Shoulder

Question 1

Pectoralis Major

Answer 1

Origin: medial clavicle, sternum and cartilage of ribs 1-6

Insertion: crest of greater tubercle of humerus

Action: all fibers adduct and medially rotate shoulder, assist to elevate thorax during forced inhalation; upper fibers flex and horizontally adduct shoulder; lower fibers extend the shoulder

Nerve: upper fibers - lateral pectoral nerve C5, 6, 7; lower fibers - lateral and medial pectoral nerve C6, 7, 8, T1

Question 2

Pectoralis Minor

Answer 2

Origin: ribs 3-5

Insertion: medical surface of coracoid process of scapula

Action: depress, abduct, and downwardly rotate the scapula; with the scapula fixed, assist to elevate the thorax during forced inhalation

Nerve: medial pectoral nerve, lateral pectoral nerve C6, 7, 8, T1

Question 3

Subclavius

Answer 3

Origin: 1st rib and cartilage

Insertion: inferior surface of clavicle

Action: depress clavicle and draw it anteriorly; elevate first rib; stabilizes sternoclavicular joint

Nerve: subclavian nerve C5, 6

Question 4

Serratus Anterior

Answer 4

Origin: external surfaces of ribs 1-9

Insertion: anterior surface of medial border of scapula

Action:

• with origin find, abduct, upwardly rotate, and depress scapula, hold medial border of scapula against rib cage
• with scapula fixed, may act to elevate thorax during forced inhalation

Nerve: long thoracic nerve C5, 6, 7 8

Question 5

Deltoid (Anterior)

Answer 5

Origin: lateral clavicle

Insertion: deltoid tuberosity

Action: abduct shoulder; flex, medially rotate, and horizontally adduct shoulder

Nerve: axillary nerve C5, 6

Question 6

Deltoid (Middle)

Answer 6

Origin: acromion

Insertion: deltoid tuberosity

Action: abduct shoulder

Nerve: axillary nerve C5, 6

Question 7

Deltoid (Posterior)

Answer 7

Origin: spine of scapula

Insertion: deltoid tuberosity

Action: abduct shoulder; extend, laterally rotate, and horizontally abduct shoulder

Nerve: axillary nerve C5, 6

Question 8

Teres Major

Answer 8

Origin: inferior angle and lateral border of scapula

Insertion: crest of lesser tubercle of humerus

Action: extend, adduct, and medially rotate shoulder

Nerve: lower subscapular nerve C5, 6, 7

Question 9

Subscapularis (Rotator Cuff)

Answer 9

Origin: subscapular fossa of scapula

Insertion: lesser tubercle of humerus

Action: medially rotate the shoulder, stabilize head of humerus in glenoid cavity

Nerve: upper and lower subscapular nerve C5, 6, 7

Question 10

Supraspinatus

Answer 10

Origin: supraspinous fossa of scapula

Insertion: greater tubercle of humerus

Action: abduct shoulder, stabilize head of humerus in glenoid cavity

Nerve: suprascapular nerve C4, 5, 6

Question 11

Infrapinatus

Answer 11

Origin: infraspinous fossa of scapula

Insertion: greater tubercle of humerus

Action: laterally rotate and adduct shoulder; stabilize head of humerus in glenoid cavity

Nerve: suprascapular nerve C4, 5, 6

Question 12

Teres Minor

Answer 12

Origin: lateral border of scapula

Insertion: greater tubercle of humerus

Action: laterally rotate and adduct shoulder; stabilize head of humerus in glenoid cavity

Nerve: axillary nerve C5, 6