How much wood would a woodchuck chuck if a woodchuck could chuck wood is difficult to say. What muscles work together to allow this to be spoken?

Correct Answer: B

Rationale: Speaking the tongue twister requires tongue mobility, handled by palatoglossus (elevates tongue), styloglossus (retracts), genioglossus (protrudes), and hyoglossus (depresses). Masseter and temporalis move the jaw, buccinator compresses cheeks, and platysma affects the neck less critical for tongue action. Risorius and zygomaticus muscles shape smiles, not speech. Mentalis and orbicularis oris move lips, secondary here. Tongue muscles are the correct answer, as they coordinate the rapid, precise movements needed for articulating this phrase, central to speech production.

Correct Answer: B

Rationale: The muscular system is an organ system, comprising muscles skeletal, smooth, cardiac working together for movement, stability, and vital functions like circulation. It's not just large or small, as size varies, but a coordinated system of organs (muscles) with specific roles. 'Unique system' is vague, lacking anatomical precision. 'Small system' underestimates its scope, covering half the body's weight. As an organ system, it integrates with skeletal and nervous systems for locomotion, digestion, and heartbeat, distinguishing it from mere size descriptors, reflecting its organized, functional unity essential for life.

Correct Answer: A

Rationale: Within a muscle fiber, the sarcolemma, the cell membrane, extends inward as transverse tubules, known as T-tubules. These structures penetrate deep into the fiber, ensuring rapid transmission of action potentials from the nerve impulse to trigger contraction. This allows synchronized calcium release across the fiber, critical for muscle function. The sarcoplasmic reticulum, while closely associated, is a separate organelle storing calcium, not an extension of the sarcolemma. Myofibrils are the contractile units, composed of actin and myosin, but they don't extend from the membrane. Sarcomeres are segments of myofibrils, defining the contractile zone, not membrane extensions. T-tubules' role in signal conduction distinguishes them, enabling efficient, uniform contraction, unlike the storage, structural, or organizational roles of the others, aligning with their anatomical and physiological purpose in muscle activation.

Correct Answer: D

Rationale: Relaxation requires multiple steps: the nerve impulse stopping halts T-tubule signals, calcium being pumped back into the sarcoplasmic reticulum (SR) removes it from troponin, shifting tropomyosin to block actin sites, and ATP binding myosin detaches it from actin, ending cross-bridges. One alone like impulse cessation won't suffice without calcium removal and detachment. Calcium pumping alone leaves myosin bound if ATP's absent. ATP detachment needs prior steps. All must occur, ensuring contraction ceases fully, distinct from partial processes, restoring the muscle to rest, integral to its cyclic function.

Correct Answer: D

Rationale: The tibialis anterior's name reflects its location anterior (front) of the tibia in the lower leg. Muscle names often denote position, here indicating its role in dorsiflexing the foot from the shin's front. Size (e.g., maximus) or shape (e.g., deltoid) apply elsewhere, not here. Fiber direction (e.g., oblique) isn't the focus location is. This positional naming distinguishes it, aligning with anatomical convention for identifying muscle placement and function.