The neck of the sac of a femoral hernia, then, has behind it the fascia iliaca and the ligamento cartilaginous material that covers the sharp edge of the linea ileo-pectinea : internally it has the junction of the fascia iliaca and transversalis, the attachment of the fascia lata to the linea ileo-pectinea, and Gimbernat's ligament; inter nally it must also have the spermatic cord in the male and the round ligament in the female; anteriorly it has the fascia transversalis and Poupart's ligament, and immediately above the fleck and in close contact with it is the sper matic cord, of course including the spermatic artery : externally is the membranous slip in terposed between it and the femoral vein. The epigastric artery is also external to it, but although this vessel is somewhat irregular both in origin and position, yet the full breadth of the vein must be always interposed between it and the neck of the sac. But there is an irregular vascular distribution that must be borne in mind. In a great number of subjects (perhaps one out of every four or five) the obturator artery, instead of coming off from the internal iliac, arises by a common trunk along with the epigastric, which it soon leaves, and passing downwards and inwards crosses the superior aperture of the femoral canal hefore it dips into the pelvis to reach the obturator foramen. In this course it sometimes passes the border of the canal posteriorly, but much more frequently in front; and in this latter case, if a hernia existed, the vessel would embrace two-thirds of the circle of the displaced peri toneum close to and immediately above the neck. It appears, then, from these anatomical relations that in all subjects a considerable degree of danger may arise from too free and unguarded a use of the knife in operation—a danger that is necessarily enhanced in the male subject: indeed in consequence of the risk of hemorrhage Scarpa seemed disposed to trust to dilatation and laceration of Poupart's ligament fur relieving the stricture, and where these means were insufficient he recommended a new and particular direction to be given to the incision. But from careful dissection and ex amination of these parts I am disposed to believe there is always sufficient space to free a stricture without endangering either time sper matic or the irregular obturator artery. It must be recollected that if the intestine is sufficiently liberated to permit the passage of gas through the immediate seat of the stricture, its return is perfectly practicable, and a very small incision will be sufficient to accomplish this. Now these vessels lie, not on the neck of the sac, but above it ; and there is quite space enough to set the stricture free without interfering with them : when they are wounded, it is in consequence of the introduction of the cutting edge of the bistoury too far within the stricture.
When a portion of intestine has escaped through the femoral ring, (and by reason of the small size of the aperture hernia` here are seldom large,) it lies at first within the crural canal, where it is restricted by the fascia lata, and its existence recognized with difficulty. It has happened that patients have perished from the incarceration of a small fold or knuckle of intestine without the circumstance ever having been discovered during life. But after it has passed the crescentic edge of lley's ligament, and is relieved from the pressure of the fascia, it comes forward, and if it increases farther, its direction is rather inwards and upwards, so that it may assume the position of an inguinal hernia to the extent of being mistaken for it. Baying proceeded so far, the hernial sac has assumed somewhat of the form of an arch : it has passed, first downwards through the femoral canal, then forwards under the sharp edge of the fascia lata, either passing through the weak cellular portion of it or pushing it before, and then upwards and inwards in front.
The hollow of this arch looks upwards, and is occupied by the crescentic edge of lley's liga ment. Perhaps this particular position of the hernia, as well as the extreme straitness and un yielding nature of the crural canal, has con tributed to the frequency of strangulation to which this form of hernia is liable.
When a person stands erect and without exertion, Poupart's ligament forms nearly a direct line between the anterior superior spinous process of the ileum and the crest of the pubis, and all the fascia connected to it are in their natural state and sufficiently relaxed ; but if the thigh is strongly extended or the body bent backward, the ligament then becomes tense and is arched backward toward the thigh. The effect of the general tension of the limb in this position would be to convert the arch formed by the hernia into an angle, against the hollow of which the edge of lley's ligament would be firmly compressed, and a sufficient degree of resistance thus created to the return of the venous blood to produce a congested condition of the viscus. The operation of such a cause as this can hardly be considered as permanent, but the mischief once commenced is not easily controlled, and an intestine might soon be placed in such a condition as to render incar ceration at the ring inevitable.
The situations at which erural hernia may he strangulated have not been satisfactorily described, although there is no subject on which inure anatomical labour has been bestowed. If I was to speak from my own experience alone, I should say that though the hernia itself is superficial, the seat of the strangulation is always deep—somewhere at or in the imme diate neighbourhood of the neck of the sac. I found the opinion partly on the dissection of subjects that had died of the disease, but more particularly on the phenomena I have observed during the progress of an operation on the living : still the experience of one individual can scarcely ever be sufficient to establish a great pathological principle, and there is autho rity that cannot be questioned for believing that crural hernia is frequently strictured at a far less depth from the surface. Besides the neck of the sac, by which this hernia is con fessedly strictured in very many cases, Sir A. Cooper places the seat of strangulation, first in the crural sheath and semilunar or inflated edge of the fascia lata, and secondly in the posterior edge of the fascia lata.* Mr. Colles says that the neck or constricted part of crural hernia does not always appear at the same depth from the surface, and explains the cir cumstance thus : "The hernia having descended into the femoral sheath, it escapes through one of those apertures in it for transmitting the lymphatic vessels, and also passes through a corresponding opening in the iliac portion of the fascia lata. As it passes through a small aperture in each of these parts at nearly the same spot, it must there be liable to great con striction ; for these two layers of fascia will be compressed together, and thus their strength and resistance be considerably augmented. Hence we should find the seat of stricture in strangulated femoral hernia frequently to be at some distance below and to the pubic side of the crural ring."t The descriptions of Iley and Burns I cannot profess clearly to understand, and I fear they were taken rather from sound subjects than from those in which hernim were actually present. Scarpa does not distinctly point out the anatomy of the scat of stricture, but from the general bearing of his descriptions, and above all from the anxiety he expresses relative to the danger of wounding the sper matic artery in operation, which vessel, if pre sent, must lie close to the neck of the sac, I would hazard an opinion that he believed the seat of strangulation to be always deeply seated.