SCHULTE, SEI WHALE. 425 



inclusive. Thus they are separated into two districts, that of the neck and upper thorax and 

 that of the lumbar region and pedicle. In the neck a great muscle complex is formed, in which 

 the elements of the lateral group (scalene) are very imperfectly differentiated from those of the 

 mesal (recti antici capitis). The complex is of great size and extends its insertion far upon the 

 basis cranii, as well as its origin upon the ribs and spine. From these two sources the fasciculi 

 converge and unite inside the arch of the first rib, thence extending as a single mass to the skull, 

 so that the whole complex has the form of an inverted Y, the diverging arms of which embrace 

 the dome of the pleura and limit its extension rostrad. Carte and MacAlister have an accurate 

 description of this muscle, which they interpreted as "corresponding to the longus colli, longus 

 atlantis, and rectus capitis anticus muscles, and in part also to the scalenus posticus and medius 

 and supracostal muscles." 



The lateral portion (scalene) arises broadly from the ectal surfaces of the first three ribs, 

 interdigitating with the obliquus externus, and by narrower slips from the fourth and fifth ribs, 

 dorsal to the origins of the serratus anticus. The fasciculi from the latter retain a measure of 

 independence and forming the dorsal border of the muscle, ascend to the extremities of the 

 transverse processes of the cervical vertebra?, into the dorsal aspects of which they are inserted 

 from the second to the seventh inclusive. 



They thus represent a highly developed and partially independent scalenus posticus. The 

 fasciculi from the first three ribs are reinforced laterally by a portion of those from the fourth 

 and fifth, and mesad by a very considerable increment from the ental surface of the first rib. 

 These last arise from the region of the bifurcation ventrad for about two thirds of the length 

 of the rib between its bifurcation and its sternal extremity, and occupy this surface in its whole 

 breadth. Entally they rest against the pleura. They seem therefore the equivalent of the 

 scalenus minimus of human anatomy. In their ascent to the spine they occupy a mesal and 

 caudal position in the scalene mass, so as to reach the transverse process of the seventh cervical 

 vertebra. They are however incorporated so intimately in the general complex that they can- 

 not be traced as a separate element, and many of them extend to a higher level in company with 

 the bundles derived from the first three ribs. As these pass dorsal to the subclavian vessels they 

 correspond to the scalenus medius, the anticus being absent. The insertion is into the ventral 

 aspect of the cervical transverse processes close to their tips, and in common with the rectus 

 anticus upon the basi-occipital, occupying with reference to the fasciculi of spinal origin a lateral 

 position in the common belly. Near the first rib the muscle is cleft for the passage of the nerves 

 of the brachial plexus, those of the cervical piercing it separately and somewhat laterad as well 

 as rostrad to the brachial hiatus. It is innervated by short branches from the cervical nerves 

 as they pass through its substance. 



The mesal group falls into two planes, a massive superficial portion extending from the 

 thoracic vertebrae to the basioccipital, which enters into relation with the scalene, and which 

 I believe is better interpreted as an enormously extended rectus anticus major, and a small 

 deeper stratum confined to the spine and having the arrangement typical of the longus colli. 

 In addition a considerable belly arises from the atlas and joins the deep surface of the belly to 

 the occipital bone; this seems clearly to be the rectus capitis anticus minor. 



The superficial stratum arises from the venter and sides of the first five dorsal vertebrae, 

 extending caudad to the point where the aorta comes into contact with the spine. In the region 

 of the upper dorsal and last cervical vertebrae it receives very delicate tendons from the sides 



