Chronic pain characterized by achy pains, tenderness, stiffness of muscles, and substance P found in the blood stream describes the condition called

Correct Answer: C

Rationale: Fibromyalgia features chronic muscle pain, tenderness, stiffness, and elevated substance P, a pain neurotransmitter, with no clear cause. Cancer may cause pain but isn't muscle-specific or tied to substance P. Diabetes affects nerves, not primarily muscles. Tetanus causes spasms from infection, not chronic ache. Fibromyalgia's diffuse, persistent symptoms set it apart, a musculoskeletal disorder.

Correct Answer: B

Rationale: Type IIb (or IIx in humans) muscle fibers are fast-twitch, with high motor unit strength and fast contractile speed, suited for explosive efforts like sprinting, but they have low oxidative capacity, relying on anaerobic glycolysis, leading to rapid fatigue. High fatigue resistance, typical of slow-twitch (Type I) fibers with rich mitochondria and myoglobin, doesn't fit Type IIb's profile they tire quickly due to limited aerobic endurance. Low oxidative capacity aligns with their anaerobic nature, and strength and speed reflect their power. Fatigue resistance misaligns with their design, distinguishing them from endurance-focused fibers, key to understanding muscle fiber specialization.

Correct Answer: B

Rationale: Flexion decreases the angle between bones, as in bending the elbow (humerus and radius/ulna), bringing bones closer via flexor muscles like biceps. Increasing the angle occurs in extension, the opposite motion. Moving away from the body describes abduction, not flexion, which is joint-specific. Moving toward the body's center could fit some flexions (e.g., hip), but it's less universal than angle decrease, which defines flexion across joints like elbow, knee, or neck, distinguishing it from extension, lateral, or midline motions.

Correct Answer: B

Rationale: The inferior oblique, an extraocular muscle, resides in the eye socket, originating near the orbit's front and inserting on the eyeball, elevating and abducting it. Abdominal muscles (e.g., obliques) flex the trunk. Anterior neck hosts muscles like sternocleidomastoid. Facial muscles (e.g., zygomaticus) move skin. The inferior oblique's orbital location and eye movement role distinguish it, essential for gaze, unlike trunk, neck, or facial functions.

Correct Answer: D

Rationale: Sartorius, a long, strap-like muscle, flexes, abducts, and laterally rotates the hip, then flexes the knee, enabling leg crossing. Gluteus maximus extends the hip. Piriformis rotates it. Gracilis adducts, not crossing fully. Sartorius' multi-joint action distinguishes it, critical for this coordinated motion.