Hyoid bone doesn"t articulate with any other bone in body. Cervical (7), thoracic (12), lumbar (5), sacral (1) 5 fused vertebrae, coccygeal (1) Between superior/inferior articular processes plane joints, little gliding occurs but small movements related to flexing,extending,rotation occur. Functions: encloses and protects spinal cord, supports the skull, supports weight the head, neck, and trunk, transfers weight to the lower limbs, helps maintain upright body position. Spinal curves: four curves; cervical curve, thoracic curve, lumbar curve, sacral curve. Thoracic and sacral curves called primary curvatures because they appear in fetal development, protect heart/lungs and reproductive organs. Lumbar and and cervical curves called secondary curvatures because they don"t appear for months after birth. Kyphosis: normal thoracic curve becomes exaggerated posteriorly (round back) common in ppl with osteoporosis. Lordosis: abdomen and buttocks protrude abnormally, caused by anterior exaggeration of lumbar curve. Bodies of neighboring vertebrae are connected by ligaments and separated by pads of fibrous cartilage called intervertebral discs.