Posterior Abdominal Wall

Question 1

What muscles form the boundaries of the posterior abdominal wall?

Answer 1

Superiorly - diaphragm
Medially - psoas major and minor
Laterally - quadratics lumborum
Inferiorly - iliacus

Question 2

Psoas major OIIA

Answer 2

Origin: bodies of T12 to L5 vertebrae and related TP’s of lumbar vertebrae

Insertion: lesser troch

Innervation: anterior rami of L1-L3

Main function: hip flexion, trunk flexion from sitting to standing

Question 3

Psoas minor OIIA

Answer 3

Origin: bodies of T12 and L1 vertebrae and intervertebral disc

Insertion: pectineal line of the pelvic broom and iliopubic eminence

Innervation: anterior rami of L1

Main function: helps w/ posterior pelvic tilt

Question 4

Iliacus OIIA

Answer 4

Origin: upper 2/3 of iliac fossa

Insertion: lesser troch

Innervation: femoral n (L2 and L3)

Main function: flexion of thigh at hip joint

Question 5

QL OIIA

Answer 5

Origin: iliac crest and iliolumbar ligament

Insertion: TP’s of L1-L4 vertebrae and inferior border of rib 12

Innervation: anterior rami of T12 and L1-L4

Main action: depress and stabilize rib 12 and lateral bending of trunk

Question 6

What are the main structures passing through the diaphragm?

Answer 6

Aorta, thoracic duct, esophagus, anterior and posterior vagal trunks, inferior vena cava, R and L phrenic n

Question 7

Where are the diaphragms domes during normal expiration? When is it important to remember these?

Answer 7

L dome at intercostal space 5 and R dome at rib 5
percussing the thorax

Question 8

What happens to the diaphragm domes during inspiration

Answer 8

Diaphragm contracts, flattens domes, enlarges thoracic cavity and reduces intra-thoracic pressure

Question 9

What innervates the diaphragm?

Answer 9

Phrenic and intercostal n’s

Question 10

Where do the R and L phrenic n innervate diaphragm?

Answer 10

R passes w/ inferior vena cava, L passes through muscle by itself