Intrinsic muscles of the shoulder

Question 1

Origin of deltoid

Answer 1

Scapula and clavicle

Question 2

Attachment of deltoid

Answer 2

Deltoid tuberosity on lateral humerus

Question 3

What are the intrinsic muscles of the shoulder

Answer 3

Deltoid,
Teres major,
Rotator cuff muscles (supraspinatus, infraspinatus, subscapularis, teres minor)

Question 4

Actions of deltoid

Answer 4

Anterior fibres flex arm at shoulder,
Middle fibres abduct arm at shoulder (15-90)
Posterior fibres extend arm at shoulder

Question 5

Innervation of deltoid

Answer 5

Axillary nerve

Question 6

Origin of teres major

Answer 6

Posterior surface of inferior angle of scapula

Question 7

Attachment of teres major

Answer 7

Intertubercular groove of humerus

Question 8

Action of teres major

Answer 8

Adduction and medial rotation of arm at shoulder

Question 9

Innervation of teres major

Answer 9

Lower subscapular nerve

Question 10

Origin of supraspinatus

Answer 10

Supraspinatous fossa of scapula

Question 11

Attachment of supraspinatus

Answer 11

Greater tubercle of humerus

Question 12

Innervation of supraspinatus

Answer 12

Suprascapular nerve

Question 13

Action of supraspinatus

Answer 13

Abduction 0-15 and assists deltoid for 15-90

Question 14

Origin of infraspinatus

Answer 14

Infraspinatous fossa of scapula

Question 15

Attachment of infraspinatus

Answer 15

Greater tubercle of humerus

Question 16

Innervation of infraspinatus

Answer 16

Suprascapular nerve

Question 17

Action of infraspinatus

Answer 17

Lateral rotation of arm

Question 18

Origin of subscapularis

Answer 18

Subscapular fossa on costal surface of scapula

Question 19

Attachment of subscapularis

Answer 19

Lesser tubercle of humerus

Question 20

Innervation of subscapularis

Answer 20

Upper and lower subscapular nerves

Question 21

Action of subscapularis

Answer 21

Medial rotation of arm

Question 22

Origin of teres minor

Answer 22

Posterior surface of scapula adjacent to its lateral border

Question 23

Attachment of teres minor

Answer 23

Greater tubercle of humerus

Question 24

Innervation of teres minor

Answer 24

Axillary nerve

Question 25

Action of teres minor

Answer 25

Lateral rotation of arm

Question 26

What is rotator cuff tendinitis

Answer 26

Inflammation of tendons of rotator cuff muscles (supraspinatus tendon and subacromial bursa), usually secondary to repetitive shoulder use.
During abduction of arm, the supraspinatus muscle rubs against the coracoacromial arch

Question 27

Treatment of rotator cuff tendinitis

Answer 27

Rest, analgesia and physiotherapy

More severe cases require steroid injections and surgery