FEMORAL ARTERY. 



235 



The fat of the duck and the turkey nearly 

 resembles the above. 



11. Among insects, peculiar kinds of fat 

 have been obtained from ants, and from the 

 cochineal insect. The latter has been examined 

 by Pelletier and Caventou. (Ann. de Ch. et 

 Phys. viii. 271.) It is obtained by digesting 

 bruised cochineal in ether, evaporating and re- 

 dissolving the residue in alcohol, till it remains 

 upon evaporation in the form of colourless 

 pearly scales, insipid and inodorous, and fusible 

 at 104. 



12. Under the term adipocere, we have else- 

 where described a species of fatty matter which 

 appears to result from the slow decomposition 

 of fibrine; and in some diseased states of the 

 body, a large proportion of the flesh occasion- 

 ally puts on the appearance of fat. In the 

 former case, it has been supposed that the pro- 

 duct is the fat originally existing in the body, 

 which, during the putrefaction of the other 

 parts, has become acidified, that is, converted 

 into margaric, stearic, and oleic acids; and 

 that these acids are more or less saturated by 

 the ammonia which is at the same time gene- 

 rated, and by small quantities of lime and 

 magnesia resulting from the decomposition of 

 certain salts of those earths pre-existing in the 

 animal matter. This view of the nature of adi- 

 pocere appears so far correct ; but the quantity 

 of the altered fatty matter which was found in 

 the cases alluded to, and in others where heaps 

 of refuse flesh have been exposed to humid pu- 

 trefaction, is sometimes such as to render it 

 highly probable that a portion of the fatty 

 matter is an actual product of the decay, and 

 not merely an educt or residue. 



In regard to the apparent morbid conver- 

 sion of muscle into fat in the living body, 

 Berzelius observes that, because the muscles 

 become white, it has been assumed that they 

 are actually converted into fat, but that the 

 appearance depends solely upon the absence 

 of red blood, for the muscles under such 

 circumstances do not lose their power of mo- 

 tion. The truth is that, in these cases, the 

 accumulation of fat goes on to such an extent 

 in the interstitial cellular membrane of the 

 muscular fibre, as gradually to occasion its 

 almost entire absorption, and such of the mus- 

 cles as undergo this change gradually lose 

 their contractile powers. Two mutton-chops, 

 which have undergone this change, and in 

 which the altered muscle and the ordinary ex- 

 ternal layer of adipose membrane are quite dis- 

 tinct, are preserved in the Museum of the 

 College of Surgeons, and there is a printed 

 pamphlet giving an account of the symptoms 

 under which the sheep laboured. What may 

 be the chemical peculiarities of the fat depo- 

 sited among the fibres, as compared with the 

 ordinary fat, has not been ascertained. 



The above is an enumeration of such of the 

 varieties of animal fat as have been chemically 

 examined. In their general characters they 

 closely resemble the corresponding compounds 

 of the vegetable kingdom ; and, with the excep- 

 tions specified, the process of saponification 

 effects upon them very similar changes : they 



are also similarly acted on by the acids. Some 

 of them seem to afford distinct products when 

 subjected to destructive distillation, and during 

 the decomposition of whale oil for the produc- 

 tion of carburetted hydrogen for the purposes 

 of gas illumination, a variety of binary com- 

 pounds of hydrogen and carbon, with some 

 other products, are obtained, the nature of 

 which has been ably investigated by Professor 

 Faraday.* 



( W. T. Erande.) 



FEMORAL ARTERY (arteria cruralis; 

 Germ, die Schenkelarterie). The femoral ar- 

 tery is the main channel through which the 

 lower extremity is supplied with blood : in an 

 extended sense it might, with propriety, be 

 understood to comprehend so much of the 

 artery of the extremity as is contained within, 

 the thigh, intermediate to those of the abdo- 

 men and the leg; but the variety in the situ- 

 ation and relations of that vessel in different 

 stages of its course is so great that it has been 

 distinguished into two, the proper femoral 

 and the popliteal ; the former appellation being 

 applied to so much of the vessel as is situate 

 in the superior part of the limb, and the latter 

 to that portion which is contained in the lower, 

 in the popliteal region. The comparative ex- 

 tent of the two divisions of the artery differs 

 considerably, the femoral predominating much 

 in this respect, and occupying two-thirds of 

 the thigh, while the popliteal occupies but one; 

 hence the particular extent of each may be 

 exactly defined by dividing the thigh, longi- 

 tudinally, into three equal parts, of which the 

 two superior will appertain to the former, and 

 the inferior to the latter. 



The proper femoral artery, then, engages 

 the two superior thirds of the main artery of 

 the thigh, continued from the external iliac 

 artery above, and into the popliteal below. It 

 emerges from beneath Poupart's ligament into 

 the thigh, external to the femoral vein, and on 

 the outside of the ilio-pectineal eminence of 

 the os innominatum, and it passes into the 

 popliteal region below through an aperture cir- 

 cumscribed by the tendons of the adductor 

 magnus and vastus internus muscles. Its 

 course is oblique from above downward, and 

 from before backward, corresponding to a line 

 reaching from a point midway between the 

 anterior superior spinous process of the ilium, 

 and the symphysis pubis upon the front of the 

 limb above, to another midway between the 

 two condyles of the femur, on the posterior 

 aspect of the bone below. Its mean direction 

 is straight, or nearly so, corresponding to the 

 line which has been mentioned, or, according 

 to Harrison,f to a line drawn from the centre 

 of Poupart's ligament to the inner edge of the 

 patella; but its course is, for the most part, 

 more or less serpentine, the vessel forming as 

 it descends curvatures directed inward and 

 outward. The presence and degree of these 

 curvatures, however, are influenced very much 



* Phil. Trans. 1825. 



t Surgical Anatomy of the Arteries, vol. ii. 

 p. 137. 



