Axillary artery

Topography and syntopy

The vessel begins at the level below the clavicle in the clavipectoral triangle (trigonum clavipectorale), where the initial segment of the artery is covered by the subclavius muscle. The trunk ends at the lower border of the pectoralis major muscle, beyond which the vessel changes its name and continues as the brachial artery (a. brachialis).

Along its path, the artery lies in close proximity to other important anatomical structures. Anteriorly and medially to it runs the subclavian vein (v. subclavia). Furthermore, at various levels the artery is surrounded by the trunks and cords of the brachial plexus (plexus brachialis), which is of immense clinical significance.

Division into topographic segments

For ease of study and surgical navigation, the vessel is divided into three parts. The main landmark is the anterior wall of the axillary fossa, specifically the pectoralis minor muscle (m. pectoralis minor):

1. Part I — from the level of the clavicle to the upper border of the pectoralis minor muscle. Here, the artery lies on the upper digitations of the serratus anterior muscle and is covered anteriorly by the clavipectoral fascia.
2. Part II — located directly posterior to the pectoralis minor muscle. In this region, the cords of the brachial plexus (medial, lateral, and posterior) lie adjacent to the artery on their respective sides.
3. Part III — the segment from the lower border of the pectoralis minor muscle to the lower border of the pectoralis major muscle. Externally, the vessel borders the coracobrachialis muscle.

Branches of the axillary artery

Each of the segments gives off specific branches that supply the surrounding tissues.

Branches of the first part:

• Superior thoracic artery (a. thoracica superior) — descends medially, supplying the upper two intercostal spaces, the serratus anterior, the pectoral muscles, and the mammary gland.
• Thoracoacromial artery (a. thoracoacromialis) — perforates the clavipectoral fascia and immediately divides into four branches: clavicular (to the sternoclavicular joint and subclavius muscle), deltoid (runs in the sulcus between the deltoid and pectoralis major muscles), acromial (participates in forming the acromial network), and pectoral branches (supply the pectoral muscles and give off lateral branches to the mammary gland).

Branches of the second part:

• Lateral thoracic artery (a. thoracica lateralis) — descends along the lateral border of the pectoralis minor muscle. This is a significant source of blood supply to the lateral quadrant of the mammary gland and the axillary lymph nodes.

Branches of the third part:

• Subscapular artery (a. subscapularis) — the largest branch. After giving off branches to the subscapularis muscle, it divides into two large arteries. The first is the circumflex scapular artery (a. circumflexa scapulae), which passes posteriorly through the triangular space into the infraspinous fossa. The second is the thoracodorsal artery (a. thoracodorsalis), which descends along the lateral wall of the axillary fossa to the latissimus dorsi muscle.
• Anterior humeral circumflex artery (a. circumflexa humeri anterior) — runs laterally beneath the short head of the biceps brachii and the coracobrachialis muscle, winding around the surgical neck of the humerus anteriorly.
• Posterior humeral circumflex artery (a. circumflexa humeri posterior) — courses posteriorly through the quadrilateral space along with the axillary nerve, winding around the surgical neck of the humerus posteriorly.

Anastomoses and clinical significance

The branches of the axillary artery form dense vascular networks. The most significant of these are the scapular network (rete scapulare) and the acromial network (rete acromiale). The scapular network connects the systems of the axillary and subclavian arteries. If ligation of the main trunk becomes necessary, these anastomoses provide collateral (bypass) blood flow.

In plastic surgery, the thoracodorsal artery plays a crucial role as the main axial vessel in forming the latissimus dorsi flap.

In addition, the anterior and posterior humeral circumflex arteries lie closely against the surgical neck of the humerus and supply blood to the capsule of the shoulder joint. These are at high risk of injury during shoulder dislocations and fractures.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Topography of the axillary fossa and its walls
• Formation of the trunks and cords of the brachial plexus
• Anatomy of the triangular and quadrilateral spaces
• Blood supply sources of the mammary gland
• Structure of the scapular and acromial anastomotic networks

Other topics in the "Angiology" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.