Axillary ArteryWindsor University School of Medicine

outline

• Origin• Relations• parts and branches• Termination

Origin and termination

• The axillary artery begins at the lateral border of the 1st rib as the continuation of the subclavian artery and ends at the inferior border of the teres major

Relation and course

• It passes posterior to the pectoralis minor into the arm and becomes the brachial artery when it passes the inferior border of the teres major, at which point it usually has reached the humerus

PARTS

• the axillary artery is divided into three parts by the pectoralis minor

• 1st

• 2nd

• 3rd

3 parts

• The first part of the axillary artery is located between the lateral border of the 1st rib and the medial border of the pectoralis minor; it is enclosed in the axillary sheath and has one branche

- the superior thoracic artery• The second part of the axillary artery lies posterior to

pectoralis minor and has two branches the -thoracoacromial and -lateral thoracic arteries which pass medial and lateral

to the muscle, respectively.

• The third part of the axillary artery extends from the lateral border of pectoralis minor to the inferior border of teres major and has three branches.

- subscapular artery is the largest branch of the axillary artery.

- the anterior circumflex humeral and - posterior circumflex humeral

• 1st part -the superior thoracic arteryarises just inferior to the subclavius

Supply: the subclavius, muscles in the 1st and 2nd intercostal spaces, superior slips of the serratus anterior, and overlying pectoral muscles

• 2nd part-• The thoracoacromial artery,• a short wide trunk, divides into four branches

(acromial, deltoid, pectoral, and clavicular)

• The lateral thoracic artery• supplies :the pectoral, serratus anterior, and

intercostal muscles, the axillary lymph nodes, and the lateral aspect of the breast.

• 3rd part-The subscapular artery, descends along the lateral border of the subscapularis on the posterior axillary wall. terminates by dividing into the circumflex scapular and thoracodorsal arteries. Supply: muscles on the dorsum of the scapula). It participates in the anastomoses around the scapula

• The thoracodorsal artery inferior angle of the scapula ,latissimus dorsi. It also participates in the arterial anastomoses around the scapula.

• The smaller anterior circumflex humeral artery passes laterally, deep to the coracobrachialis and biceps brachii. It gives off an ascending branch that supplies the shoulder.

• The larger posterior circumflex humeral artery passes medially through the posterior wall of the axilla via the quadrangular space with the axillary nerve to supply the glenohumeral joint and surrounding muscles

Arterial Anastomoses around the Scapula

• Several vessels join to form networks on the anterior and posterior surfaces of the scapula:

• the dorsal scapular(deep transverse cervical), suprascapular, and subscapular arteries (via the circumflex scapular).

• the subscapular artery receives blood through several anastomoses with the suprascapular artery, transverse cervical artery, and intercostal arteries.

Importance of Arterial Anastomoses around the Scapula

• Ligation of the axillary artery(1st rib and subscapular artery)

• Vascular stenosis (atherosclerotic lesion )

• surgical ligation of the axillary artery between the origins of the subscapular artery and the deep artery of the arm will cut off the blood supply to the arm because the collateral circulation is inadequate

Aneurysm of the Axillary Artery

• The first part of the axillary artery may enlarge (aneurysm of the axillary artery) and compress the trunks of the brachial plexus, causing pain and anesthesia (loss of sensation) in the areas of the skin supplied by the affected nerves. Aneurysm of the axillary artery may occur in baseball pitchers because of their rapid and forceful arm movements.

Axillary vein• The axillary vein lies initially (distally) on the anteromedial side of

the axillary artery, with its terminal part anteroinferior to the artery

• This large vein is formed by the union of the brachial vein (the accompanying veins of the brachial artery) and the basilic vein at the inferior border of the teres major.

• Also has 3 parts:the initial, distal end is the third part, whereas the terminal, proximal end is the first part. The axillary vein (first part) ends at the lateral border of the 1st rib, where it becomes the subclavian vein.

Injuries to the Axillary Vein

• Wounds in the axilla often involve the axillary vein because of its large size and exposed position. When the arm is fully abducted, the axillary vein overlaps the axillary artery anteriorly. A wound in the proximal part of the axillary vein is particularly dangerous, not only because of profuse bleeding but also because of the risk of air entering it and producing air emboli (air bubbles) in the blood.