Posterior Abdominal Wall

Question 1

Thwart are the walks of the abdominal period”v8c cavity?

Answer 1

The abdominal and pelvic cavities are continuous

Upper boundary- thoraco-abdominal diaphragm

Lower boundary- pelvic diaphragm

Pelvic inlet- the division between the abdominal and pelvic cavities

Parietal peritoneum- Lines the abdominal wall and the pelvic organs serving as an additional separation

Question 2

What is the diaphragm?

Answer 2

Muscular and tendinous separation between the thorax and abdomen

-Lined with peritoneum (inferiorly), except for the area superior to the bare area of the liver

Diaphragm as a muscle changes size of the thoracic cavity to facilitate airflow of the lungs during breathing

Question 3

What are the three large openings of the diaphragm ?

Answer 3

Inferior vena cava T8 vertebral level

Esophagus T10 vertebra level

Aorta T12 vertebral level

Question 4

What is the blood supply of the diaphragm?

Answer 4

• superior and inferior phrenic arteries
• musculophrenic arteries
• pericardioohrenic arteries

Question 5

What is the innervation of the diaphragm?

Answer 5

Phrenic nerves (C3,4,5)

Question 6

Where does the inferior vena cava enter the diaphragm?

Answer 6

Caval hiatus(T8)

Question 7

Where does the esophagus enter the diaphragm?

Answer 7

Esophageal hiatus (T10)

Along with esophagus, anterior and posterior vagal trunks

Question 8

What enters the diaphragm: through the median articulate ligament?

Answer 8

At T12

Aorta and thoracic duct

Question 9

What is the function of the psoas major?

Answer 9

Action: flexes hip

Question 10

What is the innervation of the psoas major?

Answer 10

Innervated by ventral rami of L1-3

O/I vertebral bodies & transverse processes T12-L5 to lesser trochanter

Question 11

What is the function of the Quadratus lumborum?

Answer 11

Depresses & stabilizes rib 12, lateral bending (lateral flexion)

Question 12

What is the innervation of the Quadratus lumborum?

Answer 12

Innervated by ventral rami of T12-L4

O/I transverse process of L5, iliac crest and iliolumbar ligament to transverse processes of L1-4 and rib 12

Question 13

What is the action of the iliac?

Answer 13

Action: flexion of hip

Question 14

What is the innervation of the iliacus?

Answer 14

Innervated by femoral nerve

O/I iliac fossa and upper portion of lateral sacrum to lesser trochanter

Question 15

What is the location and function of the lumbar plexus?

Answer 15

The nerve supply of the posterior abdominal wall, pelvic walls and floor and lower limb are closely related

The lumbar plexus serves the abdomen, anterior and medial thigh
The sacral plexus receives a contribution from the lumbar plexus- lumbosacral trunk

 -The sacral plexus supplies the pelvic muscles, gluteal region and posterior lower limb

Question 16

What nerves are applied to the lumbar plexus?

Answer 16

Iliohypogastric nerve

Ilioinguinal

Genitofemoral

Lateral femoral cutaneous

Femoral

Obturator

Question 17

What is the function of the iliohypogastric nerve of the lumbar plexus?

Answer 17

T12-L1: iliohypogastric: internal oblique transversus muscles, skin above pubis (suprapubic) and gluteal region

Question 18

What is the function of the ilioinguinal nerve of the lumbar plexus?

Answer 18

L1: ilioinguinal:Internal oblique- transversus muscles, skin over upper medial thigh, anterior scrotum and labia majora

Question 19

What is the function of the genitofemoral nerve of the lumbar plexus?

Answer 19

L1-L2

Genital branch: supply cremaster and scrotum

Femoral branch: skin of the femoral triangle

Question 20

What is the function of the lateral femoral cutaneous nerve of the lumbar plexus?

Answer 20

L2-3: lateral femoral cutaneous: skin of anterior and lateral thigh

Question 21

What Is the function of the femoral nerve of the lumbar plexus?

Answer 21

L2-L4: femoral nerve: skin of the anterior thigh, medial part of thigh, hip and knee joints. Quadriceps femoris, pectineus, sartorius muscles. (Anterior muscle compartment of thigh)

Question 22

What is the function of the obturator nerve of the lumbar plexus ?

Answer 22

L2-4: obturator: skin on medial side of thigh, adductor muscles (medial muscle compartment on thigh)

Question 23

Describe the cremaster Reflex

Answer 23

Genital branch of the genitofemoral nerve supplies the cremaster muscle-this is the efferent limb of the cremaster reflex arc

Ilioinguinal nerve supplies the upper medial portion of the thigh -this is the afferent limb of the cremaster reflex arc

Femoral branch of the genitofemoral nerve supplies the area over the femoral triangle

Lightly touching the skin over the medial side of the upper thigh invokes the cremaster reflex-testis is pulled upward

Strong in infants

Question 24

What are the afferent and efferent pathways of the cremaster reflex?

