Posterior Wall Muscles

Question 1

Posterior abdominal wall muscles

Answer 1

1. Diaphragm
2. Psoas major
3. Quadratus lumborum
4. Iliacus
5. Psoas minor

Question 2

Psoas major origin

Answer 2

1. Front and lower borders of all lumbar vertebrae transverse processes
2. Adjacent sides of lumbar bodies and intervertebral discs
3. Tendinous arches bridging over lumbar vessels

Question 3

Psoas major insertion

Answer 3

Descends along pelvis brim medial to Iliacus, where both join forming iliopsoas tendon, which passes deep to Inguinal ligament entering thigh to be inserted into femur lesser trochanter

Question 4

Psoas major nerve supply

Answer 4

Lumbar plexus (L2,L3, and L4)

Question 5

Psoas major action

Answer 5

1. Main thigh flexor and medial rotator
2. Thigh lateral rotator only when femur neck is fractured due to change of rotation axis:
   - Trunk lateral bending
   - Both Psoas bend trunk forward

Question 6

Psoas minor origin

Answer 6

From adjoining parts of last thoracic and 1st lumbar vertebrae with intervertebral discs in between

Question 7

Psoas minor insertion

Answer 7

Descends in front of Psoas major to be inserted into iliopectineal eminence

Question 8

Psoas minor nerve supply

Answer 8

1st lumbar nerve

Question 9

Psoas minor action

Answer 9

If it is present (60%), it will assist in trunk flexion

Question 10

Quadratus lumborum origin

Answer 10

1. Iliolumbar ligament
2. Medial part of iliac crest inner lip

Question 11

Quadratus lumborum insertion

Answer 11

1. Last rib medial 1/2
2. By tendinous slips into transverse processes tips of upper 4 lumbar vertebrae

Question 12

Quadratus lumborum actions

Answer 12

1. Fixes last rib, helping diaphragm to contract more effectively during respiration
2. Lateral flexion (bending) of vertebral column)
3. If both muscles act together, extend vertebral column lumbar part

Question 13

Iliacus origin

Answer 13

Iliac fossa of hip bone

Question 14

Iliacus insertion

Answer 14

Passes deep to Inguinal ligament to be inserted into femur lesser trochanter with Psoas major

Question 15

Iliacus nerve supply

Answer 15

Femoral nerve (main trunk) in abdomen

Question 16

Iliacus action

Answer 16

Thigh flexion