Anatomy of the axilla

Question 1

What are the muscles of the pectoral region?

Answer 1

1) Pectoralis major
2) Pectoralis minor
3) Subclavius

Question 2

What is the origin of the pectoralis major muscle?

Answer 2

1) Clavicular head

• Medial half of the front of the clavicle (attached to the anterior surface of the clavicle)

2) Sterno-costal head

1) Anterior surface of the sternum

2) Upper 6 costal cartilages

3) Aponeurosis of the external oblique muscle

Question 3

Which part of the pectoralis major muscle arises from the medial half of the front of the clavicle?

Answer 3

The clavicular head

Question 4

Where is the pectoralis major inserted?

Answer 4

It is inserted into the lateral lip of the bicipital groove of the humerus via a flattened bilaminar tendon

Question 5

What are the nerve supply of the pectoralis major muscle?

Answer 5

1) Lateral pectoral nerve

2) Medial pectoral nerve

Question 6

What is the origin of the pectoralis minor?

Answer 6

3rd, 4th & 5th rib close to their cartilages

Question 7

What is the movements produced by the pectoralis major muscle?

Answer 7

Clavicular head:
1) Flexion of the arm

Sterno-clavicular head:
1) Brings the flexed arm to the resting position

The two heads (clavicular & sterno-costal):
1) Adduction
2) Medial rotation of the arm

Question 7

Where is the pectoralis minor inserted?

Answer 7

Into the medial border and upper surface of the coracoid process of the scapula

Question 7

What is the nerve supply of the pectoralis minor?

Answer 7

The medial pectoral nerve

Question 8

What are the movements of the pectoralis minor muscle?

Answer 8

1) Brings the scapula downward and forward

2) Depresses the shoulder

3) Elevates the ribs of origin (3-5) in forced inspiration

Question 9

What is the origin of the subclavius?

Answer 9

The upper surface of the 1st rib close to its costal cartilage

Question 10

Where is the subclavius inserted?

Answer 10

In the groove under the clavicle surface of the 1/3 intermediate

Question 11

What are the nerve supply of the subclavius?

Answer 11

Upper trunk of brachial plexus C5 & 6

Question 12

What is the function of the subclavius muscle?

Answer 12

1) Steadies the clavicle when moving the shoulder girdle

2) A buffer that protects great vessels & nerves from the bones

Question 13

What is the clavipectoral fascia?

Answer 13

• A strong fibrous sheet situated under cover of the clavicular head of the pectoralis major
• It occupies the gap between the clavicle and the pectoralis minor

Question 14

Where is the clavipectoral fascia attached?

Answer 14

1) Medially it is attached to the 1st rib

2) Laterally it is attached to the coracoid process

3) From above it splits to enclose the subclavius and attach to the clavicle

4) From below it encloses the pectoralis minor

Question 15

What is the suspensory ligament?

Answer 15

It is the downward continuation of the clavipectoral fascia which joins the fascial floor of the axilla

Question 16

what forms the costo-coracoid membrane?

Answer 16

It is the clavipectoral fascia, forming this membrane as it moves downwards from the subclavius to the pectoralis minor

Question 17

What is the function of the clavipectoral fascia?

Answer 17

1) Protects the content of the axilla via filling the gap between the clavicle and pectoralis minor

2) The suspensory ligament raises the skin of the armpit when the clavicle is elevated

Question 18

What are the structures that pierces the clavipectoral fascia?

Answer 18

1) Cephalic vein
2) Thoraco-acromial artery
3) Lateral pectoral nerve
4) Medial pectoral nerve
5) Lymphatic vessels

Question 19

Which structure maintains the concavity of our axilla when it is raised?

Answer 19

The suspensory ligament of the clavipectoral fascia

Question 20

Which nerve innervates both the pectoralis major and minor?

Answer 20

Medial pectoral nerve (which branches from the medial cord)

Question 21

Describe the axilla

Answer 21

Pyramidal shaped space between the upper part of the arm and the side wall of the chest it has (lateral, anterior, posterior, middle walls, apex & a big base)

Question 22

Describe the apex of the axilla

Answer 22

• Triangular bony space bounded by:

1) Anteriorly, posterior surface of the clavicle

2) Posteriorly, upper border of the scapula

3) Medially, outer border of the 1st rib

Question 23

Describe the base of the axilla

Answer 23

It is directed downwards and formed by the skin and the axillary fascia - Basically the armpit

Question 24

What covers the anterior wall of the axilla?

