The skeletal system consists of both axial and appendicular parts. The axial skeleton includes the skull, vertebral column, ribs, and sternum. The skull contains both single and paired bones that protect the brain and form cavities for sensory organs. The vertebral column is made up of vertebrae which vary based on region. The appendicular skeleton connects the limbs to the axial skeleton and includes the shoulder girdle, upper limbs, pelvic girdle and lower limbs. Long bones have a shaft and two ends, and different bone types serve various protective and movement functions.