Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc.

Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
Joseph E. Muscolino, DC Instructor, Purchase College State University of New York Owner, The Art and Science of Kinesiology Stamford, Connecticut Kinesiology: The Skeletal System and Muscle Function Second Edition Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved.

Chapter 9: Joints of the Upper Extremity
Joseph E. Muscolino, DC ● This chapter concludes our study of the regional approach to the structure and function of the joints of the body. The major purpose of the upper extremity is to place the hand in desired positions, and move the hand as necessary to perform required tasks.

Lesson 9.1 Objectives Define the key terms of this chapter and state the meanings of the word origins of this chapter. Describe why the term shoulder corset might be a better term than shoulder girdle. Explain why the term shoulder joint complex is a better term than shoulder joint when describing movement of the shoulder. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 3

Lesson 9.1 Objectives (cont’d.)
Describe the concepts of mobility and stability as they pertain to the glenohumeral joint, and explain why the glenohumeral joint is often called a muscular joint. Explain why the scapulocostal joint is considered to be a functional joint, not an anatomic joint. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 4

Lesson 9.1 Objectives (cont’d.)
Describe why the sternoclavicular joint can be classified as either biaxial or triaxial. Explain why stabilization of the sternoclavicular joint is important toward proper functioning of the upper extremity. Describe the importance of acromioclavicular joint motion to motion of the shoulder girdle. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 5

Joints of the Upper Extremity
Shoulder joint complex Glenohumeral joint Scapulocostal joint Sternoclavicular joint Acromioclavicular joint Elbow joint complex Elbow joint ● This chapter concludes our study of the regional approach to the structure and function of the joints of the body. The major purpose of the upper extremity is to place the hand in desired positions, and move the hand as necessary to perform required tasks. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 6

Joints of the Upper Extremity (cont’d.)
Radioulnar joints Wrist joint complex Carpometacarpal joints Saddle joint of the thumb Intermetacarpal joints Metacarpophalangeal (MCP) joints Interphalangeal joints (IP) of the hand ● The remaining joints of the upper extremity will be covered in later lessons. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 7

Section 9.1—Shoulder Joint Complex
● Most every movement of the arm at the glenohumeral joint requires a coupled movement of the shoulder girdle. ● Why might the term shoulder corset be a better term than shoulder girdle? Although the scapulae and clavicles, along with the manubrium of the sternum encircle the upper trunk and act as a stable base like a girdle, the two scapulae do not articulate with each other. The muscles that attach the scapulae to the spine are similar to the lacing of a corset, so the term shoulder corset might be more appropriate. Figure 9-1 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby. Courtesy Joseph E. Muscolino Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 8

Section 9.1—Shoulder Joint Complex (cont’d.)
Joints of the Shoulder Joint Complex: Glenohumeral (GH) joint Sternoclavicular (SC) joint Acromioclavicular (AC) joint Scapulocostal (ScC) joint ● The term shoulder joint complex is a better term to employ when describing motion of the shoulder because most movement patterns of the shoulder require motion to occur at a number of these joints. ● Which of these joints can be considered the master joint that orients the position of the scapula? The sternoclavicular (SC) joint may be looked at as the master joint because motion of the clavicle at the SC joint results in motion of the scapula at the scapulocostal joint. Augmentation also occurs at the acromioclavicular (AC) joint. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 9

Section 9.1—Shoulder Joint Complex (cont’d.)
Average Ranges of Motion: Flexion degrees Extension degrees Abduction degrees Adduction degrees Lateral rotation degrees Medial rotation degrees ● Pure adduction of the arm at the shoulder joint from anatomic position is blocked because of the presence of the trunk. How is further adduction possible? If the arm is first flexed or extended, further adduction is possible anterior or posterior to the trunk. ● What term describes the coupling of shoulder girdle movement and arm movement? It is called scapulohumeral rhythm. Because motion of the clavicle is also required, a better term might be scapuloclaviculohumeral rhythm. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 10

Section 9.2—Glenohumeral Joint
● Generally, the term shoulder joint refers to the glenohumeral (GH) joint. ● What sagittal plane actions are illustrated in these figures? Figure 9-2a shows flexion of the arm at the shoulder joint. Figure 9-2b shows extension of the arm at the shoulder joint. Figure 9-2 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 11

Section 9.2—Glenohumeral Joint (cont’d.)
● The glenohumeral (GH) joint allows abduction and adduction in the frontal plane around an anteroposterior axis. ● What type of movements are these? They are axial movements. Figure 9-3 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 12

● Lateral rotation and medial rotation of the arm at the shoulder joint take place in what plane? They are transverse plane actions. ● Around which axis do these axial movements take place? Lateral rotation and medial rotation take place around a vertical axis. Figure 9-4 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 13

Structure: Synovial joint Ball-and-socket joint Function: Diarthrotic Triaxial Major motions: Flexion/extension Abduction/adduction Lateral/medial rotation ● What is the location of the glenohumeral joint? It is located between the glenoid fossa of the scapula and the head of the humerus. ● In addition to these major motions, what reverse actions occur at the GH joint? The scapula can move at the GH joint relative to the humerus if the arm is fixed. Reverse actions of the scapula that can occur at the glenohumeral joint are upward rotation and downward rotation. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 14

