MUSCLES CONNECTKD WITH THE SHOULDER-JOINT. 6 



figured 



i id in a broad tendinous aponeurosis over the 



sternum, opposite the third and fourth costal cartilages. It is probable, on the u hole, that tin 

 fascicle e o may be really the homologue of the muscular slip which is called " rectus thoracis " 

 by Professor Turner, /. c, and which, as figured and described by him, appears to have a 

 tendency to be produced obliquely inwards towards the sternum. (Sec ' Cambridge •Journal of 



Anatomy and Physiology/ May 18G8, pp.398, 894, ibique citatai) 



scl. Subclavius or triangul 



coracoid" of Mivart (J 



.4 



pectoralis secundus " of Haughton, and u rosfco* 



Its superficial layer arises from tin- 



free cartilage of the second thoracic rib, and from the intermediate and sternal element! of tin 

 third and fourth thoracic ribs, and is inserted along the posterior edge of the cor; oid. Thn 

 muscle is obviously homologous with the similarly stratified muscle of similar origin and 

 insertion in the bird, which is ordinarily called u subclavius/' e.g. by Schcipss (Meckel's Arelnv, 

 1829) ; but it cannot be homologous with the pectoralis secundus or levator humeri of the bird, 

 inasmuch as the two muscles coexist with each other there. Hie same reasoning shows that it 

 is not homologous with a pectoralis minor, though the slip which, in Alligator lucim, it gives to 

 the muscle e i may be so in part. 



^ 



humeral edg 



be. Tendon of biceps, passing to be inserted on cephalic edge of r oracoid. 



4. Muscles in connexion with the scapulo-coracoid arch and upper extremity of the Emu, Dramaius 



Novm Hollandia. 



pin. Pectoralis major. This muscle has a few fibres of origin in an aponeurosis playing over the 



lower- and outer angle of the coracoid; it arises also from the three anterior sternal ribs, and 

 from a triangular space on the sternum, lying between the two other points of origin. It i 

 inserted into the great tuberosity of the humerus by a tendon attached distallv and internally 

 to those of the epicoraco-humeral and deltoid. 



eh. Epicoraco-humeral muscle. It arises from the mesial point of the sternum or " rostrum 11 of the 



bone, from the coraco-clavicular membrane extending from the sternal rostrum up to the clavicle, 

 and, thirdly, from an irregularly quadrangular praeglenoid headland, which, as verified in ; 

 young specimen, is constituted by scapula as well as by coracoid. It is inserted into thi 

 humerus a little proximally and internally to the deltoid, and superficially to the coraco- 

 brachialis. It is obviously the homologue of the pectoralis secundus s. levator humeri ot 

 ordinary birds. (See Meckel on Anatomy of Cassowary, Meckel's Archiv, 1830, p. 25."). 5.) 



be. Tendon of biceps inserted into the humeral, and not, as in the Crocodile, into the cephalic edge 



of the coracoid. Between this tendon and that of the epicoraco-humeral or pectoralis m eundns 

 is seen the coraco-brachialis muscle, much reduced in size as compared with its homologue in 

 the Crocodile. It has lost all the portion which arose m< ially to the insertion of the biceps, 

 and which Meckel called u coraco-brachialis inferior s. pectoralis tertina/ 1 and Schopss /. r. " pec- 

 toralis medius." Neither Schoepss nor Meckel seems (as far as the name w deltoides inferior " 

 can show, which they have given to the small muscle arising in ordinary birds from the lip of 

 the coracoid underneath the tendon of the biceps, and inserted into the upper part of the great 

 pectoral tuberosity) to have recognized its homology with the upper part of the coraco-brachialis 

 muscle of the Crocodile and the coraco-brachialis bretns s. rotator humeri ("Wood) of mammals. 

 The only difference, how r ever, between the muscle which Meckel and Schoepss call "deltoides 

 inferior" in the common Fowl and that which I have called in the Emu rr coraco-brachialis * 

 is that the larger biceps of the former animal has overlaid and stunted the muscle which the 

 smaller biceps of the Emu has allowed to retain its reptilian proportions superiorly to its own 



insertion. 



from 



Triceps 