Answer 24

1) Pectoralis major 2) pectoralis minor 3) Subclavius 4) Clavipectoral fascia

Question 25

What forms the posterior wall of the axilla?

Answer 25

1) Subscapularis 2) Teres major 3) Latissimus dorsi 4) Scapula

Question 26

What forms the medial wall of the axilla?

Answer 26

1) Upper 2nd-6th rib 2) Upper 6 intercostal muscles 3) The upper part of serratus anterior

Question 27

What forms the lateral wall of the axilla?

Answer 27

Biceps muscles and the intertubercular groove (bicipital groove)

Question 28

Describe the surface anatomy of the axilla

Answer 28

1) Anterior axillary line (formed by the inferolateral border of pectoralis major) 2) Midaxillary line (middle of the axilla) 3) Posterior axillary line (formed by the latissimus dorsi muscle and teres major)

Question 29

What are the contents of the axilla?

Answer 29

1) Axillary vessels 2) Axillary lymph nodes 3) Axillary tail of breast 4) Axillary fat and loose areolar tissue 5) Cords and branches of brachial plexus

Question 30

What is meant by the brachial plexus?

Answer 30

It is a network of nerves that originates from the spinal cord and controls muscle movement and sensation in the 1) Shoulder 2) Arm 3) Hand

Question 31

What are the different axillary lymph nodes?

Answer 31

1) Anterior (Pectoral): located at the inferior border of pectoralis minor 2) Posterior (subscapular): over subscapularis 3) Lateral (humeral): draining from the upper limb 4) Central: in the center 5) Apical: running with the axillary vein at the apex of the axilla

Question 32

What are the body regions that drains into the lateral lymph node?

Answer 32

From the whole upper limb except few lymphatics accompany cephalic vein.

Question 33

What are the body parts that drains into the posterior lymph node?

Answer 33

upper part of the trunk posteriorly, Axillary tail of the breast

Question 34

What are the body parts that drains into the anterior lymph node?

Answer 34

Upper part of the trunk anteriorly, Lateral & central parts of the breast

Question 35

Which nodes empty their contents into the central node?

Answer 35

- Located in the center 1) Anterior 2) Posterior 3) Lateral

Question 36

Which body parts and lymph nodes empty into the apical node?

Answer 36

1) Upper part of the breast, which accompany cephalic vein 2) Lateral node 3) Posterior node 4) Anterior node

Question 37

The content of the apical lymph node gets emptied into where?

Answer 37

1) Subclavian lymph trunk Then from the left side it goes to the thoracic duct and Right lymphatic duct from the right side

Question 38

Describe the origin of the axillary artery

Answer 38

- It arises from the aortic arch which give rise to the subclavian artery, and once its passes the outer border of the 1st rib it becomes the axillary artery

Question 39

What are the divisions of the axillary artery in the axilla?

Answer 39

it is divided into 3 regions by the pectoralis minor muscle 1) Proximal 2) Deep 3) After P.minor once it reaches Teres major it changes to become the brachial artery

Question 40

What are the branches of the axillary artery?

Answer 40

1) First part will give the superiothoracic artery 2) The medial (deep into the pectoralis minor) will give thoracoacromial & lateral thoracic artery 3) The third part after the pectoralis minor and before teres major will give rise to (subscapularis artery, antero and posterio circumflex humeral artery "these two artery will anastomose around the surgical neck of the humerus)

Question 41

What is the origin of the serratus anterior muscle?

Answer 41

The 8 digitation of the outer surface of the upper 8 ribs

Question 42

Where is the insertion of the serratus anterior muscle?

Answer 42

1) The 1st digitation is inserted in the costal surface of the superior angle 2) The 2nd & 3rd digitations are inserted to the whole length of the costal surface of the medial border 3) The lower 5 digitations are inserted to the costal surface of the inferior angle

Question 43

What is the nerve supply of the serratus anterior muscle?

Answer 43

Long thoracic nerve

Question 44

What is the function of the serratus anterior muscle?

Answer 44

1) Protracts the scapula forward 2) The lower 5 digitations draw the lower angle of the scapula forward and assist in rotating the scapula upward "raises the arm above the head"

Question 45

What happens if you injured the long thoracic nerve?

Answer 45

- It passes down the lateral thoracic wall on the external surface of the serratus anterior muscle It causes the loss of function of the serratus anterior muscle and causes winging of the scapula - It is highly vulnerable to damage during superficial injuries