This chapter outlines some interesting observations about skeletal muscle. The structure of skeletal muscle and muscle contraction are introduced. Testing motor power is discussed including the five grades and corresponding percentage motor deficit as outlined in the American Medical Association (AMA) Fifth Edition. An alternative guide for assessing percentage motor deficit that includes motor weakness, range of motion of affected joint(s), and muscle wasting is also presented. Other topics included in this chapter are isolating the action of the clavicular head of pectoralis major, tenodesis and tenodesis effect. The function of latissimus dorsi and teres major is also discussed, and internal rotation, extension, and adduction are discussed with illustrations.