Anatomy of Shoulder Flashcards
What are the four main bones forming the shoulder complex?
Scapula, Coracoid, Humerus, Clavicle.
What nerve is at risk in a fracture of the surgical neck of the humerus?
Axillary nerve.
What are the clinical signs of axillary nerve injury?
Paralysis of deltoid and loss of sensation over the ‘sergeant’s stripes’ area (regimental badge area).
What is the role of the scapula in shoulder motion?
Acts as a dynamic base, allowing wide range of motion and adjusting glenoid orientation.
What happens during a FOOSH (fall on outstretched hand)?
Forces the glenoid medially; transmitted to the clavicle via the coraco-clavicular ligament, potentially causing ligament tear or clavicle fracture.
How does the shoulder capsule contribute to mobility?
It is loose and allows a wide range of motion but sacrifices stability.
What happens to the glenoid with movement around the vertical axis?
It faces more anteriorly.
What happens to the glenoid with movement around the horizontal axis?
It faces more supero-laterally.
What is the function of the labrum glenoidale?
Deepens the glenoid cavity to improve joint stability.
What is the clinical consequence of a labral tear?
Pain, instability, and clicking sensations; may contribute to recurrent dislocations.
What is the main role of short muscles around the shoulder?
Stabilize and control fine movement of the shoulder joint.
Name the four rotator cuff muscles.
Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.
Where is the rotator cuff deficient, and what can this lead to?
Inferiorly; leads to anterior-inferior dislocations.
Name one function of long muscles connecting the upper limb to the trunk.
Provide large, powerful movements and assist in positioning the scapula.
What is the function of shoulder bursae?
Reduce friction between tendons and bones during movement.
What does a painful arc typically indicate?
Impingement or inflammation of the rotator cuff, often the supraspinatus tendon.
How is elevation of the arm (180°) divided between scapula and shoulder joint?
60° by scapular rotation, 120° by glenohumeral joint.
Why is the shoulder joint more prone to dislocations?
It prioritizes mobility over stability due to its large range of motion and shallow socket.
What is the most common direction of shoulder dislocation?
Anterior-inferior.
What structures are at risk in a shoulder dislocation?
Axillary nerve, labrum, capsule, and rotator cuff tendons.
What are the three main bones of the shoulder skeleton?
Scapula, Humerus, Clavicle.
What are the key prominences of the scapula?
Coracoid process and acromion process.
What joint does the head of the humerus articulate with?
Glenoid cavity of the scapula.
Where do rotator cuff muscles attach on the humerus?
Greater and lesser tubercles.
