Anatomical study of the nervous and blood supply of the internal oblique abdominal muscle with reference to its clinical application

ABSTRACT

To study neurovascular supply of the internal oblique. Sixteen internal oblique muscles were dissected in 8 human cadavers. The external iliac artery was washed by saline, then injected with latex/lead oxide mixture, followed by dissection of the deep circumflex iliac artery and its branches. Dissection of arterial supply showed that the main arterial supply was through the deep circumflex iliac artery. It had an inguinal straight course and iliac curved course, medial and lateral to the A.S.I.S. Its iliac part coursed between the transversalis fascia and fascia iliaca. It ran on iliacus muscle separated from it by iliacus fascia. It gave muscular branches to internal oblique and iliacus muscle. The main branch of deep circumflex iliac artery was the ascending branch, originated from the main stem either within 1 cm medial to A.S.I.S. [in about 62.5% of dissections] or 2 to 4 cm medial to A.S.I.S. [in 37.5% of dissections]. It coursed between the transversus abdominis and internal oblique to be intimately related to the lower thoracic spinal nerves. The deep circumflex iliac artery ended by piercing the transversus abdominis. In 2 cadavers the deep circumflex iliac artery pierced also the internal oblique to end in the external oblique. The internal oblique was innervated by lower 3 thoracic spinal nerve, subcostal nerve, iliohypogastric and ilioinguinal nerves, arranged in a segmental manner. It was concluded that the internal oblique had a unique neurovascular supply, firstly because the motor nerves [lower thoracic spinal nerves, subcostal nerve and L[1]] were not accompanied by the main vascular pedicle [ascending branch of deep circumflex iliac artery] as in most skeletal muscles, secondly, the main arterial supply was single pedicle while, the motor nerve supply was multiple and separate with segmental arrangement. The abnormal course of deep circumflex iliac artery passing between the transversus abdominis and internal oblique may be mistaken with its ascending branch. The deep circumflex iliac artery had a long pedicle length with good diameter making it suitable for free tissue transfer