Revision of PNS - Theory Flashcards
what are the two kinds of neurones?
multipolar - more common
unipolar
what are characteristics of multipolar neurones?
2 or more dendrites
all motor neurones of skeletal muscle and ANS
cell body in CNS
what are characteristics of unipolar neurones?
double process
sensory neurone
cell body in PNS
how many pairs are there of all the different spinal nerves?
8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
where are spinal nerves found?
intervertebral foramina
what do spinal nerves connect with?
structures of the soma via rami
the spinal cord segment of the same number via roots and rootlets
what is difference between anterior and posterior rami?
posterior = smaller, on posterior body wall
anterior = larger, on anterolateral body wall
what is the course of all sensory axons?
pass from the spinal nerve into posterior root
then into posterior rootlets
then into posterior horn of spinal cord
what is the course of all motor axons?
pass from anterior horn of spinal cord
into anterior rootlets
then into anterior root
then into spinal nerve
what is a dermatome?
area of skin supplied with sensory innervation from single spinal nerve
what is a myotome?
the skeletal muscles supplied with motor innervation from a single spinal nerve
what does a large area of numbness suggest?
at least 2 or 3 spinal nerves damaged
what is the dermatomal segments of:
a) nipple?
b) umbilicus?
c) posterior scalp, neck and shoulder?
d) upper limb?
e) lower limb, gluteal region and perineum?
a) T4
b) T10
c) C2-C4
d) C5-T1
e) L2-Co
what is a nerve plexus?
intermingled anterior rami from a number of adjacent spinal nerves
what is the nerve roots of the following and what do they supply:
a) cervical plexus?
b) brachial plexus?
c) lumbar plexus?
d) sarcral plexus?
a) C1-C4 - posterior scalp, neck and diaphragm
b) C5-T1 - upper limb
c) L1-L4 - lower limb
d) L5 - S4 - lower limb, gluteal region and perineum
what is the course of sympathetic outflow?
control centres in brain
passes down spinal cord
leaves spinal cord through T1 to L2
take 1 of 4 roots
what 4 routes can sympathetic outflow take?
ascend then synapse
synapse at level of entry
descend then synapse
pass through sympathetic trunk without synapsing to enter an abdominopelvic splanchnic nerve
what is the course of sympathetic outflow to heart?
presynaptic axons synapse in T1 or paravertebral ganglia (sympathetic chain)
postsynaptic axons pass in cardiopulmonary splanchnic nerves to SA and AV nodes and myocardium
what is course of sympathetic outflow to lungs?
presynaptic axons synapse in upper thoracic paravertebral ganglia
postsynaptic axons pass in cardiopulmonary splanchnic nerves to bronchial smooth muscle and mucous glands
what is course of sympathetic outflow to abdominopelvic organs?
presynaptic axons synapse in one of the prevertebral ganglia
- celiac ganglion of celiac plexus (foregut)
- aorticorneal ganglion (kidney)
- superior mesenteric ganglion of SM plexus (midgut)
- inferior mesenteric ganglion of IM plexus (hindgut and pelvic organs)
what is the course of sympathetic outflow to adrenal medulla?
presynaptic axons pass through aorticocorenal ganglion to synapse directly onto the adrenaline / noradrenaline secreting cells of adrenal mucosa
presynaptic parasympathetic axons leave CNS via what?
cranial nerves III, VII, IX and X
as well as sacral spinal nerves
what do they travel via?
ciliary ganglion - eye
parasympathetic ganglia in head - lacrimal gland and salivary gland
vagus nerve - organs of neck, chest and abdomen as far as mid-gut
sacral spinal nerves - hindgut, pelvis and perineum
what is symptoms of horners syndrome?
miosis
ptosis
reduced sweating (anhydrosis)
increased warmth and redness
what causes horners syndrome?
impaired sympathetic innervation to head and neck
- root of neck trauma
- carotid dissection
- IVJ engorgement
- deep cervical node metastases
- pancoast tumour (lung apex)
