Cervical venous organization in the transverse foramen.

The most widely accepted description of venous anatomy in the transverse foramen involves the presence of one or two veins running along and parallel to the external side of the vertebral artery. For most surgeons, the vertebral artery is surrounded by a rete of veins which is continous with the wide sinusoids which surround the thecal sac (internal vertebral venous plexus). The goal of this study was to ascertain the exact structure of the venous system in the transverse canal by micro dissection and histology. Six spinal segments (C1 to C7) removed from cadavers embalmed using 5% diluted formalin or not and studied with or without injection of colored latex after bilateral catheterization of the internal jugular vein, vertebral vein, common carotid artery, and vertebral artery. An anatomical study was performed by optical microscopy. After fixation and decalcification, tissue specimens were stained using hematoxylin-eosin-safran (HES) and immunocytochemical markers including CD43, CD31, and desmine (specific for vascular endothelium). Findings showed that venous blood in the transverse canal flows through a space formed by the periosteum. There was no evidence of a vein inside the transverse canal. The periosteum spans the space between the transverse processes and gives off fibrous leaflets to the artery thus forming a compartmentalized space lined with vascular endothelium around the artery. The venous system in the transverse canal presents itself as a sinus similar to the intracranial sinus structure.