Shoulder

Question 1

Pectoralis Minor

Answer 1

Origin: outer surface of upper margin of ribs 3-5

Insertion: coracoid process

Innervation: medial pectoral nerve

Blood Supply: pectoral branch of thoracoacromial and intercostal lateral thoracic arteries

Action: lowers lateral angle of scapula and protracts scapula

Question 2

Pectoralis Major

Answer 2

Origin: sternal 1/2 of clavicle, sternum to 7th rib, cartilage of true ribs, and aponeurosis of external oblique

Insertion: lateral lip of intertubercular sulcus of humerus

Innervation: medial pectoral nerve and lateral pectoral nerve

Blood Supply: pectoral branch of thoracoacromial artery and perforating branches of internal thoracic artery

Action: flexes arm, adducts arm, and medially rotates arm

(medial border of deltopectoral triangle)

Question 3

Subclavius

Answer 3

Origin: upper border of 1st rib and its cartilage

Insertion: inferior surface of middle 1/3 of clavicle

Innervation: nerve to subclavius

Blood Supply: clavicular branch of thoracoacromial artery

Action: anchors clavicle and depresses clavicle

Question 4

Subscapularis

Answer 4

Origin: subscapular fossa

Insertion: lesser tubercle of humerus

Innervation: upper and lower subscapular nerves

Blood Supply: subscapular artery and lateral thoracic artery

Action: medially rotates arm at shoulder, adducts arm at shoulder, and helps hold the humeral head in glenoid cavity

(rotator cuff)

Question 5

Serratus Anterior

Answer 5

Origin: lateral surface of upper 8-9 ribs

Insertion: anterior surface of medial border of scapula

Innervation: long thoracic nerve

Blood Supply: lateral thoracic artery

Action: protracts scapula, rotates scapula, and holds scapula against thoracic wall

Question 6

Supraspinatus

Answer 6

Origin: supraspinous fossa

Insertion: superior facet of greater tubercle of humerus

Innervation: suprascapular nerve

Blood Supply: suprascapular artery

Action: initiates arm abduction (1st 15 degrees)

(rotator cuff)

Question 7

Infraspinatus

Answer 7

Origin: infraspinous fossa

Insertion: middle facet of greater tubercle of humerus

Innervation: Suprascapular nerve

Blood Supply: Suprascapular artery

Action: laterally rotates arm

(rotator cuff)

Question 8

Teres Minor

Answer 8

Origin: upper 2/3 of posterior surface of lateral border of scapula

Insertion: inferior facet of greater tubercle of humerus

Innervation: axillary nerve

Blood Supply: circumflex scapular artery

Action: laterally rotates arm

(rotator cuff)
(superior border of quadrangular space and triangular space)

Question 9

Teres Major

Answer 9

Origin: posterior surface of inferior angle of scapula

Insertion: medial lip of intertubercular sulcus of humerus

Innervation: lower subscapular nerve

Blood Supply: circumflex scapular artery

Action: adducts arm and medially rotates arm

(inferior border of quadrangular space and triangular space)

Question 10

Deltoid

Answer 10

Origin: lateral 1/3 of anterior clavicle, lateral acromion process, and inferior edge of spine of scapula

Insertion: deltoid tuberosity of humerus

Innervation: axillary nerve

Blood Supply: posterior circumflex humeral artery and deltoid branch of thoracoacromial artery

Action: anterior part - flexes arm and medially rotates arm, middle part - abducts arm beyond initial 15 degrees, posterior part - extends arm and laterally rotates arm

(lateral border of deltopectoral triangle)