What structures attach a muscle to a bone?

Correct Answer: A

Rationale: Tendons, fibrous extensions of muscle, anchor it to bone, transmitting force for movement e.g., Achilles tendon. Fasciculi are fibre bundles, sarcomeres are contractile units, and intercostals are rib muscles, not attachment structures. Tendons' role in linking muscle to skeleton distinguishes them, essential for biomechanical function and contrasting with ligaments' bone-to-bone role.

Correct Answer: A

Rationale: A skeletal muscle fibre contains myofibrils, each a chain of sarcomeres repeating units between Z-lines that shorten during contraction via actin-myosin sliding. Sarcolemma is the membrane, sarcoplasm the cytoplasm, and fasciculus a fibre bundle not contractile units. Sarcomeres' role as the smallest contractile segment distinguishes them, summing to fibre-wide contraction, fundamental to muscle mechanics and force production.

Correct Answer: A

Rationale: An agonist drives movement (e.g., biceps in flexion), not opposes antagonists (e.g., triceps) do. Origin is the fixed attachment, skeletal cells are syncytial (multinucleate), and fixators stabilize. The agonist's role as prime mover distinguishes the error, key to movement dynamics.

Correct Answer: D

Rationale: Sternocleidomastoid names origins (sternum, clavicle) and insertion (mastoid process), guiding neck motion. Tibialis anterior, extensor digitorum longus, and rectus femoris denote location, action, or fibre direction not attachments. This origin-insertion naming distinguishes it, aiding precise anatomical mapping.