innervation of organs Flashcards
explain parasympathetic entry to lung
via vagus nerve, relayed to pulmonary plexuses on each side
parasympathetic fibres pass into the lungs around the pulmonary arteries
ramification of arteries accompanied by a similar divergence of nerve fibres
afferent division explained
sensory fibres pass superiorly to the inferior ganglion of the vagus to synapse in the nucleus solitarius of the medulla
how are sensations detected?
receptors include unmyelinated free nerve endings in the sub epithelial layer of the bronchial tree
involved in cough reflex
efferent division explained
cell bodies in the dorsal motor nucleus of the vagus nerve within the medulla
synapse with post ganglionic nerves in the walls of the bronchial mucosa
passage of right vagus nerve
descends from cranial vault through jugular foramina, penetrating carotid sheath between the internal and external carotid arteries
right vagus gives rise to recurrent laryngeal nerve , ascends into the neck between the trachea and oesophagus
right vagus then crosses anterior to right subclavian artery and runs posterior to superior vena cava and posterior to right main branches
here it contributes to cardiac, pulmonary and oesophageal plexuses
enters the diaphragm as the posterior vagal trunk through oesophageal hiatus
passage of left vagus nerve
enters thorax between left common carotid and left subclavian
descends on the aortic arch
gives rise to the left recurrent laryngeal nerve
hooks around the aortic arch and ascends between the trachea and oesophagus
breaks up into pulmonary plexus and continues into oesophageal plexus
enters abdomen as anterior vagal trunk in the oesophageal hiatus of the diaphragm
sympathetic innervation of heart from which spinal levels
T1-L2
what does the sympathetic nervous system innervate?
atria, SAN, ventricles and conduction system of heart
what does the parasympathetic system innervate?
right vagus nerve- SAN
left vagus nerve- AV node
atria partially
ventricles not at all
what does sympathetic stimulation result in?
release of noradrenaline leading to the binding to b1 receptors
increase chrontropy, isotropy
sympathetic innervation of airways
b2 receptors present- sympathetic innervation results in PKA- prevents myosin light chain kinase form working
bronchodilation of smooth muscle
parasympathetic innervation of airways result
m3 receptors
secretion of muscarine leads to gq coupled, release of calcium, bronchoconstriction
what is horner’s syndrome?
syndrome due to the damage of sympathetic trunk at head of first ribs affecting sympathetic innervation of the head
leads to droopy eyelids
sympathetic innervation of abdominal viscera
thoracic splanchnic nerves that arise from the sympathetic trunk in the thorax, then travel inferiorly to the abdomen
what do the nerves contain?
preganglionic sympathetic fibres and general visceral afferent fibres
2 important sympathetic nerves
greater and lesser splanchnic
passage of greater splanchnic
through diaphragm
fibres synapse with celiac ganglia
modulate enteric nervous system activity in foregut and supply adrenal medulla
passage of lesser splanchnic
fibres synapse with superior mesenteric ganglia
modulate activity of the midgut
vagal innervation of gut
foregut and midgut structures
hindgut innervation
parasympathetic innervation via the pelvic splanchnic nerves
sympathetic innervation via lumbar splanchnic nerves
what are the pelvic splanchnic nerves?
arise from anterior rami of the sacral nerves S2,S3,S4
contain preganglionic parasympathetic fibres as well as visceral afferent fibres
parasympathetic supply to pelvic organs
pelvic splanchnic nerves
sympathetic supply to pelvic organs
T12-L2, sacral splanchnic nerves
formed of the hypogastric nerves
what spinal levels do the innervation of the perineum come from mainly?
S2-S2 pudendal nerve
what time of nerve is the pudendal nerve?
somatic
pudendal nerve function
sensation to the pelvic area
muscles of the pelvic floor
external urethral sphincter
external anal sphincter (via inferior rectal nerve branch)
autonomic innervation of bladder
sympathetic- hypogastric nerve T12-L2, causes relaxation of detrusor and promotes urine retention
parasympathetic- pelvic nerve S2-S4- contraction of detrusor
innervation of internal urinary sphincter
sympathetic hypogastric- leading to contraction
parasympathetic innervation of kidney
vagus nerve
sensory input from kidney
T10-T11
sensed in corresponding dermatome