Average Ranges of Motion: Flexion degrees Extension degrees Abduction degrees Adduction degrees Lateral rotation degrees Medial rotation degrees ● Pure adduction from anatomic position is blocked because of the presence of the trunk. However, further adduction is possible anterior or posterior to the trunk if the arm is first flexed or extended. ● Because the majority of the stability that the glenohumeral joint has is derived from musculature, the GH joint is often referred to as a muscular joint. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 15

Major ligaments: Fibrous joint capsule Superior glenohumeral ligament Middle glenohumeral ligament Inferior glenohumeral ligament Coracohumeral ligament ● The fibrous joint capsule of the GH joint is extremely lax and permits a great deal of motion. ● What other ligament is also involved with the GH joint? The coracoacromial ligament is also involved with the GH joint. ● What is the closed-packed position of the GH joint? It is lateral rotation and abduction. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 16

Ligaments of the Glenohumeral Joint: ● These ligaments stabilize the right shoulder joint complex. Which ligaments are thickenings of the anterior and inferior GH joint capsule? The superior, middle, and inferior GH ligaments are thickenings of the GH joint capsule. ● The coracohumeral ligament runs from the coracoid process of the scapula to the greater tubercle of the humerus. The coracoclavicular ligament runs from the coracoid process to the lateral clavicle; the coracoacromial ligament runs from the coracoid process to the acromion process; and the acromioclavicular ligament runs from the acromion process to the lateral clavicle. Figure 9-5 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 17

● This illustration shows the glenoid labrum, which is a rim of cartilage surrounding the glenoid fossa of the scapula. ● What is the function of the glenoid labrum? It deepens the glenoid fossa and cushions the GH joint. Figure 9-6 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 18

● The subacromial bursa is shown here between the acromion process of the scapula and the rotator cuff tendon of the supraspinatus muscle. ● What is the role of the subacromial bursa? It reduces friction between the rotator cuff tendon inferiorly and deltoid muscle superiorly. ● Why do rotator cuff tendinitis and subacromial bursa problems usually occur together? They usually occur together because the subacromial bursa actually adheres to the underlying rotator cuff tendon. Figure 9-6 B, from Muscolino JE: The muscular system manual, ed 2, St Louis, 2005, Mosby Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 19

Section 9.3—Scapulocostal Joint
● What is another name for the scapulocostal (ScC) joint? It is also known as the scapulothoracic joint. ● The scapulocostal joint involves the anterior surface of the scapula and the posterolateral surface of the ribcage Figure 9-7 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 20

Section 9.3—Scapulocostal Joint (cont’d.)
Nonaxial Actions at the Scapulocostal Joint: ● What are the nonaxial actions of the scapula shown in these illustrations? Figure 9-8a shows elevation of the right scapula, Figure 9-8b shows depression of the right scapula, Figure 9-8c shows protraction of the right scapula, and Figure 9-8d shows retraction of the right scapula. ● The left scapula is in anatomic position in all figures. Figure 9-8 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 21

Upward Rotation at the Scapulocostal Joint: ● This figure illustrates upward rotation of the right scapula at the scapulocostal joint. The left scapula is in anatomic position of full downward rotation. ● Can the scapular action of upward rotation be isolated? No, it must accompany humeral motion. In this case, the humerus is abducted at the shoulder joint. ● Upward rotation and downward rotation of the scapula occur within the frontal plane around an anteroposterior axis. Figure 9-9 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 22

Tilt Actions at the Scapulocostal Joint: ● What tilt actions are illustrated in these figures? Lateral tilt of the right scapula is illustrated in Figure 9-10a with the left scapula in anatomic position of downward tilt. Upward tilt of the right scapula is shown in Figure 9-10b with the left scapula in anatomic position of medial tilt. ● Upward and downward tilt and lateral and medial tilt are accessory axial movements at the scapulocostal joint. ● What is the lay term for lateral tilt? It is winging of the scapula. Figure 9-10 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 23

Structure: Functional joint Major motions: Protraction/retraction Elevation/depression Upward/downward rotation ● What is unusual about the ScC joint? It is unusual in that it is not an anatomic joint because no actual union of the scapula and the ribcage is formed by connective tissue. ● Which of these major motions can be primary movements at the scapulocostal joint? Elevation/depression and protraction/retraction are the scapular actions that can each be created separately by itself. The other actions must occur secondary to an action of the arm at the GH joint. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 24

Section 9.4—Sternoclavicular Joint
● The sternoclavicular joint is located between the manubrium of the sternum and the medial end of the clavicle. Figure 9-11 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 25

Section 9.4—Sternoclavicular Joint (cont’d.)
Structure: Synovial joint Saddle Function: Diarthrotic Biaxial Major motions: Protraction/retraction Elevation/depression Upward/downward rotation ● The sternoclavicular joint actually permits motion in three planes about three axes; therefore it could also be classified as triaxial. Why, then, is it most often classified as biaxial? It is most often classified as being biaxial because (similar to the saddle joint of the thumb) its rotation actions cannot be isolated. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 26

Major ligaments: Fibrous capsule Anterior sternoclavicular ligament Posterior SC ligament Interclavicular ligament Costoclavicular ligament ● The SC joint is the only osseous joint that connects the upper extremity (i.e., hand, forearm, arm, scapula, and clavicle) to the axial skeleton. ● Which of these ligaments limits all motions of the clavicle except depression? The costoclavicular ligament limits these motions. ● What is the closed-packed position of the SC joint? It is full upward rotation of the clavicle. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 27

