Nervous System Anatomy, Embryology Flashcards
what produces cerebrospinal fluid?
choroid plexus in the brain ventricles
where can a spinal tap be collected in adults vs children?
adult spinal cord ends at L1-L2
child spinal cord ends at L3-L4
CSF can be collected via spinal tap caudal (below) these levels
_____ cells line the brain ventricles and spinal cord central canal for regulation of CSF production and flow
ependymal cells
name 4 infective agents with which Guillain-Barré Syndrome is associated?
- campylobacter jejuni
- mycoplasma pneumoniae
- cytomegalovirus (CMV)
- Epstein-Barr
molecules produced mimic myelin gangliosides —> antibodies produced demyelinate peripheral nerves
unmyelinated nerve fibers in the [PNS/CNS] are engulfed/nested within [Schwann cells/oligodendrocytes] ?
unmyelinated nerve fibers in the PNS are engulfed/nested within Schwann cells
unmyelinated fibers in the CNS are not invested by oligodendrocytes
what shape are efferent vs afferent neurons?
efferent/motor: multipolar (soma on one end, surrounded by dendrites)
afferent/sensory: pseudounipolar (soma in middle, dendrites and axons on opposite ends)
what is contained within the dorsal root ganglion of the spinal cord?
pseudounipolar (soma in middle) cell bodies of sensory neurons
where are unmyelinated axons found within the CNS?
gray matter = cell bodies, unmyelinated axons
white matter = myelinated axons
in which segments of the spinal cord are sympathetic vs parasympathetic neurons found?
sympathetic: T1-L2 (“thoracolumbar”) spinal cord, somas within gray matter’s lateral horn
parasympathetic: brainstem + S2-S4 (“craniosacral”), somas within grey matter nuclei
the preganglionic neuron of [para/sympathetic] is longer than the postganglionic neuron
parasympathetic: long preganglionic neuron, short post-ganglionic neuron
sympathetic: short preganglionic neuron, long post-ganglionic neuron
what receptor types are found on the target tissues of somatic vs parasympathetic vs sympathetic neurons?
somatic —> nicotinic 1 (N1) cholinergic receptors
parasympathetic —> muscarinic receptors
sympathetic —> adrenergic receptors
preganglionic sympathetic motor neuron cell bodies are located in…
lateral horns of T1-L2 (thoracic vertebrae only)
axons exit ventral root —> spinal nerve —> ventral ramus —> white ramus communication (T1-L2 only) —> sympathetic chain
how does the location of motor sympathetic synapses differ for innervation of sweat glands/ arrector pili/ vascular smooth muscle at T1-L2 level vs beyond?
for motor innervation at level of T1-L2, preganglionic sympathetics immediately synapse in the paravertebral ganglion of the sympathetic chain
for motor innervation outside of T1-L2, preganglionic sympathetics ascend or descend the sympathetic chain, then synapse at the ganglion
what are the 2 ways by which sympathetic motor neurons innervate internal organs?
- preganglionic sympathetics synapse in the sympathetic chain and postganglionic sympathetic motor neuron axons exit medially via visceral nerves to reach internal organs
- preganglionic sympathetics pass through sympathetic chain and synapse at prevertebral ganglia in the abdomen
which cranial nerves and which spinal cord nerves give parasympathetic innervation?
CN III, CN VII, CN IX —> head/neck
CN X (vagus) —> thoracic, abdominal
S2-S4 (pelvic splanchnic nerves) —> distal GI and pelvic organs
postganglionic parasympathetic neuron cell bodies are located in…
organ walls
what are the embryonic brain vesicles and what do they become? (3)
- prosencephalon (forebrain): divides into telencephalon (cerebral hemispheres, CN I) and diencephalon (optic cups, pineal gland, thalamus, hypothalamus, posterior pituitary, CN II)
- mesencephalon (midbrain): associated with CN III, IV
- rhombencephalon (hindbrain): divides into metencephalon (pons, cerebellum, CN V, VI, VII, VIII) and myelencephalon (medulla, CN IX, X, XI, XII)
what are the 2 components into which the prosencephalon (forebrain) divides, and what do these respectively become?
- telencephalon: cerebral hemispheres, lateral ventricles, associated w CN I
- diencephalon: optic cups, pineal gland, thalamus, hypothalamus, posterior pituitary, 3rd ventricle, associated w CN II
what are the 2 components into which the rhombencephalon (hindbrain) divides, and what do these respectively become?
- metencephalon: pons, cerebellum, associated w CN V, VI, VII, VIII
- myelencephalon: medulla, associated w CN IX, X, XI, XII
neurons in nuclei associated with cranial nerves form from ________, while neurons in ganglia associated with cranial nerves form from ________
neurons in nuclei associated with cranial nerves form from neuroepithelium of the neural tube,
while neurons in ganglia associated with cranial nerves form from neural crest cells and ectodermal placodes
the lumen of the developing neural tube eventually becomes…
the ventricular system, whose choroid plexus produces CSF
formation of the neural tube is complete by the end of week ___
four
describe how the neural tube forms (neurulation)
- induction of ectoderm into neuroectoderm via signals from underlying notochord mesoderm
- neuroectoderm cells organize in midline as thickening called neural plate
- neural plate buckles to form depression called neural groove with raised bilateral neural folds
- neural folds fuse to form neural tube, which detaches from epidermis-forming ectoderm
- caudal end of neural tube becomes spinal cord, cranial end becomes brain
[note the notochord becomes the nucleus pulposus of intervertebral discs]
craniorachischisis
“cleft skull and spine”
Defective closure of the entire CNS neural tube is seen as an open furrow on the dorsal surface of the head and body and results in a fatal deformity
