Blood supply to the human sternocleidomastoid muscle and its clinical implications for mandible reconstruction

Objectives/Hypothesis: The use of the sternocleidomastoid (SCM) flap for reconstructive surgery of the mandible seems to be a practicable although underestimated option. Study Design: This study was conducted on 15 cadavers that had been neoprenelatex injected in the middle and inferior pedicles. Methods: Lengths of the SCM were equally divided into upper, middle, and lower thirds. Each third was then subdivided into numbered quadrants. This procedure defined six levels in the SCM, each corresponding to two quadrants: one medial and the other lateral. For each third of the SCM, the origin of the main pedicles was recorded. The quadrants where neoprenelatex was detected were reported in the dissection book. Results: The upper third of the SCM muscle was constantly supplied by branches of the occipital artery. The middle third of the SCM muscle received its blood supply from a branch of the superior thyroid artery (right SCM/left SCM: 53%/53%), the external carotid artery (27%/20%), or branches of both (20%/27%). The lower third of the muscle was supplied by a branch arising from the suprascapular artery (73%/73%), the transverse cervical artery (7%/13%), the thyrocervical trunk (13%/13%), or the superficial cervical artery (7%/0%). The neoprenelatex injected into the subclavian artery reached the four lower levels in all SCMs studied (the middle third of the SCM). In 13% of the SCMs, this injection also reached level II (the upper third of the SCM). With a double injection (inferior and middle pedicles), levels I and II were reached in 100% of the cases. Conclusions: This study shows that, used alone, the lower pedicle does not have the ability to ensure the full vascularization of the SCM muscle. A composite flap might be safely raised only if the integrity of both inferior and middle pedicles is respected.