Which is not a part of the os coxa?

Correct Answer: D

Rationale: The os coxa (hip bone) comprises the ilium, ischium, pubis, acetabulum (socket), and obturator foramen. The capitulum is a feature of the humerus, not the os coxa.

Correct Answer: B

Rationale: The periosteum is a dense connective tissue membrane covering the outer surface of bones, aiding in growth, repair, and attachment. The pericardium surrounds the heart, perichondrium covers cartilage, and endosteum lines the medullary cavity—only periosteum fits the description.

Correct Answer: B

Rationale: Vertebrae are classified as irregular bones due to their complex, unique shapes that don’t fit the long, short, or flat categories. Long bones (e.g., femur) are elongated, flat bones (e.g., sternum) are thin, and short bones (e.g., carpals) are cuboidal—vertebrae match none of these.

Correct Answer: B

Rationale: The ulna is a long bone in the forearm, characterized by a shaft (diaphysis) and ends (epiphyses), typical of long bones that support weight or enable movement. Ribs are flat, phalanges are short (despite length, they’re classified as short due to structure), and the mandible is irregular.

Correct Answer: B

Rationale: The cranium has a vault (the upper, domed portion) and a base (the lower portion), with the base divided into anterior, middle, and posterior cranial fossae supporting the brain. 'Vault/base' correctly orders these anatomical regions.