True pelvis refers to :
**Core Concept**
The true pelvis is the part of the pelvis that is formed by the pelvic girdle and the sacrum, excluding the pelvic diaphragm and the pelvic floor muscles. It is a bony structure that plays a crucial role in supporting the abdominal organs and facilitating childbirth.
**Why the Correct Answer is Right**
The true pelvis is a bony structure that is bounded by the iliopectineal lines on the innominate bones, the sacrum, and the coccyx. It is divided into two halves by an imaginary plane running from the sacral promontory to the pubic symphysis. The true pelvis is an important landmark in obstetrics, as it determines the shape and size of the birth canal.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the true pelvis. The false pelvis is the part of the pelvis that is formed by the iliac wings and the sacral promontory, and it does not include the pelvic girdle or the sacrum.
**Option B:** This option is incorrect because it is a distractor that does not pertain to the true pelvis. The pelvic diaphragm is a muscular structure that separates the pelvic cavity from the perineal cavity.
**Option C:** This option is incorrect because it is a distractor that does not accurately describe the true pelvis. The pelvic floor muscles are a group of muscles that support the pelvic organs and are not part of the bony structure of the true pelvis.
**Clinical Pearl / High-Yield Fact**
The true pelvis is a critical structure in obstetrics, and its shape and size can affect the ease of childbirth. A pelvis that is too small or irregularly shaped can increase the risk of complications during delivery.
**Correct Answer: C. True pelvis refers to the part of the pelvis that is formed by the pelvic girdle and the sacrum, excluding the pelvic diaphragm and the pelvic floor muscles.