The Axilla

Question 1

What is the axilla?

Answer 1

Pyramidal shaped space between upper arm & lateral thoracic wall

Question 2

What are the names of the axilla boundaries?

Answer 2

Apex, Base, Anterior wall, Posterior wall, Medial wall and Lateral wall

Question 3

What structures form the apex of the axilla (also called axillary inlet)?

Answer 3

The apex forms the cervicoaxillary canal:
Anterior: Clavicle
Posterior: Superior border of scapula
Medially: Outer border of the rib

Question 4

What structures form the base of the axilla?

Answer 4

The base is formed by skin, superficial fascia & deep fascia
Anterior: Anterior axillary fold (lower border of pectoralis major)
Posterior: Posterior axillary fold (latissimus dorsi’s tendons & teres major)
Medially: Upper 4-5 ribs and chest wall
Laterally: Arm

Transverse section of axilla

Question 5

What structures form the anterior wall of the axilla?

Answer 5

Superficial: Pectoralis major
Deep: Pectoralis minor, subclavius, clavipectoral fascia and suspensory ligament of axilla

Question 6

What structures form the posterior wall of the axilla?

Answer 6

Subscapularis
Teres major
Latissimus dorsi
Long head of triceps

Question 7

What structures form the medial wall of the axilla?

Answer 7

Upper 4-5 ribs & serratus anterior
Long thoracic nerve

Question 8

What structures form the lateral wall of the axilla?

Answer 8

Intertubercular sulcus of humerus & long tendon of biceps brachii

Question 9

Contents of the axilla?

Answer 9

Brachial plexus
Axillary artery
Axillary vein
Axillary lymph nodes

Question 10

Which nerves form the brachial plexus?

Answer 10

The brachial plexus is formed by the anterior rami of C5,C6,C7,C8, and most of the anterior ramus of T1.

Question 11

Describe the route of the brachial plexus

Answer 11

It originates in the neck, passes laterally and inferiorly over rib 1, and enters the axilla

Question 12

What are the divisions of the brachial plexus?

Answer 12

Roots, Trunks, Divisions, Chords

Question 13

What are the roots of the brachial plexus?

Answer 13

Ventral rami of C5,C6,C7,C8 & T1

Question 14

What are the trunks of the brachial plexus?

Answer 14

Upper trunk: C5 & C6
Middle trunk: C7
Lower trunk: C8 & T1

Question 15

What are the divisions of the brachial plexus?

Answer 15

All the trunks divide into anterior & posterior division

Question 16

What are the chords of the brachial plexus?

Answer 16

Lateral chord: Anterior division of upper & middle trunk
Medial chord: Anterior division of lower trunk
Posterior chord: Posterior divisions of all three trunks

Question 17

What nerves originate from the roots of the brachial plexus?

Answer 17

Dorsal scapula nerve
Long thoracic nerve

Question 18

What nerves originate from the trunk of the brachial plexus?

Answer 18

Nerve to subclavius
Suprascapular nerve

Question 19

What nerves originate from the lateral chord?

Answer 19

LML
Lateral pectoral nerve
Musculocutaneous nerve
Lateral root of the median nerve

Question 20

What nerves originate from the medial chord?

Answer 20

M4U
Medial pectoral
Medial cutaneous nerve of arm
Medial cutaneous nerve of forearm
Medial root of median nerve
Ulnar nerve

Question 21

What nerves originate from the posterior chord?

Answer 21

*ULTRA
Upper subscapular
Lower subscapular
Thoracodorsal nerve
Radial nerve
Axillary nerve

Question 22

What is the axillary artery?

Answer 22

Continuation of third part of subclavian artery

Question 23

What are the parts of the axillary artery?

Answer 23

First part: Proximal to muscle
Second part: Behind the muscle
Third part: Distal to the muscle

Question 24

What are the branches of the first part of the axillary artery?

Answer 24

Superior thoracic artery

Question 25

What are the branches of the second part of the axillary artery?

Answer 25

Thoracoacromial artery Lateral thoracic artery

Question 26

What are the branches of the third part of the axillary artery?

Answer 26

The third part is subscapular **Anterior circumflex humeral**: Passes anterior to the surgical neck of the humerus **Posterior circumflex humeral**: Passes anterior to the surgical neck of the humerus

Question 27

What is the axillary vein and its location?

Answer 27

The axillary vein is a continuation of basilic vein Lies medial to axillary vein At the outer border of first rib it continues as subclavian vein

Question 28

What are the divisions of the axillary lymph nodes?

Answer 28

Posterior group (scapular group) Lateral group Central group Apical group Pectoral group

Question 29

Where does the posterior group receive lymph from?

Answer 29

From posterior wall of upper half of trunk and axillary tail of spence

Question 30

Where does the lateral group receive lymph from?

Answer 30

Upper limb

Question 31

Where does the central group receive lymph from?

Answer 31

Receive lymph from the lateral and posterior

Question 32

Where does the apical group receive lymph from?

Answer 32

Central group and upper part of the breast