The splenius capitis muscle runs along the back of the neck and joins the skull and spine. It is narrow and pointed at its origin from the last four cervical vertebrae and the supraspinous ligament of the first and second thoracic vertebrae. It becomes broader, dividing into two portions with separate insertions. The splenius capitis is inserted into the mastoid process of the temporal bone and the splenius colli (splenius cervicis) is inserted in two or three upper cervical vertebrae. The splenius capitis is innervated by dorsal branches of the second to sixth cervical nerves and is supplied by muscular branches of the aorta. It is used to rotate and tilt the head from side to side. Research Splenius Capitis