Posterior Shoulder and Rotator Cuff Flashcards
What are the muscles that attach to the scapula and the humerus?
Deltoid, trapezius, levator scapulae, rhomboids, rotator cuff muscles, pectoralsi major and minor, serratus anterior
What action does the posterior (spinal) part of the deltoid perform?
Extension of the shoulder
What action does the middle (acromial) part of the deltoid perform?
Abduction at the shoulder (takes over from supraspinatus beyond 15 degrees)
What action does the anterior (clavicular) part of the deltoid perform?
Mainly flexion at the shoulder
What actions does the trapezius perform?
Ascending part = scapular depression
Middle part = scapular retraction
Descending part = scapular elevation
What actions does the levator scapulae perform?
Elevation of the scapula and inferior rotation of the glenoid fossa
What two muscles make up the rhomboids?
Rhomboid major and minor
What action does the rhomboids perform?
Retraction of the scapula and inferior rotation of the glenoid fossa
What are the rotator cuff muscles?
Supraspinatus, infraspinatus, teres minor, subscapularis
What actions does supraspinatus perform?
Stabilises head of humerus in glenoid, first 15 degrees of abduction at shoulder
What actions does infraspinatus and teres minor perform?
Stabilise head of humerus in glenoid, lateral rotation at the shoulder
What action does subscapularis perform?
Stabilises head of humerus in glenoid, medial rotation at the shoulder
What additional site of attachment do pectoralis major and minor, and serratus anterior have?
Attach to pectoral girdle
What must happen in order for full adduction/abduction of the upper limb to occur?
Scapula must rotate so that the glenoid fossa faces more inferiorly/superiorly respectively
Why is superior rotation of the glenoid required?
To prevent the greater tubercle of the humerus from impinging on the acromion of the scapula
Where do the rotator cuff muscles attach distally and proximally?
Distal = tubercles of the head of the humerus Proximal = between scapula
What do the distal tendons of all of the rotator cuff muscles blend with?
Blend with and reinforce the fibrous capsule of the shoulder joint
What is the function of the fibrous cuff of the shoulder joint?
Stabilises the shallow ball and socket of the shoulder joint
What are the distal insertions of the rotator cuff muscles?
Greater tubercle of humerus = supraspinatus, infraspinatus, teres minor
Lesser tubercle of humerus = subscapularis
What innervates the rotator cuff muscles?
Branches of the brachial plexus
What is painful arc syndrome?
Impingement of supraspinatus tendon between humerus and acromion causes pain during 50-130 degrees of abduction
What will patients with supraspinatus paralysis/tendon tears do?
Throw their upper limb to the side in order to initiate abduction
