(3.35)

Now we'll move on to take a look at the major veins of the head and neck. Outside the cranial cavity, the smaller veins generally run close to the corresponding arteries. We'll look only at the larger veins, starting with the principal vein of the head and neck region, the internal jugular vein.

To see the internal jugular vein we'll start with a dissection in which it's been removed. Here's the internal carotid artery, about to enter the carotid canal. The internal jugular vein begins here at the jugular foramen, where, as we've seen, it's continuous with the sigmoid sinus.

Now we'll add the internal jugular vein to the picture. The upper part of the internal jugular vein lies behind the internal carotid artery. It lies just medial to the styloid process, and medial also to the the styloid muscles, and the posterior belly of the digastric. Just below the level of the angle of the mandible, which we'll add to the picture, the internal jugular vein receives this large vein, the common facial vein.

The common facial vein is formed by a joining together of veins that drain the face, the infratemporal region, the oral and nasal cavities, and the larynx. The internal jugular vein continues down the neck, behind the common carotid artery and lateral to it. It's crossed by the omohyoid muscle.

Down here behind the clavicle the internal jugular vein ends by joining with the subclavian vein to form the brachiocephalic vein. As shown in Tape 3, the two brachiocephalic veins pass through the superior thoracic aperture. In the thorax the two brachiocephalic veins join to form the superior vena cava.

The internal jugular vein is covered over by the sternocleidomastoid muscle. We'll add just the upper and lower ends of the muscle to the picture. Here's the lower end of the muscle, here's the upper end. Above, the vein lies slightly in front of the sternocleidomastoid muscle.

Below, it lies just lateral to the interval, between the sternal and clavicular insertions of the muscle. We'll add the rest of the sternocleidomastoid muscle to the picture, then we'll add the major superficial veins of the neck.

This is the external jugular vein. Its formed below the ear by a joining of veins from the scalp and face. The external jugular vein crosses the lateral border of the sternocleidomastoid muscle, and passes behind the clavicle to join the subclavian vein, which is here.

This is the anterior jugular vein, it's quite small in this individual. It also empties into the subclavian vein.

To make the veins clearly visible in the dissection we've seen, they were filled with a colored material. Normally when we're upright and at rest, gravity keeps the veins of the head and neck almost empty. They fill up when we lie down, or raise our intrathoracic pressure.