The splenius capitis (Latin: musculus splenius capitis) is a broad straplike muscle located in the back of the neck that belongs to the deep or intrinsic muscles of the back. The upper part of the muscle lies deep below the sternocleidomastoid, while its lower part - underneath the trapezius.
The splenius capitis originates from the lower half of the nuchal ligament and the spinous processes of the seventh cervical to third thoracic vertebrae (C7 - T3).
The main actions provided by the splenius capitis are extension of the head, as well as rotation and lateral flexion of the cervical spine. It is involved in movements such as shaking the head.
The splenius capitis is innervated by the posterior branches (dorsal rami) of the third to sixth cervical nerves (C3 - C6).