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The QUADRATO Musculo LOMBI is located in the posterior abdominal wall between the iliac crest and the 12th coast. It is formed by two incomplete muscular layers between them. The anterior layer originates from the apex of the coastal processes of L2-L5 and is inserted at the lower edge of the 12th coast; the lower layer originates from the inner lip of the iliac crest and from the upper margin of the ileolumbar ligament, to then insert the lower margin of the 12th rib and at the apex of the coastal processes of L1, L2, L3, L4.
It is lined anteriorly by a band that separates it from the large psoas muscle, from the kidney and from the ascending and descending colon
Contracting lowers the 12th rib (expiratory muscle); laterally tilts the spine and pelvis. Bilateral contraction extends the lumbar spine.
It is innervated by the intercostal nerve (T12) and by the internal branches of the lumbar nerves (L1-L3).
ORIGIN Anterior layer: from the apex of the costly processes of L2-L5 Lower layer: from the inner lip of the iliac crest and from the upper edge of the ileolumbar ligament |  |
INSERTION Front layer: lower margin of the 12th coast Lower layer: lower margin of the 12th rib and apex of the coastal processes of L1, L2, L3, L4 | |
| ACTION Contracting lowers the 12th rib (expiratory muscle); laterally tilts the spine and pelvis | |
| INNERVATION INTERCOSTAL NERVE (T12) and internal branches of the lumbar nerves (L1-L3) |
| Upper limb | Lower limb | Trunk | Abdomen | Articles |
