Muscles of the Trunk

Question 1

Rectus Abdominis

Answer 1

O: pubic crest and pubic symphysis
I: xiphoid process/costal cartilage of ribs 5-7
A: trunk flexion/assists in lateral flexion
I: T5-T11 intercostal nerves/subcostal (T12)

Question 2

external oblique

Answer 2

O: outer surface of ribs 5-12
I: anterior half of iliac crest/linea alba
A: trunk flexion/lateral flexion to same side/rotation to opposite side
I: T7-T12 intercostal nerves/subcostal (T12)

Question 3

internal oblique

Answer 3

O: lateral third of inguinal ligament/anterior half of iliac crest/thoracolumbar fascia
I: inferior borders of ribs 10-12/linea alba
A:trunk flexion/lateral flexion to same side/rotation to same side
I: T6-T11 intercostal nerves/subcostal/iliohypogastric/ilioinguinal

Question 4

transversus abdominis

Answer 4

O: iliac crest/lateral third of inguinal ligament/thoracolumbar fascia/cartilage of ribs 7-12
I: linea alba/pubic crest
A: compresses and holds viscera/increases intra-abdominal pressure and tenses thoracolumbar fascia
I: T6-T11 intercostal nerves/subcostal/iliohypogastric/ilioinguinal

Question 5

Quadratus lumborum

Answer 5

O: iliac crest
I: last rib/transverse processes of L1-L4
A: laterally flexes trunk
I: subcostal (T12)/ L1-L4 spinal nerves