What terms can be used to describe forearm muscle movements at the wrist but NOT on the fingers at the interphalangeal joints?

Correct Answer: A

Rationale: At the wrist, forearm muscles enable flexion (bending), extension (straightening), abduction (radial deviation), and adduction (ulnar deviation). At the interphalangeal joints of fingers, only flexion and extension occur, as abduction/adduction apply to spreading fingers at metacarpophalangeal joints, not interphalangeal ones. Thus, flexion, extension, abduction, and adduction describe wrist movements but not interphalangeal finger actions, making it the correct answer. Other options omit key wrist motions or include finger-relevant terms, missing the distinction required by the question, which hinges on joint-specific movement capabilities.

Correct Answer: C

Rationale: Tendons are dense, fibrous tissues linking muscle to bone, transmitting force to enable movement. Made of collagen, they anchor muscles like the quadriceps to bones like the tibia, facilitating actions like kicking. Bone-to-bone connections are ligaments' role, stabilizing joints. Ligaments themselves connect bones, not tendons' function. Cartilage cushions joints but doesn't attach to tendons directly tendons bypass it to reach bone. This muscle-to-bone connection defines tendons' purpose, distinct from ligaments' skeletal linking or cartilage's padding. Their strength and flexibility ensure efficient motion, critical for skeletal muscle function, highlighting their unique role in the musculoskeletal system over other structures misaligned with this mechanical linkage.

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.