The human lumbar spine is located in the middle part of the body and is connected to the cervical and thoracic vertebrae above and the sacral vertebrae below. There are five lumbar vertebrae, each of which basically consists of a vertebral body, a vertebral arch, and protrusions emanating from the arch, including the upper and lower articular processes, transverse processes, and spinous processes. The vertebrae of the lumbar spine are larger than those of the cervical and thoracic spine and are composed mainly of cancellous bone with a thin outer layer of dense bone. The vertebral arch is located in the posterior part of the vertebral body and includes seven protrusions: the pedicle, the plate, the upper and lower articular processes, the spinous process and the transverse process. The lumbar vertebrae are more mobile and subject to more gravity, which can easily cause pain in the back and intervertebral disc lesions.