Subclavian artery: Regional approach and mnemonic
The subclavian artery is a paired arterial vessel of the thorax. The right and left arteries have different origins; the left subclavian artery originates directly from the aortic arch, while the right subclavian artery originates from the brachiocephalic trunk.
In relation to the anterior scalene muscles, the subclavian artery can be divided into three segments that include the prescalene, retroscalene, and postscalene parts.
This article will discuss the anatomy and function of the subclavian artery.
Left subclavian artery: Aortic arch
Right subclavian artery: Brachiocephalic trunk
Internal thoracic artery
Dorsal scapular artery
Mnemonic: 'VIT C and D'
|Upper limbs, thorax, neck region, brain
Origin and course
The subclavian arteries are among the largest arteries of the thorax and neck regions and are located just inferior to the clavicles.
The left subclavian artery arises directly from the aortic arch, just distal to the origin of the left common carotid artery. The right subclavian artery originates from the brachiocephalic trunk along with the right common carotid artery. Although the two subclavian arteries originate from the different arterial vessels, they follow the same course within the neck region.
From their origin, the left and right subclavian arteries arch superolaterally and course towards the axillary region. Along their course, they pass posterior to the anterior scalene muscles and anterior to the middle scalene muscles. Based on their relation to the anterior scalene muscles, the subclavian arteries can be divided into three parts which include:
- Prescalene part - the part before the medial border of the anterior scalene muscle.
- Retroscalene part - the part located posterior to the anterior scalene muscle.
- Postscalene part - the part after the lateral border of the anterior scalene muscle.
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Branches and supply
Along its course, the subclavian artery gives off several branches that supply various structures of the upper body. These branches can be organized into three groups according to the part of the artery from which they arise.
Branches of the first (prescalene) part of the artery include:
- The vertebral artery is the first branch of the subclavian artery. It courses superiorly along each side of the neck region and ultimately merges with its counterpart at the pontomedullary junction to form the basilar artery. The vertebral artery supplies the upper spinal cord, brainstem, cerebellum and posterior part of the brain.
- The internal thoracic artery, in contrast to the vertebral artery, descends along the inner surface of the anterior chest wall. It gives rise to several branches along its course to supply the anterior thoracic wall and the breast.
- The thyrocervical trunk is a short and wide branch that arises close to the medial border of the anterior scalene muscle. Its major branch, the inferior thyroid artery, supplies several important structures in the neck including the larynx, pharynx, trachea, platysma, esophagus, thyroid and parathyroid glands).
The second (retroscalene) part gives off a single branch called the costocervical trunk. This is a short artery that supplies the posterior cervical muscles and upper thorax.
The third (postscalene) part of the subclavian artery also usually has only one branch, the dorsal scapular artery. This artery provides arterial supply for muscles of the upper back and shoulder including the trapezius muscle, levator scapulae muscle and rhomboid muscles.
Test your knowledge of the main arteries of the head and neck with this quiz.
One smart and fun way to remember the correct order and names of the most important branches of the subclavian artery is to learn the mnemonic 'VIT C and D'. It covers the following structures:
- Vertebral artery
- Internal thoracic artery
- Thyrocervical trunk
- Costocervical trunk
- Dorsal scapular artery
Subclavian steal syndrome
Subclavian steal syndrome is a condition in which the subclavian artery is occluded proximal to the origin of the vertebral artery. When this occurs, blood can reverse its flow, which results in 'stealing' of blood from the vertebral artery. This syndrome is usually asymptomatic and may be found accidentally during ultrasonography (US), angiography, or physical examination (reduced pulse or blood pressure on one upper limb). In some cases, however, patients may develop ischemia (lack of arterial blood flow) to the upper limb. Patients may also develop neurologic symptoms in situations of increased demand such as during exercise due to posterior circulation ischemia (vertebrobasilar insufficiency).
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