The axillary artery is a major blood vessel in the upper limb that carries oxygenated blood from the heart to the arm and hand. It is a continuation of the subclavian artery and plays a crucial role in the circulatory system of the upper limb. In this article, we will explore the anatomy and clinical significance of the axillary artery.
Anatomy of the Axillary Artery
The axillary artery is a long and narrow blood vessel that begins at the outer border of the first rib and extends down to the lower border of the teres major muscle, where it becomes the brachial artery. The axillary artery is located within the axillary sheath, which is a continuation of the prevertebral fascia in the neck.
The axillary artery is divided into three parts by the pectoralis minor muscle, and each part gives off branches that supply blood to different structures in the upper limb.
First Part
The first part of the axillary artery includes the superior thoracic artery, which supplies the pectoralis major and minor muscles.
Second Part
The second part includes the acromiothoracic artery, which pierces the clavipectoral fascia and often divides into four terminal branches: the deltoid, clavicular, acromial, and pectoral (A-Acromial B-Breast C-Clavicular D-Deltoid) arteries. It also includes the lateral thoracic artery, which supplies the lower border of the pectoralis minor muscle and is larger in women as it supplies the breast.
Third Part
The third part of the axillary artery includes the subscapular artery, the largest branch of the axillary artery, with two terminal branches:
- Circumflex scapular artery
- thoracodorsal artery.
The circumflex scapular artery passes through the upper triangular space and participates in the formation of the scapular anastomosis. The thoracodorsal artery supplies the latissimus dorsi muscle. It also includes the anterior circumflex humeral artery and the posterior circumflex humeral artery (SAL SAP).
Scapular anastomoses
Scapular anastomosis refers to the network of arteries that connect the first part of the subclavian artery with the third part of the axillary artery around the scapula, or shoulder blade. This network plays an important role in providing a collateral circulation when the distal part of the subclavian artery or the proximal part of the axillary artery is blocked.
There are two main anastomosing networks around the scapula: one around the body of the scapula and the other over the acromian process of the scapula.
The anastomosis around the body of the scapula includes the following arteries:
- Suprascapular artery: a branch of the thyrocervical trunk
- Deep branch of transverse cervical artery (dorsal scapular artery): a branch of the thyrocervical trunk
- Circumflex scapular artery: a branch of the subscapular artery
The anastomosis over the acromian process of the scapula includes the following arteries:
- Acromian branches of the suprascapular artery
- Acromiothoracic artery: a branch of the axillary artery
- Posterior circumflex humeral artery: a branch of the axillary artery
Clinical Significance of the Axillary Artery
In clinical practice, the axillary artery and its branches are often encountered during surgical procedures in the upper limb. For example, during a radical mastectomy, a surgical procedure to remove breast cancer, the axillary artery and its branches are often encountered during the dissection of the axilla.
The axillary artery is also important in the management of arterial occlusions, or blockages, in the upper limb. Arterial occlusions can lead to a decrease in blood flow to the arm and hand, causing pain, numbness, and muscle weakness. Interventional radiologists may use catheters and other medical devices to access the axillary artery and perform procedures such as angioplasty or stenting to restore blood flow.
The scapular anastomosis is clinically important in cases of coarctation of the aorta, a condition in which the aorta is narrowed and blood flow is restricted. In such cases, the scapular anastomosis can provide an alternative route for blood to flow and help maintain circulation.
Quiz:
Axillary Artery
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