Abdominal Pain Flashcards
List the 2 abdominal pain pathways.
Abdominal pain pathways include:
1 - Somatic pain pathway.
2 - Visceral pain pathway.
Which nerves travel with pain fibres that originate from:
Abdominal organs?
Abdominal wall?
Pelvic organs?
- Pain fibres from abdominal organs travel with sympathetic nerves.
- Pain fibres from the abdominal wall travels with peripheral cutaneous nerves.
- Pain fibres from pelvic and thoracic organs travel with parasympathetic nerves.
Describe the pathway taken by pain fibres originating in abdominal organs.
- Pain fibres from abdominal organs travel with sympathetic nerves:
1 - The A-delta or C fibre passes through the sympathetic paravertebral ganglia without synapsing.
2 - The fibre then passes through the dorsal root ganglion, where its cell body is located.
3 - It synapses and decussates at the level of origin.
4 - It then ascends in the lateral spinothalamic tract.
5 - It terminates in the thalamus.
*The difference between the somatic pathway and visceral pathway is that the somatic pathway enters the spinal cord with peripheral cutaneous nerves whereas the visceral pathway enters the spinal cord via the sympathetic chain.
Describe the pathway taken by pain fibres originating in the abdominal wall.
- Pain fibres from the abdominal wall travels with peripheral cutaneous nerves:
1 - Along with other peripheral cutaneous nerves, the fibre passes through the dorsal root ganglion, where its cell body is located.
2 - It synapses and decussates at the level of origin.
3 - It then ascends in the lateral spinothalamic tract.
4 - It terminates in the thalamus.
*The difference between the somatic pathway and visceral pathway is that the somatic pathway enters the spinal cord with peripheral cutaneous nerves whereas the visceral pathway enters the spinal cord via the sympathetic chain.
What is the difference between A-delta and C pain fibres?
- A-delta pain fibres are myelinated, and so transmit pain sensation relatively quickly.
- C pain fibres are unmyelinated, and so transmit pain sensation relatively slowly.
- A-delta pain fibres are therefore responsible for the initial well-localised sharp pain at first injury, whereas C fibres are responsible for the later poorly-localised dull pain.
How does referred pain occur?
Why is somatic pain never referred?
- Visceral pain fibres travel with other autonomic nerve fibres (abdominal pain fibres travel with sympathetics whereas pelvic and thoracic pain fibres travel with parasympathetics).
- These autonomic nerves will have their cell bodies at a particular spinal level (e.g. the spinal nerve roots of the autonomic nerves supplying the heart are T1-4).
- Pain is therefore perceived in the dermatomes covered by spinal nerves of the same root (e.g. heart pain is felt in the left jaw, left shoulder and left arm, as this is the left T1-T4 dermatome).
- Somatic pain is never referred because somatic pain fibres travel with other afferent peripheral cutaneous nerves from the same affected area, so the pain is felt in the nerve territory of that area.
- The reason for referred pain is because organs migrate during development, taking their original innervation with them.
Why does inflammation of viscera sometimes produce a well-localised pain of the surrounding skin if the pain should be referred?
Inflamed viscera might produce a well-localised pain if the inflammation affects the surrounding skin (e.g. orchitis can sometimes be felt in the scrotum if the inflammation spreads to the skin surrounding the testicle, and pain from appendicitis can be well-localised if inflammation spreads to the abdominal wall).
What is included in the foregut, midgut and hindgut?
- The foregut includes the lower oesophagus to the 2nd part of the duodenum. It also includes the liver, , gallbladder, bile duct and pancreas.
- The midgut includes the 3rd part of the duodenum to the first 2/3 of the transverse colon.
- The hindgut includes the last 1/3 of the transverse colon to the dentate line, which is a line that divides the upper two thirds and lower third of the anal canal.
Describe the innervation of the foregut, midgut and hindgut.
- The foregut is innervated by the greater splanchnic nerve (spinal nerve roots T5-T9).
- The midgut is innervated by the lesser splanchnic nerve (spinal nerve roots T10-T11).
- The hindgut is innervated by the least splanchnic nerve (spinal nerve roots S2-S4).
What are the spinal nerve roots of the parasympathetic nerves innervating the pelvic organs?
Parasympathetic nerves innervating the pelvic organs have spinal nerve roots S2-S4.
If the gallbladder is a foregut structure, and therefore has sympathetic innervation of roots T5-T9, why is cholecystitis (inflammation of the gallbladder) felt in the right shoulder?
Cholecystitis affects the right shoulder as it irritates the diaphragm, which has spinal nerve roots C3-C5.
How is referred pain originating from retroperitoneal organs felt differently to referred pain originating from intraperitoneal organs?
What about pain fibres travelling with parasympathetics (thoracic and pelvic)?
- Referred pain from intraperitoneal organs is felt in the front of the abdomen.
- Referred pain from retroperitoneal organs is felt in the back.
- Referred pain travelling with parasympathetics is also felt in the back.
Why does abdominal pain often begin as colicky pain and change to constant pain as the condition develops?
The change from colicky to constant pain is due to the inflammation affecting the abdominal wall as the condition develops, which causes a constant somatic pain.
Does the peritoneum produce visceral or somatic pain?
- The parietal peritoneum produces somatic pain.
- The visceral peritoneum produces visceral pain.
Describe the pain pattern of appendicitis.
- The pain is initially felt in the umbilicus, but then transitions to the right iliac fossa (as the inflammation spreads to the parietal peritoneum).
- There is a transition from colicky to constant pain.
- Rovsing sign: applying pressure to the left iliac fossa increases pain felt in the right iliac fossa.
- Psoas sign: irritation to iliopsoas indicates that the appendix is retrocaecal (most people don’t have a retrocaecal appendix).
