Term
| what are the three components of the brainstem from caudal to cranial |
|
Definition
| Starting just above the skull. Medulla oblongata, superior to that is the pons and cerebellum (pons anterior), then superior to that is the midbrain. |
|
|
Term
| What are the two parts of the forebrain? |
|
Definition
| the Thalamus/hypothalamus and the cerebral hemispheres. |
|
|
Term
| what are the four ventricles in the brain? |
|
Definition
| lateral ventricles, the third ventricle, the cerebral aqueduct, and the fourth ventricle. |
|
|
Term
| do cranial nerves carry somatic or autonomic function. |
|
Definition
| both: they innverate the head and neck and carry motor info (volunatary and involuntary) as well as sensory, general and special. |
|
|
Term
| is the autonomic system a subdivision of the cns or pns? |
|
Definition
| it is a subdivision of both!!! |
|
|
Term
| at what levels of the vert. column is the symp. n.s. found? |
|
Definition
| T1-L2 (the symp. trunk/chain goes from cranial to sacral however) |
|
|
Term
| where do neural crest cells come from? |
|
Definition
| the crest of the neural folds. |
|
|
Term
| the neural crest cells give rise to what sensory neurons? |
|
Definition
| All at the spinal level (both somatic and autonomic sensory at the spinal level) they also give rise to cranial autonomic while cranial sensory is derived from n. c. cells and placodes |
|
|
Term
| What longitudianl groove forms on each side of the lumen of the neural tube during neurulation? |
|
Definition
| the sulcus limitans...forms on each side of the tube, divides the tube into dorsal and ventral halves. |
|
|
Term
| the alar plate is what half? |
|
Definition
| alar=dorsal .... ADAS (alar, dorsal, afferent, sensory) |
|
|
Term
| the basal plate is what half? |
|
Definition
| the ventral half. (BEMV) Basal, efferent, motor, ventral. |
|
|
Term
| the basal plate extends to what section of the folds? |
|
Definition
| mesencephalon.... making the diencephalon and telencephalon derived from the alar plate. |
|
|
Term
| where are the roof and floor plates formed... what is their role? |
|
Definition
| they are formed at the dorsal and ventral midlines....they serve imp. patterning functions and guide axons as they travel with the neural tube! |
|
|
Term
| Where do differentiating neurons reside? |
|
Definition
| they reside in the mantle layer---which will form the gray matter of the cns |
|
|
Term
| where do the neural processes of these differentiating neurons reside? |
|
Definition
| they form the marginal layer---which will become the white matter of the cns. |
|
|
Term
| So how then does the spinal cord form...? |
|
Definition
| the neural tube initially consists of neuroepithelial cells (these are proliferative undifferentiated cells that span the width of the tube). |
|
|
Term
| what is the ventricular layer? |
|
Definition
| its where the cell bodies of these neuroepithelial cells reside, this layer immediately surrounds the central canal. |
|
|
Term
|
Definition
| so these neuroepithelial cells (the ventricular layer) start to differentiate now that the neural tube has closed, they differentiate as neuroblasts and migrate away from this ventricular layer. |
|
|
Term
| this migration creates and immediate layer called? |
|
Definition
| the mantle layer---will be the gray matter. |
|
|
Term
| as these neuroblasts differentiate into neurons, they send out axons that collect and form what layer? |
|
Definition
| the marginal layer,---which will become the white matter. |
|
|
Term
| how does dorsal/ventral patterning occur? |
|
Definition
| signals from outside the neural plate begin to establish a d/v pattern. |
|
|
Term
| what is the ventrally secreted signal and where does it come from? |
|
Definition
| Shh (sonic hedgehog) secreted by the notochord is the ventral signal.... |
|
|
Term
|
Definition
| induces neighboring neuroectoderm to develope floorplate which also produces Shh and induces ventral progenitor cells to make motor neurons and other ventral cell types. |
|
|
Term
| what are the dorsal signals? |
|
Definition
| BMP's are dorsal signals that originate from the epidermal ectoderm adjacent to the neural tube. PAX3 and PAX7 are also involved in dorsal signaling... |
|
|
Term
| what effects to dorsal and ventral signals have on each other? |
|
Definition
| they are usually oposing effects like with Shh and BMP as well as the pax genes which are suppressed by Shh. |
|
|
Term
| What happens with PAX 3 mutants? |
|
Definition
| PAX3 mutations in humans causes waardenburg syndrome (a neural crest abnormalities, not neural tube defects) |
|
|
Term
|
Definition
