Copyright Goodheart-Willcox Co., Inc. Chapter 5 The Skeletal System 143 Shoulder Complex The bones surrounding the shoulder are referred to as the shoulder girdle, or pectoral girdle. This structure includes the left and right clavicle, or collarbone, and a left and right scapula, or shoulder blade (Figure 5.20). These bones serve as sites of attachment for the numerous muscles that enable the arms to move in so many different directions at the shoulders. As Figure 5.21 shows, there are two bony projections on the scapula, known respectively as the acromion and the coracoid process. The prominent suprascapular notch, which cradles nerves, is found just medial to the coracoid process. The lateral end of the clavicle attaches to the acromion process to form the acromioclavicular joint (Figure 5.20). The medial end of the clavicle attaches to the sternum to form the sternoclavicular joint. T he appendicular skeleton, as the name sug- gests, includes the body’s appendages. These include both the bones of the upper extremity (the shoulder complex, arms, wrists, and hands) and those of the lower extremity (the pelvic girdle, legs, ankles, and feet). Altogether, there are approximately 126 bones in the appendicular skeleton. The appen- dicular skeleton is built for motion. Upper Extremity The upper extremity is well designed for all of the tasks that people routinely ask it to perform. The muscles, bones, and joints of the upper extremity enable movements as diverse as carrying a load, throwing a ball, and threading a needle. The different movements of hammering a nail, texting on a cell phone, and performing a handspring are also made possible by this unique design. Review Questions 1. Explain the function of the axial skeleton and list the bones included in it. 2. The bones of the skull are often divided into two groups. Name those two groups. 3. In what respect are sutures and fontanels similar? 4. List the five named sections of the spine and state how many vertebrae are included in each of these sections. 5. Name at least five structural features common to most vertebrae. 6. Which bone of the skull is freely movable? 7. Why is it important to protect and cradle a baby’s head when you are holding the baby? 8. Compare and contrast lordosis, kyphosis, and scoliosis. 9. How does the composition of an intervertebral disc relate to its functions of acting as a shock absorber and allowing the spine to bend? 10. Explain the different ways in which ribs are attached to the sternum. 11. What are the primary and secondary spinal curves? Explain why and distinguish between them. SECTION 5.4 The Appendicular Skeleton Objectives • Identify the bones and joints of the upper extremity and describe their motions. • Identify the bones and joints of the lower extremity and describe their motions. Key Terms appendicular skeleton calcaneus carpal bones clavicle false pelvis femur fibula humerus lower extremity metacarpal bones metatarsal bones patella pectoral girdle pelvis phalanges radius scapula shoulder complex tarsal bones tibia true pelvis ulna upper extremity