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 theparticular 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 bebre backward, corresponding to a line reaching from a point midway between the anterior superior spinous process of the ilium, and the svmphysis 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 Ilarrison,-1- 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 by the state of the vessel and by the position of the limb; when the artery is empty, they are less marked than when it is full; and when the limb is extended, they are removed; when flexed, they are reproduced ; while in some subjects again, they appear to be absent, the line of the vessel's course being almost direct. The degree to which the artery passes back ward is not equally great at all parts of its course: in its upper half, i. e. from l'oupart's ligament until it lies upon the adductor longus muscle, the vessel inclines much more back ward than in the remainder, and at the same time describes a curve concave forward, but both the latter particulars are more remarkable when the thigh is flexed, and in thin subjects, than when the limb is extended and in sub jects which are in good condition ; in the last case the vessel is supported and held forward by the deep fat of the groin situate behind it. In its lower half the artery inclines less back ward, being supported by the muscles against which it rests.
The femoral artery is also described as in clining inward during its descent ; but this statement requires correction, or at least ex planation. The vessel certainly does incline inward at some parts of its course, and for the most part it does so as it descends from the os innominatum into the inguinal space, form ing thereby the curvatures which have been mentioned ; but the general direction of it is either slightly outward, or at the most directly downward, not inward : the opinion that it is inward has arisen, it is to be supposed, from a partial view of its course, which, in conse quence of its serpentine direction, is likely to mislead, and is at variance with that of the popliteal artery, (the lower part of the same vessel,) which is decidedly outward. In order to be assured of the true direction of the vessel, the writer has tested it carefully by means of the plumb-line, and he has always found that it inclined somewhat outward from the perpendicular : the degree, however, to which the proper femoral artery does so, is not considerable, though sufficient to place the matter beyond doubt.