Average Ranges of Motion: Elevation degrees Depression degrees Protraction degrees Retraction degrees Upward rotation degrees Downward rotation degrees ● In what plane and around what axis do these motions occur? Elevation and depression occur within the frontal plane around an anteroposterior axis. Protraction and retraction of the clavicle occur within the transverse plane around a vertical axis. Upward rotation and downward rotation of the clavicle occur within the sagittal plane around a mediolateral axis. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 28

● What movements are shown in these illustrations? Figure 9-12a depicts elevation of the right clavicle at the sternoclavicular (SC) joint. Figure 9-12b shows depression of the right clavicle. ● Elevation and depression motions of the clavicle at the sternoclavicular joint are not oriented perfectly in the frontal plane. At rest, the clavicle is actually oriented approximately 20 degrees posterior to the frontal plane. Figure 9-12 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 29

● What movements are shown in these illustrations? Figure 9-13a illustrates protraction of the right clavicle at the sternoclavicular (SC) joint. Figure 9-13b shows retraction of the right clavicle. Figure 9-13 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 30

● This figure illustrates upward rotation of the right clavicle at the sternoclavicular joint. What position is the left clavicle in? The left clavicle is in anatomic position, which is full downward rotation. ● Upward rotation of the clavicle cannot be isolated. In this figure the arm is abducted at the shoulder joint, resulting in the scapula upwardly rotating, which results in upward rotation of the clavicle at the sternoclavicular joint. Figure 9-14 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 31

● In this anterior view of the sternoclavicular joints, the right joint is shown in a frontal section; the left joint remains intact. ● What stabilizes the SC joint? It is stabilized by its fibrous capsule, anterior and posterior SC ligaments, the interclavicular ligament, the costoclavicular ligament, and by the attachments of the sternocleidomastoid, sternohyoid, and sternothyroid muscles. Figure 9-15 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 32

Section 9.5—Acromioclavicular Joint
● The acromioclavicular joint, also known as the AC joint, involves the acromion process of the scapula and the lateral end of the clavicle. Figure 9-16 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 33

Section 9.5—Acromioclavicular Joint (cont’d.)
Structure: Synovial joint Plane Function: Diarthrotic Nonaxial Motions allowed: Upward/ downward rotation ● What action would occur without motion at the AC joint? The scapula and clavicle (i.e., the shoulder girdle) would be forced to always move as one fixed unit. The AC joint allows for independent motion between the scapula and clavicle. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 34

● What are the major actions that occur at the AC joint? The major actions that occur at the AC joint are upward rotation and downward rotation of the scapula at the AC joint. ● What are the accessory actions that also occur at the AC joint? Lateral and medial tilt of the scapula and upward and downward tilt of the scapula also occur at the AC joint. ● Note: When the scapula moves relative to the clavicle at the AC joint, it also moves relative to the ribcage at the scapulocostal joint. Figure 9-17 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 35

Major ligaments: Fibrous capsule Acromioclavicular (AC) ligament Coracoclavicular ligament Closed-packed position: Full upward rotation of the scapula ● The AC joint does not allow a great degree of motion; nonetheless, motion at the AC joint is necessary to allow motion between the clavicle and scapula. ● In light of this information, what other joints of the body are similar to the AC joint? In this regard, the AC joint is similar to the sacroiliac and pubic symphysis joints in that these joints are located between the bones of the respective girdles and allow motion within the girdles. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 36

● What stabilizes the AC joint? The AC joint is stabilized by its fibrous capsule, the AC ligament, and the coracoclavicular ligament. ● What are the two parts of the coracoclavicular ligament? They are the trapezoid and conoid ligaments. Figure 9-18 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 37

Lesson 9.2 Objectives Explain the concept of scapulohumeral rhythm, and give an example for each of the six cardinal ranges of motion of the arm at the shoulder joint. Describe the concept and importance of the carrying angle. Describe the component motions that occur at the proximal and distal radioulnar joints that create pronation and supination of the forearm. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 38

Shoulder joint complex Glenohumeral joint Scapulocostal joint Sternoclavicular joint Acromioclavicular joint Elbow joint complex Elbow joint ● Lesson 9.2 discusses scapulohumeral rhythm and covers the elbow joint complex and elbow joint. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 39

Radioulnar joints Wrist joint complex Carpometacarpal joints Saddle joint of the thumb Intermetacarpal joints Metacarpophalangeal joints Interphalangeal joints of the hand ● The three radioulnar joints are also included in this lesson. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 40

Section 9.6—Scapulohumeral Rhythm
Sagittal plane actions Frontal plane actions Transverse plane actions Other coupled actions ● Scapulohumeral rhythm is the coupled joint actions of the arm, scapula, and clavicle. ● Of all aspects of scapulohumeral rhythm, the most well researched and published motion is frontal plane abduction of the arm. ● In each plane and in other coupled movements, the coupled action of the scapula facilitates further movement of the arm in the direction it is moving. The scapula usually begins to move before the arm moves as much as it can; from that point onward, motion is a combination of arm and shoulder girdle movements. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 41

Section 9.6—Scapulohumeral Rhythm (cont’d.)
● Figure 9-19a illustrates a right arm that has been abducted relative to the trunk 180 degrees. Figure 9-19b shows that of the 180 degrees of abduction of the arm relative to the trunk, only 120 degrees of that motion is the result of abduction of the arm at the GH joint. ● The remaining 60 degrees of motion are the result of what action? They are the result of the upward rotation of the scapula at the scapulocostal joint. Figure 9-19 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby. Courtesy Joseph E. Muscolino Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 42

