MSK - Shoulder And Back Flashcards
What lines the articulating surface of the shoulder joint?
How is the glenoid cavity deepened?
Hyaline cartilage
Glenoid labrum
What makes the shoulder joint relatively unstable?
How is stability achieved? (4)
Shallow glenoid cavity
Disproportion of articular surfaces
Multiplanar movements
Lax capsule
Rotator cuff muscles
Other muscles
Ligaments
Capsule
What is the capsule of the shoulder attached to?
What feature allows movement?
What allows full abduction?
Glenoid labrum and margins of glenoid cavity
Anatomical neck of humerus
Tough but lax
Bridges intertubular groove and dips down medially to surgical neck
What is the purpose of the synovial membrane?
The tendon of what muscle lies within the joint cavity?
What does the tendon acquire as it enters the joint?
What does the gap in the capsule allow?
Line capsule and lines bone within capsule up to edge of articulating surfaces
Long head of biceps
Acquires a tubular sleeve of synovium which surrounds tendon up to its insertion
Synovium and joint cavity to be continuous with subscapular bursa
What are the three extracapsular ligaments?
And what are their locations?
Coracoacrmoial ligament - between acromion and Coracoid process
Coracohumeral ligament - base of Coracoid process to anterior part of greater tubercle
Transverse humeral ligament - holds tendon of long head of biceps in place during shoulder movement
What are the intracapsular ligaments?
Where do they extend between?
What reinforces the capsule anteriorly?
Three gleno-humeral ligament - Superior, middle, inferior
Glenoid labrum and humerus
Part of fibrous capsule - can only be seen from inside the capsule
What forms the coraco acromial arch?
Coracoacromial ligament, acromion and coracoid process
What type of joint is the shoulder joint?
What is another name of the shoulder joint?
What does this type of joint allow?
What commonly occurs at this joint?
Ball and socket type - Synovial joint
Gleno humeral joint
Wide range of movements in multiple planes
Most mobile, least stable.
Dislocations
What are the four rotator cuff muscles?
What is the most important factor giving stability to the joint?
Supraspinatus
Infaspinatus
Teres minor
Subscapularis
SITS
Rotator cuff muscles
What arch does the supraspinatus tendon pass under?
Where is the subscapularis inserted into?
Coraco-acromial arch
Less tubercle
What strengthens the rotator cuff?
The tendons blend to form a cuff which fuses with the capsule and strengthens it
What characteristic of the muscles holds the head a close to the glenoid capsule?
Tone in the muscles
What separates the supraspinatus tendon from the Coracoacromial arch?
Subacromial bursa
What are the actions of the rotator cuff muscles?
Stabilise the shoulder joint, holding the head of the humerus in the glenoid cavity
Supraspinatus - initiation and first 15 degree of abduction
Infraspinatus - lateral rotation of the arm
Teres minor - lateral rotation of the arm and weak adductor
Subscapularis - medial rotation of the arm
What other muscles stabilise the shoulder joint?
Deltoid
Long head of biceps
Long head of triceps
What are the two types of bursae?
Subacromial bursa - facilitates movement of supraspinatus tendon under the Coracoacromial arch and deltoid muscle over the shoulder joint capsule and greater tubercle of humerus
Subscapular bursa - facilitates movement of subscapularis tendon over scapula
What is painful arc syndrome?
Inflammation of the subacromial bursitis - causes pain on abduction of the arm between 50 and 130 degrees
What are the movements of the glenohumeral joint?
Flexion Extension Abduction Adduction Medial rotation Lateral rotation
What muscles cause medial and lateral rotation
Medial - subscapularis, teres major, pec major and lat dorsal
Lateral - infraspinatus and teres minor
What muscles cause flexion, extension, abduction and adduction of the shoulder joint?
Flexion - pec major, anterior fibres of deltoid, coracobrachilais and biceps brachii
Extension - posterior fibres of deltoid, lattisimus dorsi and teres major
Abduction - 0-15 = supraspinatus, 15-90 = deltoid, above 90 = rotation of scapular - trapezius, serratus anterior
Adduction - pec major, lattisimus dorsi, teres major
What is the blood and nerve supply to the shoulder joint?
