Nerve supply to and the true nature of anterior supracostal muscle: three cases of the anterior supracostal muscle innervated by the external muscular branch of the first intercostal nerve having lateral cutaneous branch.
316 body-halves were examined in order to clarify nerve supply to human anterior supracostal muscle and to reveal the true nature of this particular muscle. 14 body-halves were found to have this muscle. It was innervated by the external muscular branch of the first intercostal nerve having lateral cutaneous branch in 3 out of 14 cases, and by the external muscular branch of the first intercostal nerve lacking lateral cutaneous branch in the remaining 11. As the former 3 cases have not been reported yet, we have examined the anatomy of these muscles in detail, and nerve supply to the anterior supracostal muscle and the true nature of this muscle were discussed in the present study. As a result, it was found that the anterior supracostal muscle is innervated essentially by an element of the components of the external muscular branch, and the muscle is derived from the first external intercostal muscle or rarely from the first and second external intercostal muscles. Moreover, it was inferred that the frequency of occurrence of the anterior supracostal muscle innervated by the intercostal nerve having lateral cutaneous branch is very low.
Tachibana
G
G
Department of Anatomy, Medical College of Oita, Japan.
Miyauchi
R
R
D005260:Female; D006801:Humans; D007366:Intercostal Muscles / Q000033:anatomy & histology / Q000294:innervation*; D007367:Intercostal Nerves / Q000033:anatomy & histology*; D008297:Male; D013900:Thoracic Nerves / Q000033:anatomy & histology*