Suboccipital triangle musculature. The right suboccipital region has been exposed and shows the muscles that form the suboccipital triangle: obliquus capitis inferior, obliquus capitis superior, and rectus capitis posterior major.  Emerging from within the triangle is the suboccipital artery (of Salmon) that arises from the third segment of the vertebral artery that occupies a groove on the posterior arch of the atlas. This vessel is accompanied by a plexus of veins, the suboccipital venous plexus. Within this triangle is the suboccipital nerve (not labeled). It is the dorsal ramus of the C1 spinal nerve and motor nerve supply to the suboccipital muscles. The rectus capitis posterior minor is located medially. It extends from the posterior tubercle of the atlas to the inferior nuchal line of the occipital bone. The greater occipital nerve (dorsal ramus of C2) can be seen emerging from beneath the lower border of the obliquus capitis inferior. It provides sensory innervation to the posterior half of the scalp. The occipital artery, a posterior branch of the external carotid artery, emerges deep to the longissimus capitis and supplies the posterior scalp. (Image courtesy of AL Rhoton, Jr.)