Abdominal Wall

Question 1

External Oblique

Answer 1

Origin: external surfaces of ribs 5-12

Insertion: anterior part of the iliac crest, abdominal aponeurosis to linea alba

Action:

• unilaterally: laterally flex vertebral column to same side, rotate vertebral column to opposite side
• bilaterally: flex the vertebral column, compress abdominal contents

Nerve: T5-T12

Question 2

Internal Oblique

Answer 2

Origin: lateral inguinal ligament, iliac crest, and thoracolumbar fascia

Insertion: internal surface of lower three ribs, abdominal aponeurosis to linea alba

Action:

• unilaterally: laterally flex vertebral column to same side, rotate vertebral column to same side
• bilaterally: flex the vertebral column, compress abdominal contents

Nerve: T7-L1

Question 3

Transverse Abdominus

Answer 3

Origin: lateral inguinal ligament, iliac crest, and thoracolumbar fascia, and internal surface of lower six ribs

Insertion: abdominal aponeurosis to linea alba

Action: compress abdominal contents

Nerve: T7-L1

Question 4

Rectus Abdominis

Answer 4

Origin: pubic crest, pubic symphysis

Insertion: cartilage of fifth, sixth, and seventh ribs and xiphoid process

Action: flex vertebral column, tilt pelvis posteriorly

Nerve: T5-T12

Question 5

Psoas Major

Answer 5

Origin: bodies and transverse processes of lumbar vertebrate

Insertion: lesser trochanter

Action:

• with the origin fixed, flex the hip, may laterally rotate hip
• with insertion fixed, flex trunk toward thigh, tilt pelvis anteriorly
• unilaterally: assist to laterally flex lumbar spine

Nerve: lumbar plexus L1, 2, 3, 4

Question 6

Iliacus

Answer 6

Origin: iliac fossa

Insertion: lesser trochanter

Action:

• with origin fixed, flex the hip, may laterally rotate hip
• with insertion fixed, flex trunk toward thigh, tilt pelvis anteriorly

Nerve: femoral nerve L(1), 2-3, 4

Question 7

Quadratus Lumborum

Answer 7

Origin: posterior iliac crest

Insertion: last rib and transverse processes of first through fourth lumbar vertebrae

Action:

• unilaterally: laterally tilt pelvic, laterally flex vertebral column to same side, assist to extend vertebral column
• bilaterally: fix last rib during forced inhalation and exhalation

Nerve: lumbar plexus T12, L1, 2, 3