9 The Shoulder Complex Flashcards
What are the four joints of the shoulder?
- glenohumeral (GH)
- acromioclavicular (AC)
- sternoclavicular (SC)
- scapulothoracic (ST)
Where is the only articulation between the upper limb and the trunk?
The SC joint
What structures are in the subacromial space? Inflammation of what ligament might compress these?
- supraspinatus tendon
- biceps long head tendon
- subacromial bursa
inflammation of the coracoacromial ligament might compress these structures
This labrum deepens the GH socket and improves articulation.
(fibrocartilagenous) Glenoid Labrum
This forms a vault for the protection of the humeral head. If it thickens, it can contribute to impingement syndrome
coracoacromial ligament
What kind of joint is the acromioclavicular?
synovial plane
What kind of joint is the sternoclavicular?
triaxial saddle with a disk
What nerves primarily innervate the shoulder complex?
- nerve roots C5-T1 (brachial plexus)
- supraclavicular nerves (C3-C4)
What are the coracoclavicular ligaments?
conoid and trapezoid
In which direction does the medial clavicle move relative to scapula during elevation/depression? During protraction/retraction?
- elevation/depression: opposite direction of scapula
- protraction/retraction: same direction as scapula
When does the clavicle rotate?
Rotation of the clavicle occurs as an accessory motion with humeral elevation >90°. This cannot occur as an isolated, voluntary movement.
Where does the Scapulothoracic joint reside?
(not a true jt) Typically resides between ribs 2 and 7, with the root of the scapula at rib 3.
What direction of tipping occurs with normal scapular downward or upward rotation?
- upward rotation: posterior tipping
- downward rotation: anterior tipping
Scapular retraction aka…
adduction
Scapular protraction aka…
abduction
When this ligement thickens, it can contribute to impingement syndrome of the shoulder
coracoclavicular ligament (tends to thicken due to repetitive trauma during overhead movements and excessive superior translation of humeral head)
What direction does the SC joint move with GH flexion, scaption or abduction?
superiorly, anteriorly
What direction does the AC joint move with GH flexion, scaption or abduction?
moves with scapula (superiorly with posterior rotation)
What direction does the ST joint move with GH flexion, scaption or abduction?
upward rotation, protraction
(note that with GH flexion, at end range, the scap retracts and posteriorly tips)
What direction does the SC joint move with GH extension?
inferiorly, posteriorly
What direction does the AC joint move with GH extension?
moves with scapula (anteriorly and inferiorly)
What direction does the ST joint move with GH extension?
downward rotation, retraction, anterior tipping
This shoulder mm extends to the lumbar spine and can therefore cause excessive lordosis with overhead humeral movement if short.
latissimus dorsi
Under the hook of the acromion and coracoacromial ligament reside several structures, including supraspinatus tendon and subacromial bursa. These structures are vulnerable to impingement due to several factors. These factors are:
- Acromial shape
- Weak external rotators
- Short internal rotators
- Weak scapular depressors
What are the degrees of motion of the GH relative to the scapula with elevation of the humerus (flexion, scaption, abduction) througth various ROMs?
(GH:scap)
- 0-30° - 1:0 (movement is almost purely GH)
- 30°-120° - 1:1 (both move together)
- 120°-180° - 2:1
If there is early or excessive movement of either the GH or scapula during flexion, scaption or abduction, what is likely happening at the other.
other joint is likely restricted
What are things to look for when assessing the shoulder?
- scapular position (wing? tilt? protracted? rotation?)
- GH rotation
- T-spine position
- C-spine
- clavicle level
- pelvis and L-spine
