Plate 45.--figure 1

PLATE 45, Fig. 2.--There exists a very evident analogy between the canals through which both herniae pass. The infundibuliform fascia, 3, 3, of the spermatic vessels is like the infundibuliform sheath, 9, 9, of the femoral vessels. Both sheaths are pro­ductions of the general fibrous membrane of the abdomen. They originate from nearly the same locality. The ring of the femoral canal, 12, is situated immediately below, but to the inner side of the internal inguinal ring, 3. The epigastric artery, 1, marks the width of the interval which separates the two rings. Poupart's ligament, 5, being the line of union between the oblique aponeurosis of the abdominal muscle and the fascia lata, merely over­arches the femoral sheath, and does not separate it absolutely from the spermatic sheath.

PLATE 45.--FIGURE 2

PLATE 45, Fig. 3.--The peritonaeum, 2, 3, closes the femoral canal, 12, at the femoral ring, in the same way as this membrane closes the inguinal canal at the internal inguinal ring, 3, Fig. 2, Plate 45. The epigastric artery always holds an intermediate position between both rings. The spermatic vessels in the inguinal tube, 3, 3, Fig. 2, Plate 45, are repre­sented by the round ligament in the female inguinal canal, Fig. 3, Plate 45. When the bowel is about to protrude at either of the rings, it first dilates the peritonaeum, which covers these openings.

PLATE 45.--FIGURE 3

PLATE 45, Fig. 4.--The place of election for the formation of any hernia is that which is structurally the weakest. As the space which the femoral arch spans external to the vessels is fully occupied by the psoas and iliacus muscles, and, moreover, as the abdominal fibrous membrane and its prolongation, the femoral sheath, closely embrace the vessels on their outer anterior and posterior sides, whilst on their inner side the membrane and sheath are re­moved at a considerable interval from the vessels, it is through this interval (the canal) that the hernia may more readily pass. The peritonaeum, 2, and crural septum, 13, form at this place the only barrier against the protrusion of the bowel into the canal.

Plate 45.--figure 4

102 Commentary on plates 45 & 46.

PLATE 45, Fig. 5.--The hernia cannot freely enter the compartment, 10, occupied by the artery, neither can it enter the place 11, occupied as it is by the vein. It cannot readily pass through the inguinal wall at a point internal to, 9, the crural sheath, for here it is opposed by, 4, the conjoined tendon, and by, 8, Gimbernat's ligament. Neither will the hernia force a way at a point external to the femoral vessels in preference to that of the crural canal, which is already prepared to admit it. [Footnote] The bowel, therefore, enters the femoral canal, 9, and herein it lies covered by its peritonaeal sac, derived from that part of the membrane which once masked the crural ring. The septum crurale itself, having been dilated before the sac, of course invests it also. The femoral canal forms now the third covering of the bowel. If in this stage of the hernia it should suffer constriction, Gimbernat's ligament, 8, is the cause of it. An inci­pient femoral hernia of the size of 2, 12, cannot, in the undissected state of the parts, be detected by manual operation; for, being bound down by the dense fibrous structures which gird the canal, it forms no apparent tumour in the groin.

[Footnote: The mode in which the femoral sheath, continued from the abdominal membrane, becomes simply applied to the sides of the vessels, renders it of course not impossible for a hernia to protrude into the sheath at any point of its abdominal entrance. Mr. Stanley and M. Cloquet have observed a femoral hernia external to the vessels. Hesselbach has also met with this variety. A hernia of this nature has come under my own observation. Cloquet has seen the hernia descend the sheath once in front of the vessels, and once behind them. These varieties, however, must be very rare. The external form has never been met with by Hey, Cooper, or Scarpa; whilst no less than six instances of it have come under the notice of Mr. Macilwain, (on Hernia, p. 293.)]