Posterior coronal view of dissection through the posterior cranial fossa and spinal canal. In this dissection, both cerebellar hemispheres rest on the floor of the occipital bone. At the top of the image, a portion of the transverse sinus can be seen, which, when followed laterally, becomes the sigmoid sinus at the temporal-occipital bone junction. The foramen magnum is open to reveal the continuation of the medulla as the spinal cord. In addition, fibers forming the spinal accessory nerve emerge from its lateral borders between ventral and dorsal rootlets of cervical spinal nerves and ascend through the foramen along with the vertebral arteries that have traversed transverse foramina of the axis and atlas vertebrae. In addition, basilar and marginal sinuses are in continuity with the external vertebral venous plexus (not labeled) surrounding the vertebral column. Occipital arteries, branches of the external carotid, can be seen emerging from the deep surface of the longissimus capitis muscles enroute to supplying the posterior scalp. (Image courtesy of M Nunez)