Steps in Far-Lateral Craniotomy, Following Cutaneous Incision. A, After cutaneous incision, the scalp flap is reflected downward and medially showing the most superficial muscle layers formed by sternocleidomastoid, laterally, and trapezius muscle, medially. The trapezius attaches to the medial superior nuchal line and external occipital protuberance, as well as the spinous processes of cervical and thoracic vertebrae. Laterally it attaches to the shoulder on the scapula and the lateral third of clavicle, covering the semispinalis capitis. In this picture it is cut in order to show the occipital artery. The sternocleidomastoid source is the superior nuchal line and the mastoid process running downward and medially across the lateral aspect of neck until attaching to the clavicle and sternum. It covers partially the splenius capitis muscle. B, The same picture in a closer view. Note that the trapezius muscle and sternocleidomastoid muscle cover the second muscle layer composed by the splenius capitis and semispinalis capitis muscles. C, A lateral view of the former muscles. Note the muscle fibers distinct paths what helps to distinguish the muscles during the surgical dissection. Trapezius fibers are vertical. Sternocleidomastoid muscle fibers are diagonal going from superior to inferior and posterior to anterior. (Images courtesy of E de Oliveira)