Section 9.7—Elbow Joint Complex
● The elbow joint is unusual in what way? It is unusual in that three articulations are enclosed within one joint capsule. ● This figure shows an anterior view of the right elbow joint complex. Figure 9-20 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 43

Section 9.7—Elbow Joint Complex (cont’d.)
Three Articulations: Humeroulnar joint Humeroradial joint Proximal radioulnar joint ● These three articulations are enclosed within one joint capsule and share one joint cavity, therefore they can be considered anatomically to be one joint, or one joint complex. However, because three separate articulations are involved, physiologically they can be considered to be three separate joints. ● The proximal radioulnar joint is functionally separate from the elbow joint and will be included with the radioulnar joints. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 44

Section 9.8—Elbow Joint Humeroulnar Joint: Structure: Synovial joint Hinge Function: Diarthrotic Uniaxial ● The humeroulnar joint is functionally more important than the humeroradial joint. ● The humeroulnar joint is located between the distal humerus and the proximal end of the ulna. ● What is another name for the humeroulnar joint? It is also known as the ulnotrochlear joint. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 45

Section 9.8—Elbow Joint (cont’d.)
Humeroradial Joint: Structure: Synovial joint Atypical ball-and-socket Function: Diarthrotic Biaxial ● The humeroradial joint is located between which bones? It is located between the distal end of the humerus and the proximal end of the radius. ● The humeroradial joint is also known as the radiocapitular joint because the radius articulates with the capitulum of the distal humerus. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 46

● When motion occurs at the elbow joint, it occurs at these two joints. ● Because the elbow joint is a uniaxial hinge joint, it is quite stable and experiences few pathologic injuries. Figure 9-21 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 47

● The elbow joint allows flexion and extension of the forearm in the sagittal plane around a mediolateral axis. ● Figure 9-22a shows flexion of the forearm at the elbow joint. Figure 9-22b illustrates extension of the forearm at the elbow joint. ● The average ranges of motion of the forearm at the elbow joint from anatomic position are: 145 degrees of flexion and 0 degrees of extension. Usually 5 degrees of hyperextension of the forearm are possible at the elbow joint from anatomic position. Figure 9-22 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 48

● Figure 9-23a gives a medial view of the elbow joint capsule and the medial collateral ligament. What are the three parts of the medial collateral ligament? They are the anterior part, posterior part, and transverse part. ● Figure 9-23b demonstrates a lateral view of the elbow joint capsule, lateral collateral ligament, and the annular ligament of the proximal radioulnar joint. ● The lateral collateral ligament has two parts: annular fibers and ulnar fibers. Figure 9-23 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 49

Major actions: Flexion/extension Major ligaments: Fibrous capsule Medial collateral ligament Lateral collateral ligament ● The reverse action is that the arm can move relative to the forearm at the elbow joint. ● What are some examples of this reverse action? Pull-ups, using a banister to go upstairs, handicap bars, and using oars in a canoe are all common examples of this reverse action. ● The closed-packed position of the elbow joint is extension. ● The medial collateral ligament is also known as the ulnar collateral ligament. The lateral collateral ligament is also called the radial collateral ligament. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 50

● The carrying angle of the upper extremity is formed by the intersection of two lines; one through the long axis of the humerus and the other through the long axis of the ulna. ● What is the usual carrying angle? It is usually between 5 and 15 degrees. ● The carrying angle is formed because the axis of movement of the humeroulnar joint is not horizontal. ● Another term for carrying angle is cubitus valgus. Figure 9-24 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 51

Section 9.9—Radioulnar Joints
Three Radioulnar Joints: Proximal radioulnar joint Middle radioulnar joint Distal radioulnar joint ● The three RU joints are functionally related in that their combined movements allow pronation and supination of the forearm. However, they are anatomically distinct from each other. ● The proximal radioulnar joint shares its joint capsule with the elbow joint. The distal RU joint shares its joint capsule with the radiocarpal joint of the wrist joint complex. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 52

Section 9.9—Radioulnar Joints (cont’d.)
Major actions: Pronation/supination Ranges of Motion: Pronation degrees Supination degrees ● The proximal RU joint and the distal RU joint are both synovial pivot joints and are classified functionally as diarthrotic and uniaxial. ● The middle radioulnar joint is a syndesmosis fibrous joint and is functionally classified as a uniaxial amphiarthrotic joint. ● During pronation and supination, the radius does the vast majority of the movement. ● Forearm pronation and supination are often measured from a neutral “thumbs-up” position. From this position 85 degrees of supination and 75 degrees of pronation are possible. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 53

● The proximal RU joint is located between the head of the radius and the radial notch of the ulna. ● The middle RU joint is located between the shafts of the radius and ulna. ● The distal RU joint is located between the head of the ulna and the ulnar notch of the radius. Figure 9-25 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 54

Pronation and Supination at the RU Joints: ● Pronation and supination are joint actions created by a combination of motions at the proximal, middle, and distal RU joints. ● Figure 9-26a illustrates pronation of the right forearm. Figure 9-26b shows supination, which is the anatomic position for the forearm. Figure 9-26 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 55

