Week 8 - Shoulder

Question 1

How many muscles are in the Pectoral region? What are they?

Answer 1

3; Pectoralis Major, Pectoralis Minor, and Subcalvius

Question 2

Pectoralis Major - Origin

Answer 2

Clavicular head - Medial 1/2 of clavicle
Sternocostal head - anterior sternum and costal cartilage of 1st 6-7 ribs

Question 3

Pectoralis Major - Insertion

Answer 3

Intertubercular groove of humerus

Question 4

Pectoralis Major - Action

Answer 4

Flexion, Adduction, and medial rotation of glenohumeral joint.

Question 5

The clavicular head of the Pectoralis Major muscle can _________ a __________ arm

Answer 5

flex; extended

Question 6

The sternal head of the Pectoralis Major muscle can _________ a __________ arm

Answer 6

extend; flexed

Question 7

Pectoralis Major - Reverse Function

Answer 7

Expand the chest (assist in respiration)

Question 8

Pectoralis Major - Innervation

Answer 8

Medial and Lateral pectoral nerves.

Question 9

Where is the Clavipectoral Fascia? What is its purpose?

Answer 9

Deep to Pec major; invests pec minor and subclavius, and forms the anterior wall of the axilla (armpit)

Question 10

Pectoralis Minor - Origin

Answer 10

Anterior surface of ribs 3-5

Question 11

Pectoralis Minor - Insertion

Answer 11

Coracoid process of scapula

Question 12

Pectoralis Minor - Action

Answer 12

Downward movement of shoulder (depression) and protraction of scapula; no standard anatomical movement of GH joint for this muscle

Question 13

Pectoralis Minor - Innervation

Answer 13

Medial pectoral nerve; some contribution from lateral pectoral nerve

Question 14

Subclavius - Origin

Answer 14

Superior surface of 1st rib and costal cartilage

Question 15

Subclavius - Insertion

Answer 15

Inferior surface of clavicle “subclavian groove”

Question 16

Subclavius - Action

Answer 16

• Pulls tip of shoulder down
• Pulls clavicle medially (to stablize sternoclavicular joint)
• posterior axial rotation of clavicle, required during abduction and flexion

Question 17

What is the most important function of the subclavius? Why?

Answer 17

Posterior axial rotation of the clavicle; this is required during abduction and flexion of the glenohumeral joint, especially at 90+ degrees

Question 18

Subclavius - Innervation

Answer 18

Nerve to subclavius

Question 19

What is the significance of subclavius in aging populations?

Answer 19

In about 70% of people, by 70 years old, this muscle turns to fibrous tissue; this is one of the reasons that elderly individuals might not reach full end range shoulder flexion.

Question 20

Deltoid - Origin

Answer 20

Spine of scapula, acromion, and lateral 1/3-1/2 of clavicle

Question 21

Deltoid - Insertion

Answer 21

Deltoid tuberosity of humerus (lateral shaft of humerus)

Question 22

Deltoid - Action

Answer 22

Posterior fibers - assist extension
Middle fibers - Abduction from 30-90 degrees
Anterior fibers - assist flexion

Question 23

What is the purpose of the anterior and posterior fibers of the deltoid muscle during abduction?

Answer 23

They stabilize the glenohumeral joint by co-contracting in flexion and extension.

Question 24

Deltoid - Innervation

Answer 24

Axillary Nerve

Question 25

How many muscles are in the Scapular region? What are they?

Answer 25

4; Supraspinatus, Infraspinatus, Teres Minor, Teres Major

Question 26

Supraspinatus - Origin

Answer 26

Supraspinous fossa of scapula

Question 27

Supraspinatus - Insertion

Answer 27

Greater tubercle of humerus

Question 28

Supraspinatus - Action

Answer 28

Abduction of glenohumeral joint from 0-30 degrees (initiates abduction)

Question 29

Supraspinatus - Innervation

Answer 29

Suprascapular Nerve

Question 30

In order to reach it's insertion, the tendon of the supraspinatus passes _____________

Answer 30

under the acromion.

Question 31

Overuse of the supraspinatus muscle

Answer 31

Causes inflammation in the bursa (bursitis), which can impact the tendon (tendinitis), and can eventually cause the tendon to ossify and fracture.

Question 32

Infraspinatus - Origin

Answer 32

Infraspinous fossa of scapula

Question 33

Infraspinatus - Insertion

Answer 33

Greater tubercle of humerus

Question 34

Infraspinatus - Action

Answer 34

Lateral rotation

Question 35

Infraspinatus - Innervation

Answer 35

Suprascapular Nerve

Question 36

Teres Minor - Origin

Answer 36

Lateral border of scapula

Question 37

Teres Minor - Insertion

Answer 37

Greater tubercle of humerus

Question 38

Teres Minor - Action

Answer 38

Lateral Rotation

Question 39

Teres Minor - Innervation

Answer 39

Axillary Nerve

Question 40

The Axilla is the space bound by the three __________: 1. ___________, 2. _________, 3. __________

Answer 40

muscular regions; 1. Pectoral 2. Deltoid 3. Scapular