The musculus quadratus lumborum is the deepest of the abdominal muscles and located at the posterior abdominal wall. It is also commonly referred to as a back muscle. The quadratus lumborum muscle is involved in the breathing as well as motions of the trunk.

Musculus quadratus lumborum – structure and functions

The musculus quadratus lumborum fills the area between the posterior iliac crest and the twelfth rib. It originates at the iliac crest from where it runs upward. On its way the quadratus lumborum muscle inserts by small tendons into the transverse processes of the upper four lumbar vertebrae and finally into the twelfth rib.

The musculus quadratus lumborum has the following functions:

  • It lowers (pulls down) the twelfth rib and helps to incline the trunk sidewards (one side contracts),
  • extends the lumbar vertebral column (both sides contract),
  • elevates the iliac bone when thorax is fixated (both sides contract), and
  • fixates the floating ribs (especially the twelfth) during forced exhalation.


Musculus quadratus lumborum – training

The musculus quadratus lumborum usually is not focused during workout sessions for the abdominals. Commonly, athletes perform exercises for the musculus rectus abdominis and the obliques. Especially when we practise exercises that emphasise the obliques the quadratus lumborum muscle will be activated as well. But it is important to also work out the muscles of the lower back. If the quadratus lumborum gets too strong and the lower back remains too weak the risk of back problems increases.

The musculus quadratus lumborum is the deepest abdominal muscle and located in the lumbar region what actually makes it a back muscle. It supports the respiration and certain movements of the trunk. A well-pronounced quadratus lumborum muscle requires a strong muscle of the lower back to prevent back problems.


Musculus quadratus lumborum

Musculus quadratus lumborum

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