Trunk (thorax, abdomen, back)
Iliocostalis Lumborum (Lumbar Part)
Musculus iliocostalis lumborum
- Origin
- Sacrum, iliac crest and the thoracolumbar fascia
- Insertion
- Angle of the 7th through 12th ribs
- Function
- Extension and, unilaterally, lateral flexion of the lumbar spine
- Innervation
- Dorsal rami of the lumbar spinal nerves
- Movement & chain
- Largest and most lateral part of erector spinae in the lumbar region; essential when rising from a forward-bent position, together with multifidus and the hamstrings.
- Palpation
- Felt as a thick muscle belly lateral to the spinous processes in the low back, especially during resisted extension.
- Clinical
- Frequent source of low back pain with overuse or asymmetric lifting movements; myofascial trigger points are common here.
- Segmental innervation
- Dorsal rami of the lumbar spinal nerves, segmental per level.
- In clinical practice
- Ergonomic patient repositioning (log-roll technique in spinal trauma) and pressure offloading; maintain neutral spinal alignment in bedridden patients.
- Region in the model
- Trunk (thorax, abdomen, back)