Similarly to other vertebrae, each lumbar vertebrae has a vertebral body and a vertebral arch.

The vertebral arch is formed by a pair of pedicles and a pair of laminae, it encloses the vertebral foramen and supports seven processes.

The first four lumbar vertebrae (L1 - L4) are considered typical, while L5 is an atypical lumbar vertebrae because of its distinguishing features.

The features of a typical lumbar vertebra include:

Body - large and cylindrical, typically, wider from side to side than from front to back.
Pedicles - directed backward from the upper part of the vertebral body. The pedicles significantly increase in width and in angulation in the axial plane from upper lumbar to lower lumbar vertebrae.
Laminae - are typically broad and short. They form the posterior portion of the vertebral arch, and they connect the spinal process with the pedicles.
Vertebral foramen - triangular when viewed from above. It is larger in the lumbar vertebrae than the thoracic vertebrae, but smaller than in the cervical vertebrae. The vertebral foramina create the spinal canal, which surrounds and protects the spinal cord.
Spinal process of the typical lumbar vertebra is thick, broad, and somewhat quadrilateral. It projects backward and ends with a thick, uneven border.
Superior and inferior articular processes are well-defined, and they project upward and downward, respectively, arising from the junctions of pedicles and laminae.
Transverse processes - usually thin and long (in contrast, the atypical vertebra L5 has massive and somewhat cone-shaped transverse processes). The transverse process of a lower lumbar vertebra is marked by three portions: the lateral or costiform process - directed laterally, the mammillary process - directed superiorly (cranially), and the accessory process - projecting inferiorly (caudally).

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Typical lumbar vertebrae