Shoulder Muscle Actions

Question 1

deltoid actions (3)

Answer 1

1. abduction: arm
2. flexion (anterior fibers)
3. extension (posterior fibers)

Origin: Acromion (lat head), Clavicle (anteiror head), Scapula Spine (posterior head)
Insertion: Humerus, Deltoid Tuberosity

Question 2

Supraspinatus

Answer 2

abduction: arms

Origin: Scapula’s Supraspinous Fossa
insertion: greater tubercle of humerus, superior asp

Question 3

Infraspinatus

Answer 3

lateral rotation: arm

Origin: infraspinous fossa
Insertion: greater tubercle, middle head

Question 4

Teres Minor

Answer 4

lateral rotation: arm

origin: scapula, lateral border
insertion: greater tubercle, inferior aspect

Question 5

teres major (2)

Answer 5

1. adductor 2. medial rotation arm

Origin: scapula, lateral border
Insertion: anteriolateral border of humerus

Question 6

subscapularis (2)

Answer 6

1. adduction 2. medial rotation arm

Origin: subscapularis
Insertion: lesser tubercle

Question 7

pectoralis major (3)

Answer 7

1. flexion 2. adduction 3. medial rotation of arm

Origin: clavicle, sternum, ribs
Insertion: later lip, intertubercle groove

Question 8

pectoralis minor (2)

Answer 8

1. depresses 2. protraction scapula

origin: ribs 3-5
insertion: coracoid process of scapula

Question 9

serratus anterior (2)

Answer 9

1. protraction 2. lateral rotation scapula

origin: ribs 1-8
insertion: anterior medial border of scapula