Blood supply = anterior and posterior circumflex humeral arteries and suprascapular artery
Nerve supply = suprascapular, Axillary nerve, lateral pectoral nerves from the brachial plexus (C5 and C6)
What is stability of the shoulder joint provided by?
Tendons of the rotator cuff Coraco acromial arch Glenohumeral ligaments Coracohumeral ligament Seeping glenoid cavity by labrum Splinting effect of the long head of biceps and long head of triceps
In what direction is the dislocation likely to be if it is caused by a trauma on a fully abducted arm?
What is it clinically defined as and why?
Inferior direction
Anterior dislocation - because the humeral head locates anteriorly due to a lull of powerful adductors
What is likely to cause recurrent dislocation?
Capsule and rotator cuff tear and poor healing
How does an anterior dislocation of the shoulder appear?
Loss of round contour of right shoulder
It appears square
Arm supported by other hand (very painful)
Head of humerus lies anteriorly, below Coracoid process
What nerve injury may result from a dislocation?
What else may cause the nerve injury?
What should you not test?
Axillary nerve injury - loss of sensation in a small area of the skin over central part of the deltoid
Fracture of surgical neck of humerus
Motor function - could cause more soft tissue damage and injury
What is painful arc syndrome?
What does it cause?
What does it lead to?
Supraspinatus tendon rubbing under the Coracoacromial arch
Causes irritation and inflammation of the supraspinatus tendon/subacromial bursa
Subacromial bursitis
Supraspinatus tendionitis
Degeneration and rupture of tendons
What are the predisposing factors to painful arc syndrome?
Repetitive overuse - sporting activities, work involving overhead use of arms
Older people - degenerate changes in tendons
Avascularity of supraspinatus tendon
Slight differences in anatomy may make impingement more likely
During what degree of abduction is pain experienced
50-130 degrees of abduction
What are the three groups of muscles of the back?
What muscles are in each group?
Superficial group - trapezius and latissimus dorsi
Deep muscles - levator scapulae and rhomboids
Scapula-humeral - deltoid, teres major and 4 rotator cuff muscles
What nerve innervates the trapezius?
What are the three parts of the trapezius? And what are their functions?
Accessory nerve
Superior part - elevates scapula
Middle part - retracts scapula
Inferior part - depresses scapula
It is a SUPERFICIAL muscle of the back
How does the scapula rotate?
What is scapula rotation responsible for?
Superior and inferior parts of trapezius act together - to rotate scapula on chest wall
Serratus anterior muscle aids upward rotation of the scapula
Abduction of the arm above horizontal (90 degrees)
Describe the latissimus dorsi.
What nerve innervates it?
Where does it extend from?
What are its functions?
Large, fan shaped muscle
Thoraco-dorsal nerve
Extends from; lower thoracic vertebrae, thoracolumbar fascia and iliac crest to flow of intertubercular groove
Power adductor of arm
Extends arm at shoulder
Medial rotator
It is a SUPERFICIAL muscle of the back
What are the two deep muscles of the back?
What is their function?
What nerve innervates them?
Levator scapulae - elevates scapula, rotates scapula depressing glenoid cavity
Rhomboids major and minor - retract scapula, rotate scapula depressing glenoid cavity
Dorsal scapula nerve
Name the three scapula humeral muscles of the back.
What is their function?
What nerve innervates each?
Deltoid muscle - important abductor of arm at shoulder joint. Powerful muscle, forms rounded part of shoulder.
Anterior fibres - flexion of arm
Middle fibres - abduct arm from 15-90 (first 15 degrees by supraspinatus muscle)
Posterior fibres - extend arm (along with Lat.dorsi)
Nerve supply = Axillary nerve
Teres major - abduct arm and medial rotator. From inferior angle or scapular to upper humerus.
Nerve - lower subscapular nerve
Rotator cuff muscles
