Radiocarpal, Hand, & Digits

28. Which bones form the radiocarpal joint? a. At which bony landmarks of those bones does this joint articulate?

articulation between distal radius and proximal row of of carpal bones.

35. In which planes of motion and about which axes of rotation can the joints of the digits move?a. Which digit movements correspond to which planes/axes of motion?

flexion extension abduction adduction

32. Which bones form the distal radioulnar joint?a. At which bony landmarks of those bones does this joint articulate?

radius and ulna

36. Muscles of the wrist and hand: a. Which muscle group originates on the lateral epicondyle of the humerus?i. What is their group function? b. Which muscle group originates on the medial epicondyle of the humerus?ii. What is their group function? c. What are the agonists of wrist motion? g. What are the agonists of thumb and finger motion?

A. wrist extensors, to extend the wrist B. wrist and phalange flexors; flex the wrist and fingers C. Primarily wrist flexion Flexor carpi radialis Flexor carpi ulnaris Palmaris longus Primarily wrist and phalangeal flexion Flexor digitorum superficialis Flexor digitorum profundus Flexor pollicis longus Posterolateral at the elbow and forearm and posterior at the hand (Fig. 7.9, D) Primarily wrist extension Extensor carpi radialis longus Extensor carpi radialis brevis Extensor carpi ulnaris Primarily wrist and phalangeal extension Extensor digitorum Extensor indicis Extensor digiti minimi Extensor pollicis longus Extensor pollicis brevis Abductor pollicis longus g. The opponens pollicis is the muscle that causes opposition in the thumb metacarpal. The abductor pollicis brevis abducts the thumb metacarpal and is assisted in this action by the flexor pollicis brevis, which also flexes the thumb metacarpal. The metacarpal of the thumb is adducted by the adductor pollicis. Both the flexor pollicis brevis and the adductor pollicis flex the proximal phalanx of the thumb.

37. What are some common clinical conditions that affect the radiocarpal joint and hand?

Although there are far too many ligaments in the wrist and hand to allow a detailed discussion, injuries involving the ulnar and radial collateral ligaments of the metacarpophalangeal and proximal interphalangeal joints are very common because of the medial and lateral stresses they often encounter. One of the more common injuries involves a sprain of the ulnar collateral ligament of the thumb metacarpophalangeal joint. This is often referred to as a gamekeeper's or skier's thumb which may require surgery when severely sprained. The wrist, hand, and fingers depend heavily on the ligaments to provide support and static stability. Table 7.1 provides a listing of the major ligaments of the wrist and hand and some of the finger ligaments are detailed in Fig. 7.6. All of the flexor tendons except for the flexor carpi ulnaris and palmaris longus pass through the carpal tunnel, along with the median nerve (Fig. 7.8). Conditions leading to swelling and inflammation in this area can result in increased pressure in the carpal tunnel, which interferes with normal function of the median nerve, leading to reduced motor and sensory function of its distribution. Known as carpal tunnel syndrome, this condition is particularly common with repetitive use of the hand and wrist in manual labor and clerical work such as typing and keyboarding. Often, slight modifications in work habits and the positions of the hand and wrist during these activities can be preventive. Additionally, flexibility exercises for the wrist and finger flexors may be helpful.

30. In which planes of motion and about which axes of rotation can the radiocarpal joint move?a. Which radiocarpal movements correspond to which planes/axes of motion?

