Mich_JointsOfUpper&LowerLimbs
A two year old child will not go to take her nap. Her mother tightly holds her left hand as she leads her to the bedroom. Refusing to go further, the child suddenly attempts to jerk away and then sits down screaming and holding her left elbow. In a attempt to calm her down her mother offers her a cookie, but she cannot supinate her left hand to receive it. Which joint was dislocated?
The correct answer is: the proximal radio-ulnar joint This girl has suffered a pulled elbow--the head of her radius has been pulled out of the annular ligament and is no longer attached to the ulna. The annular ligament should encircle the head of the radius at the proximal radio-ulnar joint. This ligament forms a collar around the head of the radius, holding the head of the radius against the ulna without directly attaching to the radius. This allows the radius to move relatively freely at its proximal articulation with the humerus. Children often dislocate this joint because their radial heads are somewhat small in relation to the size of the annular ligament. This injury often occurs when a child's upper limb is pulled while the forearm is pronated; following the injury, the child will be unable to supinate her hand. All of these signs in this case history point to a dislocation of the proximal radio-ulnar joint. The glenohumeral joint is found at the shoulder, and the distal radio-ulnar joint is found at the wrist. Although the humero-ulnar and the humero-radial joints are found at the elbow, these are not the parts of the joint that are held together by the annular ligament.
The shoulder is most often dislocated in which direction?
The correct answer is: Anterior The shoulder is covered by the muscles of the rotator cuff--subscapularis inserts on the lesser tubercle of the humerus, and supraspinatus, infraspinatus and teres minor insert on the greater tubercle of the humerus. This set of muscles provides support on the superior, anterior, and posterior sides of the shoulder joint. There are no muscles supporting the inferior aspect of the shoulder joint. However, despite the subscapularis muscle and the glenohumeral bands, most shoulder dislocations still occur in the anteroinferior direction, with the humeral head dislocating forward and downward.
A 3-year-old child walking hand-in-hand with her father screams in pain as he jerks her quickly up onto the curb to dodge a speeding car. The examining physician calls it a case of "pulled elbow", a dislocation sometimes seen in young children and caused by:
The correct answer is: The head of the radius slipping part way out of the annular ligament The defininition of the pulled elbow is that the head of the radius is pulled out of the annular ligament and is no longer attached to the ulna. The annular ligament forms a collar around the head of the radius, holding the head of the radius against the ulna without directly attaching to the radius. This allows the radius to move relatively freely at its proximal articulation with the humerus. Children often dislocate this joint because their radial heads are somewhat small in relation to the size of the annular ligament. This injury often occurs when a child's upper limb is pulled while the forearm is pronated; following the injury, the child will be unable to supinate her hand. You should understand this injury and know the clinical presentation of a child with a pulled elbow! The other injuries listed are just not the same as a pulled elbow.
You are in the emergency room when a student is brought in with a shoulder injury sustained while playing touch football. In comparing the symmetry of his two shoulders, you notice a marked elevation of the distal end of his clavicle with respect to the acromion on the injured side. X-ray exam reveals a grade III shoulder separation. In order for this to have occurred, which ligament must be torn?
The correct answer is: coracoclavicular ligament A shoulder separation is an injury to the acromioclavicular joint. A first degree separation involves stretching the ligaments, but maintenance of the joint. A second degree separation involves tearing of the joint capsule and coracoclavicular ligament, but still continuity. A third degree separation involves total disruption of the joint and the coracoclavicular ligament. Since the patient has a third degree shoulder separation, you know he must have torn his coracoclavicular ligament. The coracoacromial ligament contributes to the stability of the acromioclavicular joint, but damaging this ligament is not the hallmark of a third degree shoulder separation. The costoclavicular ligament connects the first rib to the clavicle. The superior glenohumeral ligament contributes to the stability of the shoulder joint, but not to the stability of the acromioclavicular joint. The transverse humeral ligament holds the tendon of the long head of the biceps in place in the intertubercular groove.
