Spinalis dorsi, the medial continuation of the
sacrospinalis, is scarcely separable as a distinct muscle. It is situated at the medial side of the
longissimus dorsi, and is intimately blended with it; it arises by three or four tendons from the
spinous processes of the first two
lumbar and the last two
thoracic vertebrae: these, uniting, form a small muscle which is inserted by separate tendons into the spinous processes of the upper thoracic vertebrae, the number varying from four to eight. It is intimately united with the
semispinalis dorsi, situated beneath it. ==Spinalis cervicis==