Anatomy - Referred pain

Question 1

Describe the arrangement of the enteric nervous system

Answer 1

• Ganglionic plexuses with interconnecting bundles of unmyelinated nerve fibres
• Project to sympathetic ganglia, the pancreas, gall bladder, trachea, spinal cord and brain stem
• From the oesophagus to the anus following the gut wall

Question 2

What is the function of the enteric nervous system?

Answer 2

• Allows the GI tract to perform its basic reflex functions of secretion, absorption, mixing and gut movements without influence of the CNS
• CNS can modify GI tract functions by communicating with the ENS

Question 3

Compare the function of the myenteric plexus and the submucosal plexus

Answer 3

• Submucosal plexus causes the muscularis mucosae to contract (making folds in the stomach for example)
• Myenteric plexus causes peristalsis/ segmentation via the longitudinal and circular muscle

Question 4

What are the functions of the autonomic efferent nerves in the abdomen?

Answer 4

• Motor to smooth muscle

- Secretomotor to glands

Question 5

What are the functions of the autonomic afferent nerves in the abdomen?

Answer 5

• Sympathetic responds to pain

- Parasympathetic response to functional sensation, such as stretch

Question 6

Where does the greater splanchnic nerve arise adn where does it go?

Answer 6

• T5-9

- Celiac ganglion

Question 7

Where does the lesser splanchnic nerve arise, and where does it go?

Answer 7

• T10-11

- Aorticorenal ganglion

Question 8

Where does the least splanchnic nerve arise and where does it go?

Answer 8

• T12

- Renal pelvis

Question 9

What are the two types of splanchnic nerves?

Answer 9

• Thoracic, lumbar and sacral nerves from sympathetic trunk to ganglia in the prevertebral plexus
• Pelvic splanchnic nerves are parasympathetic (S2-4) from prevertebral plexus (directly from S2-S4) to pelvis

Question 10

How many lumbar splanchnic nerves are there?

Answer 10

Two to four, pass from the lumbar part of the sympathetic trunk to the prevertebral plexus

Question 11

What is innervated by the pelvic splanchnic nerves?

Answer 11

• Fibres pass upward to enter the abdominal prevertebral plexus and distribute with the arteries supplying the hindgut
• Provides the pathway for innervation of the distal 1/3rd of the transverse colon, descending colon and sigmoid colon

Question 12

What are the three main abdominal prevertebral plexus divisions?

Answer 12

• Present in the abdominal prevertebral plexus, scattered through the length of the abdominal prevertebral plexus
• Celiac plexus
• Aortic plexus
• Superior hypogastric plexus

Question 13

Describe the position and ganglia of the celiac plexus

Answer 13

• Associated with roots of the celiac trunk and the superior mesenteric artery.
• Two celiac ganglia
• A superior mesenteric ganglia
• Two aorticorenal ganglia

Question 14

Describe the position and ganglia of the aortic plexus

Answer 14

• Just below the superior mesenteric artery

- Major ganglion is the inferior mesenteric ganglion

Question 15

Describe the position and ganglia of the superior hypogastric plexus

Answer 15

• Numerous small ganglia

- Final part of the prevertebral plexus

Question 16

What does the abdominal prevertebral plexus receive?

Answer 16

• Preganglionic parasympathetic and visceral afferent fibers from the vagus nerves [X]
• Preganglionic sympathetic and visceral afferent fibers from the thoracic and lumbar splanchnic nerves
• Preganglionic parasympathetic fibers from the pelvic splanchnic nerves.

Question 17

What do the vagus nerves innervate in the abdomen?

Answer 17

• Foregut and midgut

- Anterior (left) and posterior (right) vagal trunks

Question 18

How do sympathetic nerves in the abdomen run?

Answer 18

• With somatic nerves of the same region

- To organs they run with the arteries to the same organ

Question 19

Why does referred pain occur?

Answer 19

• The cerebral cortex has no sensory map for visceral organs and the diaphragm
• Brain cannot localise sensation, so the pain is reffered to the skin supplied by nerves with the same segmental supply (dermatomes)

Question 20

Which spinal level has no dermatome?

Answer 20

C1

Question 21

Pain from which organs cause pain in the epigastric region?

Answer 21

• Foregut structures
• Stomach
• Proximal duodenum
• Pancreas
• Liver
• Gall bladder

Question 22

Pain from which organs cause pain in the umbilical region?

Answer 22

• Pain from midgut structures

- Appendix causes a colicky pain (intermittent with bowel contractions)

Question 23

Describe the progression of pain in appendicitis

Answer 23

Pain becomes localized and constant at the right inguinal region when inflammation of the appendix spreads to surrounding peritoneum

Question 24

Pain from which organs cause pain in the suprapubic region?

Answer 24

• Hidgut organs

- Descending colon to anal canal

Question 25

What nerves supply the epigastric region?

Answer 25

T7/8

Question 26

What nerves supply the umbilical region?

Answer 26

T10

Question 27

What nerves supply the inguinal region?

Answer 27

T12/L1

Question 28

What nerves supply the suprapubic region?

Answer 28

T12/L1-2

Question 29

List the pre-aortic lymph nodes

Answer 29

• Celiac nodes (by the celiac trunk, drains the abdominal foregut as well as recieving lymph from superior/inferior mesenteric nodes to drain into the cisterna chyli)
• Superior mesenteric nodes (recieves from inferior drains into celiac, main function to drain the midgut)
• Inferior mesenteric nodes (drains the hind gut)