answers to pass
What are the Numbers of neurons and numbers of nonneuronal cells in parts of the brain? -
correct answer ✔✔- Nonneuronal cells are mostly glia, but also include other cell types such as
the ependymal cells lining the ventricles and the endothelial cells of blood vessel
- Cerebral Cortex, subcortical white matter (82% of mass) 16 billion neuronal, 61 billion non-
neuronal
- Basal Ganglia, diencephalon, midbrain, pons (8% mass) 0.7 billion neuronal, 8 billion non-
neuronal
- Cerebellum (10% of mass) 69 billion neuronal, 16 billion non-neuronal
- Dense collection of grey matter. Folded to accommodate all the grey matter
What happens in the first 4 weeks of neural tube development? - correct answer ✔✔Neural
tube closure during the fourth week. A, Neural folds begin to fuse at the cervical level of the
future spinal cord at about day 21. The total length of the neural tube at this time is about 2.5
mm. B, This and additional areas of fusion expand rapidly in both rostral and caudal directions.
C, By about day 24, the rostral end of the neural tube has closed; the caudal end will close 2 to 3
days later. Even before the neural tube has finished closing, local enlargements (the primary
vesicles) and bends begin to appear,
-Neural tube closure occurs during 4th week pregnancy. Whole neural tube about 2.5 mm
length. Makes you feel like crap at this stage in pregnancy. 2.5 mm length giving rise to brain
and SC. Neural tube earliest structure, closes up then forms swelling rostral and caudal, Rostral
swelling is prosencephalon, intermediate is the mesencephalon & rhombencephalon, the tail of
the structure in the SC. Bumps - somites - adjacent to neural tube. Notochord derivatives, give
rise to vertebrae.
What is the cellular distribution in the nervous system? - correct answer ✔✔cellular elements
of Nervous system.
,A - generic sensory neuron from skin to Nervous System
B- generic efferent neuron going to skeletal muscle
C - typical autonomic neuron connected to gland (efferent)
- Autonomic - efferent
- somatic motor neurons - efferent
- sensory neurons - afferent
-A layer of end-feet of protoplasmic astrocytes (PA) forms a leaky membrane that covers the
surface of the CNS, separating it from the PNS.
- Fibrous astrocytes (FA) are interspersed among nerve fibers in the white matter, many of which
are myelinated by oligodendrocytes (Ol).
- Small microglial cells (M) act as scavengers in response to injury, and ependymal cells (E) line
the ventricular cavities (V) of the CNS. Schwann cells and their variants are the principal glial
cells of the PNS, forming the myelin of peripheral nerve fibers (S1), enveloping unmyelinated
axons (S2), and forming satellite cells (S3) surrounding sensory neurons in peripheral ganglia
such as dorsal
root and autonomic ganglia (DRG, AG).
Non - neuronal cells:
- Glia of CNS - oligodendrocytes (myelin, CNS)
- glia of PNS - schwann cells (myelin, PNS)
- Astrocytes CNS - protoplasmic vs. fibrous (different associations with neurons in CNS)
- Ependymal cells (CNS) surround ventricles.
- Microglia - primary immune cells of CNS
- Epithelial cells line capillaries
What are the primary vesicles at the 4 week stage? - correct answer ✔✔- prosencephalon,
mesancephalon, rhombencephalon
,- Cervical fissure - between SC & rhombencephalon
- Cephalic fissure - between rhombencephalon & mesencephalon
What are the 5 secondary vesicles during the 6th week? - correct answer ✔✔6 weeks - 2
vessicles subdivide. 2 more bends, end up with 5 primary vessicles. Swellings give rise to brain
structures.
1) Telencephalon - Cortex/cerebrum
2) Diencephalon - Thalamus, hypothalamus, mamallary bodies, basal ganglia, etc.
3) Mesencephalon - midbrain
4) Metencephalon - pons, cerebellum
5) Myelencephalon - medulla
3,4,5 all brainstem
What are the primary vesicles at 4 weeks in nervous system development? What vesicles do
they give rise to in the 6th week? - correct answer ✔✔1) Proencephalon (forebrain) -
telencephalon. diencephalon
2) Mesencephalon (midbrain)
3) Rhombencephalon (hindbrain) - metencephalon, myelencephalon
What is functional neuroanatomy made up of? - correct answer ✔✔Functional neuroanatomy is
a composite of several disciplines including anatomy, physiology, neurology, neuropathology,
neurosurgery, neuropharmacology, medical imaging, behavioral sciences, and cell biology.
What are the two types of imaging? What is DTI? - correct answer ✔✔- Structural & functional
Diffusion Tensor Imaging (DTI) - based on flow of water and directionality of flow of water along
axons in brain.
, -Structural imaging
Explain the fixed and variable axes of directionality in the CNS. - correct answer
✔✔Directionality within the CNS
-Fixed axes for anatomical direction: superior-
inferior, anterior-posterior, medial-lateral.
- Variable axes (by location in the CNS) for anatomical direction: rostral-caudal and dorsal
ventral.
- For variable axes, the midbrain is the crucial anatomical landmark, i.e., above the midbrain,
rostral=anterior, and caudal=posterior).
- Note that proximal-distal is still used in neuroanatomy, albeit less commonly in the PNS.
Examples?
-Fixed axes always the same in brain and SC. Variable change depending where in CNS.
-boundary at top of midbrain.
- Below midbrain (caudal) dorsal synonymous with posterior
-if rostral to midbrain caudal synonymous with posterior.
-At and Anywhere below the midbrain (caudal), anterior is synonymous with ventral.
Rostral to midbrain, anterior is synonymous rostral
What is the difference between ipsilateral/contralateral? - correct answer ✔✔same side vs.
opposite side. Term of reference to something else
What is a nucleus/nuclei? - correct answer ✔✔nucleus in CNS: collection of cell bodies.
(neurons) Project to generally same place and generally same functions. Functionally and
anatomically related.
What is a Ganglion/ganglia? (what is the exception to this rule?) - correct answer ✔✔PNS
analogous to nucleus. In periphery. Basal ganglia exception to rule. Basal nuclei = basal ganglia