The features of the typical lumbar vertebrae (L1 - L4) are characterized as follows:

Vertebral body - large and cylindrical-shaped (vertebral bodies of the L1 and L2 appear more kidney-shaped); it is wider in the transverse than in the anteroposterior direction; the height of the back of the L1 - L2 vertebrae is taller than in the front, the height of the L3 is the same for back and front, while the height of the back of the L4 vertebra is smaller than in the front;
Vertebral foramen - triangular-shaped when viewed from above; it is very small relative to the size of the body; it is larger in the lumbar vertebrae than the thoracic vertebrae but smaller than in the cervical vertebrae;
Pedicle - directed backward from the upper part of the vertebral body; they significantly increase in width and in angulation in the axial plane from the upper lumbar to the lower lumbar vertebrae;
Lamina - typically broad and short; laminae of the upper lumbar vertebrae are taller, while the laminae of the lower lumbar vertebrae are wider;
Spinous process - short, blunt, broad and somewhat quadrilateral-shaped; it is more horizontally oriented than in other vertebrae; projects backward and ends with a thick, uneven border;
Superior articular processes and inferior articular processes - well-defined, but they are not parallel to each other; have nearly vertical facets; the superior articular facets are concave and face posteromedially, while the inferior articular facets are convex and directed anterolaterally;
Transverse process - thin and long, but smaller compared to the thoracic vertebrae; it is also called the costal or costiform process because when it forms, it fuses with the rib rudiments; L1 - L3 vertebrae present with horizontally-oriented transverse processes, while the transverse processes of the L4 vertebra slightly incline upward;
Mammillary process - bony prominence that originates from the posterior aspect of the superior articular process; serves as an attachment site for deep back muscles (such as the lumbar intertransversarii muscles and lumbar multifidus muscle);
Accessory process - bony prominence on the posterior aspect of the transverse process; projects inferiorly from the transverse process and serves as an attachment site for deep muscles of the back (lumbar intertransversarii).

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Typical lumbar vertebrae (L1-L4)