| PAX6 is a ventral signal induced by Shh |
|
|
Term
| what are the 3 primary brain vesicles corresponding to the forebrain/midbrain/and hindbrain? |
|
Definition
| Forebrain(prosencephalon), midbrain (mesencephelon), and hindbrain (Rhombencephalon). |
|
|
Term
| what happens with these 3 primary vesicles at about 5 weeks? |
|
Definition
| The forebrain (prosencephalon)vesicle and the hindbrain (rhombencephalon) vesicles further subdivide making then 5 secondary vesicles.... |
|
|
Term
| what are the 5 secondary vesicles from cranial to caudal? |
|
Definition
| Telencephalon and diencephalon (from the prosencephalon), the mesencephalon (hasnt subdivided and is therefore the same), the metencephalon and myelenchephalon (from the rhombenchephalon). |
|
|
Term
| what are these additional narrow swellings called? |
|
Definition
| Neuromeres... in the rhombocephelon these neuromeres are called rhombomeres.... |
|
|
Term
| What structures does the telenchephalon give rise to? what are the cavities? |
|
Definition
Cerebral hemispheres, basal ganglia, hippocampus, caudate, putamen
cavities: lateral ventricles... |
|
|
Term
| What structures does the diencephalon give rise to? what are the cavities? |
|
Definition
thalamus, optic vesicles
cavities: third ventricle |
|
|
Term
| What structures does the mesencephalon give rise to? what are the cavities? |
|
Definition
midbrain (red nucleus, superior colliculus)
Cavities: aqueduct |
|
|
Term
| What structures does the metencephalon give rise to? what are the cavities? |
|
Definition
cerebellum, pons
cavities: cranial 4th ventricle |
|
|
Term
| What structures does the myelencephalon give rise to? what are the cavities? |
|
Definition
medulla oblongata
cavities: caudal 4th ventricle |
|
|
Term
| The embryonic brain undergoes three major folds, in cranial to caudal dirrection what are they? |
|
Definition
| mesencephalic, cervical flexure, & pontine flexure. |
|
|
Term
| these three folds result in what shape? |
|
Definition
|
|
Term
| Describe the mesencephalic fold? |
|
Definition
| it is what its named... a fold at the mesencephalic level of the midbrain... it moves the prosencephalon ventrally. |
|
|
Term
| Describe the cervicle flexure? |
|
Definition
| this fold occurs between the hindbrain and the spinal cord... brings the tail in as well like we did with the head...giving the whole embryo kind of an upside down U shape before the last MIDDLE flexure (the pontine flexure occures). |
|
|
Term
| Describe the pontine flexure: |
|
Definition
| it folds in the opposite dirrection of the other two folds... the region of the flexure is the dorsal surface of the brain doesnt fold, as a result this flexure (the futre cerebellum)sits on top of the medulla. the point of this fold becomes the pons. |
|
|
Term
| Is the development of the brain stem similar to that of the spinal cord? |
|
Definition
| Yes, but more elaborate. ... its also divided into alar and basal columns that give rise to neurons with sensory and motor funtions respectively. but there are differences as well.... |
|
|
Term
| There are three main differences, name one? |
|
Definition
| the caudal brainstem and the dorsal neural tube of the brain are open resulting in medial lateral orgainization. |
|
|
Term
| what is another main differnce in brain formation from spinal cord? |
|
Definition
| Second, there is extensive migration of immature neurons dorsally and ventrally = a complex morphology of brainstem. |
|
|
Term
| what is the third main differnce in brain to spinal cord formation? |
|
Definition
| there are additional specialized categories of sensory and motor structures. |
|
|
Term
| as you move up the spinal column into the rhombocephalon is the neural tube actually open? |
|
Definition
| because of the thin roof plate...no, the choroid plexus will form in this reagion. |
|
|
Term
| where do the dorsal walls come back together again? |
|
Definition
| at the cranial end of the rhombocephalon called the metenchephalon, which becomes the pons and the cerebellum. |
|
|
Term
| through what does the cerebellum develope? |
|
Definition
| through the expansion of the rhombic lip. |
|
|
Term
| what is the caudal end of the rhombocephalon called and what does it become? |
|
Definition
| it is called the myelencephalon and it becomes the medulla oblongata. ...the medulla, pons and cerebellum envelope the 4th ventricle. |
|
|
Term
| explain the mesencephelon: |
|
Definition
| it is the "least developed" region and is mostly white matter (axon tracts) |
|
|
Term
| what important structures does the mesencephalon contain? |
|
Definition
