220 ARTERY. 



brachiccus externus, arises by an acute point as the contrast is between the size of the primi- 

 from the internal ridge of the os humeri, be- tive arterial trunks and that of the almost in- 

 ginning immediately below the insertion of visible capillary vessels, comparatively few 

 the teres major; it also arises from the internal divisions intervene between the two extremes 

 ridge as far down as the internal condyle, from of the arterial system, their number hardly 

 the surface of the humerus behind this ridge, exceeding twenty, as Ilaller ascertained by 

 and from the posterior surface of the internal in- counting the divisions of the arteries of the 

 termuscular ligament. The three heads unite mesentery between the place of their origins 

 above the middle of the os humeri, and cover the from the aorta, and their termination in the 

 whole of the back part of that bone ; they form capillaries of the intestines.* 

 a thick broad tendon, which is inserted into That the arteries in general are circular 

 the rough surface on the superior part of the tubes is evident from an inspection of their 

 olecranon process of the ulna, adhering closely orifices when cut across, even in the dead 

 to the ligamentous fibres covering the posterior body. The walls of the larger arteries, when 

 surface of the synovial membrane, of the empty, collapse, so as to present, on a trans- 

 elbow-joint ; the lowest fibres of the second verse section, an aperture more or less ellipti- 

 and third heads of this muscle, which arise cal : when distended, however, either by the 

 from the back of the condyles, run nearly blood during life, or by injection in the dead 

 horizontally into the tendon. body, these also are circular ; so that the 

 The triceps is covered posteriorly by the circular form may be considered as universal 

 teres minor, deltoid, fascia of the arm and in- in all parts of the animal system except at the 

 teguments ; in front it is in contact with the origins of the aorta and pulmonary artery, 

 posterior surface of the humerus, the inter- where the circumference of each of these ves- 

 muscular ligaments, and the back part of the sels is distended into three sacculated pouches 

 capsule of the elbow-joint. This muscle ex- of equal size, called the lesser sinuses ; and in 

 tends the elbow ; when the long head contracts, the ascending portion of the arch of the aorta, 

 it draws the scapula towards the humerus, which has a dilatation on its right side, in- 

 and, if the scapula be fixed, it draws the creasing with years, called the greater sinus, 

 humerus backwards. The arteries in general become smaller in 

 For BIBLIOGRAPHY, see MOSCLE, and ANATOMY tne ir course in proportion to the number of 

 (INTRODUCTION). branches arising from them. To this, however, 



(J. Hart.) there are exceptions, of which the aorta pre- 

 sents a remarkable example, being of as great 



ARTERY, (normal anatomy): agrygia,, owo a capacity near the origins of the primitive iliac 

 rov TOV , Tv%siv, ab aere servando. Fr. ar- arteries as it is in its thoracic portion, and the 

 tere. Germ. Pulsuder,Schlagader. Ital. arteria. vertebral arteries are as large where they enter 

 The arteries are the vessels which carry the the foramen magnum of the occipital bone as 

 blood from the heart, and distribute that fluid where they arise from the trunks of the sub- 

 throughout the body. The trachea was ori- clavians, notwithstanding that they have given 

 gmally called artery from the circumstance of off many branches in the intermediate part of 

 its containing the air which it transmits to the their course. 



lungs. The term artery was exclusively ap- Wherever an artery runs for some distance 



plied to the trachea by Hippocrates and his without giving off branches, it appears to suffer 



cotemporaries, by whom the vessels now called no perceptible diminution in its size, as has 



arteries were described as pulsating veins, been ascertained by the experiments referred to 



Aristotle restricted the term artery to the tra- by Baron Haller,t and repeated by Mr. Hunter,} 



cnea, and described the aorta as the lesser in which the common carotids were found as 



vein. We find these vessels called arteries capacious near the place of their division into 



in the writings of Aretseus, Pliny, and Hero- the external and internal carotids as at their 



philus, probably on account of the adoption of origins ; and the same remark being considered 



the opinion of Erasistratus, who taught that they as equally applicable to all other arteries simi- 



contamed a vapour or spirit. The vessels now larly circumstanced, it has been stated in 



known as arteries, however, were more dis- general terms that the arteries and their branches 



tmctly so designated by Galen, who affirmed are cylindrical, and that the whole of the 



they were full of blood, and described the arterial system is a series of cylindrical tubes, 

 arteries and veins as forming each a tree, whose Although the cylindrical form is pretty 

 roots implanted in the lungs, and whose general throughout the arterial system, it is by 

 ranches distributed through the body, were no means accurately preserved. Several arteries 

 united by a common trunk in the heart. increase in size in the progress of their course : 

 There are two great arterial trunksthe of this we have examples in the umbilical 

 aorta, which arises from the left ventricle of arteries, which expand -as they approach the 

 the heart, and the pulmonary artery, which placenta, and the spermatic arteries, especially 

 arises from the right ventricle of that organ, in the bull and wild boar, which enlarge con- 

 Each of these vessels has an origin, a trunk, siderably as they proceed to their destination, 

 and branches, which divide and subdivide in Moreover, Haller and Martinus have shown 

 an arborescent form, until they are reduced in 



size to the most delicate degree of minuteness, * Haller, Elementa Physiologiae, t. i. sect. 1. $ 17. 



terminating in the capillary vessels, which can * Elementa Physiologic, t. i. s. 1, $ 3. 



be traced entering into all structures except Treatise on the Blood, &c., p. 168 et seq. 



cartilage, hairs, and epidermoid parts. Striking * lltmeTaT't i si 3, $ 3. 