After ramming the point of his shoulder into a practice dummy, a football player suffered a severe shoulder separation. Although this is a dislocation of the acromioclavicular joint, several structures could be torn, including the one that gives the joint its greatest strength and stability, namely the:
The correct answer is: coracoclavicular ligament Although the acromioclavicular joint is weak, the coracoclavicular ligament is very strong. When this ligament is torn, a patient will have a third degree separated shoulder. The acromioclavicular and coracoacromial ligaments also stabilize the AC joint, but these ligaments are much weaker. The supraspinatus tendon attaches to the greater tubercle of the humerus; it is part of the shoulder joint but not the acromioclavicular joint. The tendon of the long head of biceps originates on the supraglenoid tubercle of the scapula and passes through the capsule of the shoulder joint into the intertubercular groove of the humerus. It is not part of the acromioclavicular joint.
While doing arthrography of the shoulder joint it was noted that the contrast material flowed into the subacromial (subdeltoid) bursa, along the tendon of the subscapularis and along the proximal part of the tendon of the long head of the biceps. The finding of contrast in which area was abnormal?
The correct answer is: into the subacromial (subdeltoid) bursa If the contrast is contained in the shoulder joint, it will be found along the proximal part of the tendon of the long head of the biceps, since that tendon is contained within the shoulder joint. Contrast should also be found along the tendon of the subscapularis which contributes to the rotator cuff. However, you should not see contrast in the subacromial bursa, a bursa that separates the supraspinatus tendon from the coracoacromial ligament, the acromion, and the deltoid muscle. If there is contrast in this area, the contrast has escaped from the joint capsule. This might mean that the tendon of supraspinatus has ruptured.
Which of the following structures is unique to a synovial joint?
The correct answer is: joint cavity The joint cavity, or synovial cavity, is the one structure that is unique to a synovial joint. This cavity is lined by a synovial membrane or articular cartilage and supported by a joint capsule or capsular ligament. The synovial membrane is made of vascular connective tissue which produces synovial fluid that fills the joint cavity. Accessory and collateral ligaments, bursae, and fibrocartilage may be found at synovial joints, but they are not unique to synovial joints.
Which joint would be subject to synovitis (inflammation of the synovial membrane)?
The correct answer is: metacarpophalangeal This question is asking you to pick what joint, of the joints listed, is the synovial joint. And the only one which fits the bill is the metacarpophalangeal joint, which is a condyloid synovial joint, meaning that it can move in a sagittal and coronal plane. Condyloid joints permit flexion and extension, abduction and adduction, and circumduction. Beyond the synovial membrane, synovial joints have a variety of important characteristics, including: hyaline cartilage to cover the weight bearing surface of the joint, a joint capsule made of accessory ligaments to reinforce the synovial membrane, and accessory structures (such as accessory ligaments, articular discs or menisci, muscles and tendons, and subsynovial fat). What types of joints are the other structures listed? An epiphyseal plate is a synchondrosis, a temporary cartilaginous joint in growing bones. The pubic symphysis is a permanent cartilaginous joint. The radioulnar syndesmosis is made of a fibrous ligament joining two bones. A suture is a fibrous joint that eventually fuses, forming one bone from two.
The axis of rotation (pronation/supination) at the distal radioulnar joint is through the:
The correct answer is: styloid process of the ulna The proximal and distal radioulnar joints are aligned in such a way that the axis of supination and pronation passes from the center of the head of the radius (which is at the proximal radioulnar joint) through a point just lateral to the styloid process of the ulna (which is at the distal radioulnar joint--so that's the answer). So, during pronation and supination the hand rotates around the head of the ulna (the distal end of ulna), but most specifically around the ulnar styloid process. The capitate bone is a carpal bone in the distal row of carpals. It transmits force through the hand to the radius, and it is not involved with the rotation of the forearm. The radial styloid process is found on the lateral side of the radius; it is not the axis of rotation.
