Abdomen/ Pelvis & Perioneum (Part II)

Question 1

What are the four main muscles of the posterior abdominal wall?

Answer 1

Quadratus lumborum
Psoas major and minor
Iliacus
Diaphragm

Question 2

How does the psoas minor present in the cadaver?

Answer 2

As a long shiny tendon that runs to the pubis (it also runs over the psoas major)

Question 3

True or false:

The anterior abdominal wall muscles also extend to the posterior abdominal wall. What are these muscles?

Answer 3

True

-these muscles are the transverse abdominalis, internal oblique and external oblique

Question 4

What are the three arcuate ligaments of the posterior abdominal wall?

Answer 4

Three little arches that are formed by the diaphragm. They form a passageway for certain structures.
They are the median, medial, and lateral arcuate ligaments

Question 5

What does the median arcuate ligament form and allow passage of?

Answer 5

The aortic hiatus…it allows for the passage of the aorta,, thoracic duct, greater thoracic splanchnic nerve and azygos vein

Question 6

What does the medial arcuate ligament allow for the passage of? Where is this ligament found?

Answer 6

Sympathetic trunk, psoas muscle and iliophyogastric nerve; sits on top of the psoas major

Question 7

What does the lateral arcuate ligament allow for the passage of? Where is this ligament found?

Answer 7

Quadratus lumborum muscle and subcostal nerve; sits on top of the quadratus lumborum muscle.

Question 8

Name the three arcuate ligaments in order from medial to lateral and what forms them.

Answer 8

Median= tendinous arch of the R and L crus of diaphragm
Medial= fascia of psoas muscle fro L1 body to TVP
Lateral= fascia of QL from TVP of L1 to 12th rib

Question 9

What group of nerves is formed within the psoas major muscle?

Answer 9

Lumbar plexus

Question 10

What forms the lumbar plexus?

Answer 10

Ventral primary rami of L1-L4

Question 11

What forms the lumbosacral trunk? What does it contribute to?

Answer 11

The union of part of the ventral primary rami of L4 and part of the ventral primary rami of L5…this contributes to the sacral plexus

Question 12

What are the cord levels for the 8 nerves of the lumbar plexus and the lumbosacral trunk?

Answer 12

Subcostal= T12
Iliohypogastric= L1
Ilioinguinal= L1
Genitofemoral= L1-L2
Lateral Femoral Cutatneous=L2-L3
Femoral= L2-L4
Obturator= L2-L4
(Accessory Obturator)= L2-L4
Lumbosacral trunk= L4-L5

Question 13

Where does the subcostal nerve exit?

Answer 13

Lateral arcuate ligament

Question 14

Where does the iliohypogastric (L1) nerve run? What does it pierce?

Answer 14

Pierces the transverse abdominalis and then runs between the internal and external obliques

Question 15

Where does the ilioinguinal (L1) nerve run? What does it go through?

Answer 15

It goes the inguinal canal (enters deep inguinal ring and exits superficial ring) and initially runs between the internal oblique and transverse abdominalis but then it runs between the internal and external obliques

Question 16

Where does the genitofemoral (L1-L2) nerve run?

Answer 16

In front of the psoas major muscle…it then splits and the femoral portion runs to the anterior thigh and the genital portion runs to the labia or scrotal area

Question 17

Where does the lateral femoral cutaneous nerve (L2-L3) run?

Answer 17

Exits lateral to the psoas muscle and then runs over the iliacus muscle

Question 18

Where does the obturator nerve (L2-L4) run?

Answer 18

It passes into the medial thigh to innervate the adductors….it exits through the obturator foramen

Question 19

Where would the obturator accessory nerve (L2-L4) run is present?

Answer 19

Just lateral to the obturator nerve

Question 20

Where does the femoral nerve run?

Answer 20

Lateral and posterior to the psoas major muscle

Question 21

What are the paired arteries of the posterior abdominal wall coming off the aorta? How many are there?

Answer 21

There are 6

• inferior phrenic (course up to feed the diaphragm)
• superior adrenal (suprarenal) that come off the inferior phrenic
• renal arteries (found at the hilum of the kidney)
• gonadal (ovarian or testicular)
• 4-5 pairs of lumbar (segmental) arteries
• common iliac artery

Question 22

What do the lumbar (segemental) arteries do?

Answer 22

Help feed the posterior abdominal wall and may also help feed the IVDs and spinal cord

Question 23

What do the common iliac arteries split into? What do those then do from there?

Answer 23

Common iliac splits into the external and internal iliac arteries. The external becomes the femoral artery and the internal dives deep to give off branches to the pelvic viscera

Question 24

What is special about the left renal vein?

Answer 24

It has to run across the aorta in order to reach the IVC

Question 25

What is the main collecting duct of the abdominal lymphatic system?

Answer 25

Cisterna chyli

Question 26

Where is the cisterna chyli located?

Answer 26

The the very end of the thoracic duct…about at the level of the kidneys, and posterior and slightly to the right of the abominal aorta