Lab 8—Joints of Upper/Lower Limb Acromioclavicular Joint– QuesƟons 1 of 1 1. An 18-year-old man injures the right shoulder from a down- ward blow on the point of the shoulder. The acromion of the scapula lies anteroinferior to the lateral end of the clavicle. There is tenderness in the region between the acromion and the lateral end of the clavicle and pain when abducting the right arm up to or above the level of the shoulder. Anteroposterior (AP) radiographs show that the acromioclavicular and coracoclavicu- lar spaces in the right shoulder are each more than 50% wider than the corresponding spaces in the left shoulder. The AP radi- ographs of the shoulders indicate which of the following liga- ments is significantly ruptured in the right shoulder? A. costoclavicular ligament B. coracoacromial ligament C. coracohumeral ligament D. coracoclavicular ligament E. suprascapular ligament 2. An 18-year-old man injures the right shoulder from a down- ward blow on the point of the shoulder. The acromion of the scapula lies anteroinferior to the lateral end of the clavicle. There is tenderness in the region between the acromion and the lateral end of the clavicle and pain when abducting the right arm up to or above the level of the shoulder. Anteroposterior (AP) radiographs show that the acromioclavicular and coracoclavicu- lar spaces in the right shoulder are each more than 50% wider than the corresponding spaces in the left shoulder. Which bony structure lies DIRECTLY beneath the skin at the point of the shoulder? A. acromion of the scapula B. coracoid process of the scapula C. spine of the scapula D. superior angle of the scapula E. head of the humerus 3. An 18-year-old man injures the right shoulder from a down- ward blow on the point of the shoulder. The acromion of the scapula lies anteroinferior to the lateral end of the clavicle. There is tenderness in the region between the acromion and the lateral end of the clavicle and pain when abducting the right arm up to or above the level of the shoulder. Anteroposterior (AP) radiographs show that the acromioclavicular and coracoclavicu- lar spaces in the right shoulder are each more than 50% wider than the corresponding spaces in the left shoulder. Which injury is MOST indicated by the history, physical exam, and radio- graphs? A. acromioclavicular joint sprain B. acromioclavicular joint subluxation C. acromioclavicular joint dislocation D. shoulder joint dislocation E. sternoclavicular joint dislocation 1 Lab 8—Joints of Upper/Lower Limb Acromioclavicular Joint– Answers 1. Answer D. (2) The point of the shoulder is the lat- eral-most limit of the shoulder. The acromion of the scap- ula lies directly beneath the skin here and thus gives the point of the shoulder its shape. Downward blows on the point of the shoulder strain the fibrous structures that sus- pend the scapula from the clavicle, in particular, the cap- sule of the acromioclavicular joint (AC) and the coracocla- vicular ligament (CL) . The severity of a shoulder separa- tion is assessed by comparing the widths of the acromio- clavicular and coracoclavicular spaces in an AP radio- graph of the injured shoulder with the widths of the corre- sponding spaces of the uninjured shoulder. 2. Answer A. (2) The point of the shoulder is the lat- eral-most limit of the shoulder. The acromion of the scap- ula lies directly beneath the skin here and thus gives the point of the shoulder its shape. Downward blows on the point of the shoulder strain the fibrous structures that sus- pend the scapula from the clavicle, in particular, the cap- sule of the acromioclavicular joint (AC) and the coracocla- vicular ligament (CL). The severity of a shoulder separa- tion is assessed by comparing the widths of the acromio- clavicular and coracoclavicular spaces in an AP radio- graph of the injured shoulder with the widths of the corre- sponding spaces of the uninjured shoulder. 3. Answer C. (2) A simple sprain of the acromioclavic- ular joint capsule is called a Grade I shoulder separation. In such an injury, the capsule sustains minimal tearing, and an AP radiograph of the injured shoulder shows nor- mal acromioclavicular and coracoclavicular spaces with- out deformity. A subluxation (partial dislocation) of the acromioclavicular joint is called a Grade II shoulder sepa- ration. It results from a significant rupture of the acromio- clavicular joint capsule. An AP radiograph of the injured shoulder shows an acromioclavicular space whose width is at least 50% greater than that of the uninjured shoulder. Inspection of the injured shoulder generally shows the lateral end of the clavicle a step above the acromion. A dislocation of the acromioclavicular joint is called a Grade III shoulder separation. It occurs when both the acromio- clavicular joint capsule and the coracoclavicular ligament are significantly ruptured. An AP radiograph of the injured shoulder shows acromioclavicular and coracoclavicular spaces at least 50% wider than those of the uninjured shoulder. Inspection of the injured shoulder commonly shows the acromion displaced anteroinferiorly to the lat- eral end of the clavicle. 