The subclavian arteries

11 The subclavian arteries


The importance of the subclavian arteries cannot be overstressed, as they are located at strategic crossroads in the human body. The thoracic inlet is one of the weak points of the human body. It was certainly better protected and more functional when our ancestors walked with four points of contact on the ground.



11.1 Anatomy review



11.1.1 Origin


The two subclavian arteries (Fig. 11.1) have different origins:



• The left subclavian artery springs directly from the aortic arch below the left common carotid artery. Because of this, on the left the artery is topographically thoracocervical and has intrathoracic relationships.


• The right subclavian artery arises from the bifurcation of the brachiocephalic trunk, behind the upper border of the right sternoclavicular joint at the level of T1. Thus, on the right the artery is exclusively cervical in its topography.


image

Fig. 11.1 Subclavian artery.


Despite these differences, the same maneuvers are used on both sides.



11.1.2 Dimensions


The subclavian artery has an average caliber of 9–12 mm. It is a bit smaller on the left, and on the right it is slightly narrower at its middle section by the isthmus. The left subclavian artery is 9 cm long and the right one is 6 cm long.



11.1.3 Pathway


The subclavian artery runs laterally, following a concave bend posteriorly. It passes above the first rib, between the scalene muscles. In its cervical segment, the artery is described in three parts: prescalene, interscalene, and postscalene.



11.1.4 Relations



Prescalene segment


The artery rests on the anterior slope of the pleural dome where it is surrounded by a nerve plexus composed of filaments from the inferior cervical ganglion and the subclavian loop (ansa subclavia).


It relates to the medial end of the clavicle and the sternoclavicular joint. The artery is crossed by the phrenic and vagus nerves. On the right, the recurrent laryngeal (branch of the vagus) loops around the subclavian artery. It also relates to the confluence of the subclavian vein and the internal jugular veins. The left subclavian artery has a more extensive relationship with the pleura and lung than does the right subclavian.



Interscalene segment


The artery arches between the anterior and middle scalene muscles. The main trunks of the brachial plexus are found posterior and superior to the artery. The subclavian vein runs in front of the anterior scalene muscles.



Postscalene segment


Here the most superficial part of the subclavian artery lies partly in the supraclavicular region and crosses the anterior lateral surface of the first rib. It is covered by the platysma, and by the superficial and middle cervical aponeuroses. It relates anteriorly to the subclavian vein and the subclavian muscle, by which it is separated from the clavicle.



11.1.5 Collaterals


All the collateral branches arise from the prescalene parts of the subclavian arteries, except the posterior scapular artery, which arises from the interscalene segment. The collateral vessels are the:



• vertebral artery


• thyrocervical trunk (formerly the thyrobicervicoscapular trunk)


• costocervical trunk (formerly the cervicointercostal)


• internal thoracic artery (formerly the internal mammary)


• posterior scapular artery.



11.1.6 Termination


The subclavian artery extends to the outer border of the first rib, where it becomes the axillary artery.



11.1.7 Irrigation territories


The areas irrigated underline the eminent role of these arteries. Many victims of ‘rabbit punch’ accidents (blows to the back of the head) show us this every day. The subclavian arteries are more or less directly involved in the blood supply to the following structures:



• spinal cord


• medulla oblongata


• pons


• cerebellum


• posterior brain


• inner ear


• posterior cranial dura mater


• breast.

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Nov 7, 2016 | Posted by in MANUAL THERAPIST | Comments Off on The subclavian arteries

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