MYOLOGY 173 



The triceps extends the forearm on the arm. 



A fourth muscle exists, which veterinary anatomists 

 include in the study of the three portions of the triceps which 

 we have just been discussing, in giving it the name of 

 small extensor of the forearm. But, as this muscle is no other 

 than the anconeus, and as, in human anatomy, we de- 

 scribe the latter, according to custom, in connection with 

 the forearm, it is when on the subject of the latter that we 

 will concern ourselves with it. This grouping of muscles 

 cannot fail to give greater clearness to the description of the 

 muscles of these regions. 



The Supplemental or Accessory Muscle of the Latis- 

 simus Dorsi (Fig. 76, 2 ; Fig. yy, i). — Because of the 

 relations, to which we have already referred (see p. 142), 

 of this muscle with the triceps cubiti, its description very 

 naturally follows that of the latter. 



Indeed, this supplementary muscle of the great dorsal is 

 further designated in zoological anatomy under the name 

 of long extensor of the forearm ; and this name indicates that 

 its study may be united to that of the triceps. 



Situated on the internal surface of the arm, it arises 

 from the external aspect of the tendon of the latissimus 

 dorsi ; it is very highly developed in the horse, in which it 

 also arises from the posterior border (axillary) of the 

 scapula ; then, covering in part the internal head of the 

 triceps and also the long portion, on the superior border of 

 which it is folded, it proceeds to be inserted into the ole- 

 cranon process and the anti-brachial aponeurosis. 



It extends the forearm on the arm. Further, it makes 

 tense the aponeurosis into which it is inserted ; this explains 

 the name of tensor of the fascia of the forearm, which is some- 

 times given to it. 



It seems to us interesting to add that, abnormally, we 

 sometimes find in man an analogue of this muscle. It is 

 given off from the latissimus dorsi, near the insertion of the 

 latter into the humerus ; it accompanies the long head of 

 the triceps and becomes fused with it. Sometimes it is 

 inserted into the olecranon process, at other times into the 

 antibrachial aponeurosis or the epitrochlea. It is on account 



