Which joints are the synovial joints of the pelvis?

Which joints are the synovial joints of the pelvis?

• A. The sacroiliac joint and the lumbosacral joint
• B. The sacrococcygeal joint and the pubic symphysis
• C. The hip joint and the knee joint
• D. The acetabulum and the sacroiliac joint

Answer: (A)

Synovial joints are joints that have a joint cavity enclosed by a capsule with articular cartilage on the surfaces, allowing meaningful movement. In the pelvis, the joints that fit this description are the sacroiliac joints and the lumbosacral joint. The sacroiliac joints connect the sacrum to the ilium and function as synovial joints, permitting small gliding movements to help absorb and transmit forces from the spine to the pelvis. The lumbosacral joint between the last lumbar vertebra and the sacrum is a true synovial articulation that allows flexion and extension (with some additional movement), stabilized by strong ligaments. In contrast, the pubic symphysis and the sacrococcygeal joint are fibrocartilaginous or cartilaginous joints with limited mobility, not synovial. The acetabulum is a part of the pelvis that forms the hip joint with the femoral head, which is another synovial joint, but it’s not a pelvic joint in the sense of forming a separate pelvic articulation. The knee is not a pelvic joint either.

Synovial joints are joints that have a joint cavity enclosed by a capsule with articular cartilage on the surfaces, allowing meaningful movement. In the pelvis, the joints that fit this description are the sacroiliac joints and the lumbosacral joint. The sacroiliac joints connect the sacrum to the ilium and function as synovial joints, permitting small gliding movements to help absorb and transmit forces from the spine to the pelvis. The lumbosacral joint between the last lumbar vertebra and the sacrum is a true synovial articulation that allows flexion and extension (with some additional movement), stabilized by strong ligaments. In contrast, the pubic symphysis and the sacrococcygeal joint are fibrocartilaginous or cartilaginous joints with limited mobility, not synovial. The acetabulum is a part of the pelvis that forms the hip joint with the femoral head, which is another synovial joint, but it’s not a pelvic joint in the sense of forming a separate pelvic articulation. The knee is not a pelvic joint either.