The sternocleidomastoid (SCM) muscle, an essential muscle in the human neck, is usually described as having two heads: the sternal and clavicular heads. This study explores the different anatomical variations of the SCM muscle, focusing on how often these variations occur, their clinical implications, and their significance in surgical contexts, especially the presence of extra (supernumerary) heads. Introduction: The SCM muscle is crucial for neck movement and serves as a key landmark in many clinical and surgical procedures. Reports of variations, such as additional heads, can have significant clinical implications. This study aims to document these variations and understand their impact on clinical practice. Methods: We carried out a detailed anatomical study on cadaveric specimens to identify variations in the SCM muscle. Additionally, we reviewed existing literature to supplement our findings. We measured the length, width, and distance from origin to insertion of the SCM muscle heads, noting any peculiar insertions or innervation variations. Results: Anatomy of the Sternocleidomastoid Muscle: Typically, the SCM muscle originates from the manubrium of the sternum (sternal head) and the medial part of the clavicle (clavicular head), merging at the mastoid process of the temporal bone and the superior nuchal line of the occipital bone. It is primarily innervated by the accessory nerve (cranial nerve XI) with help from the second and third cervical spinal nerves. This muscle helps in neck rotation and flexion and assists in breathing.