THE BACK. 1-8^ 



space on tlie supero-Lateral part of tlie sacrum, where it is 

 attached to the sacral and to the ilio-sacral ligaments. It 

 is attached to the transverse, oblique, and superior spinous 

 processes of all the lumbar and of the posterior dorsal ver- 

 tebrae, to the posterior part of the heads of all the ribs, and 

 to the transverse processes of the twelve anterior dorsal 

 vertebrse, and the last cervical in common with transversalis 

 costarum. At its anterior part it is separated by cervico- 

 dorsalis from complexus major ; at the posterior part of the 

 withers it comes in contact with 



Spinalis dorsi, which receives from it a large and strong- 

 tendon. It is attached posteriorly to the summits of the 

 twelve anterior superior spinous processes of the dorsal 

 vertebrge and to the posterior margins of the superior 

 spinous processes of the six anterior of these bones. 

 Anteriorly with ligamentum nuchse, it becomes attached to 

 the superior spinous processes of the three posterior cer-- 

 vical vertebrse. This muscle internally lies in contact with 

 its fellow of the opposite side, for the ligamentum nuchse 

 is here deficient. 



The posterior cervical artery, after passing between the 

 first and second ribs, and giving off the first intercostal 

 branch, runs over spinalis dorsi to reach the external sur- 

 face of ligamentum nuchse, along which it runs up the 

 neck parallel to the vertebral column. It arises on the 

 right side by a root common to it, and the dorsal artery, 

 from the right arteria innominata, round the common root, 

 the recurrent or inferior laryngeal branch of the right pneu- 

 mogastric nerve winds from without inwards and then runs 

 up the neck; on the left side these two arteries arise 

 separately, for the left recurrent nerve passes round the 

 aorta. The dorsal artery gives off a branch which runs- 

 underneath the heads of the ribs to meet the sixth inter- 

 costal artery, the first given off by the posterior aorta. 

 From this arch run the third, fourth, and fifth intercostals ; 

 the second intercostal is the next branch given off by the 

 dorsal, which subsequently passes over cervico- dorsalis 

 towards the withers. By removal of longissimus dorsi and 

 transversalis costarum we show a series of muscles running- 

 obliquely downwards and backwards from the superior 

 spinous processes to the oblique processes of the vertebrse, 

 and on examination we find this arrangement obtains in;'^ 

 the cervical lumbar and dorsal regions constituting the 



