
no
what does the rhombencephalon divide into
Metencephalon
Myelencephalon
summary of the five vesicles
- Telencephalon- cerebrum
- Diencephalon- thalamus, hypothalamus and epithalamus
- Mesencephalon- midbrain
- Metencephalon- pons and cerebellum
- Myelencephalon- medulla oblongata
describe how the brain flexures occur
With further embryonic development this brain will start to bend at certain regions.
At the end of the third week the brain grows rapidly and the telencephalon bends ventrally to form the cephalic flexure.
At the fifth week another flexure will form caudally to the metencephalon- known as the cervical flexure.
Around the seventh week another flexure forms, but this flexure forms in the opposite direction to the other two flexures and this flexure is known as the pontine flexure.
The cephalic flexure forms at the mesencephalon and is thus also known as the mesencephalic flexure.
The cervical flexure forms between the myelencephalon and the spinal cord.
The pontine flexure divides the rhombencephalon into the metencephalon and myelencephalon.
cephalic flexure
Develops in 3rd week
In region of mesencephalon
aka mesencephalic flexture
cervical flexure.
Cervical flexture
Develops in 5th week
Between myelencephalon and spinal cord
pontine flexure.
Develops in 7th week
Divides rhombencephalon into metencephalon and myelencephalon
Development of the telencephalon
During the 7th week, the cranial part of the telencephalon will give rise to two large diveticular on either side (the telencephalic vesicles).
The undistended part of the telencephalon is known as the telencephalic median
The lamina terminalis marks the closure of the anterior neural pore
Induces the formation of the cranial vault of the skull
the telencephalic vesicles will form the cerebral hemispheres
telencephalic vesicles
These diverticulars are known as the telencephalic vesicles- these form the cerebral hemipheres. The cavities with the telencephalic vesicles are the lateral ventricles. The lateral ventricles are in open communication by the telencephalon medium. These lateral opening will later narrow to form the interventricular laminae.
The third ventricle will form by the cavity of the telencephalon medium and the cavity of the diencephalon.
telencephalon medium
The unextended part of the telencephalon is known as the telencephalon medium
lamina terminalis
The lamina terminalis marks the closure of the anterior neuropore- this induces the formation of the cranial vault in the skull.
