The type of joint between the sacrum and the coccyx is a
**Core Concept**
The question is testing the student's knowledge of the anatomical classification of joints in the human body. Specifically, it is asking about the type of joint between the sacrum and the coccyx, which is a part of the pelvis.
**Why the Correct Answer is Right**
The joint between the sacrum and the coccyx is a synsacrococcygeal joint, which is a type of cartilaginous joint. It is a fibrocartilaginous joint that allows for limited movement between the two bones. The synsacrococcygeal joint is a unique joint that is formed by the fusion of the sacrum and the coccyx. It is a secondary cartilaginous joint, meaning that it is formed by the interlocking of hyaline cartilage and fibrocartilage. This type of joint is found in the pelvis and is a result of the evolutionary adaptation of the human body to support the weight of the body and facilitate movement.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the joint between the sacrum and the coccyx is not a synovial joint, which is characterized by the presence of a synovial cavity and a joint capsule.
**Option B:** This option is incorrect because the joint between the sacrum and the coccyx is not a symphysis, which is a type of cartilaginous joint that is characterized by a fibrocartilaginous disc.
**Option D:** This option is incorrect because the joint between the sacrum and the coccyx is not a plane synovial joint, which is characterized by a flat joint surface and limited movement.
**Clinical Pearl / High-Yield Fact**
It's worth noting that the joint between the sacrum and the coccyx is a unique joint that is formed by the fusion of the sacrum and the coccyx, and it is a result of the evolutionary adaptation of the human body to support the weight of the body and facilitate movement.
**Correct Answer:** C. Synsacrococcygeal joint.