Shoulder complex Flashcards
Describe the shoulder complex.
Made of:
- Pectoral girdle
- Manubrium of sternum
- Clavicle
- Scapula - Humerus
It is a highly mobile joint:
- Flexion/extension in the sagittal plane
- Abduction/adduction in the coronal plane
- Medial/lateral rotation in the transverse plane
- Circumduction - complete circular action
Pectoral girdle disconnected at posterior end.
Describe the joints of the shoulder.
3 true bi-articular (synovial) joints
- Sternoclavicular
- Acromioclavicular
- Glenohumeral
2 Physiological (functional) joints
- Subdeltoid
- Scapulothoracic
What is Hilton’s law?
The nerve and blood supply that lie close to the joint also supply that joint.
Describe the sternoclavicular (SC) joint.
- Connects upper limb with thorax
- Saddle joint
- Articular disc
- Three ligaments:
1. Sternoclavicular: Ant/post fibres, clavicular end of sternum to medial sternum
2. Interclavicular: Between clavicles
3. Costoclavicular: Between clavicle and costal cartilage of rib - Dislocation is uncommon
- Blood supply: Internal thoracic artery, subscapular artery
- Nerve supply: N. to subclavius
- Holds the clavicle in place
What is sternoclavicular subluxation?
Joint is partially separated - caused by direct trauma to the front of the chest.
Vessels at the root of neck susceptible to injury.
Anterior movement of clavicle is easy to mend
Posterior movement is dangerous as it may impede on important structures i.e nerves and arteries
Describe the Acromioclavicular (AC) joint.
- Connects the acromial end of the clavicle with the scapula
- Plane joint
- Partial articular disc that allows movement at the lateral end
- Intrinsic ligament: Acromioclavicular ligament - holds structures together
- Extrinsic ligament: Coracoclavicular
- Made of the coronoid and trapezoid ligament
- Lie perpendicular to each other
- Coronoid lies vertically (sagittal) and pulls clavicle down and stops excess movement
- Trapezoid prevents excess protraction/retraction/rotation
- Susceptible to shoulder separation in contact sports
- Blood supply: Subscapular and thoracoacromial
- Nerve supply: Suprasclavicular, lateral pectoral, axillary nerves
Describe the three grades of acromioclavicular dislocation/shoulder separation.
Grade 1: A-C ligaments stretched. Coracoclavicular ligaments intact
Grade 2: A-C ligaments torn and disrupted. Coracoclavicular ligaments intact.
Grade 3: A-C and CC ligaments ruptured. Wide separation of the joint.
Describe the Glenohumeral joint.
- Sits between the glenoid cavity and head of humerus.
- Synovial ball-and-socket joint - multiaxial
- Poor congruence between articular surfaces
- Glenoid labrum deepens socket - Made of cartilage/CT and yields more than bone. Allows for more movement without pain.
- Tendon of long head of biceps has intracapsular origin
- Blood supply: Circumflex humeral arteries
- Nerve supply: Suprascapualr, axillary, lateral pectoral nerves
- Bursae: subscapular, subacromial
What are the ligaments of the glenohumeral joint?
Intrinsic: Coracohumeral and glenohumeral (superior, middle, inferior)
Extrinsic: Coracoacromial, transverse humeral
Rotator cuff muscles act as dynamic ligaments
What are the deficiencies in the articular capsule?
- Anterior glenohumeral ligaments
- Inferior articular capsule
- Anterolateral long head of biceps
Describe mobility at the GH joint.
- Highly mobile joint with reduced stability
- Rotator cuff muscles act as fixator ligaments
- There is greatest stability during abduction and external rotation, but this is also the position for dislocation.
What are the rotator cuff muscles?
- Supraspinatus
- Infraspinatus
- Teres minor
- Subscapularis
What are the muscles acting on the shoulder joint?
Anterior:
- Pectoralis major
- Deltoid
- Coracobrachialis
- Triceps brachii
- Biceps brachii
- Brachialis
- Brachioradialis
Anterior deep:
- Subscapularis
- Coracobrachialis
- Brachialis
Posterior:
- Supraspinatus
- Infraspinatus
- Teres major/minor
- Latissimus dorsi
What are the movements at the shoulder joint? What muscles carry out these movements?
Flexor muscles produce flexion, adduction and medial rotation - pec major, deltoid, biceps, coracobrachialis, teres major, latissimus dorsi, subscapularis
Extensor muscles produce extension, abduction and lateral rotation - deletoid, teres major, latissimus dorsi, triceps, supraspinatus, infraspinatus, teres minor
Abduction is functionally and clinically important - deltoid, supraspinatus.
What are the two physiological joints?
- Subdeltoid:
- Between supraspinatus and GH joint.
- Subacromial bursa minimises friction
- Involved in painful arc syndrome - Scapulothoracic
- Between serratus and thorax
- Between serratus and scapula
- Glenohumeral rhythm - scapula and humerus 1:2 ratio (degrees of movement)
