Arteries transport oxygen-rich blood from the heart to various tissues and organs. The axillary artery, a large vessel in the shoulder region, delivers blood to the entire upper limb, including the arm, forearm, and hand, and also supplies parts of the chest and shoulder. Understanding its position and function highlights its importance in the circulatory system.
Precise Location and Course
The axillary artery begins as a continuation of the subclavian artery at the outer border of the first rib. As it transitions into the axilla (armpit), it extends downwards, ultimately becoming the brachial artery at the lower border of the teres major muscle. Its pathway through the axilla is not straight but is significantly influenced by its relationship with the pectoralis minor muscle.
The pectoralis minor muscle divides the axillary artery into three distinct parts. The first part lies proximal to the superior border of the pectoralis minor muscle, extending from the first rib to this point. The second part of the artery is positioned directly behind the pectoralis minor muscle. The third part begins at the inferior border of the pectoralis minor and continues until it reaches the lower border of the teres major muscle, where it becomes the brachial artery. Throughout its path, the axillary artery is enclosed within a fibrous structure called the axillary sheath, alongside the axillary vein and the cords of the brachial plexus.
Key Branches and What They Supply
The axillary artery gives off several branches that distribute blood to the surrounding structures. From its first part, the superior thoracic artery emerges, providing blood supply to the upper regions of the chest wall and the pectoralis major and minor muscles.
The second part of the axillary artery gives rise to two branches. These include the thoracoacromial artery, which supplies the clavicle, deltoid muscle, and parts of the pectoral muscles, and the lateral thoracic artery, which supplies the serratus anterior muscle, both pectoral muscles, and the breast.
The third part of the axillary artery produces the most branches. The subscapular artery is the largest, branching into the thoracodorsal artery (supplying the latissimus dorsi muscle) and the circumflex scapular artery (supplying the scapula). The anterior circumflex humeral artery and the posterior circumflex humeral artery also originate from this third part. These two circumflex arteries form a network around the surgical neck of the humerus, supplying the shoulder joint and the deltoid muscle.
Why It Matters
The axillary artery holds significant medical importance. Its position makes it susceptible to injury, particularly from trauma to the armpit or shoulder dislocations, which can lead to severe bleeding or a lack of blood flow to the upper limb. Such disruptions can cause conditions like ischemia, characterized by pain, paleness, and a diminished pulse in the affected limb.
Understanding the axillary artery’s anatomy is important for healthcare professionals during surgical procedures involving the shoulder or upper arm. Surgeons rely on this knowledge to avoid damaging the artery and its branches, which is relevant in operations such as axillary lymph node dissections or shoulder repairs. The axillary artery can also be a site for arterial cannulation in certain cardiac surgeries. Its consistent location makes it a reference point for locating other structures, like the brachial plexus, a network of nerves supplying the upper limb.