47; 



ARTERIES. 



passes, and is covered by the Platysma, Sterno-mastoid, Omo-hyoid, and Tra- 

 pezius muscles. 



The superficial cervical ascends beneath the anterior margin of the Trapezius, 

 distributing branches to it, and to the neighboring muscles and glands in the 

 neck. 



The posterior scapular, the continuation of the transversalis colli, passes be- 

 neath the Levator Anguli Scapulas to the superior angle of the scapula, and 

 descends along the posterior border of that bone as far as the inferior angle, 

 where it anastomoses with the subscapular branch of the axillary. In its 



Fig. 283. The Scapular and Circumflex Arteries. 



fetltricr Scaftitlar 



Animal -BranrJ 



if Thitr& 



course it is covered by the Rhomboid muscles, supplying these, the Latissimus 

 Dorsi and Trapezius, and anastomosing with the suprascapular and subscapular 

 arteries, and with the posterior branches of some of the intercostal arteries. 



Peculiarities. The superficial cervical frequently arises as a separate branch from the thyroid 

 axis ; and the posterior scapular, from the third, more rarely from the second, part of the subclavian. 



The Internal Mammary arises from the under surface of the first portion of 

 the subclavian artery, opposite the thyroid axis. It descends behind the cla- 

 vicle, to the inner surface of the anterior wall of the chest, resting upon the 

 costal cartilages, a short distance from the margin of the sternum; and, at the 

 interval between the sixth and seventh cartilages, divides into two branches, the 

 musculo-phrenic, and superior epigastric. 



At its origin, it is covered by the internal jugular and subclavian veins, and 

 crossed by the phrenic nerve. In the upper part of the thorax, it lies upon 

 the costal cartilages, and Internal Intercostal muscles in front, and is covered 

 by the pleura behind. At the lower part of the thorax, the Triangularis Sterni 

 separates the artery from the pleura. It is accompanied by two veins, which 

 join at the upper part of the thorax into a single trunk. 



The branches of the internal mammary are 



Comes Nervi Phrenici (Superior Phrenic). Anterior Intercostal. 



Mediastinal. Perforating. 



IVricardiac. Musculo-phrenic. 



Sternal. Superior epigastric. 



The comes nervi phrenici (superior phrenic), is a long slender branch, which 

 accompanies the phrenic nerve, between the pleura and pericardium, to the 



