This ring is of a different size in different individuals; and where it is large, the person may be said to have an hereditary or congenital disposition to the disease ; but a liability to it may arise from accidental circumstances also. It is obvious that in proportion as the space beneath the crural arch is well filled, and the muscles tense and plump, the aperture at the ring must be small ; also that it will be larger according to the greater breadth between the spinons process and the pubis, or as the space under the crural arch is deep. Hence it may be explained why this kind of rupture is fre quent amongst women who have borne many children, with whom the parietcs of the abdo men are relaxed ; less frequent amongst young and healthy unmarried females, and scarcely known amongst men, the pelvis of the male being narrower, and his muscle better developed by use and exercise.
The crural arch or Poupart's ligament is nothing more than the inferior pillar of the external inguinal ring, and is (as has been before stated) inserted into the crest of the pubis ; but it has another attachment to this bone, which, being in intimate relation with femoral hernia, I have delayed the description of until now. As the ligament approaches the pubis, its inferior edge becomes twisted upwards and backwards towards the linea ileo-pectinea, into which it is inserted for a length of from a half to three quarters of an inch. Its shape is triangular, its posterior attachment being somewhat shorter than its anterior ; and its base, which has its aspect towards the vein, is somewhat lunated. In the male its situation corresponds nearly with the external inguinal ring; and the sper matic cord rests on it just as it is about to pass from the inguinal canal.
The fibrous funnel-like sheath already des cribed is itself lodged within a cavity which may be called the mural canal, and is thus formed. The fascia lata of the thigh in front has two origins, one from the whole length of Po?part's ligament, the other from so much of the linea ileo-pectinea as gives origin to the pectinalis muscle, and from the ligament of the pubis. This latter portion having passed down the thigh unites with the former below the en trance of the saphena into the femoral vein, below which point they form one continuous sheath for the muscles of the limb. The por tion, however, which comes from Poupart's ligament requires more attention. At first it lies completely in front of the upper part of the thigh, and of course leaves a triangular space between it and the other portion, in which are lodged the funnel-shaped fascial sheath, with its contents, the artery and vein, lymphatic vessels, and some glands. About half an inch,
or in some subjects a little more, below Pon pares ligament the internal portion of this Fascia appears to be wanting, leaving the vessels un covered by it as far down as the point of union of the two fascias : I say appears to be wanting, because the fascia lata is really continued over this space, joins the pubic portion internally, and sends a process upwards to be inserted into the linea ileo-pectinea, external to the lunated edge of Gimbernat's ligament, and be tween it and the edge of the femoral ring; but it is here so thin and cellulated that it is generally removed in the dissection. When thus disposed of, the firm portion of the external fascia lata, as it passes to join the internal, assumes a lunated form above and below, and thus the entire apparent deficiency is made to appear of an oval figure, the edges of which are crescentic, and which have been called by the different names of Iley's ligament, Burns' liga ment, and the crescentic edge of the fascia lata. A finger pushed from above through the crural ring will easily feel the superior margin of this aperture, and its influence on hernia in this situation will soon be made apparent. The femoral or crural atrial then is from one-half to three-fourths of an inch in length, and is formed by the fascia lam : it is bounded above, anteriorly by Poupart'sligament and posteriorly by the linea ileo-pectinea; below, anteriorly by the crescentic edge of the fascia lata or lley's ligament, and posteriorly by its pubic portion : both externally and internally it is bounded by the junction of these two portions of fascia. Gimbernat's liga ment, which is usually described as forming the internal boundary of the erural ring, rarely fills up more than half the space between the crest cf the pubis and the femoral vein. This canal, as being composed of fascia, is firm, and un yielding : it cannot be influenced by the actions of any muscle in the neighbourhood, nor even so much as is generally supposed by the posi tion of the limb. It should follow from this constitution of parts that any hernia thus re strained should forcibly compress the vein and artery before it suffered strangulation itself, and so it would if the protrusion had relation to this canal alone, and was not contained within its own proper portion of the funnel-shaped sheath already described.