Question

question 33

male and female pelves differ in all of the following features except ______.

a the male pelvis is more massive
b the male pelvic outlet is smaller
c the female pubic arch is usually greater than 100 degrees
d the female coccyx is tilted posteriorly
e the female sacrum is longer

Explanation:

Analyze the question stem

The question asks to identify the feature in which male and female pelves do not differ (i.e., "differ in all of the following features except..."). This means we are looking for a statement that is false regarding pelvic sexual dimorphism, or a feature that is identical/not a point of difference.

Evaluate pelvic differences

Let's review the anatomical differences using our understanding of Pelvic Girdle Anatomy:

• Option A: "the male pelvis is more massive" — This is true. Male bones are generally heavier and thicker to support greater muscle mass.
• Option B: "the male pelvic outlet is smaller" — This is true. The female pelvic outlet is wider to facilitate childbirth.
• Option C: "the female pubic arch is usually greater than 100 degrees" — This is true. The female pubic arch (subpubic angle) is wider (usually $> 80^\circ$ to $100^\circ$ or more), whereas the male arch is narrower (usually $< 70^\circ$).
• Option D: "the female coccyx is tilted posteriorly" — This is true. The female coccyx is more movable and tilted posteriorly (backward) to increase the size of the birth canal, while the male coccyx points anteriorly.
• Option E: "the female sacrum is longer" — This is false. The female sacrum is actually shorter, wider, and less curved than the male sacrum, which is longer, narrower, and more curved. Therefore, saying "the female sacrum is longer" is incorrect, making it the exception.

Confirm the correct option

Since the female sacrum is shorter and wider compared to the longer male sacrum, Option E describes an incorrect difference, meaning they do not differ in this way (or rather, the statement itself is anatomically incorrect regarding the female pelvis). Thus, Option E is the correct answer.

Answer:

• (A) the male pelvis is more massive
• (B) the male pelvic outlet is smaller
• (C) the female pubic arch is usually greater than 100 degrees

<mcq-option>(D) the female coccyx is tilted posteriorly</mcq-correct>

• (E) the female sacrum is longer (Correct answer)