The splenius capitis is a broad strap-like 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.

• Origin: lower half of the nuchal ligament and the spinous processes of the seventh cervical to third thoracic vertebrae (C7 - T3).
• Insertion: mastoid process of the temporal bone, and the adjoining occipital bone - into its rough surface just below the superior nuchal line.
• Action: extension of the head, as well as rotation, and lateral flexion of the cervical spine; this muscle is involved in movements such as shaking the head.
• Innervation: posterior branches (dorsal rami) of the third to sixth cervical spinal nerves (C3 - C6).
• Blood supply: muscular branches of the aorta.