Voluntary muscles are contained in the

Correct Answer: B

Rationale: Voluntary muscles, or skeletal muscles, are under conscious control, enabling deliberate movements like walking or lifting. The hind limb, encompassing muscles like the quadriceps and hamstrings, exemplifies this attached to bones via tendons, they contract via somatic nervous system signals, allowing precise actions. The heart contains cardiac muscle, involuntary and self-regulating via pacemaker cells, beating without conscious input. The liver, a glandular organ, lacks muscle tissue; it metabolizes nutrients but doesn't move voluntarily. The lungs rely on the diaphragm and intercostal muscles for breathing, but these are partly involuntary, driven by autonomic reflexes, and the lung tissue itself isn't muscle. Skeletal muscles, striated and multinucleated, differ from cardiac (striated, single-nucleus) and smooth (non-striated, involuntary) types in structure and control. Anatomy texts highlight the hind limb's role in locomotion, with muscles like the gastrocnemius enabling voluntary flexion, contrasting with organs where autonomic control dominates, making it the clear site of voluntary muscle presence.

Correct Answer: B

Rationale: Psoriasis features uncontrolled skin cell growth, rapid keratinocyte proliferation causing scaly plaques, an autoimmune issue. Eczema is inflammatory, itchy, not proliferative. Dermatitis is irritation-based (e.g., contact). Acne involves oil and bacteria, not cell growth. Psoriasis's hyperproliferation, per dermatopathology, makes 'b' correct.

Correct Answer: A

Rationale: Osteoporosis is a condition where bones weaken and become brittle from reduced density, increasing fracture risk, often age-related or hormonal. It's not a fracture , infection (c, osteomyelitis), or joint disorder (d, arthritis). Its systemic bone loss, per pathology, makes 'a' correct.

Correct Answer: B

Rationale: The shoulder's glenohumeral joint is a ball-and-socket, with the humerus's ball in the scapula's glenoid, allowing wide motion (e.g., rotation). Hinge is elbow, pivot is atlas-axis, saddle is thumb. Ball-and-socket's range, per joint types, makes 'b' correct.

Correct Answer: C

Rationale: The occipital bone forms the skull's base, with the foramen magnum for spinal cord exit, supporting the brain posteriorly. Temporal is lateral, frontal is anterior, maxilla is facial. Occipital's foundational role, per skull anatomy, makes 'c' correct.