Anatomy, Thorax, Subclavian Arteries

Excerpt

The subclavian arteries lie just below the clavicles, providing blood supply to the bilateral upper extremities with contributions to the head and neck. The right subclavian artery derives from the brachiocephalic trunk, while the left subclavian artery originates directly from the aortic arch. The subclavian arteries course laterally between the anterior and middle scalene muscles. The distal limit of the subclavian artery is the lateral border of the first rib, where it becomes the axillary artery. Additional branches of the subclavian arteries include the internal thoracic artery, vertebral artery, costocervical trunk, thyrocervical trunk, and the dorsal scapular artery. During development, the left subclavian arises from the seventh intersegmental artery and the right subclavian develops in segments; proximally from the fourth aortic arch, medially from the dorsal aorta and distally from the seventh intersegmental artery.

Multiple aspects of the nervous system travel alongside or near the subclavian arteries. They include the sympathetic trunk, the vagus nerve, parts of the brachial plexus, the phrenic nerve and the right recurrent laryngeal nerve. Alongside these neuronal pathways, the arteries are also linked closely to venous pathways such as the internal jugular veins and vertebral veins. These vessels make an interconnected highway that helps fuel the cellular processes used by the neck and upper extremity muscle groups, the brain and thyroid gland.

Clinically the subclavian arteries can be host to numerous congenital and idiopathic pathologies which can be managed with physical rehabilitation and/or surgical interventions. The most common congenital anomaly is an aberrant subclavian artery which is usually a benign condition but can be symptomatic in twenty percent of cases. Within the musculoskeletal system, a condition known as thoracic outlet syndrome involves stenosis of the middle or distal ends of the arteries and can cause impeded flow to the distal tributaries. This lack of flow can manifest and weakened pulses and lead to hosts of neurological and ischemic changes in the upper extremities. If affected primarily within the arteries themselves pathologies such as Takayasu arteritis may manifest leading to inflammatory changes within the major branches of the aortic arch, including the subclavian arteries, and can clinically be seen with bilateral bruits heard in the upper lateral anterior thorax accompanied by ischemic changes to either the head and neck or the upper extremities. Another primary issue seen with the subclavian arteries is the aptly named subclavian steal syndrome which involves primary stenosis of an artery leading to retrograde flow down the opposite subclavian artery from the vertebral arteries (arising from the subclavian arteries) leading to a "steal" of blood flow from the circle of Willis, which supplies blood to the brain. Although rare, some other issues include subclavian arterial aneurysms or congenital stenosis of either artery due to redundant tissue or an aberrant variation in the anatomical location of bones and nerves.