<P> The axial skeleton is the part of the skeleton that consists of the bones of the head and trunk of a vertebrate . In the human skeleton, it consists of 80 bones and is composed of six parts; the skull bones, the ossicles of the middle ear, the hyoid bone, the rib cage, sternum and the vertebral column . The axial skeleton together with the appendicular skeleton form the complete skeleton . Another definition of axial skeleton is the bones including the vertebrae, sacrum, coccyx, ribs, and sternum . </P> <P> Flat bones house the brain and other vital organs . This article mainly deals with the axial skeletons of humans; however, it is important to understand the evolutionary lineage of the axial skeleton . The human axial skeleton consists of 80 different bones . It is the medial core of the body and connects the pelvis to the body, where the appendix skeleton attaches . As the skeleton grows older the bones get weaker with the exception of the skull . The skull remains strong to protect the brain from injury . </P> <P> The human skull consists of the cranium and the facial bones . The cranium holds and protects the brain in a large space called the cranial vault . The cranium is formed from eight plate - shaped bones which fit together at meeting points (joints) called sutures . In addition there are 14 facial bones which form the lower front part of the skull . Together the 22 bones that compose the skull form additional, smaller spaces besides the cranial vault, such as the cavities for the eyes, the internal ear, the nose, and the mouth . The most important facial bones include the jaw or mandible, the upper jaw or maxilla, the zygomatic or cheek bone, and the nasal bone . </P> <P> Humans are born with separate plates which later fuse to allow flexibility as the skull passes through the pelvis and birth canal during birth . During development the eight separate plates of the immature bones fuse together into one single structure known as the Skull . The only bone that remains separate from the rest of the skull is the mandible . </P>

Which bone is part of the axial skeleton quizlet