The axilla and brachial Plexus

Question 1

What is the axilla?

Answer 1

A space between the upper arm and upper chest, in which important neuro-vascular structures leave and enter the upper limb by. It has the shape of a truncated triangle.

Question 2

What are the contents of the axilla?

Answer 2

Axillary artery, vein and brachial plexus. There are also lymph nodes, lymphatics and fat.

Question 3

What forms the medial border of the axilla?

Answer 3

Serratus Ant.

Question 4

What forms the posterior border of the axilla?

Answer 4

Teres major, latissimus dorsi and subscapularis.

Question 5

What forms the anterior border of the axilla?

Answer 5

Pec major/minor, ( and costocorocoid lig, clavicle, subclavius and suspensory ligament of the axilla)

Question 6

Lateral border of axilla?

Answer 6

intertubecular goove (in which the long head of biceps brachii runs)

Question 7

What forms the borders of the apex?

Answer 7

1st rib (med), clavicle (ant), sup border of scapula (post)

Question 8

If C4 is included in the BP, what is this called?

Answer 8

Prefixed brachial plexus

Question 9

If T2 is included in the BP, what is this called?

Answer 9

Postfixed brachial plexus

Question 10

What are the sup and inf boundaries of the axillary artery

Answer 10

1st rib and the inf border of teres major.

Question 11

what divides the regions of the axillary art?

Answer 11

The sup and inf borders of pec minor.

Question 12

What are the important branches of the axillary art, and what do they supply?

Answer 12

Supreme Thoracic (medial wall)
Thoracoacromial (anterior wall)
Lateral thoracic (medial wall)
Subscapular (posterior)
Anterior Humeral circumflex (lateral)
Posterior humeral circumflex (lateral)

Question 13

What are the branches of the subscapular artery

Answer 13

circumflex scapular (anastamoses with suprascapular and dorsal scapular of the subclavian art)
thoracodorsal (lower posterior wall)

Question 14

Where are the lymphnodes found?

Answer 14

In the base corners of the axilla.

Question 15

What is the pattern of lymph node drainage?

Answer 15

Pectoral, humeral/brachial and subclavian nodes drain into central nodes. These drain into apical nodes.

The pectoral nodes get 75% of drainage from the breast, the rest goes to the apical nodes directly.
Lymphatics associated with the cephalic vein also do this.

Question 16

What does the Axillary nerve supply (muscular and cut) and where does it come from?

Answer 16

Comes off the posterior cord, supplies the deltoid and teres minor and the cutaneous shoulder.

Question 17

What does the Musculocutaneous nerve supply (muscular and cut) and where does it come from?

Answer 17

Is a branch of the lateral cord. It dives into the coracobrachialis and supplies ALL the muscles of the anterior arm (b.brachii, brachialis and coracobrachilais). In the forearm it becomes the ‘lateral cutaneous nerve of the forearm’ and supplies the lateral skin of the arm.

Question 18

What does the Median nerve supply (muscular and cut) and where does it come from?

Answer 18

off lateral and medial cords. Doesn’t supply anything in arm, travels with brachial artery to forearm. DIrectly supplies:
PT, FCR, PL and FDS
Its anterior interosseous branch supplies:
PQ, FPL and 1/2 FDP
It’s recurrent branch supplies:
lateral two lumbrical, and thenar muscles (Add. Pollicis brevis, Flex. Pollicis Brevis and Opponens Pollicis)

A palmar cut branch supplies the palm and skin laterally

Common palmar digital nerves (sends two slips to the 1st and 2nd lumbricals), form proper palmar digital nerves that also have dorsal branches to supply the back of the lat 3 1/2 digits.