axilla and brachial plexus

Question 1

what is an axilla

Answer 1

an area of transitition between neck and arm

Question 2

Gateway to upper limb

Answer 2

• All major structures passing into and out of
  upper limb pass through axilla

Question 3

irregularly shaped pyramid space

Answer 3

• Inlet
  
  • Four sides
  • Floor (Base)

Question 4

structures forming axilla

Answer 4

• Clavicle, scapula and humerus
  
  • Upper thoracic wall
  • Related muscles

Question 5

what is the axillary inlet horizontally oriented with

Answer 5

triangular shape continuous superiorly with neck

Question 6

apex directed laterally

Answer 6

near medial aspect of coracoid process

Question 7

margins completely formed by bone

Answer 7

• Medial margin: Lateral border of first rib
  
  • Anterior margin: Posterior surface of clavicle
  • Posterior margin: Superior border of scapula up to
    coracoid process

Question 8

how do major vessels and nerves pass between neck and axilla

Answer 8

by crossing over lateral border of first rib and through axillary inlet

Question 9

when crossing lateral margin of first rib and entering axilla what does subclavian artery become

Answer 9

axillary artery

Question 10

what does AXILLARY VEIN become as it passes over lateral margin of 1st rib and exists axilla

Answer 10

subclavian vein

Question 11

what separates artery and vein

Answer 11

insertion of anterior scalene muscle as they pass over first rib

Question 12

posterior-trunks of brachial plexus
axillary artery
anterior-axillary vein

Question 13

what lies directly on first rib

Answer 13

Inferior trunk of brachial plexus, subclavian artery and subclavian vein

Question 14

anterior axillary fold

Answer 14

• Fold of skin
  
  • Anteroinferior border of axilla
  • Inferior margin of pectoralis major muscle lies underneath

Question 15

clavipectoral fascia

Answer 15

-Thick sheet of connective tissue
-Connects clavicle to floor of axilla
-Encloses subclavius and pectoralis minor muscles
- Spans gap between muscles
-Cephalic vein, thoraco-acromial artery, and lateral pectoral nerve pass between subclavius and pectoralis minor muscles
-Lateral thoracic artery: Leaves axilla by passing through fascia inferior to pectoralis minor muscle
-Medial pectoral nerve: Leaves axilla by penetrating pectoralis minor muscle and fascia (Branches occasionally pass around lower margin of muscle and through fascia)

Question 16

medial wall consists of

Answer 16

• Upper thoracic wall (ribs and related intercostal tissues) plus serratus anterior muscle

Question 17

intercostobrachial nerve

Answer 17

• Lateral cutaneous branch of 2nd intercostal nerve
  
  • Passes directly through wall and into axilla
  • Communicates with medial cutaneous nerve of arm in
    axilla and supplies skin on upper posteromedial side of arm

Question 18

lateral wall

Answer 18

-Narrow
-Formed entirely by intertubercular sulcus of humerus

Question 19

posterior wall

Answer 19

-Bony framework formed by costal surface of scapula
-Muscles of wall: subscapularis, teres major, latissimus dorsi, long head of triceps brachii

Question 20

posterior axillary fold

Answer 20

• Fold of skin
  
  • Posteroinferior border of axilla
  • Terminal part of teres major muscle and tendon of
    latissimus dorsi muscle lie underneath
  • Anterior axillary fold more superior than posterior fold

Question 21

Gaps between muscles and bones form apertures

Answer 21

• Allow structures to pass between axilla, posterior scapular
  and deltoid regions and posterior compartment of arm

Question 22

Quadrangular space

Answer 22

Passageway between axilla and posterior scapular & deltoid regions

Question 23

boundaries of quadrangular space

Answer 23

• Inferior margin of subscapularis muscle
  
  • Surgical neck of humerus
  • Superior margin of teres major muscle
  • Lateral margin of long head of triceps brachii muscle

Question 24

^above space^Structures traversing:

Answer 24

• Axillary nerve
  
  • Posterior circumflex humeral artery
  • Posterior circumflex humeral vein

Question 25

triangular space

Answer 25

Passageway between axilla and posterior scapular region

Question 26

triangular space boundaries

Answer 26

• Medial margin of long head of triceps brachii muscle
  
  • Superior margin of teres major muscle
  • Inferior margin of subscapularis muscle

Question 27

triangular space structures traversing

Answer 27

• Circumflex scapular artery
  
  • Circumflex scapular vein

Question 28

triangular interval

Answer 28

Passageway between axilla and posterior compartment of arm

Question 29

triangular interval boundaries

Answer 29

• Lateral margin of long head of triceps brachii muscle
  
  • Shaft of humerus
  • Inferior margin of teres major muscle

Question 30

triangular interval structures traversing

Answer 30

• Radial nerve
  
  • Profunda brachii artery

Question 31

floor

Answer 31

Formed by fascia and a dome of skin
- Spans distance between inferior margins of walls
Supported by clavipectoral fascia

Structures enter and exit axilla immediately lateral to floor
- Convergence of anterior and posterior walls
- Continuation of axilla with anterior compartment of arm

Question 32

contents of axilla

Answer 32

Biceps brachii muscle (proximal part)
Coracobrachialis (proximal part)
Axillary artery
Axillary vein
Brachial plexus
Lymph nodes
Axillary process of mammary gland (breast)

Question 33

mammary gland(breast)

Answer 33

• Within superficial fascia overlying thoracic wall
  
  • Superolateral region extends along inferior margin of
    pectoralis major muscle (toward axilla)
    -Extension may pass around muscle margin to penetrate deep fascia and enter axilla
    ^^^^^^^
    axillary process
    ^^^^^^^^
    rarely reaches as high as axillary apex

Question 34

axillary artery

Answer 34

Subclavian artery becomes axillary artery at lateral margin of first rib

Question 35

Axillary artery separated into 3 parts by pectoralis minor muscle (crosses vessel anteriorly)

Answer 35

• 1st part: Proximal to pectoralis minor muscle
  
  • 2nd part: Posterior to pectoralis minor muscle
  • 3rd part: Distal to pectoralis minor muscle

Question 36

axillary artery to brachial artery

Answer 36

becomes brachial artery at inferior margin of teres major muscle