| superior and inferior colliculi, and substantia nigra, and the cerebral aqueduct. |
|
|
Term
| what does the cerebral aqueduct do? |
|
Definition
| it connects the 3rd and 4th ventricles. |
|
|
Term
| what does the choroid plexus do? |
|
Definition
| produces csf which then flows from the 3rd vent. to the 4th via the cerebral aquiduct. if this aquiduct is blocked, hydrocephalus results. |
|
|
Term
| what important structures are found in the diencephalon? |
|
Definition
| 3rd ventricle, thalamus, hypothalamus, lateral geniculate body and optic vesicle. |
|
|
Term
| what is thought to be the cranial extension of the suclus limitans? |
|
Definition
| the hypothalamic sulcus which demarcates the thalamus from the hypothalamus. |
|
|
Term
| how is the optic vessicle formed? |
|
Definition
| it begins as an evagination of the diencephalon until it is adjacent to surface ectoderm. -it is then patterned by adjacent tissue. FGF signals from lens induce neural retina. activn-like sig.'s induce non-neural retina. it then INvaginates forming the optic cup....outer layer becomes retinal epithelium/inner becomes neural retina. |
|
|
Term
| how is the pituitary formed? |
|
Definition
| in part by the diencephalon, a diverticulum from the floor of the 3rd ventricle forms the infundibulum which will develope into the posterior pituitary... a diverticulum from the roof becomes opposed to the infundibulum and makes teh anterior and intermediate lobes of the pituitary. |
|
|
Term
| what important structures does the most cranial region (the telencephalon)then have? |
|
Definition
| the two massive cerebral hemispheres...corpus striatum, olfactory bulbs, hippocampus, major commissures, corpus callosum. also the lateral ventricles (in direct communication with the third ventricle) |
|
|
Term
| how are the large hemispheres formed? |
|
Definition
| they develope by expansion of the alar plates within the telencephalon and undergo considerable growth during fetal development. |
|
|
Term
| What are the cellular events discussed in development of cns? |
|
Definition
| 1. Proliferation 2.Cell fate specification 3. migration 4. aggregation 5. Process formation and pathfinding 6. cell death 7. synaptic connections 8. myelination |
|
|
Term
| what does it mean for a cell to be "born"? |
|
Definition
| they go through their final cell division...loose their ability to divide. later in cns developement proliferation exists in the ventricular zone. |
|
|
Term
| Desribe the movement of the nucleus in neural tube proliferating neuronal cells? |
|
Definition
| the nucleus moves back and forth from the inner ventricular surface, while away from the surface it synthesizes DNA, then returns to the ventricular surface for cell division. |
|
|
Term
| describe cell specification? |
|
Definition
| neuroepithelial cells give rise first to neuroblasts. these give rise to neurons, and glioblasts. glioblasts then give rise to astocytes, oligodendrocytes, and ependymal cells. |
|
|
Term
| how does this sequential cell specification occur? |
|
Definition
| its due to complex signals both within the cell and in surrounding cell enviroments that change over time and infuence FATE of the cells. positional information in the tube i.e. ventral motor vs. dorsal sensory is also determined by location and positional information. |
|
|
Term
|
Definition
| cells are not usually born where they will always reside, rather they migrate from their birth place (like the ventricular zone). distances may be long or short. most new neurons dont reside under/below older ones they migrate on past them (inside out)development. |
|
|
Term
|
Definition
| like-types aggregate together as ganglia in the PNS, columns or nuclei in the spinal cord, and as nuclei in the brain, as laminae in the cortices. |
|
|
Term
| describe process formation and pathfinding: |
|
Definition
| young processes are called neurites and their growth tip a growht cone...they respond to signals some are attracted to certain that another neuron my be repelled by. (choose your own adventure idea again)...axons typically develope before the dentrites. neurons are molded by their enviroment. |
|
|
Term
|
Definition
| the nervous system overproduces the number it actually needs then kills 20-75% of them... its its way of making sure a neuron makes it everywhere it needs to... pretty cool. growth factors are involved in this phenomenon. |
|
|
Term
|
Definition
| the formation of functional connections between neurons |
|
|
Term
|
Definition
| improves the conduction of action potentials, large diameter axons are mylenated by oligodendrocytes in cns and schwann cells in the pns |
|
|