Ligamentous Structures of the RU Joints: ● The ligamentous structures of the proximal radioulnar joint include the fibrous joint capsule and annular ligament. ● The interosseus membrane and oblique cord, which form the middle RU joint, are illustrated here in Figure 9-27a. ● The joint capsule of the distal RU joint is also seen in Figure 9-27a and the RU disc of the distal RU joint is illustrated in Figure 9-27b. ● The RU disc is also known as the triangular fibrocartilage. Figure 9-27 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 56

Lesson 9.3 Objectives Describe the structure and function of the hand. Describe the structure and function of the wrist and, specifically, the carpal tunnel. Explain why the radiocarpal joint is the major articulation between the forearm and the hand. Describe the importance of motion at the 4th and 5th carpometacarpal joints. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 57

Shoulder joint complex Glenohumeral joint Scapulocostal joint Sternoclavicular joint Acromioclavicular joint Elbow joint complex Elbow joint Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 58

Radioulnar joints Wrist joint complex Carpometacarpal joints Saddle joint of the thumb Intermetacarpal joints Metacarpophalangeal (MCP) joints Interphalangeal joints (IP) of the hand ● Lesson 9.3 provides an overview of the wrist/hand region and covers the wrist joint complex and carpometacarpal joints. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 59

Section 9.10—Overview of the Wrist/Hand Region
Three Regions: Carpus Metacarpus Phalanges (fingers) ● The hand is located distal to the radius and ulna of the forearm and is divided into three regions. ● The carpus is composed of eight carpal bones (i.e., wrist bones). ● The metacarpus is also known as the body of the hand and is composed of five metacarpal bones. The palm is the anterior region of the metacarpus of the hand. ● The phalanges define the fingers. ● The term ray refers to a metacarpal and its associated phalanges; the hand has five rays. Figure 9-28 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 60

Section 9.10—Overview of the Wrist/Hand Region (cont’d.)
General Organization: Wrist joint Radiocarpal joint Midcarpal joint Carpometacarpal joints Intermetacarpal joints Metacarpophalangeal (MCP) joints Interphalangeal (IP) joints ● The wrist joint is a complex of two joints: the radiocarpal joint, located between the distal end of the radius and proximal carpal bones; and the midcarpal joint, located between the proximal carpal bones and distal carpal bones. ● The carpometacarpal joints are located between the distal row of carpals and the metacarpal bones. ● The intermetacarpal joints are located between adjacent metacarpal bones. ● The MCP joints are between the metacarpal bones and the phalanges. The IP joints are located between the phalanges of a finger. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 61

Arches of the Hand: ● The hand has three arches: the proximal transverse arch, the distal transverse arch, and the longitudinal arch. ● The proximal transverse arch runs transversely and is formed by the two rows of carpal bones. ● The distal transverse arch runs transversely and is located at the MCP joints. ● The longitudinal arch runs the length of the hand and is formed by the shape of the metacarpals and fingers. Figure 9-29 B modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby; A courtesy of Joseph E. Muscolino Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 62

Carpal Tunnel: ● What is the carpal tunnel and where is it located? The carpal tunnel is a tunnel formed by the arrangement of the carpal bones. It is between the archlike transverse concavity of the carpal bones and the transverse carpal ligament that spans across the top of the carpal bones. ● The carpal tunnel provides a safe passageway for the median nerve and distal tendons of the extrinsic finger flexor muscles to enter the hand. ● Carpal tunnel syndrome is a result of the impingement of the median nerve due to injury or overuse. Figure 9-30 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby; courtesy of Joseph E. Muscolino Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 63

Dorsal Digital Expansion: ● The dorsal digital expansion is a fibrous expansion on fingers #2 through #5 of the distal tendons of the extensor digitorum muscle. ● The dorsal digital expansion serves as a movable hood of tissue as the fingers flex and extend. It also serves as an attachment site for a number of intrinsic muscles of the hand. Figure 9-31 From Muscolino JE: The muscular system manual: the skeletal muscles of the human body, ed 3, St Louis, 2010, Mosby Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 64

Dorsal Digital Expansion (cont’d.): ● The dorsal digital expansion serves as an attachment site for which muscles? The lumbricals manus, palmar interossei, dorsal interossei manus, and the abductor digiti minimi manus attach to the dorsal digital expansion. ● Extensor expansion and dorsal hood are two synonyms for the dorsal digital expansion. Figure 9-31 From Muscolino JE: The muscular system manual: the skeletal muscles of the human body, ed 3, St Louis, 2010, Mosby Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 65

Section 9.11—Wrist Joint Complex
{Insert Fig. 9-32} ● Movement at the wrist joint occurs at two joints: the radiocarpal joint and the midcarpal joint. Therefore, it is better termed the wrist joint complex. Figure 9-30 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby;courtesy Joseph E. Muscolino Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 66

Section 9.11—Wrist Joint Complex (cont’d.)
Joints of the Wrist Joint Complex: Radiocarpal joint Midcarpal joint Intercarpal joints ● In addition to the radiocarpal and midcarpal joints, a great number of intercarpal joints are located between the individual carpal bones of the wrist. ● Do these intercarpal joints contribute to movement of the hand relative to the forearm at the wrist joint? No, they do not. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 67

Radiocarpal and Midcarpal Joints: Structure: Synovial joint Condyloid Function: Diarthrotic Biaxial ● The joint capsule of the midcarpal joint is anatomically separate from the joint capsule of the radiocarpal joint. ● Both the radiocarpal joint and the midcarpal joint are compound joints because more than two bones are involved with each joint. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 68