While performing an arthrogram to study an apparent rotator cuff injury, it was noted that the contrast material had spread from the shoulder joint onto the anterior lateral surface of the scapula near the joint. When asked, the first year resident responded that this was due to an anterior tear in the cuff. Having just studied the shoulder joint you respond that the contrast is in a normal extension of the joint cavity called the:
The correct answer is: subscapular bursa The subscapular bursa protects the subscapular tendon where it passes inferior to the coracoid process and over the scapular neck. This bursa communicates with the shoulder joint through an opening in the fibrous capsule, so it is really an extension of the shoulder joint. The bicipital bursa separates the biceps tendon from the anterior part of the radial tuberosity. The olecranon bursa is located behind the elbow joint. The subacromial bursa (which is also called the subdeltoid bursa) lies between the deltoid, the supraspinatus tendon, and the fibrous capsule of the glenohumoral joint. This bursa should not appear to be communicating with the shoulder joint--if it does, that is an abnormal finding! The ulnar bursa is the common sheath covering the flexor tendons in the hand--it covers the tendons of flexor digitorum superficialis and profundus.
A father and child are about to step off a curb to cross a street when a car suddenly turns around the corner. In panic the father yanks on the child's arm to pull him out of the way of the car. Safe on the curb, the child screams in pain and holds his elbow. The diagnosis is "pulled elbow;" the head of the radius has been pulled out of the socket holding it against the radial notch of the ulna. In order for the head of the radius to be dislocated in this way, what ligament must be stretched or torn?
The correct answer is: Annular A "pulled elbow" is a condition where the head of the radius has been pulled inferiorly, out of the annular ligament. It most commonly occurs in young children whose hand or forearm is suddenly yanked for some reason. Since the head of the radius is largely cartilage until about puberty, it is easily pulled from the socket formed by the annular ligament and radial notch of the ulna. You should be familar with this case history! The glenoid labrum is a fibrocartilage extension of the glenoid fossa--it makes the shoulder socket deeper. The interosseous ligament or membrane is a fibrous membrane that connects the interosseous borders located on the shafts of the radius and the ulna. Forces from the hand pass through the radius and are transferred to the ulna through the interosseous membrane. The radial collateral ligaments and ulnar collateral ligaments are found at the elbow and wrist--they stabilize the articular capsules of the wrist and elbow on the ulnar and radial sides.
A "pulled elbow" in a young child results when the radial head is dislodged from the:
The correct answer is: Annular ligament The definition of the pulled elbow is that the head of the radius is pulled out of the annular ligament and is no longer attached to the ulna. The annular ligament forms a collar around the head of the radius, holding the head of the radius against the ulna without directly attaching to the radius. This allows the radius to move relatively freely at its proximal articulation with the humerus. Children often dislocate this joint because their radial heads are somewhat small in relation to the size of the annular ligament. This injury often occurs when a child's upper limb is pulled while the forearm is pronated; following the injury, the child will be unable to supinate her hand. It is very important to understand all of the aspects of this injury! Biceps brachii inserts on the tuberosity of the radius--this muscle would be affected by the injury, but it would not cause the injury. The olecranon process is the proximal end of the ulna--it is the insertion site of the tendon of the triceps brachii. The radial collateral ligaments and ulnar collateral ligaments are found at the elbow and wrist--they stabilize the articular capsules of the wrist and elbow on the ulnar and radial sides.
An athlete has a knee injury, and the doctor performs a "drawer test" by pulling and pushing on the leg with the knee flexed. If the leg translates anteriorly, i. e. "gives" or moves anteriorly when the leg is pulled anteriorly, what joint structure is most likely injured?
The correct answer is: Anterior cruciate ligament The drawer test is designed to test the integrity of the anterior and posterior cruciate ligaments. It involves firmly grasping the leg with both hands just below the knee, with the thumbs on the tibial tuberosity. With the knee flexed, the examiner pushes and pulls the leg in a line parallel to the long axis of the femur. If the leg moves too far anteriorly, this indicates a ruptured anterior cruciate ligament. If the leg moves too far posteriorly, the posterior cruciate ligament is probably ruptured. In this case, the leg is moving anteriorly, so the anterior cruciate ligament must be injured. ACL tears often result from a blow to the lateral side of the knee. In these types of incidents, there are three structures that are commonly torn: the anterior cruciate ligament, the medial collateral ligament, and the medial meniscus. Remember, the MCL and the medial meniscus are attached, so an injury to the MCL will usually disrupt the meniscus. This constellation of injuries is sometimes referred to as "the terrible triad."
