Abdominal nerves and the perception of referred pain Flashcards
What is the point in the enteric nervous system?
Enables the GI tract to perform reflex functions of secretion, absorption, mixing and gut movements without the influence of the CNS or ANS
Where are the two plexuses in the GI tract?
Submucosal plexus - Meissner’s plexus
Myenteric plexus - Auerbach’s plexus
Where do the sympathetic nerves arise?
T1-L2 = Thoracolumbar
Where do the parasympathetic nerves arise?
Cranial - 3, 7, 9 and 10 (occulomotor, facial, glossopharyngeal and vagus)
Sacral - S2-S4
What are the roles of afferent sympathetic and parasympathetic nerve fibres?
Sympathetic - mediates pain
Parasympathetic - specific functional sensation e.g. stretch
Describe the arrangement of the splanchnic nerves.
All the splanchnic nerves (greater, lesser and least) arise in the thorax and descend into the abdomen.
Greater splanchnic = T5-T9
Lesser splanchnic = T10 + T11
Least splanchnic = T12
Describe the distribution of autonomic nerves to peripheral vessels and skin and to organs (lacking somatic innervation).
Autonomic nerves to skin and peripheral vessels run with somatic nerves to the same region
Autonomic nerves to organs lacking somatic innervation run with the arteries to the same organs.
State the autonomic abdominal ganglia in order from top to bottom
(Anterior left vagal trunk)
Coeliac ganglion
Superior mesenteric ganglion
Renal ganglion
Inferior mesenteric ganglion
Sympathetic trunk and ganglia
Superior and inferior hypogastric plexuses
Where do the testicular/ovarian arteries arise?
They arise below the superior mesenteric artery and above the inferior mesenteric artery (closer to the SMA).
State the nerves that travel to the organs supplied by the main branches of the aorta and the important abdominal plexuses.
Coeliac artery - greater splanchnic (T5-T9) + X
Superior mesenteric artery - lesser splanchnic (T10 + T11) + X
Renal artery - lesser and least splanchnic (T10-T12) + X
Testicular/Ovarian arteries - lesser splanchnic (T10 + T11) + X
Inferior mesenteric artery - T12 - L2/S2 - S4
Superior and inferior hypogastric plexuses - T12-L2/ S2-S4
What is a dermatome?
An area of skin innervated by a single spinal nerve
Why might a disruption in one nerve not cause any major changes in sensation on the skin?
Because the dermatomes overlap so you may need a disruption in three spinal nerves before you get an area of complete anaesthesia.
State the regions where pain from the foregut, midgut and hindgut is felt. State the nerves that innervate these regions.
Foregut = epigastric (T7/T8)
Midgut = umbilical (T10)
Hindgut = hypogastric (T12 - L1/2)
When would pain due to an inflamed appendix be felt in the inguinal region?
When the inflammation spread to the adjacent peritoneum - then the pain will be more localised and constant
