OCR Text |
Show 382 DR. B. C A. WINDLE AND MR. F. G. PARSONS ON THE [Apr. 6, former rises from the mid-cervical transverse processes, and is inserted into the ventral arch of the atlas as well as into the centrum of the second and sometimes the third cervical vertebra. Scalenus centralis (Scalenus anticus).-If by scalenus anticus we understand a muscle which passes from the ventral side of the cervical transverse processes to the first rib, ventral to the subclavian artery and brachial plexus, that muscle is very rare in the Carnivora. This is borne out by Gilis's researches (XLIII.); he says that the plexus passes anterior (ventral) to all the scalenes in Carnivora. Straus-Durckheim thinks that in the Cat (IL) the scalenus anticus has become fused with the rectus capitus anticus major, and describes it under the name of " Isoscele." Alix (XXX.) says that it is represented in Mustela putorlus by some fibres which are ventral to the transverse processes and are separated from the rest of the scalene mass by the nerves. W e agree with Alix that nothing should be looked upon as scalenus anticus which is not ventral to the brachial plexus. In Viverra civetta both Macalister (IX.) and Young (VIII.) describe three scalenes; Devis (X.) also speaks of a scalenus anticus in this animal, but iu his case the muscle was dorsal to the nerves. Murie (XVII.) speaks of a scalenus anticus in Hgcena brunnea, but we think that it must have been a part of what w e term scalenus longus, since it was attached to the 4th and 5th ribs and no mention is made of its relation to the brachial plexus. In no other carnivorous animal is there any mention of a scalenus anticus. Scalenus longus and brevis.-These muscles are always present. The former rises from four or five cervical transverse processes but never reaches the first; it is inserted into the outer surfaces Fig. 6. Scalene muscles of Canis familiaris. of 3, 4, or 5 ribs, beginning at the 3rd or 4th. In Cercoleptes (61), however, it is very well developed and is inserted from the 3rd to the 8th rib. At its insertion the muscle iuterdigitates with the terraius magnus and its ventral fibres reach farthest back. The |