Muscles of Respiration + Quadratus Lumborum

Question 1

External Intercostals

Answer 1

O : Inferior border of the rib above
I : Superior border of the rib below
A :
1. Elevates ribs 2-12 at sternocostal joints and costospinal joints
2. Contralaterally rotates the trunk at the spinal joints

Question 2

Internal Intercostals

Answer 2

O : Inferior border of the rib above
I : Superior border of the rib below
A :
1. Depresses ribs 1-11 at the sternocostal and costospinal joints
2. Ipsilaterally rotates the trunk at the spinal joints

Question 3

Quadratus Lumborum

Answer 3

O : Medial 1/2 of the inferior border of the 12th rib and TVP of L1-L4
I : Posteromedial iliac crest and the iliolumbar ligament
A :
1. Elevates the same side pelvis at the lumbosacral joint and laterally flexes the lower lumbar spine relative to the upper lumbar spine at the spinal joints
2. Anteriorly tilts the pelvis at the lumbosacral joint and extends the lower lumbar spine relative to the upper lumbar spine at the spinal joints