Last issue we learned about the plasticity of bone.

On this issue, we would like to talk about axial skeleton, which includes trunk bones and skull.

To be specific, the trunk consists of 24 vertebrae, a sacrum, a coccyx, a sternum, and 12 pairs of ribs that contribute to the formation of the spine, the bony thorax, and the pelvis, respectively.

The skull consists of 23 bones (the 3 pairs of ossicles in the middle ear are not counted). With the addition of the mandible and hyoid bone, the skull is firmly connected by sutures or cartilage to protect and support the brain and sensory organs. And the skull forms the starting part of the digestive and respiratory system. With the connection of the superior orbital margin, taking the superior external auricular hilum margin and the extroccipital bulge as the boundary, the skull is divided into the posterior upper cranial and the anterior lower facial cranial.

All in all, axial bone contains an important skeletal framework for human body, which provides an important carrier and protective body for human's normal life activities, including thinking and behavior and so on.