Muscles of the Pectoral Region

Question 1

How many muscles lie in the pectoral region?

Answer 1

4

Question 2

What do the muscles in the pectoral region do?

Answer 2

Exert a force on the upper limb

Question 3

What are the muscles of the pectoral region?

Answer 3

Pectoralis major
Pectoralis minor
Serratus anterior
Subclavius

Question 4

What is the most superficial of the muscles in the pectoral region?

Answer 4

Pectoralis major

Question 5

What shape is the pectoralis major?

Answer 5

Large, fan shaped

Question 6

What does the pectoralis major make up?

Answer 6

Most of the anterior wall of the axilla

Question 7

What does the pectoralis major have?

Answer 7

Two heads- a clavicular head, and a sternocostal head

Question 8

What is the proximal attachment of the clavicular head of the pectoralis major?

Answer 8

Anterior surface of medial half of clavicle

Question 9

What is the proximal attachment for the sternocostal head of the pectoralis major?

Answer 9

Anterior surface of sternum, superior 6 costal cartilages, aponeurosis of external oblique muscle

Question 10

Where is the insertion of the pectoralis major?

Answer 10

The lateral lip of the intertubercular sulcus of humerus

Question 11

How can the two heads of the pectoralis major work?

Answer 11

Independently or synergistically

Question 12

What do the two heads of the pectoralis major produce when working together?

Answer 12

Adducts and medially rotates the humerus at the shoulder, and draws the scapula anteriorly and inferiorly

Question 13

What does the clavicular head of the pectoralis major do when acting alone?

Answer 13

Flexes humerus

Question 14

What does the sternocostal head of the pectoralis major do when acting alone?

Answer 14

Extends the humerus from the flexed position

Question 15

What innervates the pectoralis major?

Answer 15

Lateral and medial pectoral nerve, derived from the brachial plexus
The clavicular head by C5 and C6
The sternocostal head C7, C8 and T1

Question 16

What is the arterial supply of the pectoralis major?

Answer 16

Pectoral and deltoid branches of the thoracoacromial artery, anterior intercostal arteries and perforating branches of internal thoracic artery

Question 17

How does the pectoralis minor muscle differ from the pectoralis major?

Answer 17

It is much smaller, and more posterior

Question 18

What does the pectoralis form?

Answer 18

With the pectoralis major, forms part of the anterior wall of the axilla

Question 19

What shape is the pectoralis minor?

Answer 19

Triangular

Question 20

Where is the proximal attachment of the pectoralis minor?

Answer 20

3rd-5th ribs near the costal cartilages

Question 21

What is the distal attachment of the pectoralis minor?

Answer 21

Medial border and superior surface of coracoid process of scapula

Question 22

What does the attachment of the pectoralis minor to the scapula form?

Answer 22

A ‘bridge’, which vessels passing into the upper limb must travel underneath

Question 23

What is the function of the pectoralis minor?

Answer 23

Stabilises the scapula by drawing it inferiorly and anteriorly against the thoracic wall (depressing the shoulder)

Question 24

What is the pectoralis minor innervated by?

Answer 24

Medial pectoral nerve (C8, T1)

Question 25

What is the arterial supply of the pectoralis minor?

Answer 25

Pectoral and deltoid branches of thoracoacromial artery

Question 26

Where is the serratus anterior muscle found?

Answer 26

More laterally in the chest

Question 27

What does the serratus anterior muscle form?

Answer 27

The medial wall of the axilla

Question 28

What does the serratus anterior consist of?

Answer 28

Several strips

Question 29

Where is the proximal attachment of the serratus anterior?

Answer 29

External surfaces of lateral parts of 1st-8th ribs

Question 30

What is the distal attachment of the serratus anterior?

Answer 30

Anterior surface of the medial border of the scapula

Question 31

What is the innervation of the serratus anterior?

Answer 31

Long thoracic nerve

Question 32

What is the main function of the serratus anterior?

Answer 32

Rotate the scapula, allowing the arm to be held above 90º

Protracts the scapula and hold it against the thoracic wall

Question 33

What is the arterial supply of the serratus anterior?

Answer 33

Lateral thoracic artery

Question 34

What happens if damage to the long thoracic nerve occurs?

Answer 34

The serratus anterior muscle will become paralysed

Question 35

What is the result of paralysation of the serratus anterior?

Answer 35

When pushing with the affected limb, the scapula is no longer held against the rib cage, and protrudes out of the back- it is said to have a winged appearance

Question 36

When can the long thoracic nerve become damaged?

Answer 36

By trauma to the shoulder, repetitive movements involving the shoulder, or by structures becoming inflamed and pressing on the nerve

Question 37

What is the proximal attachment of the subclavius?

Answer 37

Junction of the 1st rib and its costal cartilage

Question 38

What is the distal attachment of the subclavius?

Answer 38

Inferior surface of the middle third of clavicle

Question 39

What is the innervation of the subclavius?

Answer 39

Nerve to subclavius

Question 40

What is the main action of the subclavius?

Answer 40

Anchors and depresses clavicle

Question 41

What is the arterial supply to the subclavius?

Answer 41

Clavicular branch of the thoracoacromial artery