Anatomy: where is my patient's abdominal pain?

Question 1

what are the three layers of anterolateral abdominal muscles, from superficial to deep?

Answer 1

(Rectus abdominus anteriorly)
External oblique
Internal oblique
Transversus abdominus

Question 2

Does the peritoneum contain sensory receptors?

Answer 2

Yes

Question 3

Where does the inferior epigastric artery arise from?

Answer 3

The external iliac artery, just medial to the deep inguinal ring

Question 4

Where does the inferior epigastric run?

Answer 4

In the anterior abdominal wall, just deep to the rectus abdominus

Question 5

What do the omenta divide the peritoneal cavity into?

Answer 5

A greater sac and a lesser sac that communicate with each other through the omental foramen

Question 6

What lies within the free edge of the lesser omentum?

Answer 6

The portal triad

Question 7

Which ligament attaches the liver to the anterior abdominal wall?

Answer 7

The falciform ligament

Question 8

What pouch is formed by the peritoneum in the male?

Answer 8

The rectovesicle pouch

Question 9

What pouches are formed by the peritoneum in the female?

Answer 9

The rectouterine pouch

The uterovesicle pouch

Question 10

What levels do sympathetic nerves that supply the abdominal organs leave the spinal cord at?

Answer 10

T5-L2

Question 11

Do the sympathetic nerves that supply the abdominal organs synapse in the sympathetic chains?

Answer 11

No, but they pass through them.

Question 12

Which nerves do the sympathetic nerves supplying the abdominal organs leave the sympathetic chain within?

Answer 12

Abdominopelvic splanchnic nerves

Question 13

Where do sympathetic nerves supplying abdominal organs synapse ?

Answer 13

At prevertebral ganglia which are located anterior to the
aorta at the exit points of the major branches of the
abdominal aorta

Question 14

Describe the route taken by postsynaptic sympathetic nerve fibres which supply abdominal organs

Answer 14

Postsynaptic sympathetic nerve fibres pass from the 
prevertebral ganglia (celiac, superior mesenteric etc) 
onto the surface of the arterial branches leaving the 
abdominal aorta 

• They take part in “periarterial plexuses”
(around the arteries) with other nerve fibres
(parasympathetic and visceral afferent) as they
“hitch a ride” with the arteries, and their branches, towards (or away from if sensory) the smooth muscle
and glands of the organs

Question 15

Describe the nerve supply to the adrenal glands

Answer 15

The nerve supply to the adrenal glands is unique.
Sympathetic nerve fibres destined for the adrenal gland
leave the spinal cord (approx. T10-L1) and enter the
abdominopelvic splanchnic nerves, do not synapse at the
prevertebral ganglia, and are carried within periarterial
plexuses to the adrenal gland where they “synapse” directly onto cells.

Question 16

How does the vagus nerve supply abdominal organs?

Answer 16

presynaptic parasympathetic nerve fibres within the vagus nerves enter the abdominal cavity on the surface of the oesophagus (“vagal trunks”)
• travel towards and into the periarterial plexuses around the abdominal aorta
• carried to the walls of the organs where they synapse in ganglia
• supply parasympathetic nerve fibres to the GI tract + abdominal organs up to the distal end of the transverse colon

Question 17

What are the pelvic splanchnic nerves?

Answer 17

S 2, 3, 4

Question 18

What do the presynpatic parasympathetic nerve fibres in the splanchnic nerves innervate?

Answer 18

the smooth muscle/glands of the descending colon to anal canal

Question 19

Where does pain from a) the foregut structures, b) the midgut structures and c) the hindgut structures tend to be felt?

Answer 19

a) the Epigastric region
b) The umbilical region
c) the pubic region

Question 20

What do pain fibres from the vast majority of the

abdominal organs run alongside?

Answer 20

Sympathetic fibres back to the spinal cord

Question 21

Where do pain fibres from the foregut structures enter the

spinal cord?

Answer 21

Approx. T6 - T9

Question 22

Where do pain fibres from midgut structures enter the

spinal cord?

Answer 22

Approx T8-T12

Question 23

Where do pain fibres from hindgut structures enter the

spinal cord?

Answer 23

Approx T10- L2

Question 24

Where does pain from the abdominal organs tend to be felt by the patient?

Answer 24

in the dermatomes of the levels at which they enter the spinal cord, (there is a little overlap)
this can be considered a type of “referred pain”

Question 25

What are the somatic motor, somatic sensory and sympathetic nerve fibres supplying the structures (including the muscles) of the abdominal part of the “body wall” conveyed within?

Answer 25

the thoracoabdominal nerves
The subcostal nerve (T12 anterior ramus)
The iliohypogastric nerve (Half of L1 anterior ramus)
The ilioinguinal nerve (the other half of L1 anterior ramus)

Question 26

Where are the the thoracoabdominal nerves derived from?

Answer 26

the 7th to the 11th intercostal nerves travel anteriorly then their terminal branches leave the intercostal spaces, inthe plane between the internal oblique & the transversus abdominus, as the thoracoabdominal nerves