How cranial could the sternocleidomastoid muscle be split?

The sternocleidomastoid (SCM) muscle, its anatomy, and its possible uses in head and neck reconstruction have been discussed, especially during the last 2 decades. The viability of the muscle and the skin over it depends on the vascular anatomy of the SCM and the anatomical heads-anterior or sternal and posterior or clavicular-that could enable splitting of the SCM muscle or myocutaneous flap. The authors have investigated the nourishment pattern of the SCM muscle to find out whether there was an independent blood supply to the each head of the muscle-anterior or sternal and posterior or clavicular-and whether the anatomical discrimination of the heads was congruent with the vascular pattern of the heads. The distinct vascular pattern of the two heads was determined. The occipital artery supplied all the muscle, and the first minor pedicle of the muscle originating from the superior thyroid artery supplies the clavicular head. Surgically, the heads could be split cranially until the first minor pedicle. The preservation of the first minor pedicle in the split SCM flap in which the clavicular head was harvested could provide a reliable flap. The use of the sternal head till the occipital artery, leaving the minor pedicle and the clavicular head in situ, could enable safe reconstructions with the SCM flap.