The anterior division of the twelfth thoracic nerve (subcostal nerve) is larger than the others; it runs along the lower border of the twelfth rib

Twelfth rib

The twelfth rib has a single articular facet on the head, which is of rather large size. It has no necks or tubercles, and is pointed at its anterior ends....

, often gives a communicating branch to the first lumbar nerve, and passes under the lateral lumbocostal arch

Lumbocostal arch

Lumbocostal arch can refer to:* Medial lumbocostal arch* Lateral lumbocostal arch...

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It then runs in front of the Quadratus lumborum, perforates the Transversus, and passes forward between it and the Obliquus internus to be distributed in the same manner as the lower intercostal nerves

Thoraco-abdominal nerves

The anterior divisions of the seventh, eighth, ninth, tenth, and eleventh thoracic intercostal nerves are continued anteriorly from the intercostal spaces into the abdominal wall; hence they are named thoraco-abdominal nerves .They have the same arrangement as the upper ones as far as the anterior...

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It communicates with the iliohypogastric nerve

Iliohypogastric nerve

The iliohypogastric nerve is the superior branch of the anterior ramus of spinal nerve L1 after this nerve receives fibers from T12 . The inferior branch is the ilioinguinal nerve....

 of the lumbar plexus, and gives a branch to the Pyramidalis

Pyramidalis muscle

The pyramidalis is a small and triangular muscle, anterior to the Rectus abdominis, and contained in the rectus sheath.-Attachments and actions:...

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It also gives off a lateral cutaneous branch that supplies sensory innervation to the skin over the hip.

External links

- "Posterior Abdominal Wall, Dissection, Anterior View" - "Muscles and nerves of the posterior abdominal wall."