13. Posterior Abdominal Wall

Question 1

What are the motor and sensory functions of the iliohypogastric nerve?

Answer 1

Motor: internal oblique and transversus abdominis.

Sensory: posterior lateral gluteal skin, and skin in the pubic region.

Question 2

What are the motor and sensory functions of the ilioinguinal nerve?

Answer 2

Motor: internal oblique and transversus abdominis.

Sensory: skin of the upper medial thigh, and either the skin over the root of the penis and anterior scrotum – or the mons pubis and labium majus.

Question 3

Why are accessory renal arteries clinically relevant?

Answer 3

They are “end arteries,” and if they are ligated, they will cut off blood supply to their portion of the kidney.

Question 4

At what vertebral levels are the following structures located:

aortic hiatus, caval opening, esophageal hiatus.

Answer 4

Caval opening: T8

Esophageal hiatus: T10

Aortic hiatus: T12

Question 5

What would be the path of lymph draining from the descending colon?

Answer 5

Descending colon -> inferior mesenteric lymph nodes -> lumbar lymph nodes -> cisterna chyli -> thoracic duct -> left subclavian vein / internal jugular vein.

(Structures of the abdomen first drain into the lymph nodes of their embryological origin)

Question 6

At what vertebral level is the hilum of the kidney approximately located?

Answer 6

L1

Question 7

What artery do the middle suprarenal arteries branch off of?

Answer 7

The aorta directly.

Question 8

What is the name for the compression of the lateral femoral cutaneous nerve as it passes under the inguinal ligament?

Answer 8

Meralgia paresthetica.

Question 9

What artery do the inferior suprarenal arteries come off of?

Answer 9

The renal arteries.

Question 10

What muscles make up the muscular floor of the abdomen?

Answer 10

Psoas major.

Iliacus.

Quadratus lumborum.

Diaphragm.

Question 11

What is the sensory function of the lateral cutaneous nerve of the thigh (lateral femoral cutaneous nerve)?

Answer 11

Sensory: skin on the anterior and lateral thigh, down to the knee.

Question 12

What are the motor and sensory functions of the femoral nerve?

Answer 12

Motor: muscles of the anterior compartment of the thigh, as well as the iliacus and pectineus. (Hip flexors and quads).

Sensory: skin on anterior thigh and medial leg (from the saphenous branch).

Question 13

Which crus of the diaphragm encircles esophageal hiatus?

Answer 13

The right crus of the diaphragm.

Question 14

What are the three natural constriction points of the ureter?

Answer 14

At the ureteropelvic junction (at the end of the renal pelvis).

At the pelvic brim where it crosses the external iliac artery.

Where the ureter enters the bladder wall.

Question 15

What all passes through the caval opening?

Answer 15

Inferior vena cava.

Right phrenic nerve.

Question 16

Where’s the cisterna chyli found?

(At what vertebral level?)

Answer 16

At the level of L1 – behind the diaphragm.

Question 17

What specific population might be a higher risk for a psoas abscess?

Answer 17

Those with a risk of tuberculosis.

Question 18

What are the motor and sensory functions of the obturator nerve?

Answer 18

Motor: muscles of the medial compartment of the thigh – obturator externus, pectineus, etc.

Sensory: skin on the medial aspect of the thigh.

Question 19

From which vertebral segments do the preganglionic sympathetic nerves innervating the suprarenal gland originate?

Answer 19

T6-L2

Question 20

What are the signs and symptoms of a psoas abscess?

Answer 20

Psoas sign.

Back or flank pain.

Fever and infectious signs.

Possible inguinal mass.

Question 21

What nerves run posterior to the kidneys?

Answer 21

Subcostal nerve.

The roots of L1: iliohypogastric and ilioinguinal.

Question 22

What passes through the aortic hiatus?

Answer 22

Aorta.

Sometimes the azygos and the hemi-azygos veins.

Sometimes the thoracic duct as well.

Question 23

What are the motor and sensory functions of the genitofemoral nerve?

Answer 23

Motor: cremaster muscle.

Sensory: skin of anterior scrotum or mons pubis and labium majus – skin of upper anterior thigh.

(Genital and femoral sensation come from two branches, the genital branch and the femoral branch)

Question 24

Where does the right crus of the diaphragm insert?

Where does the left crus of the diaphragm insert?

Answer 24

Right crus: L3-L4

Left crus: L2-L3

Question 25

What is the “psoas sign.”

Answer 25

Pain on contraction of the psoas muscle – either resisted flexion or passive extension of the hip.

Question 26

From superior to inferior, what nerves of the abdomen exit lateral to psoas major?

Answer 26

Subcostal nerve.

Iliohypogastric nerve.

Ilioinguinal nerve.

Lateral femoral cutaneous nerve.

Femoral nerve.

Question 27

Are the sympathetic nerves approaching the suprarenal gland preganglionic or postganglionic?

Answer 27

Preganglionic. They synapse and the postganglionic nerves continue within the suprarenal gland itself.

Question 28

Non-foregut/midgut/hindgut structures on the posterior abdominal wall (such as the kidneys) drain into what lymph nodes?

Answer 28

Directly into the lumbar lymph nodes.

Question 29

What would be the path of the lymph draining from the liver?

Answer 29

Liver -> celiac trunk -> cisterna chyli -> thoracic duct -> left subclavian vein / left internal jugular vein.

Question 30

All of the lymph from the abdomen drains into what common structure?

Answer 30

Cisterna chyli.

Question 31

What passes through the esophageal hiatus?

Answer 31

Esophagus.

Anterior and posterior vagal trunks.

Esophageal arteries.

Question 32

What is covered by the median, medial, and lateral arcuate ligament respectively?

Answer 32

The median arcuate ligament is a tendinous arch of the crura of the diaphragm, covering a small portion of the aorta.

The medial arcuate ligament covers the psoas major muscle.

The lateral arcuate ligament covers the quadratus lumborum.

Question 33

What nerve of the abdomen exits anterior to psoas major?

Answer 33

Genitofemoral nerve.

Question 34

What structure does the ureter pass under in males and females respectively?

Answer 34

Males: the ureter passes under the ductus deferens.

Females: the ureter passes under the uterine artery.

Question 35

What nerves of the abdomen exit medial to psoas major?

Answer 35

Obturator nerve.

Lumbosacral trunks.

Question 36

What artery do the superior suprarenal arteries come off of?

Answer 36

The inferior phrenic artery.