Flexion (palmar flexion): Movement of the palm of the hand and/or the phalanges toward the anterior or volar aspect of the forearm; saggital Extension (dorsiflexion): Movement of the back of the hand and/or the phalanges toward the posterior or dorsal aspect of the forearm; sometimes referred to as hyperextension; saggital Abduction (radial deviation, radial flexion): Movement of the thumb side of the hand toward the lateral aspect or radial side of the forearm; also, movement of the fingers away from the middle finger; frontal Adduction (ulnar deviation, ulnar flexion): Movement of the little finger side of the hand toward the medial aspect or ulnar side of the forearm; also, movement of the fingers back together toward the middle finger; frontal Opposition: Movement of the thumb across the palmar aspect to oppose any or all of the phalanges Reposition: Movement of the thumb as it returns to the anatomical position from opposition with the hand and/or fingers

Extensor indicis muscle

Origin Between middle and distal one-third of the posterior ulna Insertion Base of the middle and distal phalanxes of the second phalange (dorsal surface) Action Extension of the index finger at the metacarpophalangeal joint Weak wrist extension Weak supination of the forearm from a pronated position Application, strengthening, and flexibility The extensor indicis muscle is the pointing muscle. That is, it is responsible for extending the index finger, particularly when the other fingers are flexed. It also provides weak assistance to wrist extension and may be developed through exercises similar to those described for the extensor digitorum. The extensor indicis is stretched by passively taking the index finger into maximal flexion at its metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints while fully flexing the wrist.

Extensor carpi radialis longus muscle

Origin Distal third of lateral supracondylar ridge of the humerus and lateral epicondyle of the humerus Insertion Base of the second metacarpal (dorsal surface) Action Extension of the wrist Abduction of the wrist Weak flexion of the elbow Weak pronation to neutral from a fully supinated position Application, strengthening, and flexibility The extensor carpi radialis longus, like the extensor carpi radialis brevis, is important in any sports activity that requires powerful wrist extension. In addition, both muscles are involved in abduction of the wrist. The extensor carpi radialis longus may be developed with the same wrist extension exercises as described for the extensor carpi ulnaris muscle. The extensor carpi radialis longus is stretched in the same manner as the extensor carpi radialis brevis.

Extensor digiti minimi muscle

Origin Lateral epicondyle of the humerus Insertion Base of the middle and distal phalanxes of the fifth phalange (dorsal surface) Action Extension of the little finger at the metacarpophalangeal joint Weak wrist extension Weak elbow extension Application, strengthening, and flexibility The primary function of the extensor digiti minimi muscle is to assist the extensor digitorum in extending the little finger. Because of its dorsal relationship to the wrist, it also provides weak assistance in wrist extension. It is strengthened with the same exercises described for the extensor digitorum. The extensor digiti minimi is stretched by passively taking the little finger into maximal flexion at its metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints while fully flexing the wrist and elbow.

Extensor carpi radialis brevis muscle

Origin Lateral epicondyle of the humerus Insertion Base of the third metacarpal (dorsal surface) Action Extension of the wrist Abduction of the wrist Weak flexion of the elbow Application, strengthening, and flexibility The extensor carpi radialis brevis is important in any sports activity that requires powerful wrist extension, such as golf or tennis. Wrist extension exercises, such as those described for the extensor carpi ulnaris, are appropriate for development of the muscle. Stretching the extensor carpi radialis brevis and longus requires the elbow to be extended with the forearm pronated while the wrist is passively flexed and slightly adducted.

Extensor digitorum muscle

Origin Lateral epicondyle of the humerus Insertion Four tendons to bases of middle and distal phalanxes of the four fingers (dorsal surface) Action Extension of the second, third, fourth, and fifth phalanges at the metacarpophalangeal joints Extension of the wrist Weak extension of the elbow Application, strengthening, and flexibility The extensor digitorum, also known as the extensor digitorum communis, is the only muscle involved in extension of all four fingers. This muscle divides into four tendons on the dorsum of the wrist to insert on each of the fingers. It also assists with wrist extension movements. It may be developed by applying manual resistance to the dorsal aspect of the flexed fingers and then extending the fingers fully. When performed with the wrist in flexion, this exercise increases the workload on the extensor digitorum. To stretch the extensor digitorum, the fingers must be maximally flexed at the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints while the wrist is fully flexed.

