WEEK 7 Flashcards
what are the four main joints of the pectoral girdle
1) glenohumeral joint
2) acrmioclavicular joint
3) sternoclavicular joint
4) scapulothoracic joint
what are the 4 functions of the clavicle
- holds the scapula and humerus away from the body to allow for free upper limb movement.
- provides bone framework for muscle attachment
- protects blood vessels and nerves
- the clavicle works as a hinge which keeps the shoulder away from the body
describe the sternoclavicular joint ( x6)
- a modified ball and socket with an articular disc= classification of the joint
- only bony attachment of upper limb to the trunk
- movements= very small
- hinge joint
- shock absorption= when fall stick out of hand, forces transmitted to the sternoclavicular joint
- loss of movement at the joint: abduction of the shoulder will not exceed approx 100 degrees.
describe the acromioclavicular joint (x3)
- gliding joint= two flat surfaces can slide against each other
- movement= allows for increased scapula range of motion
- sloped and incongruent joint surfaces predispose towards the acromioclavicular joint separation or sprain
describe a clavicle fracture (x4)
- most fractured bone
- usually middle to outer third
- children= greenstick- snap straight through
- adults= acromoclavicular or sternoclavicular
what are the 3 mechanisms to a clavicle injury
- direct trauma
- falling onto outstretched hand
- falling onto shoulder
describe the glenohumeral joint (x3)
- synovial ball and socket
- glenoid cavity is smaller than the head of humerus
- the glenoid labrum increases depth of the joint
what are the four ligaments that cross the glenohumeral joint and describe their limitations
1) coracohumeral ligaments
2) superior glenohumeral ligament
3) middle glenohumeral ligaments
4) inferior glenohumeral ligaments
- ligaments arent that thick
- no stability to prevent anterior dislocation
- notable gaps which reduce their resistance
identify and describe the 4 rotator cuff muscles
- supraspinatus= shoulder abudction
- infraspinatus= shoulder external rotation
- teres minor= shoulder external rotation
- subscapularis= shoulder internal rotation
describe the humeral head control in abducion
the downward pulling of the rotator cuff muscles act quasi isometrically to prevent the humeral head from rolling upwards into the subacromial space.
what are the 4 roles of the rotator cuff muscles
- keeps head of humerus pressed into the glenoid cavity
- enhance strength at the joint capsule
- anterior, superior and poerior movements
- rotator cuff injury can impact the abduction range of motion
define impingement syndrome and list the 3 preventions
def= athletes and workers who spend significant time with their arms raised above their heads. (near or greater than 90 degrees shoulder abduction.
preventions:
- strengthening downward pulling rotator cuff muscles
- learning scapular control
- avoiding fatigue
define and describe scapulohumeral rhythm
def= scapula dysfunction increases the risk of shoulder joint injury eg teas or bursitis
- movements at the glenohumeral joint are coupled with the scapulothoracic joint.
- ratio= 2:1
describe glenohumeral dislocations ( x3)
blow to the shoulder posteriorly
- forced abduction, external rotation
- more in males than females
describe the scapulothoracic joint (x4)
- the space between the scapular and ribcage
- range of motion at the glenohumeral joint requiring scapula movement
- doesn’t have ligaments or joint capsules however behaves like one.
- needs clavicular joints.
