Case 1 Flashcards
What does the central nervous system contain what is it composed of?
It is enclosed withing the meninges and consists of the brain and spinal chord.
Which of the three primary germ layers does the nervous system originate from?
The ectoderm.
What structure is formed by the thickening of the edges of the neural plate?
The neural groove
What embryonic structure present by roughly three weeks is thought to be the origin of the entire CNS including neurones neuroglia ependymal cells and the epithelial cells of the choroid plexus?
The neural tube.
What is the function of the choroid plexus? Where is it located?
There are four choroid plexuses each one located in a separate ventricle of the brain. Their function is the production of cerobrospinal fluid (CSF).
What parts of the developing spinal chord does the sulcus limitans divide?
The alar and basal plates
Which of the alar and basal plates are the most ventral?
The basal
Which of the alar and basal plates are the most dorsal
The alar
Neurons derived from the basal plate are predominantly what type?
Motor
Neurons derived from the alar plate are predominantly what type?
sensory
What structures are derived from the expansion of the anterior end of the neural tube, what structures do these develop into
The primary brain vesicles, these develop into the ventricular cavities of the brain.
What three distinct layers can be observed in the spinal cord once a syncytium has been formed by the cells of the spinal cord side wall, list them from most central outwards?
the ependymal , mantle and marginal layers.
What does the ependymal layer of the embryonic spinal cord go on to form?
The ependyma of the spinal chord (the lining of the inside of the spinal canal partially responsible for the production of CSN)
What are the two types of cell present in the mantle layer?
spongioblasts and germinal cells
What do the spongioblasts of the mantle layer go on to form?
neuroglia cells
What do the germinal cells of the mantle layer go on to form?
neuroblasts or young nerve cells.
What does the marginal layer go on to form
the white funiculi of the spinal cord
The filaments of syncytium connecting spongioblasts are the precursor to what trait of mature neuroglia cells
The thin processes extending from each of them.
What shape are the germinal cells where are they found?
The are large oval or round shaped cells found in the side walls of the central canal between the ependymal cells but not on the roof or floor plates.
The germinal cells give rise to the neuroblasts where do these migrate from in between the ependymal cells of the side wall of the neural canal
into the mantle layer and towards the neural crest
At what stage of development do nerve fibers begin to be present in the marginal layer
Roughly 4 weeks
What do the intersegemntal fibers of the spinal cord originate from?
The neuroblasts in the mantle zone.
What do the dorsal nerve root fibers grow into where do these cells originate from?
They grow into the spinal cord, they originate from the cells of the spinal ganglia.
Until roughly what point in development is the spinal cord the same length as the vertebral canal?
Up until roughly three months.