Posterior Shoulder Muscles

Question 1

Supraspinatus (RC)

Origin

Answer 1

-Supraspinous fossa of scapula

Question 2

Supraspinatus (RC)

Insertion

Answer 2

-Supraspinous fossa of scapula

Question 3

Supraspinatus (RC)

Innervation

Answer 3

-Suprascapular nerve (C4, C5, C6)

Question 4

Supraspinatus (RC)

Action

Answer 4

• Initiates abduction of humerus

- Stabilizes humeral head in glenoid fossa.

Question 5

Infraspinatus (RC)

Origin

Answer 5

-Infraspinous fossa of scapula

Question 6

Infraspinatus (RC)

Insertion

Answer 6

-Middle facet of greater tubercle of humerus

Question 7

Infraspinatus (RC)

Innervation

Answer 7

-Suprascapular nerve (C5, C6)

Question 8

Infraspinatus (RC)

Action

Answer 8

• Laterally rotates humerus.

- Stabilizes humeral head in glenoid fossa.

Question 9

Teres Minor   (RC)
Origin

Answer 9

-Middle part of lateral border of the scapula

Question 10

Teres Minor   (RC)
Insertion

Answer 10

-Inferior facet of greater tubercle of humerus

Question 11

Teres Minor   (RC)
Innervation

Answer 11

-Axillary nerve (C5, C6)

Question 12

Teres Minor   (RC)
Action

Answer 12

• Laterally rotates humerus.

- Stabilizes humeral head in glenoid fossa.

Question 13

Subscapularis (RC)

Origin

Answer 13

-Subscapular fossa (most of anterior surface of scapula)

Question 14

Subscapularis (RC)

Insertion

Answer 14

-Lesser tubercle of humerus

Question 15

Subscapularis (RC)

Innervation

Answer 15

-Upper and lower subscapular nerves (C5, C6, C7)

Question 16

Subscapularis (RC)

Action

Answer 16

• Adducts and medially rotates humerus

- Stabilizes humeral head in glenoid fossa.

Question 17

Teres Major

Origin

Answer 17

-Posterior surface of inferior angle of scapula

Question 18

Teres Major

Insertion

Answer 18

-Medial lip of intertubercular groove of humerus

Question 19

Teres Major

Innervation

Answer 19

-Lower subscapular nerve (C5, C6)

Question 20

Teres Major

Action

Answer 20

-Adducts and medially rotates humerus.

Question 21

Deltoid

Origin

Answer 21

• Lateral third of clavicle
• acromion
• spine of scapula

Question 22

Deltoid

Insertion

Answer 22

-Deltoid tuberosity of humerus

Question 23

Deltoid

Innervation

Answer 23

-Axillary nerve (C5, C6)

Question 24

Deltoid

Action

Answer 24

• Anterior: flexes and medially rotates humerus.
• Middle: abducts humerus.
• Posterior: extends and laterally rotates humerus.

Question 25

Triceps Brachii Long Head

Origin

Answer 25

-infraglenoid tubercle of scapula

Question 26

Triceps Brachii

Insertion

Answer 26

-Proximal end of olecranon of ulna and fascia of forearm

Question 27

Triceps Brachii

Innervation

Answer 27

-Radial nerve (C6, C7, C8)

Question 28

Triceps Brachii

Action

Answer 28

• Extends forearm

- Long head extends humerus & resists dislocation of glenohumeral joint.

Question 29

Triceps Brachii Lateral Head

Origin

Answer 29

-posterior surface of humerus, superior to radial groove

Question 30

Triceps Brachii Medial Head

Origin

Answer 30

-posterior surface of humerus, inferior to radial groove

Question 31

Anconeus

Origin

Answer 31

-Lateral epicondyle of humerus

Question 32

Anconeus

Insertion

Answer 32

-Lateral surface of olecranon and superior part of posterior surface of ulna

Question 33

Anconeus

Innervation

Answer 33

-Radial nerve (C7, C8, T1)

Question 34

Anconeus

Action

Answer 34

–Extends forearm, stabilize elbow joint, abducts ulna during pronation.