Place the following steps of endochondral ossification in chronological order. 1) Formation of bone collar. 2) Formation of primary center of ossification. 3) Formation of secondary center of ossification. 4) Ossification of epiphyseal plate.

Correct Answer: A

Rationale: Endochondral ossification follows: 1) bone collar forms around the cartilage model, 2) primary ossification center forms in the diaphysis, 3) secondary centers form in the epiphyses, 4) epiphyseal plate ossifies, closing growth. Thus, '1-2-3-4' is the correct order.

Correct Answer: D

Rationale: The zygomatic bones form the cheeks and lateral orbit rims, contributing to facial structure. The maxillae form the upper jaw, parietal the skull top, and temporal the sides, making 'zygomatic' correct.

Correct Answer: C

Rationale: The vertebral column has 7 cervical, 12 thoracic, and 5 lumbar vertebrae in adults, totaling 24 movable vertebrae (plus sacrum and coccyx). '7: 12: 5' matches this standard count.

Correct Answer: D

Rationale: The sternum, or breastbone, is the flat bone in the chest’s center, connecting ribs. The clavicle is the collarbone, manubrium is a sternum part, and scapula is the shoulder blade, making 'sternum' correct.

Correct Answer: C

Rationale: The olecranon fossa, on the humerus’ posterior side, receives the ulna’s olecranon process when the elbow extends. The capitulum and trochlea articulate with the radius and ulna, and the head is proximal, making 'olecranon fossa' correct.