thoracic regional anatomy Flashcards
thoracic sympathetic nerves: describe the distribution and function of the sympathetic chains and thoracic splanchnic nerves; explain the mechanism of referred pain from T1-5 sympathetic afferents to the chest wall and relate it to the thoracic viscera
functional divisions of CNS
somatic (skin and skeletal muscles), autonomic (organs, smooth muscle, glands)
somatic spinal nerves: where do motor go
only to skeletal muscle - cannot function without them
somatic spinal nerves: where do sensory go
body wall, not viscera
somatic spinal nerves: what might segmental nerves combine to form
plexi, supplying specialised areas (cervical, brachial, lumbosacral)
structure of plexi
ventral (efferent), dorsal horn, grey, white matter, ramus (division of mixed spinal cord of back and everything else) vs root (not mixed)
diagram of plexi
diagram from slide 24
define dermatome
area of skin supplied by single spinal nerve on one side or from single spinal cord level (not vertebral levels) (segmented); T4 is nipple
define myotome
part of skeletal muscle supplied by single spinal nerve on one side or from single spinal cord level
spinal/segmental nerves
anterior primary rami
lateral cutaneous branch
anterior and posterior
anterior cutaneous branch
medial and lateral
what to motor autonomic nerves innovate
cardiac muscle, smooth muscle, glands
what do sensory autonomic nerves innovate
visceral organs
what 2 divisions are autonomic nerves divided into
sympathetic (T1 to L2) and parasympathetic (cranial nerves 3, 7, 9, 10 and S2 to S4)
sympathetic outflow from spinal cord
emerge from spinal cord at sympathetic ganglia; follow somatic nerves to periphery; oesophagus plexus (heart) and prevertebral plexus (abdominal and pelvic viscera)
what sections of neurone do all autonomic motor pathways involve
preganglionic and postganglionic neurones; intermediolateral horn present T1 to L2 as sympathetic cell bodies present there
where do pathways to body wall synapse
in ganglia of sympathetic trunk; can go up or down before synapsing depending where going to; postganglionic neurones to heart not in chain
where do pathways to viscera synapse
in unpaired ganglia
what does the trunk do
takes fibres up or down; rami (grey-unmyelinated, white-myelinated); won’t synapse will synapse outside of chain in heart; to brain synapse in chain but not same level
function of sympathetic trunks (T1 to L2)
distribute sympathetic nerves to smooth muscle and glands, body wall synapse in ganglia of trunks, viscera synapse in unpaired ganglia, bring pain fibres back to CNS from viscera
significance of fibres from lower T5-T12
reach abdomen in bundles called splanchnic nerves
5 sets of nerves containing parasympathetic fibres
oculomotor (III) cranial nerves, facial (VII) cranial nerves, glossopharyngeal (IX) cranial nerves (all head and neck), vagus (X) cranial nerves (most important as supplies viscera of thorax and most of abdomen), sacral (S2-S4) spinal nerves
sympathetic nerves to lungs and heart
mainly from T2-T4, passing through cervical and upper thoracic ganglia or sympathetic trunk
where are many of the synapses of sympathetic nerves to lungs and heart
in micro-ganglia in pulmonary and cardiac plexuses rather than in trunk ganglia
where are splanchnic nerves located
posterior mediastinum
greater splanchnic nerve
T5-T9
lesser splanchnic nerve
T10-T11
least splanchnic nerve
T12
define referred pain
pain felt in a part of the body other than its actual source
why does referred pain occur
nerves from various parts of the body converge on their way to the spinal cord; e.g. sensory nerves from heart flow into same part of spine that gathers nerve impulses from shoulder
pulmonary plexuses
left vagus nerve, right vagus nerve, anterior pulmonary plexus, posterior pulmonary plexus
effect on bronchioles of sympathetic nerves
dilate
effect on bronchioles of parasympathetic (vagus) nerves
constrict
cardiac plexuses
superficial cardiac plexus, deep cardiac plexus
effect of sympathetic efferents on heart rate and force of contraction
increase heart rate and force of contraction
effect of parasympathetic efferents (vagus) on heart rate and diameter of coronary arteries
decrease heart rate via pacemaker tissue and constrict coronary arteries
what do sympathetic afferents relay
pain sensations from heart
nerves in inferior mediastinum
sympathetic trunks (each side of posterior mediastinum)
sympathetic trunks - none for preaortic ganglia which serve heart
receive branches from spinal nerves T1 - L2; distribute sympathetic nerves to smooth muscle and glands throughout body; nerves to body wall synapse in ganglia of trunks; nerves to internal organs (viscera) synapse in local ganglia; also bring pain fibres back to CNS from viscera; fibres from lower T5 - T12 reach abdomen in bundles called splanchnic nerves
stellate ganglion
trunk associated with T1 spinal cord segment
