Third head of sternocleidomastoid muscle

The sternocleidomastoid, a prominent landmark of neck, offers protection to the major blood vessels and the nerves of this region. In recent era, this muscle has received a great attention of oncologists, general surgeons and plastic surgeons as it can be used as an excellent myocutaneous flap in reconstructive surgeries of head and neck region. The sternocleidomastoid is the key muscle of the side of the neck which divides this quadrilateral region into anterior and posterior triangular areas. Arising by a cord-like tendinous sternal head from the anterior surface of the manubrium sterni and a broader partly aponeurotic clavicular head from the upper surface of the medial third of the clavicle, the fleshy belly of the sternocleidomastoid curves round the side of the neck to be inserted into the lateral surface of the mastoid process and adjoining part of the superior nuchal line of the occipital bone [1]. The two heads are separated from one another at their origins by a triangular interval, which corresponds to a surface depression, the lesser supraclavicular fossa. The muscle is vascularized by the branches of suprascapular, superior thyroid and occipital arteries and innervated by accessory nerve along with branches from ventral rami of C2-3 spinal nerves. The present case reports an interesting and rare unilateral variation in the clavicular head of sternocleidomastoid muscle. The surgeons should be aware of the presence of such additional slips while performing surgeries in head and neck regions as these can be used as myocutaneous flaps without disturbing the normal morphology of muscle.