splenius cervicis (muscle)

sple·ni·us cer·vi·cis (mus·cle)

flat superficial muscle of the posterior neck, distinguished from the splenius capitis primarily by its insertion onto the cervical vertebrae; origin, from supraspinous ligament and spinous processes of third to fifth thoracic vertebrae; insertion, posterior tubercles of transverse processes of first, second, and sometimes third cervical vertebrae; action, rotates and extends neck; nerve supply, dorsal primary rami of fourth to eighth cervical spinal nerves.