Lab Manual - Joints of the Upper Limb

Assignments:

Learning Objectives:

Upon completion of this session, the student will be able to:

  1. Identify the bony, cartilagenous, ligamentous and membranous components of the following joints:
  2. List the movements permitted at each joint and the ligaments that restrict them.
  3. Correlate joint movements with the muscles producing these actions at each joint.
  4. Describe the blood and nerve supply of the upper limb joints

Procedure:

1. Dissect one limb only, review as dissecting.

Dissection is carried out on one side of the body only, review as dissecting. The bones, articular surfaces, capsule, capsular and accessory ligaments and cartilages are examined in each joint.

Select a limb for joint dissection; strip all of the muscles, examining points of origin, insertion or attachment, nervous or vascular structures not previously seen. The limb can be subdivided to distribute the effort and conserve time. Different lab tables can do different joints - consult with your instructor.

Review the kinds and characteristics of true synovial (diarthrodial) joints. Examine the articular surface of the opposing bones at each joint, both on the skeleton and the cadaver. Determine movements allowed or restricted by the shape of the bones, the ligaments uniting them, and the muscles crossing each joint.

2. Dissect the sternoclavicular joint. (Play movie; View images: N 419, 423, 424, TG 2-12, 2-42A, 2-42BC)

Sternoclavicular joint. Saw off the anterior 1/3 of the joint in the frontal plane and observe the articular disc, its attachments and articular cavities. Consider the functions of this joint and its relation to the attachment and function of the pectoral girdle.

If not already done, completely reflect the deltoid muscle. Identify the coracoacromial ligament.

Acromioclavicular joint. Note the articulation between clavicle and acromion. Remove fat and connective tissue from the tip of the coracoid towards its base to expose the coracoclavicular ligament. Consider its functional role in maintaining alignment of the clavicle and scapula. What is a "shoulder separation" and what ligaments would be torn?

For each of the following joints, carefully remove the muscles crossing the joint. Review the course and relations of muscles, and identify insertions or attachments not previously seen. Consider the actions on the joint as you proceed.

3. Dissect the shoulder joint by removing surrounding muscles, opening the capsule posteriorly and chiseling off the humeral head. (Play movie; View images: N 423, 424, 425, 426,TG 2-08A, 2-08B, 2-16, 2-19, 2-42)

Glenohumeral (shoulder) joint. The supraspinatus, infraspinatus and teres minor muscles are adherent to the capsule of the shoulder joint. Carefully reflect these so as not to tear the capsule. Cut the long head of the triceps. Cut the short head of the biceps and coracobrachialis from the coracoid process. Reflect latissimus dorsi and teres major. Do not reflect the subscapularis at this time. Make a vertical incision through the posterior part of the capsule and turn the head of the humerus posteriorly and laterally. Chisel off the head of the humerus, noting the articular cartilage and its thickness at various points. Look for glenohumeral bands (superior, middle and inferior) along the interior of the anterior wall of the capsule. Do you have three? What is their relation to the subscapular bursa? Note the long head of biceps tendon, its synovial covering and mesotendon within the joint cavity (bursa). Note the looseness of the joint capsule and the absence of real ligaments. Given the looseness of the capsule and arrangement of tendons and ligaments, where would you expect dislocations to be most common?

Glenohumeral joint and glenoid labrum

Anteriorly, trace the long head (tendon) of the biceps into the bicipital groove. Identify the transverse humeral ligament. Reflect the subscapularis to completely expose the subscapular bursa. Note the glenoid labrum. Consider individual and group muscle actions of the "rotator cuff" muscles. What is a torn rotator cuff and which muscle is usually involved?

4. Open the elbow by removing the anterior and posterior capsules. (Play movie; View images: N 431, 432, 438, 438, 439, 454, 455, TG 2-17, 2-18, 2-43A, 2-43BC, 2-44A, 2-44B, 2-44C)

Elbow joint. The elbow joint consists of the humeroulnar, humeroradial (true elbow articulations), and the proximal radioulnar articulation. Though contained in a single cavity, they move independently.

Remove the muscles on both the posterior and anterior surfaces of the joint. Do not enter the joint cavity at this time. Examine carefully the biceps tendon at its insertion, noting associated bursae and dual action at elbow joint and proximal radioulnar joint. Clean the capsule and define the ulnar collateral, radial collateral and annular ligaments. Remove the capsule anteriorly and posteriorly to expose the joint surfaces, leaving the ligaments intact. Examine actions. Consider the action of pronators and supinators. What is a "pulled elbow"?

Examine the interosseous membrane and note the direction of its fibers. What is the significance of their direction? Examine the distal radioulnar joint and its articular disc. Determine the action of the proximal radioulnar joint and its axis of rotation. Do the same for the distal radioulnar joint. How does the combined motion of these two joints affect the position of the hand?

5. Dissect the wrist by making a frontal section through the distal radius and ulna, carpals and proximal metacarpals. (Play movie; View images: N 453, 454, 455A, 455B, 458, TG 2-44A, 2-44B, 2-44C, 2-45)

Radiocarpal (wrist) joint. Remove all tendons and muscles of the wrist and hand, and identify the capsule, dorsal radiocarpal, palmar radiocarpal, ulnar collateral and radial collateral ligaments.

Section the wrist in the frontal plane, in the following manner. Flex the wrist and hand. Saw through the distal end of the radius and ulna, continuing through both the proximal and distal rows of carpals and the proximal end of the four ulnar metacarpals. The procedure may require sawing in more than one plane to expose all joints. This section exposes the distal radioulnar, the radiocarpal, the intercarpal, midcarpal, carpometacarpal, and the intermetacarpal articulations. Note the extent of each synovial cavity and the interosseous intercarpal ligaments. Consider the combined actions of the "greater wrist" in flexion, extension, adduction, abduction, and circumduction. How do these articulations combine to provide these actions at the "wrist"?

Examine the carpometacarpal articulation of the thumb (saddle type).

Examine the deep transverse metacarpal ligaments. Note that each one lies between interosseous and lumbrical muscle tendons for that digit. What are their relationships to the extensor expansion and fibrous flexor sheath? Open any of the metacarpophalangeal and interphalangeal joints, noting the capsule and collateral ligaments.