The =carotis communis= artery springs from the carotid trunk of the brachio-cephalic. It is directed horizontally, ascending to the ventral side of the neck. It then extends downward to the inferior median neck region. Just after leaving its origin it gives off several small branches to the bronchi and to the esophagus, and extends toward the head. The carotid lies on the thyroid gland and at this point touches the jugular vein (Fig. 21). At this point the =thyroid arteries= are given off from the carotid trunk. The thyroid gland also receives blood from the bronchialis artery. Dorsalward and near the thyroid gland the carotid artery gives off a branch (the bronchialis) which accompanies the recurrent laryngeal nerve, along the inferior larynx and the bronchi, and supplies the lung substance and that part of the esophagus in this region. The =vertebral artery= is given off from the carotid trunk, dorsalward to the thyroid gland, and on the left side. The right vertebral artery may be given off from the brachialis dextra or right brachialis. The =inferior esophageal artery= is given off from the ventral side of the carotid, supplies the esophagus, extends then to the skin of the neck and to the trachea, is directed anteriorly toward the head and anastomoses with the vertebral artery. This artery accompanies the vagus nerve and forms a collateral artery to the carotid and the vertebral artery. The =subcutaneous colli= springs from the carotid artery near the thyroid gland and communicates with the inferior cervical artery, which, in turn springs from the vertebral artery. =The Common Carotid.=—Near the last cervical vertebra the two carotid arteries occupy the same channel, to which they are attached by fascia, and, lying close to the inferior surface of the bodies of the cervical vertebræ, are covered by the colli muscles. Near the third or the fourth cervical vertebra, the two carotid arteries separate. Near the atlas each carotid divides into the _carotis cerebralis_ and _carotis externa_. Near this division the _superior cervical artery_ branches off. This latter artery extends down the neck in company with the pneumogastric nerve and the jugular vein, supplies the skin and the neck muscles, and anastomoses with the inferior cervical artery and the subcutaneous colli artery. The _occipital artery_ originates either from the carotis communis or sometimes from the superior cervical. BRANCHES OF THE CAROTIS CEREBRALIS The branches of the carotis cerebralis are as follows: