**Core Concept**
The left-right movement of the skull is a crucial aspect of cranial mechanics, allowing for the rotation of the cranium. This movement is facilitated by the joints between the bones of the skull, specifically the atlanto-occipital joint, which enables rotation in the sagittal plane.

**Why the Correct Answer is Right**
The left-right movement of the skull occurs primarily at the atlanto-occipital joint, which is a synovial joint that connects the occipital bone of the skull to the atlas (C1) vertebra. This joint allows for rotation in the sagittal plane, enabling the head to turn from side to side. The ligaments and muscles surrounding this joint, such as the alar ligaments and the rectus capitis posterior major, also play a crucial role in stabilizing and facilitating this movement.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct joint responsible for left-right movement of the skull.
**Option B:** This option is incorrect because it is not a specific joint or location, making it a vague and incorrect choice.
**Option C:** This option is incorrect because it refers to the atlanto-axial joint, which is primarily responsible for rotation in the coronal plane, not left-right movement.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the atlanto-occipital joint is a critical location for diagnosing and treating neck pain and disorders, such as atlanto-occipital instability.

**Correct Answer:** C. The atlanto-axial joint is a synovial joint that primarily allows for rotation in the coronal plane, not left-right movement.