Identify the muscle that wrinkles the eyebrows and wrinkles the brow.

Correct Answer: B

Rationale: The frontalis, on the forehead, wrinkles the brow and raises eyebrows, creating horizontal lines, as in surprise. Buccinator compresses cheeks, aiding chewing. Orbicularis oculi closes eyes, wrinkling skin around them, not the brow. Zygomaticus lifts mouth corners for smiling. Frontalis' forehead action distinguishes it, key for facial expression above the eyes.

Correct Answer: B

Rationale: Hamstrings biceps femoris, semimembranosus, semitendinosus flex the knee and extend the hip, on the posterior thigh. Rectus femoris, an anterior quadriceps, extends the knee. Biceps brachii flexes the elbow, an arm muscle. Semimembranosus and semitendinosus are hamstrings. Rectus femoris' quadriceps role excludes it, distinct from arm or hamstring functions.

Correct Answer: B

Rationale: The joint connecting the neck to the head, specifically the atlas (C1) and skull's occipital condyles, allows rotational and nodding movements. This atlanto-occipital joint permits flexion, extension, and slight lateral tilting, while the atlas-axis (C1-C2) adds pivoting, as in turning the head side to side. This fits the pivotal joint category, where a bone rotates within a ring-like structure, exemplified by the atlas pivoting around the axis' dens. Ball-and-socket joints, like the shoulder, offer multi-axial rotation and swinging, exceeding neck motion. Hinge joints, such as the elbow, limit movement to one plane, unlike the neck's range. Fixed joints, like skull sutures, allow no motion. The pivotal joint's rotational capacity matches the neck-head junction's function, distinguishing it in skeletal articulation classifications.

Correct Answer: D

Rationale: Superficial back muscles, like trapezius (shoulder elevation), latissimus dorsi (arm adduction), and rhomboid major/minor (scapula retraction), lie under skin, moving the shoulder girdle. Vastus lateralis, a quadriceps component, is on the anterior thigh, extending the knee, not the back. Rhomboid minor, replaced here, is superficial with major, but vastus lateralis' thigh location excludes it. Its leg-focused action contrasts with back muscles' upper body roles, distinguishing it in musculoskeletal grouping.

Correct Answer: C

Rationale: Athletes should consume 1.2-1.7 g protein per kg bodyweight daily, per sports nutrition guidelines (e.g., ACSM), balancing muscle repair, synthesis, and adaptation for training demands (endurance or strength). Below 0.8 g, the sedentary minimum, risks deficiency, impairing recovery. 0.8-1.2 g suits non-athletes or light activity, insufficient for athletic stress. Over 2.0 g, common in bodybuilding, exceeds needs for most, with excess metabolized, not enhancing performance. The 1.2-1.7 g range optimizes nitrogen balance and recovery, distinguishing it as ideal, tailored to athletic workloads unlike lower or excessive intakes.