The transverse foramen is an oval opening in the transverse process of cervical vertebrae C1 through C6 (and often C7) that transmits the vertebral artery, the vertebral vein, and sympathetic plexus fibres from the vertebral artery. The vertebral artery enters the transverse foramen at C6 in most individuals (or C5-C7 in variants) and ascends through successive foramina to exit at C1 before entering the foramen magnum.
The transverse foramen must be respected during cervical spine surgery: anterior cervical discectomy with lateral exposure risks the vertebral artery at the medial edge of the transverse foramen, particularly at C5-C6 where the artery is most accessible. Screw placement into the C2 transverse process for atlantoaxial fixation carries a specific risk of vertebral artery injury. Vertebral artery injury in cervical spine trauma occurs at the foramen level. CT angiography images the vertebral artery throughout the transverse foramina, identifying loops, anomalous entry levels, and injury.
High-energy cervical fracture-dislocation tears the vertebral artery within the transverse foramina at the injury level, producing vertebral artery dissection or occlusion that may cause posterior fossa stroke; CT angiography of the cervical vessels is routine in high-energy cervical trauma to detect this injury and guide anticoagulation decisions.
