cHAr. V.J THE CATS MUSCLES. 137 



flosliy sheet, whicli envelopes the anterior part of tlic Lack and the 

 chest — being continued on into the neck and head as the platysma 

 myoides aheady noticed. At its margin the panniculus ends in an 

 aponeurosis, which connects it with parts adjacent. The muscular 

 hbres converge to the axilla, being directed forwards and outwards 

 to it on the chest, and forwards and downwards to it on the side of 

 the back. It is inserted into the deeper fascia of the upper arm, 

 passing in part on the inner side of the biceps muscle, and in part 

 continuing on down to the wrist. 



The muscle by its contraction effects those twitching movements 

 of which the cat's skin is capable. 



Next, beneath this cutaneous muscle is the trapezius, of which 

 there are two parts, closely connected inferiorly, but dorsally, by a 

 delicate fascia only. 



A. The hinder portio)i arises from the neural spines of the dorsal 

 vertebra) — from the second to the twelfth. It is inserted by 

 strong fascia into the membrane which invests the external 

 scapular muscles, the line of insertion passing obliquely across 

 the spine of the scapula at a point situated about one-third of 

 the length measured from its vertebral margin downwards, and 

 dipping slightly beneath the insertion of the anterior part of 

 the muscle {T~). 



B. The anterior part arises from the fascia in the middle of the 

 neck as far forwards as the hinder end of the origin of the 

 cephalo-humeral, with which it is connected. Its origin 

 extends backwards till within about half an inch of the origin 

 of the posterior part. It is inserted into the spine of the 

 scapula, from the metacromion process upwards to the point of 

 insertion into the scapular spine of the hinder portion of the 

 trapezius, into the scapular spine, which insertion it slightly 

 overlaps (T^). 



The h/tissi)jn(s dorsi is an exceedingly large sheet of muscle which 

 takes origin from the neural spines of the vertebra), from fifth dorsal 

 to the fourth lumbar — its origin from the lumbar vertebra) being by 

 fascia onh'. It is overlapped for almost the anterior half of its 

 origin by the posterior part of the trapezius (Ld). 



Its fibres converge to a tendon which, after blending with that of 

 the teres major, is inserted into the inner side of the shaft of the 

 humerus below the lesser tuberosity. "Virtually at its anterior end 

 it blends with adjacent fibres of the fourth part of the pectoralis, 

 and is then inserted into fascia in the neighbourhood of the 

 axilla. Before its insertion it gives ofi" a muscle — the 'i)i)ier dorso- 

 epitroclilear — which descends, and blending with the smaller external 

 dorso-epitrochlear is inserted into fascia on the inner side of the 

 olecranon. Its action is to pull the arm backwards, or, if the arm 

 be fixed, to bring the body forwards. It thus gives much aid in 

 climbing (Fig. 81, ide). 



The external dorso-epitrochlear. — This is a slender muscle 

 (Fig. 77, ed), which takes origin from fascia outside the spine of the 



