Pectoral region

Question 1

4 muscles of pectoral region

Answer 1

Pectoralis major
Pectoralis minor
Serratus anterior
Subclavius

Question 2

Pectoralis major 2 heads

Answer 2

Sternal and Clavicular

Question 3

Pectoralis major origin

Answer 3

Clavicular:
- Anterior surface medial clavicle

Sternocostal:
- Anterior surface of sternum
- Upper 6 costal cartilages
- Aponeurosis of external oblique muscle

Question 4

Pectoralis major insertions

Answer 4

Intertubercular sulcus of humerus

Question 5

Function and innervation of pectoralis major

Answer 5

• Medially rotates
• Adducts (mainly sternal head)
• Flexes the upper limb (clavicular head)

Innervation: lateral and medial pectoral nerve, branches of the lateral cord of the brachial plexus and the medial cord of the brachial plexus

Question 6

Pectoralis minor origin and insertion

Answer 6

Origin: 3rd-5th rib
Insert: Coracoid process of scapula

Question 7

Pectoralis minor function and innervation

Answer 7

Function:
Stabilises scapula by pulling it anteroinferiorly against thoracic wall

Innervation:
Medial pectoral nerve

Question 8

Serratus anterior origin and insertion

Answer 8

Originates as separate ‘slips’ from the lateral aspects of ribs 1-8

Insertion: medial border of scapula

Question 9

Serratus anterior function

Answer 9

• Protracts scapula
• Rotates medial boarder of scapula anteroinferiorly which allows the upper limb to abduct above 90 degrees at the shoulder
• Holds scapula against rib cage

Question 10

Serratus anterior innervation

Answer 10

Long thoracic nerve

Question 11

Clinical relevance long thoracic nerve

Answer 11

• Innervates serratus anterior which holds scapula against ribs
• If damaged, winging of scapula occurs (medial border protrudes posteriorly)
• Can be seen when pushing against wall

Question 12

How can long thoracic nerve be damaged?

Answer 12

Trauma (to neck/shoulder)
Heavy backpack
Surgical trauma during mastectomy (stripped with axillary nodes)

Question 13

What occurs when there is high metabolic demand (eg hyperventilating)?

Answer 13

Pectoralis major, minor and serratus anterior can act as accessory muscles of respiration by elevating ribs and allowing increased volume of thoracic cavity

Question 14

Coracobrachialis importance

Answer 14

Identify brachial plexus

Question 15

Coracobracialis O and I

Answer 15

O: Coracoid process scapula
I: medial side of humoral shaft (same level as deltoid tubercle)

Question 16

Coracobrachialis action and innervation

Answer 16

Flex arm at shoulder
Weak adductor of arm
Innervation: Musculocutaneous nerve

Question 17

Subclavius O and I

Answer 17

O: 1st rib and costal cartilage
I: Inferior surface of middle 3rd of clavicle

Question 18

Subclavius Action and innervation

Answer 18

Action: anchors and depresses clavicle
Innervation: Nerve to subclavius

Question 19

Deltoid muscle structure

Answer 19

Shaped like triangle (greek letter delta)

Anterior, middle and posterior parts

Question 20

Deltoid O and I

Answer 20

O: Anterior border and upper surface of clavicle
I: Deltoid tuberosity on lateral humerus

Question 21

Actions deltoid

Answer 21

Anterior: Flex and medially rotate arm
Middle; abduct arm from 15-90 degrees
Posterior: Extend and laterally rotate arm

Question 22

Innervation deltoid

Answer 22

Axillary nerve

Question 23

Arterial supply upper limb (proximal to distal)

Answer 23

Subclavian artery
Axillary artery
Brachial artery
Radial artery
Ulnar artery 

(SABRU)

Question 24

Axillary artery where

Answer 24

deep to pec minor

enters lateral border of first rib

Question 25

Parts of axillary artery

Answer 25

1st - proximal to pectoralis minor
2nd - posterior to pectoralis minor
3rd - distal to pectoralis minor

Question 26

Main branches of axillary artery

Answer 26

1st -
Superior thoracic

2nd -
Thoracoacromial artery,
lateral thoracic artery

3rd -
Subscapular artery
Anterior circumflex humeral
Posterior circumflex humeral

Question 27

What do anterior and posterior circumflex humeral arteries form?

Answer 27

Anastomotic network around surgical neck of humerus

Can be damaged in fractures of this region

Question 28

Axillary vein

Answer 28

First part receives supply from cephalic vein

Question 29

Superficial veins of upper limb

Answer 29

Cephalic (pre axial border lateral) and Basilic (post axial border, medial)