COMMON BRACHIOCEPHALIC TRUNK 633 
subcosial artery (A. intercostalis suprema) is the smaller. It passes backward 
along the lateral border of the longus colli with the sympathetic trunk. It gives 
off the second, third, and fourth intercostal arteries, and ends at the fifth space, 
where it anastomoses with the first aortic intercostal artery, or constitutes the fifth 
intercostal artery, or dips into the longissimus muscle. It also gives off spinal 
branches and twigs to the longus colli and the pleura. The other branch (A. 
transversa colli) is the direct continuation of the trunk. It emerges through the 
Fic. 554—Torocrapry or THorax oF Horse, Ricut Srpz, AFTER ReMovAL OF LuNG, PERICARDIUM, AND GREATER 
Part oF MEDIASTINAL PLEURA. 
1, Right ventricle; 1’, left ventricle; 2, right atrium; 2’, left atrium; 3, anterior vena cava; 4, posterior vena cava; 
5, vena azygos; 6, phrenic vein; 7, aorta; 8, right coronary artery; 9, bronchial artery; 9’, esophageal artery and vein; 
10, first aortic intercostal artery and vein; 11, right pulmonary artery; 12, pulmonary veins; 13, right brachial ve ; 
14, dorsal vessels; 14’, subcostal vessels; 15, deep cervical vessels; 16, vertebral vessels; 17, inferior cervical artery; 
18, internal thoracic vessels: 18’, musculo-phrenic artery; 19, bicarotid trunk; 20, common carotid arteries; 21, Jugu- 
lar vein; 22, thoracic duct: right vagus; 23’, esophageal continuations of vagi; 24, right recurrent nerve; 25, night 
phrenic nerve (part which crosses pericardium indicated by dotted line); 26, sympathetic trunk; 27, great splanchnic 
nerve; 28, csophagus; 29, trachea; 30, right bronchus; 31, left lung; 32, basal border of right lung indicated by dotted 
line; 33, mediastinal pleura; 34, diaphragm; 35, diaphragmatic line of pleural reflection; 36, intercostal muscle; 37, 
longus colli; 38, psoas; 39, interspinous ligament; 40, supraspinous ligament; 41, funicular part, 41’, lamellar part, of 
ligamentum nuchz. 
dorsal end of the second intercostal space, passes across the longissimus costarum and 
longissimus dorsi toward the withers, and divides into several diverging branches. 
An anterior branch passes upward and forward between the splenius and complexus 
and anastomoses with branches of the deep cervical artery; the others ascend on 
the dorso-scapular ligament under cover of the serratus ventralis and rhomboideus 
to the withers, supplying the muscles and skin of this region. 
The left dorsal artery sometimes arises with the deep cervical by a common trunk; this 
arrangement is usual on the right side, and there may be a common stem for the dorsal, deep cervi- 
eal and vertebral arteries. Occasionally the artery arises from the brachiocephalic trunk. Some- 
times it emerges through the third space. The subcostal may arise independently behind the 
dorsal or from the deep cervical artery. 
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2. The deep or superior cervical artery (A. cervicalis profunda) arises in front 
of the dorsal or by a common trunk with it. It crosses the cesophagus (left side), 
