By: MARISOL FAVELA Anna Rodriguez Skeletal System By: MARISOL FAVELA Anna Rodriguez

Divisions of Skeleton Axial skeleton- The 80 bones of the head, neck, and torso; composed of 74 bones that form the upright axis of the body and six tiny middle ear bones. Appendicular skeleton- the 126 bones that form the appendages to the axial skeleton; the upper and lower extremities.

Axial Skeleton A. Skull- made up of 28 bones in two major divisions: cranial bones and facial bones. 1. Cranial bones: Frontal bone Parietal bones Temporal bones Occipital bone Sphenoid bone Ethmoid bone

2. Facial bones Maxilla (upper jaw) Mandible (lower jaw) Zygomatic bone Nasal bone Lacrimal bone Palatine bone Inferior nasal conchae (turbinates) Vomer bone

B. Hyoid bone 1. U-shaped bone located just above the larynx and below the mandible. 2. Suspended from the styloid processes of the temporal bone. 3. Only bone in the body that articulates with no other bones. C. Vertebral column 1. Forms the flexible longitudinal axis of the skeleton. 2. Consists of 24 vertebrae plus the sacrum and coccyx. 3. Segments of the vertebral column: cervical vertebrae, thoracic vertebrae, lumbar vertebrae, sacrum, coccyx

D. Sternum 1. Dagger-shaped bone in the middle of the anterior chest wall made up of three parts: a. Manubrium- the upper handle part b. Body- middle blade part c. Xiphoid process- blunt cartilaginous lower tip, which ossifies during adult life. 2. Manubrium articulates with the clavicle and first rib. 3. Next nine ribs join the body of the sternum, either directly or indirectly, by means of the costal cartilages.

E. Ribs: 1. Twelve pairs of ribs, with the vertebral column and sternum, form the thorax. 2. Each rib articulates with the body and transverse process of its corresponding thoracic vertebra. 3. Rib attachment to the sternum: a. Ribs 1-8 join a costal cartilage that attaches it to the sternum. b. Costal cartilage of ribs 8-10 joins the cartilage of the rib above to be indirectly attached to the sternum c. Ribs 11-12 are floating ribs, since they do not attach even indirectly to the sternum.

Appendicular Skeleton A. Upper extremity: 1.Consists of the bones of the shoulder girdle, upper arm, lower arm, wrist, and hand. 2. Shoulder girdle 3. Humerus 4. Ulna 5. Radius 6. Carpal bones 7. Metacarpal bones

B. Lower extremity 1. Consists of the bones of the hip, thigh, lower leg, ankle, and foot. 2. Pelvic girdle is made up of the sacrum and the two coxal bones bound tightly by strong ligaments. 3. Femur- longest and heaviest bone in the body. 4. Patella- largest sesamoid bone in the body. 5. Tibia- The larger, and more medially and superficially located of the two leg bones. Articulates proximally with the femur to form the knee joint. 6. Fibula: The smaller, more laterally and deeply placed of the two leg bones. Articulates with the tibia. 7. Foot: Foot bones are held together to form spring arches.

Skeletal Differences in Men and Women Male skeleton is larger and heavier than female skeleton. Pelvic differences 1. Male pelvis- deep and funnel shaped with narrow pubic arch. 2. Female pelvis- shallow, broad, and flaring with a wider pubic arch.