Muscles of the Shoulder

Question 1

O: Spinous processes of T7-L5, Ribs 9 through 12 (posterior surface), Posterior iliac crest, Posterior sacrum,
I: Intertubercular groove of the humerus (medial lip)

Answer 1

LATISSIMUS DORSI (FIG. 21.36)
A: Extends the humerus, Internally/medially rotates the humerus, Adducts the humerus (posteriorly)
N: Thoracodorsal nerve

Question 2

O:, Inferior third of the lateral border of the scapula,
I: Intertubercular groove of the humerus (medial lip)

Answer 2

TERES MAJOR (FIG. 21.37)
A: Extends the humerus, Internally/medially rotates the humerus, Adducts the humerus
N: Lower subscapular nerve

Question 3

O:, Supraspinous fossa of the scapula,
I: Greater tubercle of the humerus

Answer 3

SUPRASPINATUS (FIG. 21.39)
A: Abducts the humerus
N: Suprascapular nerve

Question 4

O:, Infraspinous fossa of the scapula,
I: Greater tubercle of the humerus

Answer 4

INFRASPINATUS (FIG. 21.40)
A: Externally/laterally rotates the humerus
N: Suprascapular nerve

Question 5

O:, Superior two-thirds of the lateral border of the scapula,
I: Greater tubercle of the humerus

Answer 5

TERES MINOR (SEE FIG. 21.40)
A: Externally/laterally rotates the humerus, Adducts the humerus
N: Axillary nerve

Question 6

O:, Subscapular fossa of the scapula,
I: Lesser tubercle of the humerus

Answer 6

SUBSCAPULARIS (FIG. 21.41
A: Internally/medially rotates the humerus
N: Subscapular nerve

Question 7

O: Lateral third of the clavicle -anterior
Acromion process - middle
Scapular spine— posterior
I: Deltoid tuberosity

Answer 7

DELTOID (FIG. 21.42), Greek: delta —triangular, O: Lateral third of the clavicle -anterior, Acromion process - migdle, Scapular spine— posterior,
I: Deltoid tuberosity
A: Flexes the humerus, Internally/medially rotates the humerus (anterior fibers)
Abducts the humerus (middle fibers)
Extends the humerus, Externally/laterally rotates the humerus (posterior fibers)
N: Axillary nerve

Question 8

O: Medial half of the clavicle, Edge of the sternal body, Ribs 1 through 7 (costal cartilages),
I: Intertubercular groove of the humerus (lateral lip)

Answer 8

PECTORALIS MAJOR (FIG. 21.43)
A: Adducts the humerus (anteriorly), Internally/medially rotates the humerus, Flexes the humerus, Extends the humerus
N: Medial and lateral pectoral nerves

Question 9

O:, Coracoid process of the scapula,
I: Medial humeral shaft (middle region)

Answer 9

CORACOBRACHIALIS (FIG. 21.44)
A: Flexes the humerus, Adducts the humerus
N: Musculocutaneous nerve

Question 10

Flexion of the shoulder.

Answer 10

Pectoralis Major, Anterior Deltoid, Coracobrachialis, Biceps Brachii

Question 11

Extension of the shoulder.

Answer 11

Latissimus dorsi, Teres major, Posterior deltoid, Pectoralis major, Triceps brachii

Question 12

Abduction of the shoulder.

Answer 12

Supraspinatus, Middle deltoid

Question 13

Adduction of the shoulder.

Answer 13

Latissimus dorsi, Teres major, Teres minor, Pectoralis major, Coracobrachialis, Triceps brachii

Question 14

Medial Rotation of the shoulder.

Answer 14

Latissimus dorsi, Teres major, Subscapularis, Anterior deltoid, Pectoralis major

Question 15

External (lateral) Rotation of the shoulder.

Answer 15

infraspinatus, Teres minor, Posterior deltoid