Muscles of the Upper Extremity: Axiohumeral Muscles

Question 1

Latissimus Dorsi Proximal Attachment

Answer 1

Spinous process of T6-12, thoracolumbar fascia, posterior iliac crest, and lower ribs

Question 2

Latissimus Dorsi Distal Attachment

Answer 2

Floor of the intertubercular groove of the humerus

Question 3

Latissimus Dorsi Innervation

Answer 3

Thoracodorsal n. [C6,C7,C8]

Question 4

Latissimus Dorsi Action

Answer 4

Extends the shoulder
Adducts the shoulder
Medially rotates the shoulder
Depresses the shoulder girdle
Assists with:
-Extension of the trunk
-Lateral flexion of the trunk

Question 5

Pectoralis Major Proximal Attachment

Answer 5

Clavicular head: medial end of the clavicle

Sternocostal head: anterior sternum and costal cartilages of the first 6 ribs

Question 6

Pectoralis Major Distal Attachment

Answer 6

Lateral lip of the intertubercular groove of the humerus

Question 7

Pectoralis Major Innervation

Answer 7

Medial and lateral pectoral nn. [C5,*C6] (clavicular head)

[C7,C8,T1] (sternocostal head)

Question 8

Pectoralis Major Action

Answer 8

All fibers:
Medially rotate the shoulder
Adduct the shoulder
Clavicular head:
-Flexes the shoulder
-Horizontally adducts the shoulder
Sternocostal head:
-Extends the shoulder