Which joint is the only movable joint in the skull?

The temporomandibular joint (TMJ) is the only movable joint in the skull, allowing for a range of motions essential for functions such as chewing, speaking, and making facial expressions. This joint connects the mandible, or lower jaw, to the temporal bone of the skull. Its unique structure, including the articular disc, enables it to facilitate complex movements, including rotation and translation.

In contrast, the other joints mentioned predominantly serve structural or stabilizing roles rather than mobility. The atlanto-occipital joint allows for limited movement of the head relative to the spine but is not within the skull itself in the same context as the TMJ. The sphenopalatine joint is not a widely recognized anatomical joint, as sphenopalatine refers more to a foramen than a true joint. Lastly, the lacrimal joint does not exist as recognized anatomical terminology in the context of skull joints and serves different functions related to the lacrimal system. Thus, the temporomandibular joint stands out as the sole movable joint, fulfilling critical roles in daily functions.