Posterior Shoulder and Rotator Cuff

Question 1

What are the muscles that attach to the scapula and the humerus?

Answer 1

Deltoid, trapezius, levator scapulae, rhomboids, rotator cuff muscles, pectoralsi major and minor, serratus anterior

Question 2

What action does the posterior (spinal) part of the deltoid perform?

Answer 2

Extension of the shoulder

Question 3

What action does the middle (acromial) part of the deltoid perform?

Answer 3

Abduction at the shoulder (takes over from supraspinatus beyond 15 degrees)

Question 4

What action does the anterior (clavicular) part of the deltoid perform?

Answer 4

Mainly flexion at the shoulder

Question 5

What actions does the trapezius perform?

Answer 5

Ascending part = scapular depression
Middle part = scapular retraction
Descending part = scapular elevation

Question 6

What actions does the levator scapulae perform?

Answer 6

Elevation of the scapula and inferior rotation of the glenoid fossa

Question 7

What two muscles make up the rhomboids?

Answer 7

Rhomboid major and minor

Question 8

What action does the rhomboids perform?

Answer 8

Retraction of the scapula and inferior rotation of the glenoid fossa

Question 9

What are the rotator cuff muscles?

Answer 9

Supraspinatus, infraspinatus, teres minor, subscapularis

Question 10

What actions does supraspinatus perform?

Answer 10

Stabilises head of humerus in glenoid, first 15 degrees of abduction at shoulder

Question 11

What actions does infraspinatus and teres minor perform?

Answer 11

Stabilise head of humerus in glenoid, lateral rotation at the shoulder

Question 12

What action does subscapularis perform?

Answer 12

Stabilises head of humerus in glenoid, medial rotation at the shoulder

Question 13

What additional site of attachment do pectoralis major and minor, and serratus anterior have?

Answer 13

Attach to pectoral girdle

Question 14

What must happen in order for full adduction/abduction of the upper limb to occur?

Answer 14

Scapula must rotate so that the glenoid fossa faces more inferiorly/superiorly respectively

Question 15

Why is superior rotation of the glenoid required?

Answer 15

To prevent the greater tubercle of the humerus from impinging on the acromion of the scapula

Question 16

Where do the rotator cuff muscles attach distally and proximally?

Answer 16

Distal = tubercles of the head of the humerus
Proximal = between scapula

Question 17

What do the distal tendons of all of the rotator cuff muscles blend with?

Answer 17

Blend with and reinforce the fibrous capsule of the shoulder joint

Question 18

What is the function of the fibrous cuff of the shoulder joint?

Answer 18

Stabilises the shallow ball and socket of the shoulder joint

Question 19

What are the distal insertions of the rotator cuff muscles?

Answer 19

Greater tubercle of humerus = supraspinatus, infraspinatus, teres minor
Lesser tubercle of humerus = subscapularis

Question 20

What innervates the rotator cuff muscles?

Answer 20

Branches of the brachial plexus

Question 21

What is painful arc syndrome?

Answer 21

Impingement of supraspinatus tendon between humerus and acromion causes pain during 50-130 degrees of abduction

Question 22

What will patients with supraspinatus paralysis/tendon tears do?

Answer 22

Throw their upper limb to the side in order to initiate abduction