Left subclavian vein

At a glance

English

Left subclavian vein

Latin (TA2)

Vena subclavia sinistra

System

Vein

Region

Trunk

Side

Single, on the midline

About the left subclavian vein

The left subclavian vein drains the left upper limb and returns its blood towards the heart. It is the direct continuation of the axillary vein, taking its new name at the lateral edge of the first rib, and it ends behind the sternal end of the clavicle by joining the left internal jugular vein. Their meeting point is the left venous angle, and the vessel formed is the left brachiocephalic vein. It is a wide vein, one to two centimetres across.

From the first rib the vein arches over the upper surface of the rib, in front of the scalenus anterior, while the subclavian artery passes behind that muscle. The insertion of scalenus anterior on the first rib therefore separates vein and artery, and the artery lies between the anterior and middle scalenes. In front of the vein are the clavicle and subclavius. It usually has a valve near its end, and its wall is attached to the surrounding fascia, which keeps it from collapsing.

Its main tributaries are the external jugular vein and sometimes the anterior jugular vein. Its special feature on the left is that the thoracic duct, the main lymph trunk of the body, opens into the venous angle where it joins the internal jugular. Lymph from most of the body, including fat-rich chyle absorbed from the intestine, therefore enters the bloodstream here. This makes the left subclavian vein central to the uptake of dietary fats. On the right a much smaller lymph duct drains at the corresponding angle.

Clinically the subclavian vein is a route for central venous catheters and pacing leads, being large, wide open and fairly close to the surface below the clavicle. The approach carries risks of collapsed lung, bleeding into the chest and puncture of the subclavian artery, so other veins are often preferred. The vein can be compressed or clot at the thoracic outlet, often after heavy repetitive arm use, giving a swollen, painful, bluish arm that needs prompt treatment. On the left, injury near the venous angle can also damage the thoracic duct and cause a chylous leak.

Course and drainage

Begins at

Continues the axillary vein at the lateral border of the first rib.

Drains into

Joins the left internal jugular vein behind the medial end of the clavicle, at the left venous angle, to form the left brachiocephalic vein.

Drains

Drains the left upper limb and, through the external jugular vein, parts of the scalp and neck; its junction receives the thoracic duct.