The mandible, commonly known as the lower jaw, is classified as part of the axial skeleton. The axial skeleton comprises the bones that form the central axis of the body, which includes the skull, vertebral column, and ribcage. The mandible plays a crucial role in functions such as chewing and speaking, and its position and connection to the skull make it an integral component of the head structure.
In contrast, the appendicular skeleton consists of the bones of the limbs and the girdles that attach them to the axial skeleton. Thus, while the mandible is vital for many functions, it does not belong to the appendicular skeleton as it is not involved in limb movement or attachment.