The seventh cervical dorsal spinal rami pass posteriorly around the articular processes of C7, medial to the posterior intertransverse muscles and divides into medial and lateral branches.  Each medial branch is small and ends in the semispinalis cervicis, semispinalis capitis, multifidus and interspinales muscles.
Supply
The medial branches of the seventh cervical dorsal spinal rami supply the semispinalis cervicis and capitis, multifidus and interspinales muscles.  The lateral branches supply the iliocostalis cervicis and longissimus cervicis and capitis muscles.