Radiocarpal and Midcarpal Joints (cont’d.): Major Motions Allowed: Flexion/extension Radial/ulnar deviation Closed-Packed Position: Extension and slight ulnar deviation ● Radial deviation and ulnar deviation of the hand at the wrist joint are also known as abduction and adduction, respectively. ● Flexion is greater at the radiocarpal joint and extension is greater at the midcarpal joint. Radial deviation is greater at the midcarpal joint, and ulnar deviation occurs equally at both joints. ● In addition to these major motions, what are the accessory motions and reverse actions of the radiocarpal and midcarpal joints? The carpal bones permit a great deal of accessory gliding motions. The reverse action is the forearm moving relative to the hand at the wrist joint when the hand is fixed (closed-chain activity). Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 69

Ligaments of the Wrist Joint Complex: Fibrous capsule of the radiocarpal joint Radioulnar disc Fibrous capsule of the midcarpal joint Transverse carpal ligament Extrinsic ligaments Intrinsic ligaments ● The extrinsic ligaments limit motion primarily at the radiocarpal joint. The dorsal radiocarpal ligament, palmar radiocarpal ligaments, radial collateral ligament, and ulnar collateral ligament are all extrinsic ligaments of the wrist joint complex. ● What are the names of the intrinsic ligaments? The intrinsic ligaments of the wrist joint complex are the short intrinsic ligaments, intermediate ligaments, and long intrinsic ligaments. The long intrinsic ligaments are the dorsal intercarpal ligament and the palmar intercarpal ligament. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 70

Ligaments of the Wrist Joint Complex (cont’d.): {Insert Fig A only} ● What is the role of the palmar radiocarpal ligaments and where are they located? The palmar radiocarpal ligaments limit full extension. They are located on the palmar side from the radius to the carpal bones. ● The ulnocarpal complex includes the ligaments between the distal end of the ulna and the carpus on the ulnar side of the wrist. They are the ulnar collateral ligament, the palmar ulnocarpal ligament, and the radioulnar disc (triangular fibrocartilage). Figure 9-34 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 71

Ligaments of the Wrist Joint Complex (cont’d.): ● Most of the wrist joint complex ligaments are divided into two broad categories: the extrinsic ligaments which originate in the forearm and then attach onto the carpus and the intrinsic ligaments that originate and insert (i.e., are wholly located within) in the carpus. Figure 9-34 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 72

Section 9.12—Carpometacarpal Joints
● Five carpometacarpal (CMC) joints are formed between the distal row of carpals and the metacarpal bones. ● The CMC joints primarily allow flexion and extension and are stabilized by their joint capsules as well as carpometacarpal ligaments. ● CMC joints contribute to motion at a ray (finger). Figure 9-35 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 73

Section 9.12—Carpometacarpal Joints (cont’d.)
Second and Third CMC Joints: Structure: Synovial joint Plane Function: Synarthrotic Nonaxial ● The second CMC joint is located primarily between the trapezoid and the base of the second metacarpal. ● The third CMC joint is located primarily between the capitate and the base of the third metacarpal. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 74

First, Fifth, and Fourth CMC Joints: Structure: Synovial joint Saddle Function: Diarthrotic Biaxial ● Where are the first, fifth, and fourth CMC joints located? The first CMC joint is located primarily between the trapezium and the base of the first metacarpal. The fifth metacarpal joint is located primarily between the hamate and the base of the fifth metacarpal. The fourth metacarpal joint is located primarily between the hamate and the base of the fourth metacarpal. ● Each metacarpal and its associated phalanges make up a ray of the hand. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 75

Motion of the CMC Joints of the Hand: ● This anterior view of the right hand depicts the concept of the relative mobility of the first, fifth, and fourth CMC joints and the relative rigidity/stability of the second and third CMC joints. Figure 9-36 A, modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010 Mosby; Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 76

Motion of the CMC Joints of the Hand (cont’d.): ● Figure 9-36b shows the motion of the fourth and fifth CMC joints that is evident when the fingers flex. ● Motion of the CMC joints assists the first, fourth, and fifth rays of the hand to close around the central pillar of the hand, resulting in a firm grasp on objects held in the hand, as seen in Figure 9-36c. Figure 9-36 B and C courtesy Joseph E. Muscolino. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 77

Ligaments of the CMC Joints: Fibrous capsules Dorsal CMC ligaments Palmar CMC ligaments Interosseus CMC ligaments ● The CMC joints are stabilized by their joint capsules as well as carpometacarpal (CMC) ligaments. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 78

Dorsal CMC Ligaments of the CMC Joints: {Insert Fig A only} ● The more peripheral CMC joints are more mobile, creating more mobile rays. ● The first CMC saddle joint of the thumb is the most movable, allowing the thumb to oppose the other fingers. ● The fifth and fourth CMC joints are also fairly mobile, allowing the ulnar side of the hand to fold toward the center of the palm. Figure 9-37 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010 Mosby; Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 79

Palmar CMC Ligaments of the CMC Joints: {Insert Fig B only} ● The ability of the fourth, fifth, and first metacarpals to fold toward the center of the palm increases the distal transverse arch of the hand, creating a better grip on objects held. Figure 9-37 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010 Mosby; Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 80

