544 



Mr. J. Wood on Variations in Human Myology. [May 23, 



internal mammary also gave off an accessory inferior thyroid. No. 7, 

 having 10 muscular abnormalities, of which 7 were in the head and 

 arm, presented that remarkable irregularity — the right subclavian given 

 off from the descending aorta below the left — while the two carotids 

 came off from a common trunk*. No. 20, having 16 muscular abnor- 

 malities, 12 being found in the arm, had also a high origin of the radial 

 artery. No. 27, having 12 muscular abnormalities, of which 9 were in 

 the arm, presented the left vertebral arising from the aortic arch, and 

 the posterior- and supra-scapular coming by a common trank from tlie 

 second part of the subclavian. 



Trom the 34 cases contained in the adjoined Table, which were all 

 examined and noted with the utmost care and accuracy, a fair approxi- 

 mative idea may be deduced of the relative frequency of certain special 

 instances in the two sexes ; on both sides of the body, or on one side 



only. 



The total number of muscular abnormalities noted in 36 subjects is 

 295 (reckoning both sides as one), of which 221, or about two-thirds, 

 were found on both sides, and 74, or about one-third, on one side only ; 

 the proportion on the right side only being 39, and those on the left 

 side only 35, or nearly equal on either side. 



The individual abnormalities which exceed the above proportion on hotli 

 sides are — the cleido-occipital ; those of the pectoralis minor, coraco- 

 brachiahs, brachialis anticus, extensor carpi ulnaris, and the interossei ; 

 and the extensor medii digiti in tJie up;per extremity ; and the extensor 

 longus primi internodii hallucis, and those of the extensor brevis digi- 

 torum pedis in the lower Umh, all of which were found represented on 

 both sides ; while the proportion of the abnormalities of the latissimus 

 dorsi, the peroneus quinti, and the abductor ossis metatarsi quinti found 

 • on both sides was also greater than that above given. 



Those instances of which the proportion 07i one side only was greater 

 than the average, were found in the flexor sublimis and profundus 

 digitorum and lumbricales, and the more rare abnormality, the flexor 

 carpi radialis brevis vel profundus, all of which last were found in the 

 right arm. Of the biceps flexor cubiti and the flexor longus accessorius 

 digitorum pedis nearly as many were found on one side only as on both. 



The total number of abnormalities found in the 24 males was 215, and 

 in the 12 females 81, showing a greater proportionate frequency in the 

 male sex of almost as many more. Of this number, 15 are confined to 

 the Tiead^ nech, and thorax ; 4 of which are in females, or rather less 

 than the foregoing average. 



No less than 174 are connected with, and acting chiefly upon, the bones 

 of the upper Umh, 130 of which are in males, and 44 in females. This 

 also is proportionately less in the female than the general average. 



* For an account of the formation of this abnormality, see a paper by the author in 

 the Transactions of the Pathological Society of London, vol. x. p. 119. 



