Muscle · Head

Obliquus capitis inferior

Musculus obliquus capitis inferior

Obliquus capitis inferior is the odd one out of the suboccipital group: it is the only one that never touches the skull. It runs from the spinous process of the axis upward and outward to the transverse process of the atlas, so it acts purely on the joint between the first two neck vertebrae — the joint that supplies roughly half of all head rotation. Its single action is to turn the atlas, and with it the face, toward the same side. It forms the lower border of the suboccipital triangle and, like the rest of the group, is densely supplied with muscle spindles, making it a significant contributor to the sense of where the head is.