The Shoulder (7.2) Flashcards
What are the three bones in the shoulder joint?
Clavicle, scapula and humerus
What are some features of the clavicle?
- First bone to ossify
- Among the last the fuse
- Most commonly fractured bone
- Only bony attachment of the upper extremity is via the sternoclavicular joint
- What component affects the direction of a break in the clavicle?
Ligament action pulls the fragments in specific directions (medial fragment drawn upwards)
These breaks aren’t overly benign as close to lung and brachial plexus - has been shown that fixing them surgically is a better treatment than just leaving them to recover
What type of joint is the sternoclavicular joint?
Synovial - with articular disc
Which ligament tears in a medial clavicle dislocation?
The ligament between the sternum and the clavicle
No operating on this kind of dislocation, just try and reduce it
What is the AC joint?
The acromioclavicular joint - between the clavicle and the acromium process
How many ligaments are there that attach to the coracoid process and what are they?
There are 3:
• Coracoacromial ligament, between acromium and coracoid processes (both on scapula)
• Coracoclavicular ligament -> trapezoid and conoid ligaments, attach the clavicle to the coracoid process
How can you remember the order of the coracoclavicular ligaments?
Medial to lateral:
CT scan to diagnose (conoid then trapezium)
What is an acromioclavicular separation?
This is where the coracoclavicular ligaments tear, but the AC joint is only partially damaged
What happens in an AC dislocation?
Both the AC and coracoclavicular ligaments tear, resulting in full dislocation of the distal end of the clavicle
What type of joint is the AC joint?
Synovial, but with little movement
- What is a good indication for the side to which a scapula belongs?
The direction in which the coracoid process is pointing - it will always be pointing towards the arm and is on the front/anterior side of the bone
- How are humeral head fractures treated?
Conservative management is disproportionately successful (length/alignment/rotation), use a collar and cuff.
Alternatively, surgical intervention can be used.
Where is and what are some characteristics of the glenohumeral joint?
The joint between the humeral head and the glenoid fossa/cavity
Shallow joint, stability improved by the glenoid labrum and the ligaments
Manipulated by the rotator cuff muscles amongst others
Synovial joint, ball and socket
What are the three ligaments in the glenohumeral joint?
- SGHL: superior glenoid-humeral ligament
- MGHL: medial glenoid-humeral ligament
- IGHL: inferior glenoid-humeral ligament
How do the shoulder and hip joints compare? (In one sentence)
They are opposites - hip has a more restricted range of movement but is more stable, shoulder has a larger range of movement but is less stable.
Shoulder is likened to a golfball on a golf tee
Which ribs articulate with the scapula?
Ribs 2-7
Major contributors to shoulder motion - bursas are present
What is a bursa?
Small fluid-filled sac contained within synovial joints - act as a cushion
How many muscles attach the upper limb to the axial skeleton?
17
Ones we need to know are: deltoid, rotator cuff muscles (x4) and the biceps/attachment of the biceps tendon
What is innervated by the axillary nerve?
Deltoid and teres minor (amongst others)
What happens if the axillary nerve is damaged?
Shoulder is weakened, ability to abduct is severely lessened
What are the four rotator cuff muscles?
Subscapularis, infraspinatus, supraspinatus, teres minor
What innervates supraspinatus and infraspinatus?
The suprascapular nerve
What innervates teres minor?
The axillary nerve
What innervates subscapularis?
The subscapular nerve
What acronym can be used to remember the four rotator cuff muscles/tendons?
SITS • Supraspinatus • Infraspinatus • Teres minor • Subscapularis