Extensor carpi ulnaris muscle

Origin Lateral epicondyle of the humerus Middle two-fourths of the posterior border of the ulna Insertion Base of the fifth metacarpal (dorsal surface) Action Extension of the wrist Adduction of the wrist together with the flexor carpi ulnaris muscle Weak extension of the elbow Application, strengthening, and flexibility Besides being a powerful wrist extensor, the extensor carpi ulnaris muscle is the only muscle other than the flexor carpi ulnaris involved in wrist adduction or ulnar deviation. The extensor carpi ulnaris, the extensor carpi radialis brevis, and the extensor carpi radialis longus are the most powerful of the wrist extensors. These muscles act as antagonists to wrist flexion to allow the finger flexors to function more effectively in gripping. Any activity requiring wrist extension or stabilization of the wrist against resistance, particularly if the forearm is pronated, depends greatly on the strength of these muscles. They are often brought into play with the backhand in racquet sports. The extensor carpi ulnaris may be developed by performing wrist extension against a handheld resistance. This may be accomplished with the pronated forearm being supported by a table with the hand hanging over the edge to allow full range of motion. The wrist is then moved from the fully flexed position to the fully extended position against the resistance. Stretching the extensor carpi ulnaris requires the elbow to be extended with the forearm pronated while the wrist is passively flexed and slightly abducted.

Flexor carpi radialis muscle

Origin Medial epicondyle of the humerus Insertion Base of the second and third metacarpals, anterior (palmar surface) Action Flexion of the wrist Abduction of the wrist Weak flexion of the elbow Weak pronation of the forearm Application, strengthening, and flexibility The flexor carpi radialis, flexor carpi ulnaris, and palmaris longus are the most powerful of the wrist flexors. They are brought into play during any activity that requires wrist curling or stabilization of the wrist against resistance, particularly if the forearm is supinated. The flexor carpi radialis may be developed by performing wrist curls against a handheld resistance. This may be accomplished when the supinated forearm is supported by a table, with the hand and wrist hanging over the edge to allow full range of motion. The extended wrist is then flexed or curled up to strengthen this muscle. See Appendix 2 for more commonly used exercises for the flexor carpi radialis and other muscles in this chapter. To stretch the flexor carpi radialis, the elbow must be fully extended with the forearm supinated while a partner passively extends and adducts the wrist.

Palmaris longus muscle

Origin Medial epicondyle of the humerus Insertion Palmar aponeurosis of the second, third, fourth, and fifth metacarpals Action Flexion of the wrist Weak flexion of the elbow Application, strengthening, and flexibility Unlike the flexor carpi radialis and flexor carpi ulnaris, which are not only wrist flexors but also abductors and adductors, respectively, the palmaris longus is involved only in wrist flexion from the anatomical position because of its central location on the anterior forearm and wrist. It can, however, assist in abducting the wrist from an extremely adducted position back to neutral, and assist in adducting the wrist from an extremely abducted position back to neutral. It may also assist slightly in forearm pronation because of its slightly lateral insertion in relation to its origin on the medial epicondyle. It may also be strengthened with any type of wrist-curling activity, such as those described for the flexor carpi radialis muscle. Maximal elbow and wrist extension stretches the palmaris longus.

Flexor carpi ulnaris muscle

Origin Medial epicondyle of the humerus Posterior aspect of the proximal ulna Insertion Pisiform, hamate, and base of the fifth metacarpal (palmar surface) Action Flexion of the wrist Adduction of the wrist, together with the extensor carpi ulnaris muscle Weak flexion of the elbow Application, strengthening, and flexibility The flexor carpi ulnaris is very important in wrist flexion or curling activities. In addition, it is one of only two muscles involved in wrist adduction or ulnar flexion. It may be strengthened with any type of wrist-curling activity against resistance, such as those described for the flexor carpi radialis muscle. To stretch the flexor carpi ulnaris, the elbow must be fully extended with the forearm supinated while a partner passively extends and abducts the wrist.