Answer 24

Afferent pathway: ilioinguinal nerve (L1)

Efferent pathway: Genital branch of the genitofemoral nerve(L1,L2)

Question 25

Describe the significance of the abdominal aorta

Answer 25

Continuation of thoracic aorta Passes through the diaphragm at T12 vertebral level Gives paired and unpaired branches to both the abdominal viscera and abdominal wall Bifurcate at L4 into the common iliac arteries Common iliac arteries divide into internal and external iliac arteries

Question 26

What is the significance of internal and external iliac arteries ?

Answer 26

Internal iliac artery supplies the pelvis and gluteal region -umbilical (partially oblitered), superior vesicle, middle rectal, superior gluteal, inferior gluteal, internal pudendal, lateral sacral, obturator, iliolumbar External iliac becomes the femoral artery as it passes deep to the inguinal ligament and supplies the lower limb

Question 27

Describe the common iliac veins

Answer 27

Junction of the external and internal iliac veins at the pelvic inlet The internal iliac vein receives blood from the pelvic organs, pelvic wall and gluteal region The external iliac vein receives blood from the lower anterior abdominal wall and lower limb

Question 28

Where is the inferior vena cava?

Answer 28

Starts at L5 vertebra with the junction of the two common iliac veins The tributaries to the IVC do not correspond exactly to the branches of the aorta

Question 29

Where does the inferior vena cava DIRECTLY get blood from?

Answer 29

- lumbar - right inferior phrenic - renal - right suprarenal - right gonadal - hepatic - common iliac vein

Question 30

Where does the inferior vena cava INDIRECTLY receive blood?

Answer 30

It receives blood indirectly from the: -left inferior phrenic (via renal veins) - femoral and lower limb veins(via external iliac) - anterior abdominal wall (via external iliac) - pelvic organs(via internal iliac) - left gonadal (via left renal) - left suprarenal (via renal)

Question 31

Where do the azygos veins receive blood from?

Answer 31

Receives blood from the posterior walls of the thorax and abdomen into the superior vena cava

Question 32

What is the azygos system of veins formed by?

Answer 32

Formed by the union of the ascending lumbar veins with the right subcostal veins at the level of the 12th thoracic vertebra, ascending in the posterior mediastinum , and arching over the right main bronchus posteriorly at the root of the right lung to join the superior vena cava

Question 33

What is the sosignificance of the azygos veins?

Answer 33

A major tributary of the azygos system is the hemizygos vein, a similar structure on the opposite of the vertebral column. It also creates a cavo-caval anastomosis by offering an alternative, collateral blood flow from the lower half of the body to the superior vena cava, bypassing the inferior vena cava

Question 34

Summarize azygos system of veins

Answer 34

Ascending lumbar veins receive blood from lumbar veins and drain into azygos or hemiazygos veins on to superior vena cava

Question 35

Summarize internal thoracic veins

Answer 35

Continuous with superior and inferior epigastric veins and thus connects external iliac vein with Subclavian vein on to right atrium eventually

Question 36

Summarize the Axillary vein

Answer 36

Superficial epigastric veins which drain into the axillary vein which becomes Subclavian, brachiocephalic to form superior vena cava it’s brachiocephalic vein from contralateral vein

Question 37

Summarize the obstructed blood flow of IVC

Answer 37

Veinous drainage from the abdominal and pelvic walls and pelvic organs is via the inferior vena cava. Pathologies can result in obstruction of the IVC Several alternative drainage pathways are available. The alternative pathways may increase the size of the vessels. If these are superficial vessels they may become visible under the skin

Question 38

Summarize abdominal and lymphatics

Answer 38

Lymphatics from the posterior abdominal wall drain into the lumbar (lateral aortic) nodes These eventually drain into the cisterna chyli, a large fluid filled sac which collects lymph of the entire lower part of the body

Question 39

What are cisterna chyli?

Answer 39

A retro-peritoneal structure. In humans, it is located posterior to the abdominal aorta on the anterior aspect of the bodies of the first and second lumbar vertebrae(L1 and 2)

Question 40

How does abdominal lymphatics & cisterna chyli?

Answer 40

It forms the beginning of the primary lymph vessel, the thoracic duct, which transports lymph and chyle from the abdomen cavity via the aortic opening of the diaphragm to the junction of left Subclavian vein and left internal jugular vein -It receives lymph from the intestinal trunk and the lumbar lymphatic trunks

Question 41

Where does lymph posterior abdominal wall drain to?

Answer 41

Lymph from the posterior abdominal wall drains into the lumbar (lateral para aortic) lymph nodes which eventually drains into the cisterna chyli and continues as the thoracic duct