MST 2 - upper limb joints Flashcards
Joint stability and mobility are at the opposite ends of a continuum. What gives joints mobility/stability? Give examples.
Stable joints have congruent and often deep articular surfaces. They have a tight capsule with strong ligaments.
Mobile joints have a greater range of movement, for example, ball and socket joints. They often rely on fixator muscles for stability, and are susceptible to subluxation or dislocation due to their instability.
Name the joints of the shoulder complex.
The joints of the clavicle; sternoclavicular joint and the acromioclavicuar joint, as wel as the glenohumeral joint and the scapulo-thoracic joint.
Between which two bones is the sternoclavicular joint? What movements are allowed by this joint? What type of joint it is? List its main features.
The sternum and the clavicle, in the midline of the chest. Only point of articulation between the upper limb and the axial skeleton. It allows rotation, elevation and depression, and retraction and protraction. It is a saddle type synovial joint. The intra-articular disc in this join gives more mobility. It has a very strong capsule and is reinforced by the costoclavicular ligament.
Between which two bones is the acromioclavicluar joint? List its main features.
Between the clavicle and the scapula. It is a plane synovial joint, with a weak capsule, reinforced by the coracoclavicular ligament. It is susceptible in contact sports.
What is the correct name of the joint commonly thought of as the shoulder?
Glenohumeral joint
What type of joint is the glenohumeral joint?
A ball and socket joint. The glenoid fossa is shallow, the humerus head is large, and so the joint is very unstable.
How is the glenohumeral joint deepened?
By the glenoid labrum
What structures support the glenohumeral joint?
The coracoacromial ligament above (stops superior dislocation), the long head of biceps infront (prevents anterior dislocation) and the rotator cuff muscles above, behind and infront.
How many rotator cuff muscles are there? Name them.
- Supraspinatous, infraspinatous, teres minor and subscapularis. Their tendons blend with the joint capsule so that the contraction of these muscles tightens the capsule, pulls the humerus head towards the glenoid and makes the joint more stable.
Where is the subacromial bursa located? During what movement is it most likely to produce pain if inflamed?
Beneath the acromion process of the scapula. During shoulder abduction, particularly if the thumb is pointed down, resulting in a 60 degree painful arc of movement.
Force applied to an abducted and externally rotated arm is most likely to result in what type of shoulder dislocation?
Anterior dislocation. This is the most common type of dislocation.
Falling forward onto an outstretched arm is most likely to result in what type of shoulder dislocation?
Posterior. This is less common
A teared glenoid labrum increases the risk of what kind of clinical injury?
Shoulder dislocation.
During a shoulder dislocation, how does the humerus move relative to the glenoid fossa, and what structures are at increased risk?
The humerus drops inferiorly, and the nerves are at increased risk of injury.
Is the scapulothoracic joint a true joint or a physiological joint?
A physiological joint between the scapula and the thoracic cage.
What does scapulo-humeral rhythm refer to?
The way in which the scapulo-thoracic joint movement can work together with glenohumeral movement to allow greater abduction of the arm. The scapula can rotate 60 degrees, while the humerus lifts 120 degrees, to result in 180 degrees of abduction.
How many articulations are there at the elbow joint?
- They all share the same synovial capsule.
Between which bones are the articulations of the elbow joint, and what movements do they each allow?
Between the ulna and the humerus there is a hinge joint. Between the radius and the humerus there is a small amount of hinge also. Between the radius and the ulna there is a rotating joint which allows pronation and supination.
How is the elbow joint reinforced?
The hinge joint is prevented from sideways movement via strong collateral ligaments
Where is the proxima radio-ulnar joint?
In the elbow, between the head of the radius and the radial notch of the ulnar.
Which is the bigger epicondyle on the proximal end of the humerus at the elbow, and why?
The medial epicondyl, as more tendons attach here than do to the lateral epicondyl.
What type of joint is the proximal radioulnar joint?
A pivot type synovial joint.
Which ligament surrounds the head of the radius in the proximal radioulnar joint?
The annular ligament.
What type of joint is the distal radioulnar joint?
A pivot type synovial joint.
Between which bones is the distal radioulnar joint?
Between the head of the ulna and the ulndar notch on the distal radius
How are the ulnar and the radius linked?
By the interosseous membrane
What is the correct name for the wrist joint? Are there any other structures present?
The radiocarpal joint? It is primarily between the radius and the carpals. An articular disc is present on the ulnar side.
What type of joint is the radiocarpal joint? What movements does it allow?
It is an ellipsoid joint, and allows flexion and extension, as well as some deviation between the radius and the ulnar.
How many carpal bones are in the hand?
8
How many metacarpal bones are in the hand?
5
Between which bones are the midcarpal joints?
Between the two rows of carpal bones
Between which bones are the intercarpal joints?
Between each of the carpal bones in each row
Between which bones are the carpometacarpal joints? What kind of joints are they?
Between the carpals and the metacarpals. The firs is a saddle joint at the base of the thumb, the other 4 are ellipsoid joints.
Between which bones are the intermetaarpal articulations?
Between the metacarpals of the hand
What are the names of the bones of the fingers?
The phalanges
Between which bones are the metacarpophalangeal joints?
The metacarpals and the phalanges
What kind of joints are the metacarpophalangeal joints?
Ellipsoid and condylar joints.
What movements do the metacarpophalangeal joints allow?
Flexion and extension, and abduction and adduction.
Between which bones are the interphalangeal joints?
Between the phalanges.
How many interphalangeal joints are there in each digit?
2 in the fingers (proximal and distal), 1 in the thumb.
What kind of joints are the interphalangeal joints? What movement do they allow?
Hinge joints. They allow flexion and extension.
