splenius capitis (muscle)

sple·ni·us ca·pi·tis (mus·cle)

[TA]
flat superficial muscle of the posterior neck, distinguished from the splenius cervicis muscle primarily by its insertion onto the cranium; origin, from ligamentum nuchae of last four cervical vertebrae and supraspinous ligament of first and second thoracic vertebrae; insertion, lateral half of superior nuchal line and mastoid process; action, rotates head and extends neck; nerve supply, dorsal primary rami of second to sixth cervical spinal nerves.