MUSCULAR SYSTEM 109 



The helicis major (Fig. 71, m.h'.*) and the tragicus (m.t.} 

 (the second of which is often wanting), are to be derived from 

 the scutulo-auriculare (a portion of the depressor helicis, Euge), 

 found in those Mammals which still possess a free and movable 

 scutulum. The helicis minor (m.h".\ antitragicus (m.a'.\ and the 

 incisurse Santorini, which belong to the cartilaginous wall of the 

 external auditory ineatus, are the proper ear muscles (auriculares 

 proprii), and related to the principal cartilages and the pinna 

 alone. 



Taking all the facts into consideration, this intrinsic muscu- 

 lature of the pinna, which is no longer under the control of the 

 will, must be considered as the vestige of a primitive apparatus 

 functional either for the opening and closing, or for the widening 

 and narrowing of the auditory funnel and the external auditory 

 passage (cf. chapter on the auditory organ, infra). 



4. To the fourth class belong those mimetic muscles which 

 have undergone the greatest degeneration, i.e. those which have 

 become transformed into tendinous or membranous structures 

 (fasciae). For example, the auriculo- (temporo-) labialis muscle of 

 the Lemuroids (cf. Figs. 68 and 69) has, in Man, been replaced 

 by the fascia temporalis superficialis, and the sphincter colli 

 muscle by the fascia parotideo-masseterica. A great part of the 

 human epicranial aponeurosis (galea aponeurotica), further, 

 consists of muscle bundles of the occipitalis transformed into 

 tendons. 



[It is interesting to note that the power of contracting the platysma, the 

 ear muscles, and others not normally under the control of the will, has been 

 observed in a few cases to go hand in hand with that of a voluntary con- 

 trol of the heart's action.] * 



MUSCLES OF THE LIMBS 



The palmaris ( = p. longus) and its homologue in the hind- 

 limb, the plantaris, are time honoured (and certainly among the 

 best) examples of the gradual degeneration of a muscle. The 

 degeneration of the former has not yet proceeded as far as that of 

 the latter, as is most evident in the fact that while the palmaris 

 still reaches the palmar fascia of the hand, the plantaris only in 

 exceptional cases becomes connected with the homologous plantar 

 fascia of the foot, and in doing so regains its former significance 

 as a flexor of that organ. 



The plantaris must therefore, as an original flexor, have 



1 [Cf. E. A. Pease, Boston Med. and Surg. Jour., 30th May 1889.] 



