Muscles

Question 1

Deltoid

Answer 1

Origin: clavicle, acronium, scapular spine
Insertion: deltoid tuberousity of humerus
Innervation: axillary nerve
Main actions: flexes, medially rotates, abducts, laterally rotates, extends arm (jack of all trades!)

Question 2

Supraspinatus

Answer 2

Origin: supraspinous fossa of scapula
Insertion: greater tubercle of humerus
Innervation: Suprascapular nerve
Main Actions: hold the head of humerus in glenoid cavity; assist onset of abduction

Question 3

Infraspinatus

Answer 3

Origin: infraspinous fossa
Insertion: greater tubercle of humerus
Innervation: suprascapular nerve
Main Actions: laterally rotate arm, secure humerus in glenoid cavity

Question 4

Teres minor

Answer 4

Origin: lateral border of scapula
Insertion: greater tubercle of humerus
Innervation: axillary nerve
Main Actions: same as infraspinatus

Question 5

Subscapularis

Answer 5

Origin: subscapular fossa
Insertion: lesser tubercle of humerus
Innervation: upper and lower subscapular nerves
Main Actions: medially rotate and secure humerus

Question 6

Teres major

Answer 6

Origin: inferior angle of scapula
Insertion: shaft of the humerus
Innervation: lower subscapular nerve
Main Actions: adduct and medially rotate arm

Question 7

Pectoralis major

Answer 7

Origin: medial clavicle, sternum, costal cartilages (of ribs)
Insertion: humerus
Innervation: lateral and medial pectoral nerves
Main Actions: adducts and medially rotates humerus; it also can act as an accessory muscle of respiration

Question 8

Pectoralis minor

Answer 8

Origin: ribs 3-5
Insertion: Coracoid process of scapula
Innervation: medial pectoral nerve
Main Actions: stabilize and medially rotate scapula; it can also act as an accessory muscle of respiration

Question 9

Serratus anterior

Answer 9

Origin: ribs 1-8
Insertion: anterior surface of medial scapular border
Innervation: long thoracic nerve
Main Actions: stabilizes and rotates scapula laterally to permit abduction of the arm above the horizontal plane