Flexor digitorum superficialis muscle

Origin Medial epicondyle of the humerus Ulnar head: medial coronoid process Radial head: upper two-thirds of anterior border of the radius just distal to the radial tuberosity Insertion Each tendon splits and attaches to the sides of the middle phalanx of the four fingers (palmar surface) Action Flexion of the fingers at the metacarpophalangeal and proximal interphalangeal joints Flexion of the wrist Weak flexion of the elbow Application, strengthening, and flexibility The flexor digitorum superficialis muscle, also known as the flexor digitorum sublimis, divides into four tendons on the palmar aspect of the wrist and hand to insert on each of the four fingers. The flexor digitorum superficialis and the flexor digitorum profundus are the only muscles involved in flexion of all four fingers. Both of these muscles are vital in any type of gripping activity. Squeezing a sponge rubber ball in the palm of the hand, along with other gripping and squeezing activities, can be used to develop these muscles. The flexor digitorum superficialis is stretched by passively extending the elbow, wrist, metacarpophalangeal, and proximal interphalangeal joints while maintaining the forearm in full supination.

Flexor pollicis longus muscle

Origin Middle anterior surface of the radius and the anterior medial border of the ulna just distal to the coronoid process; occasionally a small head is present attaching on the medial epicondyle of the humerus Insertion Base of the distal phalanx of the thumb (palmar surface) Action Flexion of the thumb carpometacarpal, metacarpophalangeal, and interphalangeal joints Flexion of the wrist Abduction of the wrist Application, strengthening, and flexibility The primary function of the flexor pollicis longus muscle is flexion of the thumb, which is vital in gripping and grasping activities of the hand. Because of its palmar relationship to the wrist, it provides some assistance in wrist flexion. It may be strengthened by pressing a sponge rubber ball into the hand with the thumb and by many other gripping or squeezing activities. The flexor pollicis longus is stretched by passively extending the entire thumb while simultaneously maintaining maximal wrist extension.

Abductor pollicis longus muscle

Origin Posterior aspect of the radius and midshaft of the ulna Insertion Base of the first metacarpal (dorsal lateral surface) Action Abduction of the thumb at the carpometacarpal joint Abduction of the wrist Extension of the thumb at the carpometacarpal joint Weak supination of the forearm from a pronated position Weak extension of the wrist joint Application, strengthening, and flexibility The primary function of the abductor pollicis longus muscle is abduction of the thumb, although it does provide some assistance in abduction of the wrist. It may be developed by abducting the thumb from the adducted position against a manually applied resistance. Stretching of the abductor pollicis longus is accomplished by fully flexing and adducting the entire thumb across the palm with the wrist fully adducted and in slight flexion.

Extensor pollicis longus muscle

Origin Posterior lateral surface of the lower middle ulna Insertion Base of the distal phalanx of the thumb (dorsal surface) Action Extension of the thumb at the carpometacarpal, metacarpophalangeal, and interphalangeal joints Extension of the wrist Abduction of the wrist Weak supination of the forearm from a pronated position Application, strengthening, and flexibility The primary function of the extensor pollicis longus muscle is extension of the thumb, although it does provide weak assistance in wrist extension. It may be strengthened by extending the flexed thumb against manual resistance. It is stretched by passively taking the entire thumb into maximal flexion at its carpometacarpal, metacarpophalangeal, and interphalangeal joints while fully flexing the wrist with the forearm in pronation. The tendons of the extensor pollicis longus and extensor pollicis brevis, along with the tendon of the abductor pollicis longus, form the "anatomical snuffbox," the small depression that develops between these two tendons when they contract. The name anatomical snuffbox originates from tobacco users placing their snuff in this depression. Deep in the snuffbox the scaphoid bone can be palpated and is often a site of point tenderness when it is fractured. Due to its posterolateral relationship to the wrist it also assists in wrist abduction.

