FIG 5. Posterior overview of the craniocervical junction in a venous corrosion cast. Note prominent deep cervical veins bilaterally (m). The left posterior condylar vein (g) is clearly seen to drain into both the horizontal portion of the left vertebral artery venous plexus at the C1 level (j) and the left deep cervical vein (m). b, transverse sinus; c, sigmoid sinus; a, superior jugular bulb; f, anterior condylar vein; k, anastomosis between anterior internal vertebral venous plexus and vertebral artery venous plexus; i, anterior internal vertebral venous plexus; u, internal jugular vein.