Muscles Of The Pectoral And Axillary Regions

Question 1

Pectoralis major origin and insertion

Answer 1

O: clavicular head- anterior aspect of the clavicle, sternocostal head- sternum, superior six costal cartilages, abdominal head- fascia of the external abdominal oblique
I: intertubercular groove of the humerus

Question 2

Pectoralis major innervation and action

Answer 2

Innervation: medial and lateral pectoral nerves (C5-T1)
Action: primary horizontal adductor and shoulder internal rotation, clavicular head- helps with shoulder flexion, also sternocostal head- shoulder extension

Question 3

Pectoralis minor origin and insertion

Answer 3

O: lateral aspect of ribs 3 to 5
I: coracoid process

Question 4

Pectoralis minor innervation and action

Answer 4

Innervation: medial pectoral nerve (C8-T1)
Action: assists in protraction and downward rotation of scapula

Question 5

Serratus anterior origin and insertion

Answer 5

O: lateral aspect of ribs 1 to 8
I: medial border of the scapula

Question 6

Serratus anterior innervation and action

Answer 6

Innervation: long thoracic nerve (C5-C7)
Action: upward rotation of scapula and protraction

Question 7

Subclavius origin and insertion

Answer 7

O: lateral, inferior aspect of rib 1
I: inferior aspect of clavicle

Question 8

Subclavius innervation and action

Answer 8

Innervation: nerve to subclavius (C5-C6)
Action: prevents lateral displacement of clavicle