A, Right side. The segment of the vertebral artery coursing behind the superior articular process of C1 has been removed. The posterior condylar emissary vein passes through the posterior condylar canal and joins the sigmoid sinus. The rectus capitis lateralis attaches below to the transverse process of C1 and above to the jugular process of the occipital bone that forms the posterior edge of the jugular foramen. The internal jugular vein descends on the anterior side of the rectus capitis lateralis and the C1 transverse process. B, The cancellous bone within the occipital condyle has been drilled away while preserving the cortical and articular surfaces to expose the hypoglossal nerve in the hypoglossal canal. The posterior condylar vein passes above the occipital condyle and hypoglossal canal to empty into the sigmoid sinus. The transition between the sigmoid sinus and jugular bulb is located lateral to the occipital condyle in front of the jugular process of the occipital bone. The posterior third of the occipital condyle can be removed without entering the hypoglossal canal. The extracranial end of the hypoglossal canal is located medial to the jugular foramen. C, The portion of the rectus capitis lateralis that attaches to the jugular process of the occipital bone has been removed to expose the internal jugular vein, and the jugular process of the occipital bone has been removed to expose the jugular bulb. The facial nerve is exposed laterally at the stylomastoid foramen. Several meningeal branches of the occipital artery ascend to pass through the jugular foramen. An emissary vein passes from the jugular bulb to the vertebral venous plexus. (Images courtesy of AL Rhoton, Jr.)