L1 (1st Lumbar Vertebra)

The L1 vertebra is the uppermost or superior of the five (5) lumbar vertebrae below the thoracic vertebrae and above the fixed vertebrae of the sacrum. As the major weight-bearing bones of the spine, the lumbar vertebrae are the largest of the movable or true vertebrae, with substantial ventral bodies or centrums that are more wide than deep. As the superior or uppermost lumbar vertebra, the L1 connects to the thoracic vertebrae at the T12 vertebra, which conforms to the anatomical formation...

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    Full L1 (1st Lumbar Vertebra) Description

    [Continued from above] . . . of the lumbar region of the spine. A concave articular surface on the superior side of the cylindrical centrum matches the convex inferior section of the T12. Intervertebral discs made of cartilaginous connective tissue cushion the joints above and below to protect and support the spinal column. The vertebral arch includes strong, short, and wide laminae; substantial pedicles; long, thin transverse processes; and a fairly rectangular spinous process that extends almost horizontally from the body of the L1 vertebra. An articular process emanates from the vertebral arch between the pedicle and transverse process on each side, with a superior process and facet articulating with the T12 vertebra and an inferior process and facet articulating with the L2. Within the vertebral arch, the vertebral foramen is triangular and larger than in the thoracic vertebrae (though smaller than in the cervical spine). Like the other lumbar vertebrae, the L1 vertebra is noteworthy for the lack of transverse foramina in the transverse processes, and also by the lack of facets to either side of the centrum.