Extensor pollicis brevis muscle

Origin Posterior surface of the lower middle radius Insertion Base of the proximal phalanx of the thumb (dorsal surface) Action Extension of the thumb at the carpometacarpal and metacarpophalangeal joints Wrist abduction Weak wrist extension Application, strengthening, and flexibility The extensor pollicis brevis assists the extensor pollicis longus in extending the thumb. Because of its dorsal relationship to the wrist, it, too, provides weak assistance in wrist extension. It may be strengthened through the same exercises described for the extensor pollicis longus muscle. It is stretched by passively taking the first carpometacarpal joint and the metacarpophalangeal joint of the thumb into maximal flexion while fully flexing and adducting the wrist. Due to its lateral orientation at the wrist it assists in wrist abduction.

Flexor digitorum profundus muscle

Origin Proximal three-fourths of the anterior and medial ulna Insertion Base of the distal phalanxes of the four fingers Action Flexion of the four fingers at the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints Flexion of the wrist Application, strengthening, and flexibility Both the flexor digitorum profundus muscle and the flexor digitorum superficialis muscle assist in wrist flexion because of their palmar relationship to the wrist. The flexor digitorum profundus is used in any type of gripping, squeezing, or handclenching activity, such as gripping a racket or climbing a rope. It is the only muscle that flexes the finger DIP joints and disruption of the tendon at or near its insertion is known as a jersey or sweater finger and should be addressed surgically within approximately one week. The flexor digitorum profundus muscle may be developed through these activities, in addition to the strengthening exercises described for the flexor digitorum superficialis muscle. The flexor digitorum profundus is stretched similarly to the flexor digitorum superficialis, except that the distal interphalangeal joints must be passively extended in addition to the wrist, metacarpophalangeal, and proximal interphalangeal joints while maintaining the forearm in full supination.

31. Which soft tissue structures support the radiocarpal joint?a. What motions do they limit/resist?b. What is the function of the transverse carpal ligament?

Radial carpal collateral ligament: Reinforces the articular capsule on the lateral side of the wrist, limits ulnar deviation of wrist Dorsal radiocarpal ligaments (radiotriquetral ligament, radiolunate ligament, radioscaphoid ligament): Reinforces dorsal wrist fibrous capsule to assist in maintaining joint integrity, slight limitation to wrist flexion, limits excessive supination movement between joint surfaces Palmar radiocarpal ligament (radioscaphocapitate, radioscapholunate, long and short radiolunate): Reinforces volar wrist fibrous capsule to assist in maintaining joint integrity, slight limitation to wrist extension, limits excessive supination movement between joint surfaces

33. Which bones form the carpus?a. Where are they located? (Remember the funny way we learned them?)

Some Levers try positions that they cant handle scaphoid lunate triquetrum pisiform trapezium trapezoid capitate hamate

29. What type of joint is the radiocarpal joint?a. How does that affect its function?

The wrist joint is classified as a condyloid-type joint, allowing flexion, extension, abduction (radial deviation), and adduction (ulnar deviation) (Fig. 7.2). Wrist motion occurs primarily between the distal radius and the proximal carpal row, consisting of the scaphoid, lunate, and triquetrum. As a result, the wrist is often referred to as the radiocarpal joint.

34. What are the bones of the hand?a. What are the sections?b. Which fingers have which bones?c. What joints are formed by those bones?

carpals metacarpals proximal phalanges middle phalanges distal phalanges The thumb has only two joints, both of which are classified as ginglymus. The MCP joint moves from full extension into 40 to 90 degrees of flexion. The interphalangeal (IP) joint can flex 80 to 90 degrees. The carpometacarpal (CMC) joint of the thumb is a unique saddle-type joint having 50 to 70 degrees of abduction. It can flex approximately 15 to 45 degrees and extend 0 to 20 degrees (Fig. 7.5). Its structure also allows slight internal and external rotation.