Shoulder myology

Question 1

Rhomboid Major

Answer 1

*Origin- SP T2-T5
*Insertion- Medial border scapula
*Action- Retracts scapula & medially rotates it to depress the glenoid. Helps fix scapula to thorax
*Nerve- Dorsal scapular nerve

Question 2

Rhomboid Minor

Answer 2

*Origin- Nuchal lig & SP C7-T1
*Insertion- Medial border scapula
*Action- Retracts & medial rotates scapula, helps fix to thorax
*Nerve- Dorsal scapular nerve

Question 3

Serratus Anterior

Answer 3

*Origin- Outer surface of 8-9 ribs
*Insertion- Costal aspect of medial surface of scapular & inferior angle
*Action- Protracts & upwardly/laterally rotates scapular
- Stabilises scapular
- Powerful muscle
*Nerve- Long thoracic nerve C5-7

Question 4

Pectoralis Minor

Answer 4

*Origin- Close to costochondral jct of ribs 3- 5
*Insertion- Coracoid process
*Action- Protracts & medially rotates scapular
- Raises ribs during inspiration
*Nerve- Nerve to subclavius C5,6

Question 5

Deltoid

Answer 5

*Origin- Anterior superior border of lateral 3rd clavicle, acromion, spine of scapular
*Insertion- Deltoid tuberosity of humerus
*Action
- Abd
- Flex
- Ext
*Nerve- Axillary nerve C5,6

Question 6

Pectoralis Major

Answer 6

*Origin
- Clavicular head: anterior surface medial half of clavicle
- Sternocostal head: anterior surface of sternum, upper 6 costal cartilages, external oblique aponeurosis
*Insertion- Lateral lip of bicipital groove of humerus
*Action
- Flexion
- Adduction
- Medial Rotation
- extension
*Nerve- Medial (C8-T1) and lateral (C5-7) pectoral nerves

Question 7

Teres Major

Answer 7

*Origin- Inferior angle of scapula
*Insertion- Medial lip of bicipital groove of
humerus
*Action
- Adduction
- MR
- Extension (from a flexed position)
*Nerve- Lower sub scapular nerve C6,7

Question 8

Supraspinatus (Rotator Cuff)

Answer 8

*Origin- Supraspinous fossa of scapular
*Insertion- Superior facet of greater tubercle of humerus
*Action
- Abduction (initiates abd)
- Stabilises humeral head
*Nerve- suprascapular nerve C5,6

Question 9

Infraspinatus (Rotator Cuff)

Answer 9

*Origin- Infraspinatus fossa of the scapula
Insertion- Middle facet of greater tubercle of humerus
*Action
- External Rotation
- Stabilisation of the humerus
*Nerve- suprascapular nerve C5,6

Question 10

Teres Minor (Rotator Cuff)

Answer 10

*Origin- Lateral border of the scapular
*Insertion- Inferior facet of greater tubercle of humerus
*Action
- External Rotation
- Stabilises humerus
*Nerve- axillary nerve C5,6

Question 11

Subscapularis (Rotator Cuff)

Answer 11

*Origin- Subscapular fossa
*Insertion- Lesser tubercle of humerus
*Action
- Medial Rotation
- Assists adduction
- Stabilises humerus
*Nerve- upper and lower subscapular nerve C5-7

Question 12

Coracobrachialis

Answer 12

*Origin
- Apex of coracoid process
- (Shares tendon with short head of biceps)
*Insertion- Midway down medial aspect of humeral shaft
*Action- Flexion & Adduction of the shoulder
*Nerve supply- Musculocutaneous nerve c6,7