Human: Bones

Five arthritic lumbar vertebrae are included. The vertebrae are osteoarthritic, typical of an older adult or a person with a history of heavy labor (or both). The edges of the vertebral bodies are sharp and irregular. Bony outgrowths (osteophytes) are present. Mounted on a modified sacrum with a rod down the center, the vertebrae and intervertebral discs can be easily removed and replaced.