Shoulder Complex

4 articulations of shoulder

sternoclavicular joint, acromioclavicular joint, scapulothoracic joint, glenohumeral joint

bones of shoulder girdle

link appendicular skeleton and axial skeleton

open mechanical system

left and right not directly connected, independent movement, indirect attachment through manubrium of sternum

movements of scapula

elevation/depression, protraction/retraction, upward/downward rotation, internal/external rotation, posterior/anterior tipping

sternoclavicular motion

movement in 3 planes

elevation/depression, protraction/retraction, rotation

guides the scapula

sternoclavicular joint

saddle joint, 2 saddle shaped surfaces, articular disc between clavicle and sternum which hinges and absorbs shock

ligaments of SC joint

anterior and posterior sternoclavicular ligament, costcoclavicular ligament, interclavicular ligament

anterior/posterior stenoclavicular ligament prevents ___

anterior/posterior glide, depression of clavicle

costcoclavicular ligament prevents ___

excessive movement in all directions

interclavicular ligament prevents ___

depression of clavicle

arthokinematics of clavicle

elevation: convex of clavicle moves on concave, rolling superior and sliding inferior, sternoclavicular ligament and interclavicular ligament are slack, costoclavicular ligament is taut - helps limit motion

rotation of clavicle

occurs in one direction, integrated with scapular upward rotation, only occurs after arm is abduction above 90

acromioclavicular joint

sliding or gliding joint, allows movement between scapula and clavicle

acromioclavicular joint motion

frontal plane - turns glenoid fossa superior and inferior

transverse plane - scapula away from posterior ribs

sagittal plane - tipping scapula

what does the combination of the AC and SC joint do?

allows glenoid fossa to turn in different positions

SC joint allows more movement of clavicle, which guides motion of the scapula, AC joint is more subtle movement

acromioclavicular ligaments

acromioclavicular ligament coracoclavicular ligament coracoacromial ligament

acromioclavicular ligament

external support of joint capsule, articulates with clavicle and acromion

coracoclavicular ligament

prevents superior displacement of clavicle and medial/inferior displacement of scapula

coracoacromial ligament

prevents superior displacement of humerus, creates subacromial space

scapulothoracic joint

anterior surface of scapula and tissues that lie between it and the ribs, shock absorption and moves freely

glenohumeral joint

ball and socket joint, 3 degrees of freedom

humeral head angle at GH joint

medially, superiorly 135 degrees, and posteriorly 30 degrees

glenoid fossa position at GH joint

laterally, superiorly, and anteriorly

ligaments that stabilize GH joint

coracohumeral ligament, coracoacromial ligament, glenohumeral ligament

coracohumeral ligament

taut in ER and shoulder adduction

coracoacromial ligament

limits superior glide of humeral head

glenohumeral ligaments

continuous with capsule,

3 bands - superior, middle, inferior (anterior posterior, axillary pouch)

glenoid labrum

attached to edge around glenoid fossa, increases articulation or depth for fossa, suseptible to tearing

subacromial/subdeltoid bursae

separates supraspinatus and head of humerus from acromion, coracoid process, and deltoid

function: reduce friction, protect supraspinatus

subacromial space

contains supraspinatus, subacromial bursa, long head of triceps, and superior capsule

functions: protection from superior trauma, prevents humeral head from superior distraction

impingement of subacromial space causes

bone spurs, inadequate rotation, inadequate inferior glide, muscle imbalance, poor scapular control

rounded shoulders, tilting of scapula, downward rotation of scapula

what gets impinged in subacromial space

supraspinatus tendon, subacromial/deltoid bursa, long head of triceps