Innervation of the anterior supracostal muscle
Yamasaki, M.
Kaibogaku Zasshi. Journal of Anatomy 56(1): 19-27
1981
ISSN/ISBN: 0022-7722 PMID: 7270041 Document Number: 181649
Bilaterally occurring anterior supracostal muscles (SCA) were observed in a 73 yr old male cadaver. On the right side the muscle was supplied by a branch from the terminal nerve to the 1st ICE although their emerging points on the anterior surface of ICE coincided approximately with those of the RCL in normal cases. Either RCL itself or its anterior branch was entirely absent in all the intercostal spaces associated with the SCA,and the sole existing anterior branch of the left 4th RCL gave no twig to the left SCA. On both sides, the terminal nerve to the ICE passed superficial to the 1st ICE for a considerable extent, being covered partially by SCA. All of the 3 RSCA are derived from its superficial branch. The right SCA was apparently formed by the superficial part of the 1st ICE which was elongated inferiorly and obtained its attachments to the 4th and partly to the 3rd ribs. In the left, the part supplied by the branch RSCA might be formed by the superficial fibers of the 1st ICE. The other part supplied by RSCA was probably formed by the part of 2nd ICE which was elongated superiorly and inferiorly and obtained its attachments to the 1st, 4th and 5th ribs. The left SCA could be considered as a 2-segmental muscle composed of the 1st and 2nd external intercostal components.