Subclavian ArteryEdit
The subclavian artery is a principal vessel of the upper chest and shoulder region, delivering oxygenated blood to the upper limb, portions of the neck, and the thorax. On the right side, it originates as a branch of the Brachiocephalic trunk; on the left, it arises directly from the Aortic arch. From its origin to its distal continuation, it travels laterally and passes between muscular and bony structures near the clavicle, where it becomes the Axillary artery at the lateral border of the first rib. Its course and branches are clinically important in trauma, vascular disease, and surgical or radiologic procedures involving the upper extremity.
The artery’s typical pattern and its common variants have practical implications for clinicians. Because of its proximity to the clavicle and the first rib, it is susceptible to injury in falls or blunt trauma, and its branches contribute to collateral circulation in cases of disease affecting adjacent vessels. The subclavian artery also serves as an access route for certain interventional procedures, including catheter-based therapies that target the central circulation. Understanding its anatomy is essential for surgeons performing clavicular or thoracic procedures, radiologists planning imaging studies, and physicians evaluating upper-limb ischemia or neurovascular symptoms.
Anatomy
Origin and course - Right subclavian artery: begins as a branch of the Brachiocephalic trunk and courses laterally, usually passing anterior to the apex of the right lung and posterior to the Scalene muscles muscle before crossing the first rib. - Left subclavian artery: arises directly from the Aortic arch and follows a parallel course to the right-side counterpart, crossing the first rib near the clavicle.
- At the lateral border of the first rib, the subclavian artery becomes the Axillary artery as it enters the axillary region of the shoulder.
Relations and relations to structures - The artery runs in close relation to the Scalene muscles (notably the anterior scalene), the first rib, and the clavicle, and it lies above several venous and nerve structures that traverse the thoracic outlet. - It lies superior to the apex of the lung and has intimate relationships with nearby nerves, including the brachial plexus in its distal course.
Branches - The branches of the subclavian artery are traditionally described in three parts relative to the anterior scalene muscle, with contributions that can vary among individuals: - First part (medial to the scalene): often gives rise to the Vertebral artery, the Thyrocervical trunk (which then branches into the inferior thyroid, transverse cervical, and suprascapular arteries), and the Internal thoracic artery (also called the Internal thoracic artery in many texts). - Second part (posterior to the scalene): commonly gives rise to the Costocervical trunk (which supplies deep neck and upper intercostal regions). - Third part (lateral to the scalene): may give rise to the Dorsal scapular artery in some individuals, though this branch can also originate from the thyrocervical trunk or directly from the subclavian as an anatomic variant. - The vertebral artery, which ascends to contribute to the posterior circulation of the brain, is a key branch and traverses the transverse foramina of the cervical vertebrae before entering the skull.
Variations - Anatomical variants are common. Some individuals have a persistent costocervical trunk supplying deep cervical and intercostal branches differently; others may have a dorsalis scapulae branch arising from the subclavian or from the thyrocervical trunk. - A notable vascular variant is the aberrant right subclavian artery (arteria lusoria), where the right subclavian arises distal to the left subclavian and courses behind the esophagus in some cases, with potential clinical significance for esophageal compression in rare circumstances.
Function and clinical significance
Primary function - The subclavian artery supplies oxygenated blood to the upper limb via its distal continuation as the Axillary artery, as well as to portions of the neck and thoracic wall through its branches. Its patency is essential for perfusion of the shoulder girdle, arm, and associated musculature.
Clinical significance - Trauma: Fractures of the clavicle or severe shoulder injuries can damage the subclavian artery or its branches, risking hemorrhage or limb ischemia. - Thoracic outlet syndrome: Compression of the subclavian artery (and sometimes the brachial plexus) within the thoracic outlet can produce vascular symptoms in the upper limb, including pain, numbness, or diminished pulses. - Aneurysm and dissection: Subclavian artery aneurysms or arterial dissections, though less common than lesions in other arteries, are important causes of chest or shoulder symptoms and may require surgical or endovascular treatment. - Atherosclerosis and stenosis: As with other large arteries, atherosclerotic disease can narrow the subclavian segments, potentially causing arm claudication or contributing to vertebrobasilar insufficiency if flow to the vertebral artery is affected. - Interventional access: The subclavian route is used for certain vascular interventions, including central venous access approaches and, in some cases, catheter-based therapies for coronary or peripheral vessels. Knowledge of its course is critical to minimize complications during puncture or device placement.
Imaging and diagnosis - Noninvasive imaging, such as duplex ultrasound, CTA (computed tomography angiography), and MRA (magnetic resonance angiography), is used to assess patency, anatomy, and branch patterns. - Invasive angiography may be employed for diagnostic clarity or to guide therapeutic procedures, including stent placement or repair of aneurysms.
Interventional and surgical considerations - When planning surgical exposure or endovascular access, clinicians account for the subclavian artery’s relationship to the clavicle, first rib, and surrounding nerves and venous structures. - Alternate pathways and collateral circulation are considered in procedures involving the arm or neck, including bypass or revascularization strategies when disease affects the subclavian artery.