Patterns of the course of the arteries from the maternal trunk to the organ.
With the development of the arterial system, a primary vascular network first appears. In the extreme part of this network, more difficult conditions are created for blood circulation than in those parts that connect the organ and the maternal trunk in the shortest possible way. Therefore, one vessel lying on a straight line between the maternal trunk and the organ is preserved, while the others empty and it turns out that:
1. Arteries travel along the shortest distance, i.e. approximately in a straight line connecting the mother’s trunk with the organ. Therefore, each artery gives branches to nearby organs. This explains that the first branches of the aorta upon its exit from the heart are the arteries to the heart itself. This also explains the order of branching branches, determined by the tab and the location of organs. For example, the branches from the abdominal aorta first go to the stomach (from truncus celiacus), then to the small intestine (a. Mesenterica superior) and, finally, to the large intestine (a. Mesenterica inferior). Or, first, the arteries to the adrenal gland (a. Suprarenalis media), and then to the kidney (a. Renalis). In this case, it is the place of the laying of the organ that matters, and not its final position, which explains that a. testicula-fig does not depart from a. femoralis, and from the aorta, near which the testicle has developed. On the contrary, the scrotum, which originated in the area of the external genital organs, receives the arteries at the site of aa. pudendae externae, originating from the nearest large trunk, a. lemoralis. Knowing the law of the shortest distance and the history of development, one can always determine those organs and those branches to them that depart from a given artery.
2. Arteries are located on the flexion surfaces of the body, because when unbending the vascular tube stretches and collapses. This explains, for example, the location of the common carotid artery on the front surface of the neck, the large arteries of the hand on the palm side. In the lower limb, where the flexion side is located in the hip joint in the front, and in the knee – in the back, the femoral artery passes from the front surface of the thigh to the rear, acquiring a spiral stroke.
3. Arteries are located in sheltered places in the gutters and channels formed by bones, muscles and fascia that protect blood vessels from compression. Since the four-legged open and unprotected is the dorsal side of the body, the vessels are located on the ventral side, which is preserved in humans. This explains the location of the aorta and its branches in front of the spinal column, and the arteries in the neck and extremities – mainly on the front surface. There are no large arteries on the back.
4. Arteries enter the organ on a concave medial or internal surface facing the power source. Therefore, all the gates of the viscera are on a concave surface directed toward the midline, where the aorta lies, sending branches to them.
5. Arteries form adaptations according to the function of the organ:
a) vascular networks, rings, and arcuate anastomoses are observed in organs associated with movement. Thus, in the area of the joints, the articular network, the rete articulare, is formed from the branches of large arteries passing by them, due to which blood flows to the joint, despite the fact that during its movements a part of the vessels is compressed or stretched. Moving entrails that change the size and shape, such as the stomach and intestines, have a large number of annular and arcuate anastomoses;
b) the caliber of the arteries is determined not only by the size of the organ, but also by its function. Thus, the renal artery is not inferior in its diameter to the mesenteric, supplying the long intestine, as it carries blood to the kidney, whose urinary function requires a large flow of blood. Thyroid arteries are also more laryngeal arteries, because a hormone-producing thyroid gland requires more blood than blood supply to the larynx;
c) in connection with this, all endocrine glands receive multiple sources of nutrition. For example, the same thyroid gland – from all nearby large arteries: carotid, subclavian and aorta; adrenal gland – from a. phrenica inferior (a. suprarenalis superior), from the aorta (a. suprarenalis media) and from the renal artery (a. suprarenalis inferior).