Serratus posterior inferior
Back
Deep muscle — it lies under other muscles. X-ray makes the muscles over it see-through.
- Origin
- Spinous processes of T11 to L2 or L3 and the thoracolumbar fascia
- Insertion
- Lower borders of the lower four ribs, just beyond their angles
- Action
- Pulls the lower ribs down and back
- Nerve supply
- Intercostal nerves (T9–T11) and subcostal nerve (T12)
A thin muscle where the upper and lower back meet, under the latissimus dorsi. It draws the lower ribs down; its exact role in breathing is unclear.
Serratus posterior inferior anatomy page →