138 



REPORT 1870. 



When we reflect on the situation of the arteries of the upper and lower extre- 

 mities, we notice that at first sight they disagree with the above views, — that is, in 

 the upper part of the limbs, the brachial artery being on the flexor, whilst the 

 femoral is on the extensor aspect. For the artery of the thigh to be analogous to 

 that of the upper arm, the popliteal should be a continuation of the ischiatic, and 

 not of the femoral ; and it is so in the fowl : in man also the ischiatic passes 

 through the meshes of the lumbo-sacral as the brachial does through the brachial 

 plexus. For the representative of the femoral artery in the arm we must fix pro- 

 bably on the acromial or some other of the higher branches. The direction in 

 which the main vessels emerge from the trunk accounts for this. 



Muscles. 



Thujh. 

 Psoas niagnus, P. parvus, Iliacus. 



Arm. 



Levator ang. scapulae, Supraspinatus, 



Infraspinatus, Teres minor. 

 Pectoralis major, P. minor, Subclavius. 

 Deltoid. 

 Latissimus dorsi, Subscapularis, Teres 



major. 



Triceps, Anconeus. 



Biceps, Coraco-brachialis, Brachialis in- 

 teruus. 



Pectineus, Adductors. 



Gracilis, Sartorius, Tensor vag., Femoris. 



Gluteus maximus, Gl. medius, Gl. mi- 

 nimus. 



Pyriformis, Abductores breves. 



Rectus, Crureus, Vastus externus, \. in- 

 ternus. . 



Semitendinosus, Semimemb., Biceps, Po- 

 plitfeus. 



The above is a plan of the supposed homologies in the upper muscles of the 

 limbs. The short abductors are only present in the lower extremity, and then 

 most developed when the cervix femoris is longest and abducting force required. 

 The deltoid is peculiar to the upper limb with the clavicle and acromion, this 

 muscle agreeing with the iliacus and psoas only in its insertion between the ex- 

 tensors and flexors, but rather to be considered as belonging to the same category 

 as the trapezius. This last is a protractor, whilst the lower parts of the latissimus 

 dorsi and pectoralis major, or those parts continuous with the inner portion of tlieir 

 duplicated tendons, are its antagonists or retractors. The sartorius and gxacilis 

 appear the solo representatives of the tripartite deltoid, their insertion distant, but 

 prseaxial, between the flexors and extensors. 



With respect to the innervation of the two limbs, it appears that each set of 

 muscles, flexoi's, or extensors is supplied by nerves corresponding — that is, that no 

 nerve to a flexor supplies an extensor. The median and ulnar nerves in the arm 

 are purely flexor, the musculo-spiral extensor. The flexors have their supply espe- 

 cially from the fore part of the brachial and great sciatic plexuses, the extensors 

 from the back, and pronators and adductors may be arranged with the former, 

 supinators and abductors with the latter ; the extensor nerves also being uiostly 

 given oft" high up, as are the origins of these nmscles. The musculo-spiral in the 

 arm represents the anterior crural in the leg, plus what answers to the peroneal, or 

 part of it ; in fact the musculo-spiral supplies all the extensors of the upper extre- 

 mity, the anterior crural only those of the thigh, the peroneal lielping it out in the 

 leg," but sometimes arising high up in the plexus rather than in the middle of the 

 thigh. The peroneal muscles in man are but partially extensors, but their tendons 

 in some animals pass before the fibula. The pectoral nerves answer to the obtu- 

 rator, though the latter passes to its destination difterently from what the pectorales 

 do — of necessity, from the suppression of the fore part of the shoulder-girdle. 

 Similar reasoning applies to the course of the musculo-spiral. The gluteal and 

 subscapidar draw from all the roots of the plexus, and any diftereuce is only 

 apparent. Tlie several nerves of the latissimus dorsi and gluteus maximus also 

 correspond. 



In many animals the resemblance between the front and hind limbs is gi'eater 

 than in man ; the differences are, as already in some measure sliown, of an adaptive 

 nature, especially in the osseous and muscular parts. In the fore limb we have a 

 more varied volitional impulse, extensive pronation and supination, the opposable 



