S1: Development of the Brain Flashcards
What are the 5 major divisions of the brain?
- Cerebral hemispheres
- Diencephalon
- Midbrain
- Pons
- Medulla
What three layers make the trilaminar germ disc in which the developing embryo is made from?
Ectoderm
Mesoderm
Endoderm
What will the ectoderm form?
Skin and Nervous System
What will the mesoderm form?
Muscle
Bone
Urogenetial System
etc..
What will the endoderm form?
It will form the gut lining
etc..
What are neurocutaneous syndromes?
Disorders that affect the skin and nervous system as they are linked
What happens to the trilaminar germ disk at week 8?
Neurulation which is when the germ disc starts to fold down the midline to form a neural tube
Explain how the ectoderm forms the neural groove
- The cells down the midline of the ectoderm thicken and form the neural plate
- Lateral sides of neural plate raise up to form the neural fold
- The gutter this forms is called the neural groove
- The neural groove sinks into the mesoderm
What are the cells at the top of the neural fold called?
Neural crest cells
What do neural crest cells eventually become?
Neural crest cells eventually become the dorsal root ganglion cells
The neural crest gives rise to the sensory neurones
What are the 3 zones of the neural tube?
- Ventricular zone
This is the innermost region closest to the fluid filled lumen. It eventually forms the ventricles. This is the site of cell division, giving rise to neuronal and glial precursors. - The intermediate zone
This is the middle zone. where the neuronal cell bodies accumulate - The marginal zone
This is on the periphery of the neural tube and it is mainly composed of axons rather than cell bodies
What does the neural tube differentiate into once formed?
It diffrentiates into anterior (basal plate) and posterior (alar plate) compartments.
They are seperated by a longitudinal groove called the sulcus limitans.
What is the alar plate?
It is the posterior portion of the neural tube. It consists of sensory cells that will grow into the spinal cord.
What is the basal plate?
It is the anterior portion of the neural tube.
It consists of motor cells which will grow out of the spinal cord.
What is the middle of the neural tube called and what is it filled with?
Neural canal
It is filled with CSF
What shape does grey matter have on a transverse section of the spinal cord?
H shaped
What type of neurones merge into a spinal nerve?
Motor neurones and Sensory neurones merge into a spinal nerve that contains sensory and motor fibres.
Which part of the neural tube closes first?
The neural tube closes in the middle first and then it closes on the cranial and caudal end.
What are the openings on the cranial and caudal end on the neural tube called?
Cranial and caudal neuropores
What happens if cranial neuropore fails to close?
Encephalocele
It results in sac-like protrusions of the brain and membranes through the skull.
What happens if caudal neuropore fails to close?
Spina Bifida
This is where spinal cord protrudes out of the opening
What is hydrocephalas?
Another condition that is caused by neural tube defects
This is where there is an abnormal accumulation of the CSF in the ventricles of the brain. This causes increased intercranial pressure inside the skull (eyes to face down and head swells).
This is generally caused by an obstruction in the neural tube leading to CSF build up as it is being continuously made.
- It can be treated by a shunt
What is the development of the neural tube by the 4th week?
(Google week or month))???
The neural tube has developed into the forebrain, midbrain, hindbrain and spinal cord.
The midbrain has a 90 degrees angle called the midbrain flexture.
The spinal cord has a 90 degrees angle called the cervical flexture.
The hind brain has a small bend in the middle called the pontine flexture.
What is the hind brain also called?
The rhomboid brain
