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Anatomy Practice questions

Terms in this set (20)

The answer is supraspinatus. The greater tubercle of the humerus is the insertion site of three (of the four) rotator cuff muscles: supraspinatus, infraspinatus, and teres minor. Avulsion of this structure could result in detachment of any of these rotator cuff muscles, depending upon the size and scope of the fracture. However, the wrestler is unable to initiate abduction of the upper limb, which implies damage to the supraspinatus muscle. Long head of biceps brachii is incorrect. This muscle originates from the supraglenoid tubercle of the scapula and passes between the greater and lesser tubercles of the humerus, in the intertubercular (bicipital) groove. Detachment of the tendon of this muscle causes the biceps brachii to bulge in the anterior arm. Avulsion of the biceps brachii muscle is not related to the greater tubercle of the humerus. Long head of triceps is incorrect. The long head of the triceps brachii muscle originates from the infraglenoid tubercle of the scapula and inserts on the olecranon process of the ulna. It would not be involved in avulsion of the greater tubercle of the humerus.Subscapularis is incorrect. The fourth rotator cuff muscle, subscapularis, inserts onto the lesser tubercle of the humerus, so it would not be directly involved with this avulsion injury.Infraspinatus is incorrect. The infraspinatus muscle does insert onto the middle aspect of the greater tubercle of the humerus; however, damage to this muscle would result in weakness in external rotation at the shoulder joint, not the problems with abduction seen in this patient.
-Flexor digitorum profundus (FDP)
The answer is flexor digitorum profundus (FDP). Flexion of the distal interphalangeal joint in digits 2 to 5 is produced by the FDP. The actions of this muscle are being tested in this illustration. Extensor indicis is incorrect. The extensor indicis extends the index finger (digit 2), which enables this finger to extend independent of the other fingers. Because the muscle arises from the distal third of the ulna and the interosseous membrane, it also acts to extend the hand at the wrist. The extensor indicis muscle is not involved in flexion of the distal interphalangeal joint, which is being tested in this patient. First lumbrical is incorrect. The first lumbrical muscle extends the interphalangeal joints of the index (second) finger and flexes the metacarpophalangeal joint of the same finger. The first lumbrical is an intrinsic hand muscle that arises off the tendon of the flexor digitorum profundus and inserts into the extensor expansion of the index finger. This muscle is not involved with flexion of the distal interphalangeal joint. First dorsal interosseous is incorrect. The primary movement of the first dorsal interosseous is abduction of the index finger. However, because it inserts into the extensor expansion, it also extends the interphalangeal joints of the index (second) finger and flexes the metacarpophalangeal joint of the same finger. This muscle is not involved with flexion of the distal interphalangeal joint. Flexor digitorum superficialis (FDS) is incorrect. The FDS acts at the proximal interphalangeal joint in digits 2 to 5 and influences the distal interphalangeal joint by binding the tendons of the FDP. However, when the proximal interphalangeal joint is held in extension, the influence of the FDS is eliminated, allowing testing of only the FDP.
-Extensor pollicis longus
The answer is the extensor pollicis longus. The extensor pollicis longus inserts into the distal phalanx of the thumb. Its tendon forms what is normally the pronounced medial wall of the anatomical snuff box on the lateral side of the wrist. The combination of specific fracture point plus loss of definition of the medial wall of the snuff box indicate damage to this muscle tendon. The abductor pollicis longus and extensor pollicis brevis muscles, which form the lateral wall of the snuff box, insert into the first metacarpal bone and proximal phalanx of the thumb, respectively. Abductor pollicis brevis is incorrect. The abductor pollicis brevis is one of the small muscles forming the thenar eminence. It attaches to the proximal phalanx of the thumb and does not form a boundary of the anatomical snuff box. Extensor carpi radialis longus is incorrect. The extensor carpi radialis longus attaches to the posterior base of the second metacarpal bone. It lies medial to the anatomical snuff box. Extensor indicis is incorrect. The long tendon of the extensor indicis runs into the dorsal (extensor) expansion of the second digit. It is located medial to the snuff box. Flexor pollicis longus is incorrect. The flexor pollicis longus does insert into the distal phalanx of the thumb. However, it emerges from the anterior compartment of the forearm and runs through the anterior (palmar) aspect of the hand to its insertion. It is not related to the anatomical snuff box.
-Torn coracoclavicular ligament
The answer is torn coracoclavicular ligament. "Shoulder separation" describes a dislocation of the acromioclavicular joint. In its most severe form (grade 3), the condition includes a tearing of both the intrinsic acromioclavicular ligament and the extrinsic coracoclavicular ligament. As a result, the scapula separates from the clavicle and falls away due to the weight of the upper limb. Thus, the distal end of the clavicle is prominent. Dislocated head of the humerus is incorrect. Dislocations of the GH joint easily occur inferiorly due to its lack of muscular and ligamentous support. Thus, damage to the axillary nerve often occurs following inferior displacment of the head of humerus from the GH joint. However, the acromioclavicular joint, which is more proximal, was injured in this patient. Dislocations of the glenohumeral joint in other directions are more difficult (but not impossible) because of the support of the rotator cuff muscles (anteriorly and posteriorly) and the coracoacromial arch (superiorly). Fractured clavicleis incorrect. Radiological imaging would have detected a fractured clavicle, but these tests confirmed a shoulder separation and not a fractured clavicle. Dislocated sternal end of the clavicle is incorrect. Due to its intrinsic strength, dislocation of the sternoclavicular (SC) joint is rare. Most dislocations of the SC joint occur in persons less than 25 years of age following a fracture of the epiphysial plate of the clavicle. The epiphysis at the proximal end of the clavicle does not close until approximately age 25. Though this patient was under the age of 25, his injury was localized to the acromioclavicular joint. Torn anterior gleno- humeral (GH) ligament is incorrect. Three GH ligaments reinforce the anterior part of the joint capsule; however, the GH joint was not involved in this patient.