214 BULLETIN OF THE UNIVERSITY OF -WISCONSIN. 



branches to the shoulder, one, Ps., PL 9, going to the muscles of 

 the scapula and one, Ph., PI. 9, to the cucullaris muscle ; from 

 here it continues along the ventral surface of the buccal cavity 

 giving off one or two branches to it, a branch to the oesophagus, 

 P. oe., PL 9, and then proceeds along the dorsal side of the lung 

 giving off short branches at right angles to its course. 



The External Carotid Autery, E. C, PL 9, and fig. 1, PL 

 10, arises from the first efferent branchial; it also receives a 

 number of small anastomosing branches from the first afferent 

 branchial artery which accompany it as far as the sternohyoid 

 muscle, which it supplies with a branch. From here it contin- 

 ues cephalad along the medio-dorsal surface of the digastric 

 muscle closely applied to the hyoid arch, giving off a branch to 

 the geniohyoid and mylohyoid muscles and then anastomoses 

 with its fellow from the other side at the insertion of the digas- 

 tric muscle into the lower jaw. 



The Dorsal Aorta, A. O., PL 9, is formed by the union of 

 the two aortic roots and runs along the ventral surface of the 

 vertebral column. It is the main trunk of the arterial system 

 and gives off numerous branches as it passes backwards through 

 the abdominal cavity. 



The Subclavian, Sbc, PL 9, and fig. 2, PL 10, arises from 

 the aorta about 5 m-m posterior to the union of the aortic roots, 

 runs outward between the external oblique and erector spinae 

 muscles, makes a slight turn dorsad and continues along the 

 ventral surface of the scapula. 'ITear the glenoid fossa the con- 

 tinuation of the subclavian, now called the Axillary Artery, 

 gives off a branch which may be called the Thyroid Axis, T. A., 

 fig. 2, PL 10. This almost immediately gives off a branch, Ta., 

 fig. 2, PL 10, which enters the anconeus muscle and breaks up 

 into three smaller branches. The most anterior, T. a. c, fig. 2, 

 PL 10, passes between the anconeus and the humero antibrachia- 

 lis inferior muscles across the head of the ulna, along the surface 

 of the extensor digitorum communis to the first digit. The mid- 

 dle branch, T. a. b., fig. 2, PL 10, runs along between the head 

 of the radius and the ulna to the last digit. The smallest and 

 most j)Osterior branch, T. a. a., fig. 2, PL 10, goes to the ancon- 



