76 Commentary on plates 28 & 29.
The femoral vessels, K I, contained in their proper sheath, lie immediately beneath the iliac part of the fascia lata, in that angle which is expressed by Poupart's ligament, along the line C D above; by the sartorius muscle in the line C M externally; and by a line drawn from D to N, corresponding to the pectineus muscle internally. The femoral vein, I, lies close to the outer margin of the saphenous opening. The artery, K, lies close to the outer side of the vein; and external to the artery is seen, L, the anterior crural nerve, sending off its superficial and deep branches.
When a femoral hernia protrudes at the saphenous space L h, Pl. 28, the dense falciform process, h, embraces its outer side, while the pubic portion of the fascia, L, lies beneath it. The cord, K, is placed on the inner side of the hernia; the cribriform fascia covers it; and the upper end of the saphena vein, M, passes beneath its lower border. The upper cornu, h, Pl. 29, of the falciform process would seem, by its situation, to be one of the parts which constrict a crural hernia. An inguinal hernia, which descends the cord, K, Pl. 28, provided it passes no further than the point indicated at K, and a crural hernia turning upwards from the saphenous interval over the cord at K, are very likely to present some difficulty in distinctive diagnosis.
DESCRIPTION OF THE FIGURES OF PLATES 28 & 29.
PLATE 28.
A. The fleshy part of the external oblique muscle; a, its tendon covering the rectus muscle.
B. The umbilicus.
C. The anterior superior spinous process of the ilium.
D. The spinous process of the os pubis.
E. The point where in this instance the fibres of the aponeurotic tendon of the external oblique muscle begin to separate and form the pillars of the external ring.
F G. See Plate 29.
H. The fascia lata--its iliac portion. The letter indicates the situation of the common femoral artery; h, the falciform edge of the saphenous opening.
I. The sartorius muscle covered by a process of the fascia lata.
K. The spermatic fascia derived from the external oblique tendon.
L. The pubic part of the fascia lata forming the inner and posterior boundary of the saphenous opening.
M. The saphenous vein.
N. A tributary vein coming from the fore part of the thigh.
Plate 28
PLATE 29.
A. The muscular part of the external oblique; a, its tendon.
B. The umbilicus.
C. The anterior superior iliac spine.
D. The spine of the os pubis.
E. The cremasteric fibres, within the external ring, surrounding the cord; e, the cremasteric fibres looping over the cord outside the ring.
F. The muscular part of the internal oblique giving off, E, the cremaster; its tendon sheathing the rectus muscle.
G. The linea alba; f, g, the linea semilunaris.
H. The iliac part of the fascia lata; h, the upper cornu of its falciform process.
I. The femoral vein.
K. The femoral artery.
L. The anterior crural nerve.
M. The sartorius muscle.
N. The sheath of the femoral vessels; n, its upper part.
O. The saphena vein.
P. The pubic part of the fascia lata.
Plate 29
COMMENTARY ON PLATES 30 & 31.
THE SURGICAL DISSECTION OF THE FIFTH, SIXTH, SEVENTH, AND EIGHTH LAYERS OF THE INGUINAL REGION, AND THEIR CONNEXION WITH THOSE OF THE THIGH.
When we remove the internal oblique and cremaster muscles, we expose the transverse muscle, which may be regarded as the fifth inguinal layer, F, Pl. 30. This muscle is similar in shape and dimensions to the internal oblique. The connexions of both are also similar, inasmuch as they arise from the inner edge of the crista ilii, and from the outer half of, V, Poupart's ligament. The fleshy fibres of these two muscles vary but little in direction, and terminate at the same place--viz., the linea semilunaris, which marks the outer border of the rectus muscle. But whilst the fleshy parts of these three abdominal muscles, D E F, form successive strata in the groin, their aponeurotic tendons present the following peculiarities of arrangement in respect to the rectus muscle. The tendon of the external oblique, d, passes altogether in front of the rectus; that of the internal oblique is split opposite the linea semilunaris into two layers, which enclose the rectus between them as they pass to be inserted into the linea alba. But midway between the navel and pubes, at the point marked G, both layers of the tendon are found to pass in front of the rectus. The tendon of the transverse muscle passes behind the rectus; but opposite the point G, it joins both layers of the internal oblique tendon, and with this passes in front of the rectus. The fibrous structure thus constituted by the union of the tendons of the internal oblique and transverse muscles, e f, is named the "conjoined tendon."
The conjoined tendon, f, Plates 30 and 31, appears as a continuation of the linea semilunaris, for this latter is in itself a result of the union of the tendons of the abdominal muscles at the external border of the rectus. As the conjoined tendon curves so far outwards to its insertion into the pectineal ridge of the pubic bone, as to occupy a situation immediately behind the external ring, it thereby fortifies this part against the occurrence of a direct protrusion of the bowel. But the breadth, as well as the density, of this tendon varies in several individuals, and these will accordingly be more or less liable to the occurrence of hernia.
The arched inferior border of the transverse muscle, F, Plate 30, expresses by its abrupt termination that some part is wanting to it; and this appearance, together with the fact that the fibres of this part of the muscle blend with those of the internal oblique and cremaster, and cannot be separated except by severing the connexion, at once suggests the idea that the cremaster is a derivation from both these muscles.
Assuming this to be the case, therefore, it follows that when the dissector removes the cremaster from the space L h, he himself causes this vacancy in the muscular parietes of the groin to occur, and at the same time gives unnatural definition to the lower border of the transverse and oblique muscles. In a dissection so conducted, the cord is made to assume the variable positions which anatomists report it to have in respect to the neighbouring muscles. But when we view nature as she is, and not as fashioned by the scalpel, we never fail to find an easy explanation of her form.
In the foetus, prior to the descent of the testicle, the cremaster muscle does not exist. (Cloquet, op cit.) From this we infer, that those parts of the muscles, E F, Plate 30, which at a subsequent period are converted into a cremaster, entirely occupy the space L h. In the adult body, where one of the testicles has been arrested in the inguinal canal, the muscles, E F, do not present a defined arched margin, above the vacant space L h, but are continued (as in the foetus) as low down as the external abdominal ring.