The vertebral foramen: a report concerning its contents.

Thirteen subjects were randomly selected and embalmed according to Winckler's technique. After removal of the vertebral column and the head in one block the specimens were frozen. Transverse transpedicular cuts were performed at C6, T1, T6, L1, L3, and L5. After enlargement photography, the surface area of the vertebral foramen and its various contents were measured on a computer using the Canvas programme and analysed using the Statview programme. The mean area of the vertebral foramen occupied by the cord was 30.5% at C6, 26.1% at T1, 21.4% at T6, 12.7% at L1, 0.08% at L3. The mean area occupied by the nerve roots was 3.9% at C6, 3.3% at T1, 1.6% at T6, 14.2% at L1, 17.5% at L3, 12.2% at L5. The mean area of all the nervous tissue was 34.4% at C6, 29.5% at T1, 23% at T6, 26.9% at L1, 18.9% at L3, 19.3% at L5. The cerebrospinal fluid occupied a mean area of 25.2% at C6, 30.7% at T1, 31.6% at T6, 43% at L1, 43.5% at L3, and 28.1% at L5. The total neural tissue did not occupy more than a third of the vertebral foramen. These facts should be considered by surgeons who perform laminectomy or decompression in cases of vertebral trauma or congenital and osteoarthritic stenoses.