Chapter 5: The Skeletal System

I. Introduction. The skeletal system consists of the bones, along with the cartilage and fibrous connective tissue that make up the ligaments that connect bones to bone at joints.
A. Functions of the Skeleton.
1. The skeleton supports the body.
2. The skeleton protect soft body parts.
The skull protects the brain, the rib cage protects the heart and lungs, and the vertebrae protect the spinal cord.
3. The skeleton produces blood cells. Red bone marrow contains stem cells that produce all of the blood cells.
4. The skeleton stores mineral and fat. All bones have a matrix that contains calcium phosphate that serves as a source of calcium and phosphate ions for the blood. Fat is stored in the
Cartilage is present at two locations: the epiphyseal (growth) plates and the articular cartilage (in the joints). A band of cartilage called a growth plate remains between the ends of the bone and the shaft. The limbs keep increasing in length as long as the growth plates are present. The epiphyseal plates in the arms and legs of women close at about age 18, while they do not close in men until about age 20.

III. The Human Skeleton. The 206 bones of the skeleton can be divided into the axial and appendicular skeleton. The axial skeleton lies in the midline of the body and consists of the skull, hyoid bone, vertebral column, and the rib cage. The appendicular skeleton consists of the bones of the pectoral and pelvic girls and their attached limbs (arms, hands, legs and feet).
A. The Axial Skeleton.
1. Skull
• Cranium (Frontal, Parietal, Occipital, Temporal, Sphenoid, Ethmoid Facial bones (mandible, Maxilla, Zygomatic, Nasal)
2. Hyoid
3. Vertebral Column (Cervical, Thoracic, Lumbar, Sacrum, Coccyx)
4. Ribs
5. Sternum
B. The Appendicular Skeleton.
1. Pectoral girdle (Clavicle, Scapula)
2. Upper limb (Humerus, Radius, Ulna, Carpals, Metacarpals, Phalanges)
3. Pelvic girdle (Coxal)
4. Lower Limb (Femur, Patella, Tibia, Fibula, Tarsals, Metatarsals, Phalanges)
C. Articulations (Joints). Joints are where two bones join together. They can be classified as fibrous, cartilaginous, or synovial.
1. Fibrous Joints. In fibrous joints the