Joints of Shoulder Complex Flashcards
What are the key features of a synovial joint?
articular cartilage, fibrous capsule, ligaments, synovial membrane
What is the key feature of articular cartilage?
it is avascular and aneural
What will a tear in a synovial membrane cause?
haemarthrosis
Why dont ligaments repair quickly?
because they have a poor blood supply
When do most bones of the skeleton commence ossification?
in utero at 8 weeks
What does a fracture at the surgical neck of the humerus endanger?
the axillary nerve
What does a mid-shaft fracture of the humerus endanger?
the radial nerve
What does a supracondylar fracture of the humerus endanger?
median nerve and brachial artery
Where is the clavicle likely to fracture?
between the lateral 1/3rd and the medial 2/3rds - lateral part will be pulled down and the medial part will be pulled up
What is the scapulothoracic joint?
a pseudo joint between the scapula and the thoracic wall - sliding movement
What movements occur at the sternoclavicular joint?
elevation and depression and rotation about the longitudinal axis
What is the main limitation to movement at the sternoclavicular joint?
the costoclvicular extrinsic ligament - keeps the medial end of the clavicle down
What structure is endangered by subluxation of the sternoclavicular joint?
subclavian artery and vein
In what plane are the surfaces of the acromioclavicular joint?
the sagittal plane
What prevents upward displacement of the clavicle at the AC joint?
the coracoclavicular ligament
What causes subluxation of the AC joint?
anteroposterior force on the shoulder
What is the key feature of the glenohumeral joint?
it is incongruent - a large humeral head fitting into a small shallow glenoid fossa
What tendon has attachment to the glenoid labrum?
long head of biceps
Where does the capsule of the shoulder join?
at the anatomical neck above and the surgical neck below
What are the two deficiencies in the capsule of the glenohumeral joint?
for the long head of biceps and for the subscapular bursa
What is frozen shoulder?
when the capsule contracts - due to trauma, diabetes etc. - restricts movement
What are the muscles of the rotator cuff?
supraspinatus, infraspinatus, teres minor, subscapularis
Where to the tendons of the muscles of the rotator cuff insert?
blend with the capsule
If the rotator cuff is weak and the humerus slides upward due to the pull of deltoid, what structure may be entrapped?
supraspinatus
What will cause subacromial bursitis?
abduction movement - especially if rotator cuff is weak
Does the subacromial bursa communicate with the joint capsule?
no
In what direction is dislocation of the shoulder caused by force applied to the end of the limb?
dislocates anteriorly and the head of the humerus will then drop inferiorly due to the capsule being weakest inferiorly
What direction is dislocation of the shoulder caused by an electric shock?
posterior
What structures are endangered by shoulder dislocation?
axillary nerve
How do you assess whether the axillary nerve is damaged?
pin prick in the military badge area
