What is the structure that attaches one bone to another?

Correct Answer: A

Rationale: Ligaments are fibrous tissues attaching bone to bone at joints. Cartilage cushions, tendons attach muscle to bone, diaphysis is a bone part. Answer is A, per the document.

Correct Answer: A

Rationale: The epiphysis (end) of a long bone articulates with other bones at joints. Metaphysis is growth region, diaphysis is shaft, symphysis is a joint type. Answer is A, per the document.

Correct Answer: A

Rationale: Synovial joints have synovial fluid in a cavity between bones, enabling free movement—not immovable, tendon-held, or only ball-and-socket. Answer is A, per the document.

Correct Answer: B

Rationale: The average adult human has 206 bones, a standard anatomical count after fetal bones fuse (e.g., sacrum). 33 is the vertebral column, 639 is muscles, and variation is minimal post-development, making '206' correct.

Correct Answer: D

Rationale: The medullary cavity in long bones contains bone marrow (red for blood production, yellow for fat). Air isn’t present, blood is in vessels, cells are in matrix—not the cavity. 'Bone marrow' is correct.