The junction between the manubrium and the body of the sternum is which type of joint?

The junction between the manubrium and the body of the sternum is which type of joint?

• A. Synchondrosis
• B. Symphysis
• C. Synovial joint
• D. Primary cartilaginous joint

Answer: (D)

Main idea: joints between bones united by cartilage without a joint cavity are primary cartilaginous joints, known as synchondroses. The junction between the manubrium and the body of the sternum is such a synchondrosis. It is bridged by hyaline cartilage between the two sternum parts, which allows growth early on and can ossify with age, sometimes fusing into one bone. Because there is no synovial cavity or articular capsule, and the connection is hyaline cartilage, it is not a synovial joint and not a symphysis (which uses fibrocartilage). So this boundary is best described as a primary cartilaginous joint (synchondrosis).

Main idea: joints between bones united by cartilage without a joint cavity are primary cartilaginous joints, known as synchondroses. The junction between the manubrium and the body of the sternum is such a synchondrosis. It is bridged by hyaline cartilage between the two sternum parts, which allows growth early on and can ossify with age, sometimes fusing into one bone. Because there is no synovial cavity or articular capsule, and the connection is hyaline cartilage, it is not a synovial joint and not a symphysis (which uses fibrocartilage). So this boundary is best described as a primary cartilaginous joint (synchondrosis).