"Every generation stands on the shoulders of the generation that came before. Jealously guard the values and principles of our heritage. They did not come easy." —Ronald Reagan, 1911–2004, 40th President of the United States
This chapter investigates the shoulder complex. By the completion of this chapter, you should be able to:
Identify the bones, joints, and muscles of the shoulder complex;
Discuss the relationship between each of the joints that determine scapular motion;
Explain the relationship between movements of the scapulothoracic and glenohumeral joints and their inter-reliability;
List muscles that stabilize the scapulothoracic joint and the glenohumeral joint;
Discuss the influence of gravity and body position in determining muscles acting on the shoulder complex during functional motions;
Name muscle groups that function to position and move the shoulder complex in specific functional activities.
Ella, the clinician, is in the middle of examining Tyler, her first patient for the day. Because of the history she has taken, Ella knows that Tyler's right dominant shoulder became injured while he was working. He is a house painter who has spent the last month painting ceilings in a very large mansion. His right shoulder is painful in the area just above the glenohumeral joint, especially when he raises his arm above his head. The pain has increased so much that it now bothers him when he reaches up to comb his hair or pulls his wallet out of his back pocket. Ella knows that she must examine all of the shoulder muscles, especially those that function to move and position his arm over his head. She also realizes that in order to do the appropriate muscle tests she must first know what each of those muscles do and the best position in which to test them. As Ella begins her manual muscle tests on Tyler, she is thinking of each of these muscles and the positions she must put Tyler in to obtain the most accurate results.
The shoulder region is a complex of 20 muscles, three bony articulations, and three soft tissue moving surfaces (functional joints) that permit the greatest mobility of any joint area found in the body. The primary purpose of the shoulder is to put the hand in a position for function. The shoulder is able to place the hand in about 16,000 different positions,1 thereby allowing the hand to produce myriad functions that we usually take for granted. The shoulder complex not only provides a wide range of positions for hand placement, but it also stabilizes the upper extremity for hand motions, lifts and pushes objects, elevates the body, assists with forced respiratory inspirations and expirations, and even bears weight when walking with crutches or performing handstands. Mobility, however, is at the expense of structural stability. The only bony attachment of the upper extremity ...