Suboccipital region and posterior skull.  The suboccipital region has been dissected bilaterally to demonstrate the muscles that form the suboccipital triangle: obliquus capitis inferior, obliquus capitis superior, and rectus capitis posterior major.  A fourth muscle, rectus capitis posterior minor, is located medial to the triangle on each side.  The scalp has been removed from the occipital bone to show the attachment of some of the suboccipital muscles to the inferior nucal line.  The vertebral artery is located deep within the suboccipital triangle as it courses along a groove on the posterior arch of the atlas (C1).  The occipital artery arises from the external carotid artery on the lateral aspect of the neck and crosses the suboccipital region to supply the posterior scalp. (Image courtesy of PA Rubino)