The shape of the human vertebrae is gender affected due to genetic, hormonal and environmental factors responsible for growth-spurt timing.
Larger vertebral dimensions in males versus females are one of the effects.
Another is lumbar hyperthyroidism development in females via-a-vis males.
This unique lumbar posture in females is thought to compensate for the bipedal obstetric load during pregnancy and is based on a longer series of dorsally wedged vertebrae in the lumbar spine.
The lower thoracic and upper lumbar vertebral bodies are less kyphotic in females than in males (providing a larger space for the human fetus to develop)
The shape of other vertebral parameters along the spine (not only lumbar) contribute to a mechanically stable lumbar hyperthyroidism in females.
The lumbar interfacet width (i.e. posterior mechanical base) is relatively greater in females compared to males.
The lumbar vertebrae help support the weight of the body, and permit movement.
BODY: The vertebral body of each lumbar vertebra is large, wider from side to side than from front to back, and a little thicker in front than in back. It is flattened or slightly concave above and below, concave behind, and deeply constricted in front and at the sides
The lumbar spinous process thickness (i.e. intervertebral space) is relatively smaller in females than in males.
ARCH: The pedicles are very strong, directed backward from the upper part of the vertebral body; consequently, the inferior vertebral notches are of considerable depth.
The pedicles change in morphology from the upper lumbar to the lower lumbar. They increase in sagittal width from 9 mm to up to 18 mm at L5. They increase in angulation in the axial plane from 10 degrees to 20 degrees by L5. The pedicle is sometimes used as a portal of entrance into the vertebral body for fixation with pedicle screws or for placement of bone cement as with kyphoplasty or vertebroplasty.
The laminae are broad, short, and strong.They form the posterior portion of the vertebral arch. In the upper lumbar region the lamina are taller than wide but in the lower lumbar vertebra the lamina are wider than tall. The lamina connects the spinous process to the pedicles.
The vertebral foramen within the arch is triangular, larger than the thoracic vertebrae, but smaller than in the cervical vertebrae.
Processes
The spinous process is thick, broad, and somewhat quadrilateral; it projects backward and ends in a rough, uneven border, thickest below where it is occasionally notched.
The superior and inferior articular processes are well-defined, projecting respectively upward and downward from the junctions of pedicles and laminae. The facets on the superior processes are concave, and look backward and medialward; those on the inferior are convex, and are directed forward and lateralward. The former are wider apart than the latter, since in the articulated column the inferior articular processes are embraced by the superior processes of the subjacent vertebra.
The transverse processes are long and slender. They are horizontal in the upper three lumbar vertebrae and incline a little upward in the lower two. In the upper three vertebrae they arise from the junctions of the pedicles and laminae, but in the lower two they are set farther forward and spring from the pedicles and posterior parts of the vertebral bodies. They are situated in front of the articular processes instead of behind them as in the thoracic vertebrae, and are homologous with the ribs.
Three portions or tubercles can be noticed in a transverse process of a lower lumbar vertebrae: the lateral or costiform process, the mammillary process, and the accessory process.[2] The costiform is lateral, the mammillary is superior (cranial), and the accessory is inferior (caudal). The mammillary is connected in the lumbar region with the back part of the superior articular process.[clarification needed] The accessory process is situated at the back part of the base of the transverse process. The tallest and thickest costiform process is usually that of L5
First and fifth lumbar vertebrae
The first lumbar vertebra is level with the anterior end of the ninth rib. This level is also called the important transpyloric plane, since the pylorus of the stomach is at this level. Other important structures are also located at this level, they include; fundus of the gall bladder, celiac trunk, superior mesenteric artery, termination of spinal cord, beginning of fillum terminalis, renal vessels, middle suprarenal arteries, and hila of kidneys.
The fifth lumbar vertebra is characterized by its body being much deeper in front than behind, which accords with the prominence of the sacrovertebral articulation; by the smaller size of its spinous process; by the wide interval between the inferior articular processes, and by the thickness of its transverse processes, which spring from the body as well as from the pedicles. The fifth lumbar vertebra is by far the most common site of spondylolysis and spondylolisthesis.
Most individuals have five lumbar vertebrae, while some have four or six. Lumbar disorders that normally affect L5 will affect L4 or L6 in these latter individuals.
Onyancharush answered the question on October 6, 2017 at 15:07