The Axial Skeleton
The axial skeleton protects vital organs in the body with a total of 80 bones in the person's head and torso. A skull has 29 bones including eight cranial bones, 14 facial bones, six auditory ossicles and one hyoid bone. The cranium includes the frontal bone that extends down the forehead while two parietal bones curve around the top of the skull and down to the occipital bone. Two temporal bones form the sides of the skull. Completing the cranium is a sphenoid bone, located under the frontal bone, and an ethmoid bone inside the eye socket.
The sternum and 24 ribs compose the thorax. The vertebral column has 24 individual vertebrae, the sacrum and the coccyx. The vertebrae are categorized into cervical, thoracic and lumbar sections.
The Appendicular Skeleton
The appendicular skeleton houses 126 bones in the body's limbs and in the pectoral and pelvic girdles that connect arms and legs to the axial skeleton. The pectoral girdle's flat bone connects both arms to a person's chest. It contains a left and right clavicle bone, also called the collarbone, and a left and right scapula, or shoulder blade. Each arm has one humerus connected to the radius and ulna on the forearm at the elbow. Each hand has eight wrist bones called carpals that are then connected to the five metacarpals--one for each finger. The metacarpals are connected to 14 phalanges. The five metacarpals are connected to five proximal phalanges. The pollex, or thumb, is then connected to a distal phalange while the other four fingers have a medial phalange between their proximal and distal bones.
The pelvic girdle connects both legs to axial skeleton along the vertebral column. A pelvic girdle includes two os coxae that form the hips, the sacrum that is fashioned from fused vertebrae, and a coccyx, also called the tailbone, at the base of the spine. Each leg has one femur bone connected to the patella at the kneecap. The patella is a specific type of bone called a sesamoid that protects a tendon tissue at the site of a joint in areas such as the knee, hands and feet. Each knee has a tibia and a fibula bone. Each foot contains seven tarsal bones in the ankle, five metatarsals and 14 phalanges. The hallux, or big toe, has just a proximal and distal bone the remaining toes have a proximal, middle and distal bone to complete the appendicular skeleton.