Peripheral Nervous System Flashcards
What does the CNS consist of?
brain
spinal cord
What does the PNS consist of?
cranial nerves
spinal nerves
ganglia
collection of neuron cell bodies OUTSIDE the CNS
ganglion
How many pairs of cranial nerves are there?
12
How many pairs of spinal nerves are there?
31
Where does information flow in sensory (afferent) innervation?
environment –> CNS
Where does information flow in motor (efferent) innervation?
CNS –> muscle and glands
Which part of a neuron carries impulse out to muscle to contract?
axon
Which neuron has a cell body between 2 axon ends and forms a ganglion with other cell bodies?
sensory neuron
Somatic innervation concerns the ___ ___.
body wall
2 examples of somatic innervation
skeletal muscle
skin
bone
Visceral innervation concerns the ____ _____.
internal organs
3 examples of visceral innervation
heart
lungs
GI tract
T/F: Functional dichotomies of the nervous system do not intersect.
false: they do intersect
T/F: Both somatic and visceral innervation contain sensory AND motor neurons.
TRUE
body wall: (somatic sensory + somatic motor)
internal organs: (visceral sensory + visceral motor)
What is the target tissue of somatic motor innervation?
skeletal muscle (diaphragm included)
Is somatic motor innervation conscious/unconscious?
conscious (voluntary)
How many neurons in somatic motor innervation and what do they connect?
one
CNS –> target muscle
Somatic sensory innervation carries information about the internal/external environment?
external
Where does somatic sensory innervation carry information from?
skin
musculoskeletal system
Is somatic sensory innervation conscious/unconscious?
conscious
How many neurons in somatic sensory innervation and what do they connect?
one
site of stimulus –> CNS
Name the 5 examples of somatic sensory stimuli:
- pain (cutting, tearing, crushing, inflammation, burning-heat/chemical)
- temperature
- touch
- pressure
- vibration
STIMULI THAT CAN BE FELT BY THE SKIN
Division of the mesoderm that gives rise to bone, skeletal muscle, and dermis
paraxial mesoderm
How many pairs of somites does the paraxial mesoderm have?
37 pairs of somites
37 pairs of somites: \_\_ occipital \_\_ cervical \_\_ thoracic \_\_ lumbar \_\_ sacral \_\_ coccygeal
4 8 12 5 5 3
How many pairs of somitomeres are there?
7
What does the epaxial dermamyotome give rise to?
intrinsic (deep) back muscles and dermis that covers them
NOTHING ELSE
What does the hypaxial dermamyotome give rise to?
all other skeletal muscles and dermis below the neck including limbs
What is required for each individual somite? (2)
innervation
blood supply
Do epaxial and hypaxial dermamyotomes have combined/separate innervation and blood supplies?
separate
In what way is the spinal cord segmented?
functionally
What does each level of the spinal cord have that serves the tissues that originate from the same level, including the somite pair?
cell bodies
Each somite pair is associated with what?
pair of spinal nerves
How are spinal nerves numbered?
superior –> inferior
What are the names and numbers of the 31 pairs of spinal nerves?
8 cervical (C1-C8) 12 thoracic (T1-T12) 5 lumbar (L1-L5) 5 sacral (S1-S5; S5= dermatome only) 1 coccygeal (Co1 = dermatome only)
What components do all spinal nerves have?
somatic sensory components
somatic motor components (not S5 or Co1)
carry sympathetic axons
In which spinal nerves are parasympathetics found?
S2-S4
What are the 2 spinal nerves that do not have sensory motor components?
S5
Co1
In somatic motor innervation to the body wall, there is a __-neuron pathway between the spinal cord and the target, which is _____ _____.
one
skeletal muscle
Where are cell bodies located in the spinal cord?
ventral horn (gray matter)
How do somatic motor neurons leave the spinal cord?
via VENTRAL ROOTS of spinal nerves
Because the muscles supplied by a spinal cord segment supply muscle from different embryonic primordia, each spinal nerve has to branch into a _____ _____ and a _____ _____.
dorsal ramus
ventral ramus
Intrinsic (deep) back muscles are derived from ____ dermamyotomes and are supplied by ___ rami;
all other skeletal muscles below the head are derived from ____ dermamyotomes and are supplied by ____ rami.
epaxial
dorsal
hypaxial
ventral
