Shoulder and Arm Flashcards
What is the progression of the major artery as it passes from the torso to the arm and down to the forearm?
(Brachiocephalic trunk) Subclavian Axillary Brachial Ulnar and Radial (Paired branch)
What spinal nerve roots make up the brachial plexus?
C5-T1
What does the shoulder girdle consist of?
Scapula
Clavicle
Associated musculature
What are the dorsal muscles?
Trapezius
Rhomboids
Latissimus dorsi
What is the function of the serrates anterior?
It is a ventrolateral muscle which attaches to the medial border of the scapula and protracts and stabilises the pectoral girdle
What muscles are involved in moving the scapula?
Trapezius Levator scapulae Rhomboids Pectoralis minor Serrates anterior
What can result from weakness of the serrator anterior?
Winging of the scapula
What makes up the ventral musculature of the shoulder girdle?
Pectoralis major
Serratus anterior
What action does contraction of the ventral muscles of the shoulder girdle cause?
Adduction
What is glenohumeral rhythm?
A combination of abduction of the humerus and the upward rotation of the scapula
It allows the abduction of the arm to move further than 120° without being interrupted
What is the function of the deltoid?
Involved in almost all movements of the glenohumeral joint but chiefly abduction
What makes up the posterior group of the short scapular muscles?
Supraspinatus
Infraspinatus
Teres minor
Teres major (not stabilising - causes movement)
What makes up the anterior group of the short scapular muscles?
Subscapularis
What movements of the glenohumeral joint are caused by the posterior group of short scapular muscles?
Abduction
Lateral rotation
What movements are caused by the anterior group of short scapular muscles?
Medial rotation
What muscles attach to the greater tuberosity of the humerus?
Supraspinatus
Infraspinatus
Teres minor
What muscles attach to the lesser tuberosity of the humerus?
Subscapularis
How much is the head of the humerus retroverted by?
~30°
What are the functions of the clavicle?
Acts as a strut to support the shoulder and keep the shoulder girdle out to length for function
Protects the brachial plexus and vessels
Acts as an attachment for the muscles:
- Trapezius
- Deltoid
- Pectoralis major
- Subclavius
- Sternocleidomastoid
- Sternohyoid
What muscles attach to the clavicle?
- Trapezius
- Deltoid
- Pectoralis major
- Subclavius
- Sternocleidomastoid
- Sternohyoid
What clavicular ligaments exist?
Acromio-clavicular ligament
Coraco-acromial ligament
Coraco-clavicular ligament
What attaches to the coracoid process of the scapula?
3 Ligaments:
- Coracoacromial
- Coracoclavicular (coronoid and trapezoid)
3 Muscle origins:
- Coracobrachialis
- Short head of biceps
2 Sides:
- Lateral side
- Medial side - ‘where the clockwork lies’
How is the acromioclavicular joint disrupted?
Fall onto the point of shoulder
What type of joint is the glenohumeral joint?
Synovial ball and socket joint
What have to be balanced in a joint?
Mobility vs. Stability
Discuss whether the shoulder is more mobile or stable
Most mobile joint in the body
Most commonly dislocated are joint in the body
Static stabilisers - labrum, capsule, ligaments
Dynamic stabilisers - muscles - intrinsic (rotator cuff) and extrinsic (large)
What are the characteristics of the capsule of the glenohumeral joint?
Thin and loose
2 openings - one for the tends of the long head of the biceps, one for the sub scapular bursa
The inferior part of the capsule is the only part not reinforced by the rotator cuff muscles - the weakest area. Long, loose redundant fold hanging down into the axilla when arm is down by side.
Thin anteriorly - swelling can be seen if large effusion present
How does adhesive capsulitis appear on an MRI?
Capsule is thickened and fibrous with a reduced inferior recess
What is characteristic of a shoulder effusion?
Fusion with atrophy of the musculature (rotator cuff arthropathy)
Swelling esp. anteriorly
What is the labrum?
A fibrocartilagenous lip
Elevates the glenoid lip
Doubles the glenoid depth and increases the surface area
Acts as a channel block limiting glenohumeral translation
Where does the subacromial bursa sit?
On the top/front/side of the shoulder (similar to a Franchman’s beret)
What is the function of the subacromial bursa?
Allows free movement of supraspinatus tendon between the humeral head and acromion, of the humeral head under acromion and of deltoid over the humeral head
Where is the subacromial bursa found?
Starts superiorly in tunnel formed by acromion, coracoacromial ligament and humeral head
What do the rotator cuff muscles do?
Blend with glenohumeral joint capsule to protect and give stability
Hold head of humerus against glenoid cavity during shoulder movements allowing the big muscles to act
Infraspinatus, subscapularis and teres minor are rotators of the shoulder
What joints combine to produce shoulder function?
Sternoclavicular joint
Acromioclavicular joint
Glenohumeral joint
Scapulothoracic articulation
