The Splenius Capitis is a muscle located in the back of the neck. It originates from the spinous processes of the upper thoracic and lower cervical vertebrae and inserts into the mastoid process of the temporal bone and the occipital bone of the skull. This muscle plays a key role in head and neck movement. Functionally, the Splenius Capitis helps in extending, rotating, and tilting the head. It works in conjunction with other neck muscles, such as the Sternocleidomastoid, to facilitate these movements. Proper functioning of this muscle is important for maintaining good posture and preventing neck pain.