Development of the Peripheral Nervous System Flashcards
when does the neural tube start to form
3 weeks
what does the fourth somite on the neural tube separate
the part of the tube that develops into the brain and the part that develops into the spinal cord
central nervous system consists of
brain and spinal cord
peripheral nervous system consists of
cranial nerves, spinal nerves, ganglia, enteric plexus, sensory receptors
- anything that starts in the spinal cord or skull and leaves to go to a target muscle or gland
somatic peripheral nervous system
motor and sensory portions; voluntary and conscious movement
autonomic peripheral nervous system
motor and sensory portions; involuntary movement
parasympathetic nervous system
rest and digest; involuntary
sympathetic nervous system
fight or flight; involuntary
what three parts make up the grey matter in the spinal cord
posterior horn
lateral horn
anterior horn
posterior (dorsal) horn of the grey matter
sensory portion
lateral horn of the grey matter
autonomics
- through T1–>L2
anterior (ventral) horn of the grey matter
cell bodies of motor neurons
grey matter of spinal cord
location of cell bodies of neurons
- not myelinated (why it’s grey)
white matter of spinal cord
mostly axons
- myelinated (why it’s white)
what three parts make up the white matter in the spinal cord
posterior funiculus
lateral funiculus
anterior funiculus
posterior (dorsal) funiculus of the white matter
sensory portion
lateral funiculus of the white matter
sensory and motor portions
anterior (ventral) funiculus of the white matter
primarily motor
alar plate
sensory portion of the neural tube
basal plate
motor portion of the neural tube
sulcus limitans
groove that separates alar plate and basal plate on the neural tube
separates affarent (sensory) and efferent (motor)
central canal of neural tube
hole that forms after neural tube closes; connected to vascular system in brain
ventricular zone of the neural tube
adjacent to the central canal; contains stem cells that give rise to ependymoblast which gives rise to ependymal cells
intermediate zone of the neural tube
grey matter; consists of stem cells that have migrated in from the ventricular zone; also contains astrocytes
marginal zone of the neural tube
white matter; consists of myelinated axons; has oligodendrocytes
difference between oligodendrocytes and schwann cells
oligodendrocytes myelinate within the CNS; schwann cells myleniate in the PNS
oligodendrocytes come from neural tube; schwann cells come from neural crest
where does the spinal cord end in newborns vs adults
newborns: L2 or L3
adults: L1 or L2
why does the cauda equina form
the spinal cord and vertebral column are originally the same length, but the vertebral column grows much faster which stretches the bottom forming the cauda equina
high BMP levels activate what in the formation of the spinal cord
PAX3 and PAX7
high SHH levels activate what in the formation of the spinal cord
NKX2.2 and NKX 6.2
where are BMPs released from
roof plate and surface ectoderm
where is SHH released from
notochord and floor plate
how is the alar plate formed
high BMP –> PAX3 and PAX7 activated –> turn on sensory neuron differentiation –> alar plate
how is the basal plate formed
high SHH –> NKX2.2 and NKX6.1 activated –> turn on ventral neuron formation –> basal plate
lots of BMP results in:
dorsally patterned (sensory) cell bodies in grey matter
lots of SHH results in:
ventrally patterned (motor) cell bodies in grey matter
motor neurons and pre-ganglionic autonomic neurons develop from
neural tube
- neurons of dorsal root ganglia
- sensory ganglia of cranial nerves
- schwann cells
- sympathetic ganglia
- parasympathetic ganglia
- –all develop from: _______
neural crest
ventral root ganglia develop from
neuroectoderm
dorsal ramus sensory and motor functions
motor to dorsal muscles
sensory to dorsal integument
ventral ramus sensory and motor functions
motor to limbs, lateral and ventral body wall
sensory to integument of same regions
ramus communicantes
motor and sensory function to the viscera; how you get in and out of the autonomic ganglia
general somatic efferent (GSE) neurons
- derived from
- what they supply
type of motor neurons from the neuroectoderm; somatic muscle like biceps, rhomboids, etc
general visceral efferent (GVE) neurons
- derived from
- what they supply
type of motor neurons from the neuroectoderm; autonomics to smooth and cardiac muscle and glands (parasympathetics and sympathetics)
brachial or special visceral efferent (SVE) neurons
- derived from
- what they supply
type of motor neurons from the neuroectoderm; muscles derived from pharyngeal arches
general somatic afferent (GSA) neurons
- derived from
- what they supply
provide sensory in the skin, joint capsule, tendons, muscles
- neural crest derived
general visceral afferent (GVA) neurons
- derived from
- what they supply
provide sensory of visceral structures
- neural crest derived
special somatic afferent (SSA) neurons
provide hearing, balance, sight
special viscera afferent (SVA)
provide taste and smell
function of the autonomic nervous system
innervation of smooth muscle, cardiac muscle, and glands
ganglia and post-ganglion cells are formed from the
neural crest
pre-ganglion cells are formed from the
neuroectoderm
physical differences between preganglionic and postganglionic neurons in the sympathetic nervous system
preganglionic: shorter and myelinated
postganglionic: longer and not myelinated
where does the pre-ganglionic neuron cell body begin and end up (what’s its path)
in lateral horn of spinal cord to synapse in the ganglion cell
the cranial region of the parasympathetic nervous system consists of
primarily cranial nerves (3, 7, 9, 10)
the sacral region of the parasympathetic nervous system consists of
2nd - 4th sacral spinal nerves
S2, 3, 4
physical differences between preganglionic and postganglionic neurons in the parasympathetic nervous system
preganglionic: long and myelinated
postganglionic: short and not myelinated
what are the four parasympathetic ganglia leading to the head and neck
- ciliary ganglion
- pterygopalatine ganglion
- submandibular ganglion
- otic ganglion
when do oligodendrocytes myelinate
6 months through puberty
when do schwann cells myelinate
4th month
- motor roots are myelinated before sensory roots
where does the ependyma originate
neuroectoderm
where does the epitherlium of choroid plexus originate
neuroectoderm
where do oligodendrocytes originate
neuroectoderm
where do dendrites and axons originate
neuroectoderm
where do protoplasmic and fibrous astrocytes originate from
neuroectoderm
efferent (motor) neurons originate from
neuroectoderm
afferent (sensory) neurons originate from
neural crest cells
where are the cell bodies of the sympathetic nervous system located
in the spinal cord in the thoraco-lumbar region
- T1–>L2
what is the path of post-ganglionic neurons (where do they start and where do they end)
start in the ganglion and move out to different targets