Average Ranges of Motion: Joint Flexion Extension 5th CMC 20 degrees 0 degrees 4th CMC 10 degrees 0 degrees 3rd CMC 0 degrees 0 degrees 2nd CMC 0–2 degrees 0 degrees ● This information from Table 9-9 shows the average ranges of motions from anatomic position of the metacarpals at the second through the fifth CMC joints. ● Some abduction/adduction occurs at the fourth and fifth CMC joints. ● Some lateral rotation/medial rotation occurs at the fifth CMC joints. ● The abduction/adduction and the lateral/medial rotation motions of the fifth metacarpal at the fifth CMC joint allow for opposition/reposition of the little finger. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 81

Lesson 9.4 Objectives Describe the importance of motion at the first carpometacarpal joint (i.e., the saddle joint of the thumb). Describe the component actions of opposition and reposition of the thumb. Discuss the similarities and differences between the metacarpophalangeal joints and the interphalangeal joints. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 82

Shoulder joint complex Glenohumeral joint Scapulocostal joint Sternoclavicular joint Acromioclavicular joint Elbow joint complex Elbow joint Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 83

Radioulnar joints Wrist joint complex Carpometacarpal joints Saddle joint of the thumb Intermetacarpal joints Metacarpophalangeal (MCP) joints Interphalangeal joints (IP) of the hand ● Lesson 9.4 finishes Chapter 9 by discussing the saddle joint of the thumb, intermetacarpal joints, metacarpophalangeal joints, and interphalangeal joints of the hand. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 84

Section 9.13—Saddle (Carpometacarpal) Joint of the Thumb
● The saddle joint of the thumb is the first CMC joint. It is this joint that allows opposition, which is what allows tools to be grasped, which is what has helped humans develop civilization. In this sense, all joints of the upper extremity are subservient to the saddle joint of the thumb. Figure 9-38 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 85

Section 9.13—Saddle Joint of the Thumb (cont’d.)
CMC Joint of the Thumb: Structure: Synovial joint Saddle Function: Diarthrotic Biaxial ● The saddle joint of the thumb is located between the distal end of the trapezium and the first metacarpal. ● What is basilar arthritis? Degenerative arthritic changes are commonly found at the saddle joint of the thumb because of its tremendous use. This condition is known as basilar arthritis because the saddle joint of the thumb is the base joint of the entire thumb. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 86

Average Ranges of Motion: Abduction 60 degrees Adduction 10 degrees Flexion degrees Extension 10 degrees Medial rotation 45 degrees Lateral rotation 0 degrees ● Table 9-10 shows the average ranges of motion of the metacarpal of the thumb at the thumb saddle joint. ● Anatomic position has the thumb in near full extension and adduction. ● The trapezium of the wrist (along with the remainder of the hand) could move relative to the metacarpal of the thumb. This would be the reverse action. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 87

Actions of the Thumb at the Saddle Joint: ● Figure 9-39a and Figure 9-39b show opposition and reposition of the thumb, respectively. ● Opposition and reposition of the thumb are actually combinations of actions. The components of these actions are shown in the last four figures. What are these component actions called and in what plane do they take place? Figure 9-39c and Figure 9-39d illustrate flexion and extension, respectively, and occur in the frontal plane. Figure 9-39e and Figure 9-39f are abduction and adduction, respectively. These actions occur in the sagittal plane. ● Note: Medial and lateral rotation couple with flexion and extension, respectively. Figure 9-39 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 88

Ligaments of the Saddle Joint: Fibrous capsule Radial collateral ligament Ulnar collateral ligament Anterior oblique ligament Posterior oblique ligament 1st intermetacarpal ligament ● The CMC joint of the thumb is stabilized by its fibrous joint capsule and five major ligaments. ● The fibrous joint capsule of the thumb is loose, allowing large ranges of motion. ● Generally the ligaments of the thumb become taut in full opposition and/or full abduction or full extension. ● The closed-packed position of the saddle joint of the thumb is full opposition. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 89

● Figure 9-40a shows the palmar view of the ligaments of the first carpometacarpal joint of the right thumb in which the ulnar collateral and anterior oblique ligaments are seen. ● Figure 9-40b illustrates the radial view in which the radial collateral and posterior oblique ligaments are seen. ● The intermetacarpal ligament between the thumb and index finger is also seen. Figure 9-40 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 90

Section 9.14—Intermetacarpal Joints
● The intermetacarpal (IMC) joints are located between the metacarpal bones of the hand. Four proximal IMC joints and three distal IMC joints exist. This anterior view shows the osseous joints. ● All five metacarpals articulate with each other proximally at their bases; hence four proximal IMC joints exist. ● Only metacarpals #2 through #5 articulate with each other distally at their heads, hence three distal IMC joints exist. Figure 9-41 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 91

Section 9.14—Intermetacarpal Joints (cont’d.)
{Insert Fig B only} ● This illustration details the ligaments of the proximal and distal IMC joints. Proximal IMC joints are stabilized by intermetacarpal ligaments. Distal IMC joints are stabilized by deep transverse metacarpal ligaments. ● What are the three sets of intermetacarpal ligaments that stabilize the proximal IMC joints? They are the dorsal intermetacarpal ligaments, palmar intermetacarpal ligaments, and interosseus intermetacarpal ligaments. ● IMC ligaments of the proximal IMC joints are also known simply as metacarpal ligaments. Figure 9-41 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 92

Section 9.14—Intermetacarpal Joints (cont’d.)
Structure: Synovial joint Plane Function: Amphiarthrotic Nonaxial ● IMC joints allow nonaxial gliding motion of one metacarpal relative to the adjacent metacarpal(s). ● Motion between the metacarpals at the IMC joints increases the ability of the hand to close in around an object and grasp it securely. Therefore the first and fifth metacarpals are the most mobile. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 93

