Anatomy of Lumbar Spine

Vertebrae
The vertebral body is a thin ring of dense cortical bone. The vertebral body is shaped like an hourglass, thinner in the center with thicker ends. Outer cortical bone extends above and below the superior and inferior ends of the vertebrae to form rims. The superior and inferior endplates are contained within these rims of bone.

Pedicles
The pedicles are two short rounded processes that extend posteriorly from the lateral margin of the dorsal surface of the vertebral body. They are made of thick cortical bone.

Laminae
The laminae are two flattened plates of bone extending medially from the pedicles to form the posterior wall of the vertebral foramen. The Pars Interarticularis is a special region of the lamina between the superior and inferior articular processes. A fracture or congenital anomaly of the pars may result in a spondylolisthesis.

Intervertebral Discs
Intervertebral discs are found between each vertebra. The discs are flat, round structures about a quarter to three quarters of an inch thick with tough outer rings of tissue called the annulus fibrosis that contain a soft, white, jelly-like center called the nucleus pulposus. Flat, circular plates of cartilage connect to the vertebrae above and below each disc. Intervertebral discs separate the vertebrae, but they act as shock absorbers for the spine. They compress when weight is put on them and spring back when the weight is removed.

Intervertebral discs make up about one-third of the length of the spine and constitute the largest organ in the body without its own blood supply. The discs receive their blood supply through movement as they soak up nutrients. The discs expand while at rest allowing them to soak up nutrient rich fluid. When this process is inhibited through repetitive movement, injury or poor posture, the discs become thinner and more prone to injury. This may be a cause of the gradual degeneration of the structure and function of the disc over time.

Facet Joints
Joints between the bones in our spine are what allow us to bend backward and forward and twist and turn. The facet joints are a particular joint between each vertebral body that help with twisting motions and rotation of the spine. The face joints are part of the posterior elements of each vertebra. * Each vertebra has facet joints that connect it with the vertebrae above and the vertebrae below in the spinal column. The surfaces of the facet joints are covered with smooth cartilage that help these parts of the vertebral bodies glide smoothly on each other.

Ligamentum Flavum
The ligamentum flavum is a strong ligament that connects the laminae of the vertebrae. The term “flavum” is used to describe the yellow appearance of this ligament in its natural state. The ligamentum flavum serves to protect the neural elements and the spinal cord and stabilize the spine so that excessive motion between the vertebral bodies does not occur. It is the strongest of the spinal ligaments and often has a thinner middle section. Together with the laminae, it forms the posterior wall of the spinal canal.

-Satwik

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~ by pcl4 on September 18, 2008.

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