External jugular vein

Structure

The external jugular vein commences in the substance of the parotid gland, on a level with the angle of the mandible, and runs perpendicularly down the neck, in the direction of a line drawn from the angle of the mandible to the middle of the clavicle superficial to the sternocleidomastoid muscle.

In its course, it crosses the sternocleidomastoid muscle obliquely, and in the subclavian triangle perforates the deep fascia, and ends in the subclavian vein lateral to or in front of the scalenus anterior, piercing the roof of the posterior triangle.

It is separated from the sternocleidomastoid muscle by the investing layer of the deep cervical fascia, and is covered by the platysma, the superficial fascia, and the integument; it crosses the cutaneous cervical nerve, and its upper half runs parallel with the great auricular nerve.

Valves

It is provided with two pairs of valves, the lower pair being placed at its entrance into the subclavian vein, the upper in most cases about 4 cm above the clavicle. The portion of vein between the two sets of valves is often dilated, and is termed the sinus.

These valves do not prevent the regurgitation of the blood, or the passage of injection from below upward.

Variation

The external jugular vein varies in size, bearing an inverse proportion to the other veins of the neck, it is occasionally double.