Vertebrae – Lumbar

This video showcases the human vertebral column with a particular emphasis on the lumbar region, which is highlighted in orange.
The lumbar spine is a critical segment composed of five robust vertebrae, distinguished by their larger size to support the upper body’s weight. These vertebrae play a pivotal role in providing mobility and flexibility to the torso, allowing for a range of movements including bending and twisting, while also safeguarding the delicate spinal cord within.

The spinous process is a prominent posterior projection on a vertebra. It extends backward from where the two laminee join and serves as a point of attachment for muscles and ligaments. In the lumbar spine, these processes are particularly robust due to the significant amount of muscle attachment and the forces they sustain, enabling extension, flexion, and rotational movements of the spine.

The spinous processes also play a role in protecting the spinal cord that runs through the vertebral column. Here we have two key structures of a lumbar vertebra, the superior articular process and the inferior articular process. The superior articular process is an upward-facing projection that articulates with the inferior articular process of the vertebra above it.Conversely, the inferior articular process, which faces downward, articulates with the superior articular process of the vertebra below. These articulations form facet joints, which are synovial joints that allow for the smooth movement of the vertebral column and contribute to spinal stability.

The orientation and shape of these processes vary throughout different parts of the spine to accommodate the types and ranges of motion specific to each region. In the lumbar spine, they are particularly important for permitting flexion and extension while limiting rotation. The pedicle is a cylindrical bone segment that connects the posterior elements of a vertebra to the vertebral body. It’s a critical architectural feature that forms the bridge between the front and back of the spine.

The pedicles are strong bony structures that help protect the nerve roots and support the vertebral arch. In this image, the pedicle is shown from a lateral view, which demonstrates its position as a key component of the vertebral structure, connecting the body of the vertebra to the transverse and articular processes. The vertebral body is the thick disc-shaped anterior portion of a vertebra. As the largest part of a vertebra, it bears the majority of the axial load of the body, providing structural support and stability to the spine.

The vertebral body is also essential in protecting the spinal cord, which runs through the vertebral foramen just behind it. The cylindrical shape of the vertebral body allows it to efficiently distribute compressive forces while its trabecular bone structure absorbs shocks and helps prevent fractures. This component of the vertebra plays a crucial role in the overall biomechanics of the vertebral column. The vertebral foramen is the central canal within a vertebra through which the spinal cord passes. It is bounded by the body of the vertebra at the front and the vertebral arch at the back.

This hollow region provides a protective bony enclosure for the spinal cord, spinal meninges, and cerebrospinal fluid. The size and shape of the vertebral foramen vary among the different regions of the spine to accommodate the differing dimensions of the spinal cord along its length. In the context of the entire spinal column, the aligned vertebral foramina form the vertebral canal, which runs the length of the spine from the base of the skull to the sacrum. The vertebral arch is the posterior part of a vertebra that encircles the vertebral foramen. It is composed of two pedicles and two laminae, forming the walls of the foramen and providing points of attachment for muscles and ligaments. The arch protects the spinal cord and nerves that pass through the vertebral foramen. It also contributes to the structure of the vertebral column, facilitating the complex range of movements while maintaining stability and strength.

The vertebral arch, along with the intervertebral discs, facet joints, and other vertebral components work synergistically to support bodily motions and bear loads. The transverse process is a bony projection on either side of the vertebral arch. Extending laterally from the points where the laminae join the pedicles, the transverse processes serve as important attachment sites for muscles and ligaments that stabilize the vertebral column. In the lumbar region, they are particularly substantial, reflecting the large muscles that attach to them and help facilitate movements of the trunk and maintain posture.

Additionally, these processes contribute to the articulated framework of the spine, providing leverage and points of articulation for the ribs in the thoracic region. The lamina is the flattened or arched part of the vertebral arch which forms the roof of the vertebral canal, the space through which the spinal cord runs. Each vertebra has two laminae, which connect to the pedicles anteriorly and converge to form the spinous process posteriorly. The lamina provide protection for the spinal cord and serve as the attachment for ligaments and muscles, including those responsible for extending the spine. They are integral components of the vertebral arch, playing a significant role in the overall anatomy and function of the spine.