194 ANATOMY OF VERTEBEATES. 



carotid, sends off a branch backward, Avliich passes over the neck 

 of the scapula and is lost among the muscles on the posterior part 

 of the shoulder, inosculating with the articular and other arteries 

 about the joint : this branch might be called the siqjra-scapular, 

 ib. 5. In the Duck we have observed it, before it makes the turn 

 over the scapula, to send an artery upward along the muscles of 

 the neck. The trunk of the vertebral artery proceeds obliquely 

 upward, and having entered the foramen in the transverse pro- 

 cess of the penultimate cervical vertebra, gives off a large branch 

 downward, which is distributed between the vertebras, and to the 

 spinal canal, in the manner of the intercostal arteries, with which 

 it anastomoses upon arriving in the thorax. The remainder of 

 the vertebral artery is continued upward in the canal formed by 

 the pleur- and di-apophyses of the cervical vertebrae, diminishing 

 gradually in consequence of the branches it sends off between each 

 vertebra to the myelon and the muscles of the neck. Near the 

 head the artery is found considerably reduced, and within the 

 uppermost foramen in the transverse processes terminates entirely 

 by inosculation with the reflected occipital branch of the carotid, 

 as before noticed. 



^ After the common trunk of the carotid and vertebral is detached 

 from the arteria innominata, this vessel may assume the name of 

 the subclavian, fig. 93, 14. While passing under the coracoid it 

 sends off some important branches : the first might be called the 

 pectoral artery ; it proceeds upward upon the internal surface of 

 the pectoralis minor muscle, which it supplies, and then dividing 

 into two branches, one passes over the anterior edge of the 

 coracoid, and under the pectoralis medius, between which and the 

 sternum it runs, detaching its branches to the muscle ; the other 

 sends first along the under side of the coracoid a branch which is 

 again subdivided and distributed to the outside of the shoulder- 

 joint and to the deltoid muscle, in which it inosculates with the 

 articular artery. The vessel then passes between the coracoid and 

 the furculum, and on a ligament which connects the head of the 

 coracoid to that of the scapula, and disperses its branches upon 

 the upper part of the shoulder-joint, forming anastomoses with the 

 neighbouring arteries. 



' The next branch of the subclavian is the humeral artery, 

 ib. 15; it arises from the upper side of the vessel, and makes a 

 slight curve to reach its situation on the inside of the arm in order 

 to disperse its branches in the manner hereafter described. 



' The internal mammary artery, fig. 94, 2+, is given off just as 

 the subclavian leaves the chest. It divides into three branches : 



