Which of the following muscles is NOT named after its location in the body?

Correct Answer: B

Rationale: Adductor longus names its action (adduction) and size (long), not location, unlike latissimus dorsi (back), rectus femoris (thigh), and biceps brachii (arm). Located on the thigh, its name prioritizes function, distinguishing it from location-centric terms, useful for understanding muscle roles beyond positional cues.

Correct Answer: D

Rationale: Acetylcholine, released by somatic motor neurons, crosses the neuromuscular junction, binding sarcolemma receptors to depolarize the membrane, triggering an action potential. Inorganic phosphate and ADP relate to ATP cycling, calcium regulates contraction internally not membrane depolarization. Acetylcholine's neurotransmitter role initiates muscle activation, distinguishing it from intracellular or energy-related molecules, key to voluntary movement.

Correct Answer: C

Rationale: Cardiac muscle is striated but involuntary (autonomic), not voluntary unlike skeletal (striated, voluntary, syncytial) and smooth (visceral, involuntary, non-striated). This mischaracterization distinguishes cardiac's automatic heart function, critical for physiological accuracy, contrasting with skeletal's conscious control.

Correct Answer: C

Rationale: Gluteus maximus is avoided for injections due to sciatic nerve proximity; gluteus medius, deltoid (shoulder), and vastus lateralis (thigh) are safer, with ample muscle mass. This safety distinction marks gluteus maximus as non-standard, critical for clinical practice.