428 ANGIOLOGY. 



circiilus arteriosus. At its origin, a retrograde branch passes to- 

 the bulb of the frog ; and after traversing the preplanter groove, 

 it gives off a second retrograde, which supplies the external part of 

 the lateral cartilage, one twig inosculating below with the circumflex 

 artery. It supplies numerous ascending and descending branches 

 which ramify in the sensitive lamina, anastomosing with those 

 of the coronary arch and circumflex artery. 



The Plantar ungual is the terminal branch of the digital ; 

 it passes through the plantar foramen on the tendinous surface 

 of the OS pedis, and enters the bone, within which it inosculates 

 with its fellow, forming the circulus arteriosus, or plantar circle, 

 from which spring ascending and descending branches. The 

 former are the anterior laminals, which leave the bone through 

 numerous apertures on its wall, and ramify among the sensitive 

 laminae ; the latter are the inferior communicating arteries, 

 which average fourteen in number ; they pass through the 

 foramina situated just above the edge of the os pedis, and 

 unite outside to form the circumflex artery, which rims round 

 the toe, giving off ascending branches to the sensitive laminae, 

 and about fourteen descending ones, the solar arteries, which 

 supply the sensitive sole, uniting posteriorly to constitute 

 the inferior circumflex artery. 



Anterior Aorta. 



(Fig. 154. e'.) 

 The anterior aorta is rather more than one inch in length, ami 

 passes obliquely upwards and forwards, between the layers of the 

 anterior mediastinum, over the right auricle, under the trachea, 

 and to the left of the anterior vena cava ; after furnishing a few 

 insignificant twigs to the pericardium and mediastinum, it divides 

 into the right and left arteria innominata, or brachial arteries. 



BRACHIAL ARTERIES. 

 (Fig. 154. i, k.) 



The brachial arteries separate at an acute angle, the left being 

 uppermost, and pursue a diverging course towards the anterior 

 aperture of the thorax, whence they proceed to the pectoral limbs> 

 winding round the first ribs, and below the scalenus muscles; the 

 right one gives off the common carotid trunk ; hence it is 

 distinctively known as the brachio-cephalic artery, and is larger 



