A 53-year-old man comes to the office with a dull ache in his right shoulder. The pain is worse with movement and often interferes with his sleep. The patient cannot recall any traumatic events prior to the start of the pain but did experience increased discomfort after helping his daughter move into her college dorm room a week ago. His past medical history includes dyslipidemia and hypertension, for which he takes the appropriate medications. Physical examination reveals localized tenderness just below the acromion. The physician asks the patient to abduct his arms 90 degrees to the side and flex them 30 degrees forward with his thumbs pointing to the floor. She then applies downward force to his arms. This maneuver elicits pain in the patient's right shoulder and reveals right-sided weakness as compared to the left side. A tendon of which of the following muscles is most likely injured in this patient?

Question

A 53-year-old man comes to the office with a dull ache in his right shoulder.  The pain is worse with movement and often interferes with his sleep.  The patient cannot recall any traumatic events prior to the start of the pain but did experience increased discomfort after helping his daughter move into her college dorm room a week ago.  His past medical history includes dyslipidemia and hypertension, for which he takes the appropriate medications.  Physical examination reveals localized tenderness just below the acromion.  The physician asks the patient to abduct his arms 90 degrees to the side and flex them 30 degrees forward with his thumbs pointing to the floor.  She then applies downward force to his arms.  This maneuver elicits pain in the patient's right shoulder and reveals right-sided weakness as compared to the left side.  A tendon of which of the following muscles is most likely injured in this patient?

Quizplus · Accepted Answer

11ec160b_35ef_507c_9249_0f149a451906_MD0001_00 The rotator cuff consists of the tendons of the supraspinatus, infraspinatus, teres minor, and subscapularis (SITS) and contributes to the stability and motion of the glenohumeral joint. During abduction of the humerus, the supraspinatus initiates movement through the first 10-15 degrees; subsequently, the deltoid provides the primary abductive force while the supraspinatus provides stability to the joint. Of all the rotator cuff structures, the supraspinatus tendon is most commonly affected in rotator cuff syndrome. This tendon is vulnerable to chronic repeated trauma from impingement between the head of the humerus and the acromion during abduction. Inflammation and fibrosis can worsen the problem by increasing friction between the head of the humerus and the acromion, as well as causing inflammation of the subacromial bursa. On examination, the action of the supraspinatus can be isolated with the "empty-can" supraspinatus test: abduction of the humerus in parallel to the axis of the scapula (30 degrees forward flexion) while in full internal rotation (thumbs pointed to the floor). (Choice A) The long head of the biceps brachii originates on the supraglenoid tubercle of the scapula and inserts on the radius. It primarily flexes and supinates the forearm, although it also contributes to shoulder flexion. Biceps tendonitis is characterized by tenderness at the bicipital groove (separates lesser and greater tubercles of the humerus). (Choice B) The deltoid originates on the clavicle, the acromion, and the spine of the scapula; it inserts on the lateral humerus. Deltoid injuries are less common than supraspinatus injuries and usually manifest as sudden-onset shoulder pain after overloading the arm while in abduction. (Choice C) The tendons of the levator scapulae insert on the superomedial border of the scapula and on the transverse processes of the C1 through C4 vertebrae. The levator scapulae does not contribute to the stability of the glenohumeral joint. (Choice D) The serratus anterior originates on the lateral surfaces of the first 8 ribs and inserts on the scapula. Its primary action is to pull the scapula forward and rotate it to raise the glenoid. Injury to the long thoracic nerve causes paralysis of this muscle and "winging" of the scapula. Educational objective: The supraspinatus muscle assists in abduction of the arm and stabilization of the glenohumeral joint. The supraspinatus tendon is vulnerable to injury due to impingement between the acromion and the head of the humerus. Supraspinatus tendinopathy is the most common cause of rotator cuff syndrome. __________ References: Chronic shoulder pain: part I. Evaluation and diagnosis. (http://www.ncbi.nlm.nih.gov/pubmed/18326164)

A 53-Year-Old Man Comes to the Office with a Dull