e below,
to produce the desired result, the choice of the operator is determined
accordingly. The steps of the operation performed at the situation W,
where the artery is about to pass beneath the sartorius, are these: an
incision of sufficient length--from two to three inches--is to be made
over the course of the vessel, so as to divide the skin and adipose
membrane, and expose the fascia lata, through which the inner edge of
the sartorius muscle becomes now readily discernible. A vein (anterior
saphena) may be found to cross in this situation, but the saphena vein
proper is not met with, as this lies nearer the inner side of the thigh.
The fascia having been next divided, the edge of the sartorius is to be
turned aside, and now the pulsation of the artery in its sheath will
indicate its exact position. The sheath is next to be opened, for an
extent sufficient only to carry the point of the ligature-needle safely
around the artery, care being taken not to injure the femoral vein,
which lies close behind it, and also to exclude any nerve which may lie
in contact with the vessel.

[Footnote: This is the situation chosen by Scarpa for arresting by
ligature the circulation through the femoral artery in cases of
popliteal aneurism. The reasons stated in the text are those which
determine the surgeon to perform the operation in this place in
preference to that (the lower third of the thigh) where Mr. Hunter first
proposed to tie the vessel.]

If an aneurism affect the common femoral portion of the artery, the
external iliac part would require to be tied, because, between the seat
of the tumour and the epigastric and circumflex ilii branches above,
there would not be sufficient space to allow the ligature to rest
undisturbed; and even if the aneurism arose from the femoral below the
profundus branch in the upper third of the thigh, or if, after
amputation of the thigh, a secondary haemorrhage took place from the
femoral and the profunda arteries, a ligature would with more safety be
applied to the external iliac part than to the common femoral; because
of this latter, even when of its clear normal length, presenting so
small an interval between the epigastric and profundus branches. In
addition to this, it must be noticed, that occasionally the profundus
itself, or some one of its branches, (external and internal circumflex,
&c.), arises as high up as Poupart's ligament, close to the origin of
the epigastric and circumflex