Posterior Abdominal Wall

Question 1

What bones does the posterior abdominal wall consist of?

Answer 1

Lumbar vertebrae, sacrum (upper margin), pelvic bones (medial side of ea ilium), ribs 11 and 12

Question 2

What muscles form each boundary?

Answer 2

Superior: diaphragm
Inferior: iliacus
Medial: psoas major and minor
Lateral: QL

Question 3

Psoas major OIIA

Answer 3

O: bodies of T12-L5 and related, TP of lumbar vertebrae and intervertebral discs

I: lesser troch of femur

I: anterior rami of L1-L3

A: hip flexion, trunk flexion from sitting to standing

Question 4

Psoas minor OIIA

Answer 4

O: bodies of T12-L1 vertebrae and intervertebral discs

I: pectineal line of pelvic brim and iliopubic eminence

I: anterior rami of L1

A: helps w/ posterior pelvic tilt, weak trunk flex (VB)

Question 5

Iliacus OIIA

Answer 5

O: upper 2/3 of iliac fossa

I: lesser troch

I: femoral n (L2-L3)

A: flexion of thigh at hip joint

Question 6

QL OIIA

Answer 6

O: iliac crest and Iliolumbar lig

I: TP of L1-L4 and inferior border of rib 12

I: anterior rami of T12 and L1-L4

A: depress and stabilize rib 12 and trunk SB; important for respiration

Question 7

Which crus is longer?

Answer 7

Right

Question 8

Describe each major structure that passes through the diaphragm

Answer 8

-aorta: passes posterior to diaphragm and anterior to vertebral bodies at T12

-thoracic duct

-esophagus: passes through R crus at T10

-anterior and posterior vagal trunks: passes w/ esophagus

-IVC: passes from ab cavity to thoracic cavity

-R phrenic n: passes w/ IVC

-L phrenic: passes through muscle of diaphragm anterior to central tendon on L side

Question 9

What forms the diaphragm dome on each side?

Answer 9

R - liver
L - stomach and spleen

Question 10

Where does normal expiration place the L and R dome? When is it important to know?

Answer 10

R - rib 5
L - intercostal space 5
Percussing the thorax

Question 11

What happens to diaphragm during inspiration?

Answer 11

-central tendon moves inferiorly
-flattens domes, enlarges thoracic cavity, reduces intra-thoracic pressure

Question 12

What branches off the internal thoracic artery? Thoracic aorta? Abdominal aorta?

Answer 12

-musculophrenic and pericardiophrenic a.
-superior phrenic
-inferior phrenic

Question 13

Innervation of diaphragm

Answer 13

-phrenic n’s: provide motor, sensory to central part
-intercostal n’s: sensory to peripheral areas of diaphragm