An example of a temporary cartilaginous joint is a/an:
The correct answer is: Epiphyseal plate or growth plate An epiphyseal plate is an example of a synchondrosis, which is a temporary cartilaginous joint present in growing bones. The epiphyseal plate will eventually ossify into solid bone, and the cartilage will disappear. Articular discs or menisci are pads of fibrocartilage found in synovial joints. Intervertebral discs are examples of symphyses, which are permanent cartilagenous unions. Primary ossification centers are important structures in developing bone which will be discussed in more detail in histology.
The fibrocartilaginous structure which deepens the shoulder socket is the:
The correct answer is: Glenoid labrum The glenoid cavity of the scapula provides a site where the head of the humerus articulates with the scapula. This cavity is slightly deepened by the glenoid labrum, which is a ring of fibrocartilage around this glenoid cavity. None of the other structures listed are important for deepening the glenoid cavity. As a synovial joint, the glenohumeral joint has an articular capsule and articular cartilage. The articular capsule of the shoulder joint is a loose fibrous capsule that covers the glenohumeral joint -- it is strengthened by the superior, middle, and inferior glenohumeral ligaments. The articular cartilage is the cartilage covering the surface of the bones in the synovial joint. Finally, the lateral meniscus is a structure of the knee joint--it is not found in the shoulder.
While walking to class on an icy winter morning, a student slips and falls on her outstretched hand. The intense pain forces her to go to the emergency room. After X-rays of her wrist are taken, the attending says," You were lucky, there is no Colles' nor scaphoid fractures, but you have dislocated the middle carpal bone of the proximal row." Which bone was dislocated?
The correct answer is: Lunate It is fairly common for the lunate to be dislocated anteriorly--this injury may result from a fall on a dorsiflexed wrist. The lunate may be pushed out of its place on the floor of the carpal tunnel and move toward the palm of the wrist. This dislocation may compress the median nerve and lead to carpal tunnel syndrome. You should also remember that the lunate is the middle carpal bone in the proximal row, with scaphoid sitting laterally and triquetrum medial to the lunate. (Pisiform is just a small sesamoid bone on triquetrum, providing a protective function for the flexor carpi ulnaris tendon). Capitate and trapezoid are in the distal row of carpal bones. Triquetrum, the medial bone in the proximal row of carpal bones, is not frequently injured in this sort of fall. Scaphoid, the lateral bone in the proximal row of carpals, is frequently fractured when someone falls on an outstretched wrist.
It was determined that a football player tore his coracoclavicular ligament. This is an example of a:
The correct answer is: Separated shoulder A shoulder separation is the dislocation of the acromioclavicular joint. The injury often occurs from a hard fall on the shoulder with the impact taken by the acromion or from a fall on the outstretched upper limb. The injury is severe if the AC and the coracoclavicular ligaments are torn. A pulled elbow occurs when the head of the radius slips out of the annular ligament. This is a common injury in children whose forearms are pulled forcefully. A rotator cuff tear is damage to the tendon of one of the muscles in the rotator cuff. It can lead to rupture of one or more of the tendons of the muscles forming the rotator cuff. Acute tears may occur when the arm is violently pushed into abduction. A dislocated shoulder occurs when the humeral head slips out of the labrum; this often happens in the anterior direction. Finally, a Colles' fracture is a common fracture of the radius. The distal end of the radius is broken, and distal fragment is displaced dorsally and is often broken into pieces. The fracture results from forced dorsiflexion of the hand, usually as the result of trying to ease a fall by outstretching the upper limb.
