Muscles are made of ...

Correct Answer: D

Rationale: Muscles consist of fibres (elongated cells) bundled together, enabling contraction. Silica is in trace amounts, polyester is synthetic, calcium/phosphorus are bone minerals, making 'groups of cells called fibres' correct.

Correct Answer: A

Rationale: Gliding joints allow sliding movements, as seen in the intercarpal joints (between wrist bones). The radiocarpal joint is a condyloid joint, intervertebral joints are cartilaginous (amphiarthroses), and phalangeal joints are hinges—not gliding.

Correct Answer: C

Rationale: The tibia, a long bone, has a diaphysis (shaft), epiphyses (ends), articular cartilage (at joints), and a medullary cavity (marrow space). Scapula and sacrum are flat/irregular bones, and the patella (sesamoid) lacks a medullary cavity.

Correct Answer: C

Rationale: The talus, in the ankle, articulates distally with the calcaneus (heel bone) below it, forming the subtalar joint. The navicular and cuneiforms are more distal, and the first metatarsal is further forward.

Correct Answer: B

Rationale: Bone marrow consists of adipose tissue (yellow marrow, fat storage), areolar tissue (loose connective tissue supporting structure), and blood (red marrow, site of hematopoiesis producing blood cells). Fibroblasts are present but not a major component, making B the most complete and accurate description.