L5 (5th Lumbar Vertebra)

The L5 vertebra (or the lumbar vertebra 5) is the last of the five lumbar vertebrae, positioned at the bottom of the lumbar curve of the back and just above the sacrum. Generally speaking, the lumbar vertebrae (L1 through L5) are distinct in being larger than the other vertebrae and in their lack of transverse foramina. Their articulating bodies are especially large and rather kidney-shaped with slightly concave faces above and below, plus a more deeply concave curve in the back. The L5...

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    Full L5 (5th Lumbar Vertebra) Description

    [Continued from above] . . . additionally lacks costal facets. Located in the lumbar (from the Latin for 'loins') or pelvic region, the lumbar vertebrae provide substantial support to the rest of the spinal column rising above it. In particular, the fifth lumbar vertebra is distinct from the L1-4 vertebrae in being much larger on its front side than in the back. Its spinous process, on the other hand, is smaller than in the other lumbar vertebrae with a wide, four-sided shape that comes to a rough edge and a thick notch. The L5 vertebra's transverse process is particularly thick, and a wider space separates the inferior articular processes. However, like the other lumbar vertebrae, the L5 lumbar vertebra has strong pedicles, broad laminae, and long, thin transverse processes. The laminae are wider than they are tall, and the resulting vertebral arch encloses a triangular vertebral foramen somewhat smaller than that found in the cervical vertebrae but larger than the thoracic. Significant among its seven processes are three tubercles, among them the superior mammillary process and in the inferior position the accessory process.