Texas Medical Assistant Certification Practice Test

Which structure lines the outside of the bone?

1. Endosteum

2. Periosteum

3. Diaphysis

4. Osteoblasts

The correct answer is: Periosteum

The periosteum is the correct answer as it is the dense connective tissue that covers the external surface of bones, except where the bone forms joints with other bones. It serves several important functions, including providing a protective layer, serving as an attachment point for tendons and ligaments, and playing a role in the growth and repair of bones due to its rich supply of blood vessels and nerves. The periosteum contains osteoblasts, which are essential for the formation of new bone, and it also helps in the healing process after a fracture. The endosteum, on the other hand, lines the internal surfaces of the bone, such as the medullary cavity, and is involved in bone remodeling. The diaphysis refers to the elongated shaft of a long bone, while osteoblasts are specialized cells responsible for bone formation but do not represent a structure that lines the bone. Understanding the periosteum's role highlights its significance in bone health and maintenance, reinforcing why it is the correct answer.