Section 9.15—Metacarpophalangeal Joints
{Insert Fig. 9-42} ● Where are the metacarpophalangeal (MCP) joints located? They are located between the heads of the metacarpals of the palm and the bases of the proximal phalanges of the fingers. ● Rheumatoid arthritis (RA) is a progressive degenerative arthritic condition that weakens and destroys the capsular connective tissue of joints. The MCP joints of the hand are particularly hard hit by this condition. Figure 9-42 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 94

Section 9.15—Metacarpophalangeal (MCP) Joints (cont’d.)
Structure: Synovial joint Condyloid Function: Diarthrotic Biaxial ● There are five metacarpophalangeal joints. ● A finger can move at three joints, a metacarpophalangeal joint and two interphalangeal joints. It is actually the proximal phalanx of a finger that moves at an MCP joint. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 95

Section 9.15—Metacarpophalangeal Joints (cont’d.)
Major motions allowed: Flexion/extension Abduction/adduction Major ligaments: Fibrous capsules Radial collateral ligaments Ulnar collateral ligaments Palmar plates ● The MCP joints allow a great deal of passive glide in all directions, as well as passive rotation. ● What are the reverse actions at the metacarpophalangeal joints? A metacarpal of the palm of the hand can move toward the proximal phalanx of a finger. ● In addition to the usual ligaments that a joint has, the MCP joints and interphalangeal joints have an additional stabilizing structure called a palmar plate. It serves to resist extension beyond anatomic position. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 96

● These radial views of the fingers at the metacarpophalangeal joints are shown here illustrating flexion and extension, respectively, of fingers #2 through #5 at the MCP joints. ● Flexion of the fingers at the interphalangeal joints is also seen. Figure 9-43 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 97

● This figure illustrates abduction and adduction of fingers #2 through #5 at the MCP joints. ● The reference for abduction/adduction of the fingers at the MCP joints is an imaginary line through the middle finger in anatomic position. Figure 9-43 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 98

● Lateral movement of the middle finger is termed radial abduction; medial movement of the middle finger is termed ulnar abduction. ● Radial abduction and ulnar abduction of the middle finger at the third MCP joint are illustrated here. Figure 9-43 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 99

● Figure 9-44a shows an anterior view of the fibrous capsules, collateral ligaments, and palmar plates of the MCP joints (and the palmar plates of the interphalangeal joints). ● The palmar plate is a ligamentous-like thick disc of fibrocartilage. What is another name for the palmar plate? It is also known as the volar plate. Figure 9-44 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 100

● Figure 9-44b shows an ulnar view of a finger illustrating the fibrous capsule, ulnar collateral ligament, and palmar plate of the MCP joint (and the palmar plate of the IP joint). ● The closed-packed position of the MCP joints is 70 degrees of flexion. Figure 9-44 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 101

Section 9.16—Interphalangeal Joints of the Hand
{Insert Fig. 9-45} ● The interphalangeal (IP) joints of the hand are located between the phalanges of the fingers. There are nine IP joints found in the hand. ● There is one IP joint in the thumb. It is located between the proximal and distal phalanges of the thumb. ● Each of fingers #2 through #5 has three phalanges. Two IP joints exist in each of these fingers; a proximal interphalangeal (PIP) joint and a distal interphalangeal (DIP) joint. Figure 9-45 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 102

Section 9.16—Interphalangeal Joints of the Hand (cont’d.)
Structure: Synovial joint Hinge Function: Diarthrotic Uniaxial ● The PIP joint (manus) is located between the middle and distal phalanges. The DIP joint (manus) is located between the middle and distal phalanges. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 103

Major Motions Allowed: Flexion Extension ● Flexion of the fingers at the interphalangeal joints is shown here in Figure 9-46a. Flexion is also seen at the MCP joints. ● Extension of the fingers at the PIP and DIP joints is shown in Figure 9-46b. Extension is also seen at the MCP joints. ● What is the closed-packed position of the interphalangeal joints? It is approximately full extension. Figure 9-46 Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 104

Major Ligaments of the IP Joints: Fibrous capsule Radial collateral ligaments Ulnar collateral ligaments Palmar plates Check-rein ligaments (PIP joint only) ● In addition to the usual ligaments that a joint has, the IP joints (and MCP joints) have an additional stabilizing structure called a palmar plate, which serves to resist extension beyond anatomic position. ● The check-rein ligaments are located only at the PIP joint and are found immediately anterior to the palmar plate. The check-rein ligaments strengthen the connection between the palmar plate and the bones of the joint. The check-rein ligaments also restrict hyperextension of the PIP joint. Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 105

● This illustration shows a dorsal view of the IP joints with the IP joints opened up. The PIP joint is stabilized by a fibrous capsule, collateral ligaments, a palmar plate, and two check-rein ligaments. The DIP joint is stabilized by a fibrous capsule, collateral ligaments, and a palmar plate. Figure 9-47 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved. 106

● In this view, the relationship of the check-rein ligaments can be seen relative to the palmar plate and the tendons of the flexor digitorum superficialis (FDS) and the flexor digitorum profundus (FDP). Figure 9-47 Modeled from Neumann DA: Kinesiology of the musculoskeletal system: foundations for physical rehabilitation, ed 2, St Louis, 2010, Mosby Copyright © 2011, 2007 by Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved.

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