2 Lab 8—Joints of Upper/Lower Limb Shoulder Joint — QuesƟons 1 of 1 1. The origination of the rotator cuff muscles is on this 5. A patient has a torn rotator cuff of the shoulder joint as bone. the result of an automobile accident. Which of the follow- A. Ulna ing muscle tendons is intact and has normal function? B. Radius A. Supraspinatus C. Humerus B. Subscapularis D. Scapula C. Teres major E. Clavicle D. Teres minor E. Infraspinatus 2. The shoulder or pectoral girdle is formed by the scapu- lae and clavicles and is completed in front by the manu- brium of the sternum. How many muscles are included in the musculotendinous (rotator) cuff of the shoulder joint? A. 6 B. 5 C. 4 D. 3 E. 7 3. You are evaluating a radiograph of the only bony artic- ulation between the upper limb and the trunk. Which of the following joints are you evaluating? A. Glenohumeral B. Acromioclavicular C. Humeroclavicular D. Coracoclavicular E. Sternoclavicular 4. You are explaining the anatomy of the shoulder to a young athlete who has sustained an injury to one of his shoulders. You tell him that the chief stability to this joint is from which of the following? A. Glenohumeralligaments B. Acromioclavicular ligament C. Rotator cuff muscles D. Coracoclavicular ligaments E. Coracohumeral ligament 3 Lab 8—Joints of Upper/Lower Limb Shoulder Joint — Answers 1. Answer D. (2) The rotator cuff muscle stabilizes the 5. Answer C. (1) The rotator cuff consists of the ten- head of the humerus in the glenoid cavity of the scapula. dons of the supraspinatus, infraspinatus, subscapularis, To do so, they must originate from the scapula and insert and teres minor muscles. It stabilizes the shoulder joint by on the humerus. holding the head of the humerus in the glenoid cavity dur- ing movement. The teres major inserts on the medial lip of the intertubercular groove of the humerus. 2. Answer C. (2) The capsule of the shoulder joint is thin and has little mechanical strength. As the supraspina- tus, infraspinatus, teres minor and subscapularis pass to their insertions, they blend with the shoulder joint capsule and with each other, thus forming a musculotendinous cuff. This cuff, which is also called the rotator cuff, is in- complete only below and provides the major strength of the shoulder joint. The four component muscles keep the head of the humerus in place and are important fixators in various movements of the shoulder. 3. Answer E. (11) The upper limb is attached to the trunk only at the sternoclavicular joint. The primary attach- ment is muscular. 4. Answer C. (11) The primary stability to the gleno- humeral joint is provided by the tendons of the rotator cuff. 4 Lab 8—Joints of Upper/Lower Limb Elbow Joint—QuesƟons 1 of 1 1. An 18-month-old girl is brought to urgent care by her mother for evaluation of a painful right arm. The mother had been shopping with her toddler earlier that day and was holding her child's right hand when the child saw a toy that she liked; the child started pull- ing her mom in the direction of the toy. The mother pulled back on the child's hand, and that is when the toddler started screaming. On examination you note a well-developed, well-nourished 18- month-old girl. She is tearful and cries when you touch her right elbow or try to move her forearm. A complete survey of the rest of her body reveals no evidence of other trauma. This history is most consistent with what injury? A. Nursemaid's elbow B. Colles' fracture C. Fracture of the scaphoid D. Fracture of the ulnar shaft E. Fracture of the distal radius 5 Lab 8—Joints of Upper/Lower Limb Elbow Joint—Answers 1. Answer A. (2) (Nursemaid's elbow (annular ligament dis- placement or radial head subluxation) is usually caused by an adult pulling or yanking on the outstretched arm of a toddler. The radial head slips through the annular ligament, which is then displaced towards the elbow joint. The child will usually hold the elbow partial- ly flexed and will refuse to move the arm. Reduction can readily be carried out by supination and extension of the forearm followed by full flexion of the forearm. This restores the annular ligament back to its normal anatomical position. Immobilization is not necessary and usually the child regains normal use of the joint within 20 minutes. Another maneuver called the pronation maneuver or handshake maneuver is also used.