**Core Concept**
The arthroscopy of the knee involves visualizing the intra-articular structures of the knee joint to diagnose and treat various conditions. The knee joint is a complex structure consisting of bones, ligaments, tendons, and menisci. The arthroscopic examination allows visualization of these structures, but there are certain structures that are not normally visualized during the procedure.

**Why the Correct Answer is Right**
During arthroscopy of the knee, the visualization is limited to the joint space and the surrounding structures that are accessible through the arthroscopic portals. The structures that are not normally visualized during arthroscopy of the knee include the cruciate ligaments' extracapsular portions, the meniscofemoral ligaments, and the popliteus tendon. These structures are located outside the joint space and are not accessible through the standard arthroscopic portals.

**Why Each Wrong Option is Incorrect**
**Option A:** The menisci are normally visualized during arthroscopy of the knee, as they are located within the joint space and can be easily visualized through the arthroscopic portals.
**Option B:** The cruciate ligaments are partially visualized during arthroscopy of the knee, as the intra-articular portions of the ligaments can be seen through the arthroscopic portals.
**Option C:** The popliteus tendon is not normally visualized during arthroscopy of the knee, as it is located outside the joint space and is not accessible through the standard arthroscopic portals.
**Option D:** The meniscofemoral ligaments are not normally visualized during arthroscopy of the knee, as they are located outside the joint space and are not accessible through the standard arthroscopic portals.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that arthroscopy of the knee has its limitations, and certain structures may not be visualized during the procedure. A thorough knowledge of the anatomy and the limitations of arthroscopy is crucial for accurate diagnosis and treatment.

**Correct Answer: C. The popliteus tendon.**