What is the gluteus maximus named for? Its

Correct Answer: A

Rationale: Gluteus maximus denotes size maximus means largest relative to gluteus medius and minimus, all on the buttocks. Shape (e.g., trapezius), action (e.g., adductor), and origin-insertion (e.g., sternocleidomastoid) aren't specified. Its large mass aids hip extension, but size defines the name, distinguishing it in gluteal anatomy, reflecting naming conventions prioritizing relative scale.

Correct Answer: B

Rationale: Gluteus medius indicates size intermediate between maximus and minimus among gluteal muscles. Sternocleidomastoid names origin-insertion, flexor digitorum profundus action-depth, and trapezius shape. Medius' size-based naming distinguishes it, reflecting relative scale in gluteal anatomy, useful for comparative identification.

Correct Answer: B

Rationale: Thin myofilaments comprise actin (structure), tropomyosin (covers binding sites), and troponin (calcium receptor), regulating contraction. Thick myofilaments are myosin only, with heads forming cross-bridges not binding sites and lack tropomyosin/troponin. Myosin isn't in thin filaments. This composition distinguishes thin filaments' regulatory role, critical for controlled muscle action, contrasting with thick filaments' motor function.

Correct Answer: C

Rationale: Sarcomeres, within myofibrils, contract by sliding actin and myosin, shortening the myofibril and thus the cell. Sarcoplasm houses organelles, sarcolemma conducts signals, and sarcoplasmic reticulum stores calcium not contractile. Sarcomeres' role as the contractile engine distinguishes them, essential for muscle movement mechanics.

Correct Answer: A

Rationale: Calcium ions bind troponin, shifting tropomyosin to reveal actin's binding sites, initiating contraction. Acetylcholine triggers nerve signals, phosphate and ADP relate to ATP not regulation. Calcium's specific troponin role distinguishes it, pivotal for muscle activation, contrasting with nerve or energy molecules.