Ligaments of the lumbosacral spine and their role in possible extraforaminal spinal nerve entrapment and tethering.

The extraforaminal ligaments of the lumbosacral spine were studied in 34 cadavers. The corporotransverse ligament attached to the body and transverse process of the same vertebra. The ligament may entrap the exiting nerve root below it in rotary subluxation or in complete disk space loss. The lumbosacral ligament extends from the transverse process of L5 and the L5-S1 disk to the sacral ala, forming the roof of the lumbosacral tunnel through which the L5 spinal nerve passes. This may be the site of extraforaminal entrapment if lateral disk herniations, osteophytes, or tumor metastasis are also present. The nerve suspensory ligament attaches to the nerve sheath and to the disk and is felt to be significant as a vehicle for mechanoreception.