The synovial cavity of the glenohumeral joint communicates with the subdeltoid (subacromial) bursa after the rupture of the:
The correct answer is: Supraspinatus tendon The shoulder joint is separated from the subacromial bursa by the supraspinatus tendon, which is inserting on the greater tubercle of the humerus. So, if the supraspinatus tendon is ruptured, the synovial cavity of the shoulder will be able to communicate with the subacromial bursa. If contrast dye is injected into the cavity of the shoulder joint following a rupture of the supraspinatus tendon, the contrast will flow in to the subacromial bursa. This can be observed in imaging studies. You should know this relationship between the supraspinatus tendon and the subacromial bursa! The tendon of infraspinatus also inserts on the greater tubercle of the humerus--however, it does not communicate with the subacromial bursa. The middle glenohumeral ligament strengthens the capsule of the shoulder joint. The subscapularis tendon inserts on the lesser tubercle of the humerus--it is not near the subacromal bursa. Finally, the tendon of the long head of the biceps originates on the supraglenoid tubercule of scapula and travels through the shoulder joint, lying in the intertubercular groove of the humerus. It is not a structure that communicates with the subacromial bursa
The interosseous membrane between the radius and ulna is the uniting structure in a type of fibrous joint classified as a:
The correct answer is: Syndesmosis A syndesmosis is a fibrous membrane or ligament that joins two bones. The connections between the shafts of the radius and ulna and the tibia and fibula are 2 classical examples of syndesmoses. A suture is a fibrous joint that eventually fuses, forming one bone from two--a synostosis is the name of the joint formed after fusing. A symphysis is a permanent cartilagenous union. Symphyses always have hyaline cartilage on the bony surfaces concerned, and these cartilaginous surfaces are joined by fibrous tissue or fibrocartilage. Synchondroses are temporary cartilagenous joints present in growing long bones.
Which muscle contributes to the "rotator cuff"?
The correct answer is: supraspinatus The rotator cuff holds the head of the humerus in the glenoid cavity of the scapula; supraspinatus is a part of the rotator cuff. The four muscles that comprise the rotator cuff all insert on the greater or lesser tubercle of the humerus. Supraspinatus inserts into the upper facet of the greater tubercle of the humerus and into the capsule of the shoulder joint. Infraspinatus inserts into the middle facet of the greater tubercle of the humerus and into the capsule of the shoulder joint. Teres minor inserts into the lower facet of the greater tubercle of the humerus and into the capsule of the shoulder joint. Subscapularis inserts onto the lesser tubercle of the humerus. The other four muscles listed are not parts of the rotator cuff.
A patient presented to his physician with chronic shoulder pain. It was noted that when asked to abduct his arm, he initially leaned laterally, and then straightened up. When iodinated contrast was injected into his shoulder joint it was found to be in the subdeltoid bursa as well as in the joint cavity. Which structure was damaged to produce the shoulder pain?
The correct answer is: supraspinatus muscle Remember, if contrast in the shoulder cavity is also in the subdeltoid (subacromial) bursa, this is an abnormal finding! The subacromial bursa separates the supraspinatus tendon from the coracoacromial ligament, the acromion, and the deltoid muscle; if the supraspinatus tendon has ruptured, contrast will flow into the subacromial bursa. An injury to the supraspinatus muscle also fits with this patient's symptoms. Since supraspinatus initiates abduction, it makes sense that this patient had trouble abducting his arm. The acromioclavicular ligament connects the acromion to the clavicle--it does not contribute to the integrity of the shoulder joint. The long head of biceps brachii originates from a tendon that crosses through the shoulder joint, but injuring this tendon or muscle would not lead to contrast in the subacromial bursa. Subscapularis muscle is a muscle of the rotator cuff that inserts on the lesser tubercle of the humerus. It is not located near the subacromial bursa. The glenohumeral bands are superior, middle, and inferior capsular ligaments that connect the humerus to the glenoid process. They reinforce the anterior part of the capsule and are evident only on the internal aspect of the capsule.
