pns Flashcards
how many pairs of spinal nerves
31 pairs of spinal nerves
Somatic afferent nerves convey information
from skin, skeletal muscle and joints
Somatic efferent nerves convey information
to skeletal muscles
Dermatome
An area of skin that is supplied by a single spinal nerve
Myotome
Group of muscles innervated by a single spinal nerve.
Sympathetic efferent nerves innervate
innervate the viscera (organs) and periphery (vasculature and sweat glands)
Parasympathetic efferent nerves innervate
the viscera (organs) only
what is A ganglion
collection of cell bodies outside the CNS
what is A plexus
network of interconnecting nerves
nerves from different spinal levels mix to produce a peripheral nerve
what is A nucleus
a collection of cell bodies inside the CNS
All afferent (somatic and visceral) fibres have their cell bodies
n spinal ganglia
Visceral efferent nerves synapse in
in a peripheral ganglion.
what are Peripheral nerves arranged in
fasciculi (bundle)
how many of connective tissues are there
3
what are they
epineurium
perineurium
endoneurium
what is the epineurium
External vascular layer
covering all bundles
perineurium
Individual fascicles
covering a bundle
endoneurium
Individual axons
what are the Two classification systems
One based on conduction velocity (Uses letters A, B & C – with A the fastest)
One based on axonal diameter (sensory only)
Uses Roman numerals I-IV – with I the largest diameter
what are extrenal receptors called
exteroceptors
what are the internal receptors called (2)
Proprioceptors
Enteroceptors
what do Enteroceptors do
sensation recieved in the body, like movement through gut, blood ph
Proprioceptors
supply information regarding movement and join position
Chemoreceptors
detect
Detector molecules which bind to receptor, e.g. in olfactory bulb
Photoreceptors
Detect light in retina
Thermoreceptors
Detect temperature in skin
Mechanoreceptors
Mechanical opening of ion channels, e.g. touch receptors in skin
Nociceptors
Detect tissue damage, interpreted as pain
what do Muscle spindles
detect
Detect changes in muscles length
Golgi tendon organs
Detect changes in tension in tendons
Joint receptors
Found in joint capsules – detect start and end of movement
what is a Neuromuscular junction
Specialised synapse between a motor neuron and a muscle fibre
what is a Motor unit
A single motor neuron together with all the muscle fibres that it innervates. It is the smallest functional unit with which to produce force.
what is a Reflex action
An involuntary coordinated pattern of muscle contraction and relaxation elicited by peripheral stimuli.
where do you strike a hammer when testing
patella ligament
pathway for a mono synaptic reflex
- Stretching stimulates SENSORY RECEPTOR (muscle spindle)
- SENSORY NEURON activated
- Within INTEGRATING CENTRE (spinal cord) sensory neuron activates motor neuron
- MOTOR NEURON activated
- EFFECTOR (same muscle) contracts and relieves the stretching
what else happens
reflex inhabition of the antagonist muscle
to help with the reflex
from what points does the sypmathetic system have its outtflow
t1 to l2 spinal segments
and psns
from brainstem to sacral
what is the parasypmathetic outflow supply known as
craniosacral outflow
symp
thoroculumbar
what does the Visceral sensory relay sensory info about
Pain, fullness, blood pressure
if symp where do they enter
T1-L2
and if ps
S2-S4
and what cranial nerves do they use
IX and X
Visceral motor
controls…
Controls pupils, sweat glands, salivary glands, heart muscle, airways
if s
Thoracolumbar (T1-L2
ps
craniosacral outflow (cranial nerves III, VII, IX, X)
are there any symp nerves emerging from cervical spinal cord
no
what are the sypmathetic chains/s paravertebral trunks
protect the vertebral column
what are the collection of nerves sourrounding the heart called
cardiac plexus
