The third cervical dorsal spinal rami are slightly smaller than the second but larger than the fourth cervical dorsal spinal rami.  They pass posteriorly around the articular processes of C3, medial to the posterior intertransverse muscles and divide into medial and lateral branches.

Each medial branch runs into the interval between semispinalis capitis and semispinalis cervicis, passes through the splenius and trapezius muscles to terminate in the skin.  The third occipital nerve arises deep to trapezius as an offshoot of the medial branch and terminates in the skin of the lower occipital region.  The lateral branches may connect with the lateral branches of the dorsal rami of C2.

Supply
The third cervical dorsal spinal rami supply the splenius capitis muscles.