530 MR. J. C. GALTON ON DASYPUS SEXCINCTUS 



Deltoid. — This muscle appears to consist of three factors, which are as follow : 

 1. Clavicular, a flat muscular slip, arising from the acromial extremity of the clavicle. 

 It lias a rhomboidal (but almost approaching a triangular) shape, and narrows in breadth 

 towards its insertion into a smooth oval facet situated on the outer aspect of the deltoid 

 trochanter of the humerus. This portion of the muscle, before its insertion, fuses with 

 tli rounded superior portion of the pectoralis major, at the termination of this latter, 

 and with the factor of the deltoid, next to be described. 



2. Acromhd, a stout, fleshy, subcylindrical muscle, arising, slightly tendinous at origin, 

 from the posterior half of the long acromial offset of the scapula, immediately in front 

 of the " metacromial process " of Parker. It passes obliquely forward, and, after fusing 

 with the clavicular factor of the deltoid, shares with it its insertion. 



3. Scapular. This, the largest factor of the muscle, is triangular in shape, and arises 

 from the wliole length of the outer side of the principal (superior) spine of the scapula, 

 from its termination at the base of the bone to its origin at the spring of the acromion ; 

 being overlapped for the last inch and a half of its origin by the dorsal portion of the 

 trap nm. It passes obliquely forwards, narrowing very rapidly from its broad base, to 

 be inserted into the ridge bounding the facet which gave insertion to the two former 

 factors of the muscle, but becomes, moreover, continuous with the fascia of the arm, to 

 which the occipital portion of the trapezius, as already described, furnishes a contribution. 

 '! Ins factor of the deltoid overlaps that portion of the acromion which affords origin to 

 t he factor which I have termed acromial. 



Supra*pimtt».~mB muscle has no peculiarities worthy of record. It arises from 

 the whole of the supraspinous fossa of the scapula, and has a very broad fleshy insertion 

 into the upper edge of the external tuberosity of the humerus. 



Infraspinatus.- -In the small infraspinous, or rather interspinous , fossa which lies 

 between the greater and lesser spines of the scapula, arises the above muscle, which is 

 inserted into the outer tuberosity of the humerus, at a point a little above that of the 

 termination of the muscle next to be described. 



Teres minor -A muscle of no great breadth, arising from the whole length of the 

 lesser (inferior) spine of the scapula, above the origin of the « long » head of the triceps. 

 Pacing forwards, parallel with the ridge from which it takes origin, it is inserted into a 

 spmous projection below the outer tuberosity of the humerus, developed upon a ridge 

 - - * runs upwards from the outer edge of the deltoid trochanter. Overlapping the 



ol the "long" head of the triceps, and, close to its insertion, the origin of the 



hich 



^71^1°: I,* 1 *, TT, mUSCle ' * is 0Verla PP ed * **n by the most posterior ( 



pular) portion of the deltoid 



scnuh Z tl ^ , mUS f e t3keS " S ° l ' dinar y ™S™ fro » ^e inner aspeet of the 



Si 2! m 7 I a br ° ad tend0U int ° the inner ^^ * «» humerus. 



( or in erior ' /!, ^ P ° Steri ° V trian § ula r s P a ^ W*8 between the lesser 



(or mh nor) spxne of the seapula and the inferior angle of the hone". At their origin, 



'" •■■ • p. 352.) ' neUP f ( ' f " f ° m ^ remarquable P ar 8a courbure et sa saillie aigue." (Cuvier's Lemons, 2nd ed, 



