The intertransversarii laterales lumborum connect adjacent transverse processes on their anterior surfaces and are innervated by the anterior rami of lumbar nerves — distinguishing them from the intertransversarii mediales which are innervated by posterior rami. They consist of ventral and dorsal fascicles and contribute to lateral stabilisation of the lumbar spine.
| Origin | Anterior surface of the transverse process of each lumbar vertebra (L1-L5) |
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| Insertion | Anterior surface of the transverse process of the vertebra immediately above |
| Nerve Supply | Anterior rami of lumbar spinal nerves (ventral rami) |
| Blood Supply | Lumbar segmental arteries |
| Actions | Lateral flexion of the lumbar spine ipsilaterally; Stabilisation of the lateral lumbar column during trunk movements |
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The lateral intertransversarii are routinely disrupted during lateral lumbar interbody fusion approaches (LLIF/XLIF) where the psoas must be traversed. Their denervation (from anterior rami involvement) can contribute to post-operative lumbar lateral instability. They are rarely assessed or imaged clinically but contribute to the proprioceptive stability of the lateral lumbar column. Their anterior rami innervation distinguishes them from the posterior rami-innervated mediales in electrodiagnostic studies.
Not directly palpable due to their deep retroperitoneal position adjacent to the lumbar transverse processes.
Division of the lateral intertransversarii during trans-psoas lateral lumbar surgery contributing to lateral lumbar instability and post-operative paraspinal muscle atrophy.
