The different parts of the axial skeleton are the skull, the vertebral column, the rib cage and sternum, according to Anatomy Expert. This is in contrast to the appendicular skeleton, which is composed of the pelvis, limbs and pectoral girdle.
The axial skeleton is made up of 80 bones. The skull consists of 22 bones, most of which are flat plates that articulate directly with one another at immobile joints. There are 14 bones of the face and eight of the cranium or brain case.
The vertebral column contains 24 bones and includes the bones of the spine, continues Visible Body. Despite their close proximity to the pelvis, the sacrum and coccyx are considered part of the vertebral column rather than the appendicular skeleton. The thoracic cage consists of the ribs and sternum, but not the clavicles. The sternum is actually three different bones, consisting of the manubrium, sternum body and the xiphoid process.
Often grouped with the bones of the skull are the bones of the throat and inner ear. These bones are unique in that they do not articulate with the main skeleton. The ear bones were once part of the jaw, as noted by Live Science. During the evolution of mammals, they completely detached from the rest of the skull. In humans, the inner ear bones only articulate with one another. These bones probably evolved in this way to increase sensitivity to air vibrations, improving their ability to hear, adds Animal Diversity Web.
The hyoid, located in the throat, is the only bone of the human body that does not articulate with any bones at all, notes Healthline. It serves as an anchor point for the cartilaginous laryngeal skeleton, notes Visible Body. It is key to the production of speech.