innervation of organs

Question 1

explain parasympathetic entry to lung

Answer 1

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

Question 2

afferent division explained

Answer 2

sensory fibres pass superiorly to the inferior ganglion of the vagus to synapse in the nucleus solitarius of the medulla

Question 3

how are sensations detected?

Answer 3

receptors include unmyelinated free nerve endings in the sub epithelial layer of the bronchial tree

involved in cough reflex

Question 4

efferent division explained

Answer 4

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

Question 5

passage of right vagus nerve

Answer 5

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

Question 6

passage of left vagus nerve

Answer 6

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

Question 7

sympathetic innervation of heart from which spinal levels

Answer 7

T1-L2

Question 8

what does the sympathetic nervous system innervate?

Answer 8

atria, SAN, ventricles and conduction system of heart

Question 9

what does the parasympathetic system innervate?

Answer 9

right vagus nerve- SAN

left vagus nerve- AV node

atria partially

ventricles not at all

Question 10

what does sympathetic stimulation result in?

Answer 10

release of noradrenaline leading to the binding to b1 receptors

increase chrontropy, isotropy

Question 11

sympathetic innervation of airways

Answer 11

b2 receptors present- sympathetic innervation results in PKA- prevents myosin light chain kinase form working

bronchodilation of smooth muscle

Question 12

parasympathetic innervation of airways result

Answer 12

m3 receptors

secretion of muscarine leads to gq coupled, release of calcium, bronchoconstriction

Question 13

what is horner’s syndrome?

Answer 13

syndrome due to the damage of sympathetic trunk at head of first ribs affecting sympathetic innervation of the head

leads to droopy eyelids

Question 14

sympathetic innervation of abdominal viscera

Answer 14

thoracic splanchnic nerves that arise from the sympathetic trunk in the thorax, then travel inferiorly to the abdomen

Question 15

what do the nerves contain?

Answer 15

preganglionic sympathetic fibres and general visceral afferent fibres

Question 16

2 important sympathetic nerves

Answer 16

greater and lesser splanchnic

Question 17

passage of greater splanchnic

Answer 17

through diaphragm

fibres synapse with celiac ganglia

modulate enteric nervous system activity in foregut and supply adrenal medulla

Question 18

passage of lesser splanchnic

Answer 18

fibres synapse with superior mesenteric ganglia

modulate activity of the midgut

Question 19

vagal innervation of gut

Answer 19

foregut and midgut structures

Question 20

hindgut innervation

Answer 20

parasympathetic innervation via the pelvic splanchnic nerves

sympathetic innervation via lumbar splanchnic nerves

Question 21

what are the pelvic splanchnic nerves?

Answer 21

arise from anterior rami of the sacral nerves S2,S3,S4

contain preganglionic parasympathetic fibres as well as visceral afferent fibres

Question 22

parasympathetic supply to pelvic organs

Answer 22

pelvic splanchnic nerves

Question 23

sympathetic supply to pelvic organs

Answer 23

T12-L2, sacral splanchnic nerves

formed of the hypogastric nerves

Question 24

what spinal levels do the innervation of the perineum come from mainly?

Answer 24

S2-S2 pudendal nerve

Question 25

what time of nerve is the pudendal nerve?

Answer 25

somatic

Question 26

pudendal nerve function

Answer 26

sensation to the pelvic area

muscles of the pelvic floor

external urethral sphincter

external anal sphincter (via inferior rectal nerve branch)

Question 27

autonomic innervation of bladder

Answer 27

sympathetic- hypogastric nerve T12-L2, causes relaxation of detrusor and promotes urine retention

parasympathetic- pelvic nerve S2-S4- contraction of detrusor

Question 28

innervation of internal urinary sphincter

Answer 28

sympathetic hypogastric- leading to contraction

Question 29

parasympathetic innervation of kidney

Answer 29

vagus nerve

Question 30

sensory input from kidney

Answer 30

T10-T11

sensed in corresponding dermatome