In reconstructing a defect of the mandible after removing tumor of an oral cavity or facial region, various musculocutaneous flaps are used. Among those, SCM musculocutaneous flaps are clinically frequently used due to its near donor site and it can be done without an additional operation. Because the SCM muscle is supplied by many vessels of the external carotid artery and subclavian artery, it is essential to the figure out its distribution to the SCM muscle, clavicle and the skin before making an osseomusculocutaneous flap including the clavicle. Especially, understanding the distribution status of the origin of superior thyroid artery and SCM branch is very important in making a SCM musculocutaneous flap including the clavicle and deciding the rotation arc of the musculocutaneous flap. The authors have dissected SCM muscles and arteries distributed to the SCM muscle of 50 cadavers and found the following results. The average distance from the origin of superior thyroid artery to SCM branch entering to SCM muscle was 30.1 mm (16.0 ~37.7 mm), and some were to have 2 ~3 branches inserted simultaneously into the SCM muscle. The average distance from the origin of superior thyroid artery to clavicular head of SCM muscle was 87.6 mm (57.7 ~123.8 mm), and to sternal head of SCM muscle was 131.2 mm(99.7 ~166.8 mm). After the SCM branch of superior thyroid artery distributed to the SCM muscle, the bifurcation point into clavicular branch and sternal branch is located at an average 58.8 mm(28.4 ~130.4 mm) above the clavicle. All of the nutrition artery distributed to the clavicle were branches of the thoracoacromial artery, and the SCM branch of superior thyroid artery distributed throughout the SCM muscle and downwards to the periosteal artery of the clavicle. The pattern of the superior thyroid artery was divided into 6 types. Among the branches of superior thyroid artery such as laryngeal, SCM and thyroid branch, The type I (36%) that the laryngeal branch arised first was most common. Next, the incidence of type II that all three branches arised at one point was 16%. In addition, the incidence of the case that SCM branch arised directly from the external carotid artery was 26%. In conclusion, because the origin of superior thyroid artery from the external carotid artery is located relatively close to the mandible above the neck, the length of SCM musculocutaneous flap including the SCM branch of superior thyroid artery is sufficient to reconstructing the mandible and the SCM osseomusculocutaneous flap including the clavicle is useful in reconstruction of the mandible.