Muscles of the Pectoral Region Flashcards Preview

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Flashcards in Muscles of the Pectoral Region Deck (41):
1

How many muscles lie in the pectoral region?

4

2

What do the muscles in the pectoral region do?

Exert a force on the upper limb

3

What are the muscles of the pectoral region?

Pectoralis major
Pectoralis minor 
Serratus anterior 
Subclavius

4

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

Pectoralis major

5

What shape is the pectoralis major?

Large, fan shaped

6

What does the pectoralis major make up?

Most of the anterior wall of the axilla

7

What does the pectoralis major have?

Two heads- a clavicular head, and a sternocostal head

8

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

Anterior surface of medial half of clavicle

9

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

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

10

Where is the insertion of the pectoralis major?

The lateral lip of the intertubercular sulcus of humerus

11

How can the two heads of the pectoralis major work?

Independently or synergistically

12

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

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

13

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

Flexes humerus

14

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

Extends the humerus from the flexed position

15

What innervates the pectoralis major?

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

16

What is the arterial supply of the pectoralis major?

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

17

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

It is much smaller, and more posterior

18

What does the pectoralis form?

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

19

What shape is the pectoralis minor?

Triangular

20

Where is the proximal attachment of the pectoralis minor?

3rd-5th ribs near the costal cartilages

21

What is the distal attachment of the pectoralis minor?

Medial border and superior surface of coracoid process of scapula

22

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

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

23

What is the function of the pectoralis minor?

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

24

What is the pectoralis minor innervated by?

Medial pectoral nerve (C8, T1)

25

What is the arterial supply of the pectoralis minor?

Pectoral and deltoid branches of thoracoacromial artery

26

Where is the serratus anterior muscle found?

More laterally in the chest

27

What does the serratus anterior muscle form?

The medial wall of the axilla

28

What does the serratus anterior consist of?

Several strips

29

Where is the proximal attachment of the serratus anterior?

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

30

What is the distal attachment of the serratus anterior?

Anterior surface of the medial border of the scapula

31

What is the innervation of the serratus anterior?

Long thoracic nerve

32

What is the main function of the serratus anterior?

Rotate the scapula, allowing the arm to be held above 90º
Protracts the scapula and hold it against the thoracic wall

33

What is the arterial supply of the serratus anterior?

Lateral thoracic artery

34

What happens if damage to the long thoracic nerve occurs?

The serratus anterior muscle will become paralysed

35

What is the result of paralysation of the serratus anterior?

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

36

When can the long thoracic nerve become damaged?

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

37

What is the proximal attachment of the subclavius?

Junction of the 1st rib and its costal cartilage

38

What is the distal attachment of the subclavius?

Inferior surface of the middle third of clavicle

39

What is the innervation of the subclavius?

Nerve to subclavius

40

What is the main action of the subclavius?

Anchors and depresses clavicle

41

What is the arterial supply to the subclavius?

Clavicular branch of the thoracoacromial artery