The distal branches ([Fig. 128]) of the tibialis anterior have been [described] in the general description of the artery.
THE VEINS. VENÆ.
Venæ pulmonales. The Pulmonary Veins.
The pulmonary veins follow in the lungs the course of the bronchi. They enter the left auricle in three groups ([Fig. 116], [page 276]). The first of these (i) comes from the anterior and middle lobes of the right side, the second (h) from the corresponding lobes of the left side, and the third (g) from the terminal lobes of both sides. Each group is composed of two or three veins and opens into a sinus or extension of the auricle. The sinuses are from their position dextral (i), sinistral (h), and dorsal (g).
The Veins of the Body.
The veins of the body may be classified into three main groups: (1) the veins of the heart; (2) the superior vena cava and its branches; (3) the inferior vena cava and its branches. The portal system of veins will be considered with the inferior vena cava.
1. Veins of the Heart.
The veins of the heart consist of one large vein, the vena cordis magna, and a number of small veins.
Vena cordis magna ([Fig. 118], 3).—This arises as a number of scattered branches on the surface of both ventricles. These unite to form two main trunks. One of these, on the ventral side of the heart, marks externally the septum between the two ventricles. It passes beneath the left auricular appendage, then turns to the left and passes along the sulcus coronarius to the dorsal side of the heart. Here it unites with the second main trunk which ramifies over the surface of the left ventricle. Arriving at the base of the right auricle it enters this by the coronary sinus, which lies just beneath the opening of the inferior vena cava.
In addition to the vena cordis magna and its branches there are a number of small veins, especially in the wall of the right ventricle. These enter the right auricle by a number of small separate openings along the sulcus coronarius.