The subject lying upon its back, the thigh abducted, and rotated out, the knee flexed, so that the foot of the side to be dissected rests upon the opposite thigh.
1. From immediately below the centre of Poupart's ligament along the upper two thirds of a line leading to the internal Condyle of the Femur.
2. An oblique incision at the upper end of No. 1, reaching for one and a half inches on either side, parallel with Poupart's ligament.
3. A transverse cut at the lower end of No. 1, for one and a half inches on either side.
Reflect the flaps inwards and outwards, and expose the superficial fascia.
This will be found at the upper part of the thigh to consist of two layers, which are most easily separable on the inner side of the Saphenous vein.
Dissect out in it—
1. The Superficial External Pudic artery, at the upper and inner part.
2. The Superficial Epigastric artery, passing upwards over the centre of Poupart's ligament.
3. The Superficial Circumflex Iliac artery at the upper and outer part.
4. Small arteries derived from the Femoral trunk will be seen, with the several cutaneous nerves to be mentioned below.
5. The Long Saphenous vein receiving branches corresponding to the three above-named arteries, and at the upper part a large branch which collects the blood from the inner and back parts of the thigh; sometimes there is a corresponding branch on the outer side.
6. Cutaneous twigs of the Internal Cutaneous nerve, one perforating near the Saphenous opening, and one or more lower down the thigh.
7. The Middle cutaneous nerve perforating the deep fascia at about the centre of the thigh, about three inches below Poupart's ligament. There are two branches, of which the outer is only seen to a small extent.
8. The Crural branch of the Genito-crural nerve cutaneous, near the middle line, about one inch below Poupart's ligament. It is seen to communicate below with the Middle Cutaneous nerve.
9. Numerous lymphatic vessels in front of the thigh running upwards to lymphatic glands, which are found arranged in a row along the Long Saphenous vein.
Remove the preceding structures, and expose the deep fascia.
At the upper and inner part of the thigh, immediately below Poupart's ligament, the Saphenous opening will be displayed : and the deep layer of the superficial fascia (Cribriform fascia) which is attached to its margins being removed, a portion of the Femoral sheath will appear at its outer part.
a. Clear away the deep fascia. In doing this the attachment of the superior Cornu of the Saphenous opening to Poupart's ligament must be divided. The cutaneous nerves should be preserved.
b. Remove fat, fascia and lymphatics, from Scarpa's triangle. There will now be exposed—
1. The lower portions of the Sartorius and Adductor longus muscles.
2. The Psoas and a portion of the Iliacus muscles at the upper and outer part, most external of those forming the floor of Scarpa's triangle ; the Iliacus being outermost.
3. The lower part of the Pectineus muscle.
4. A small piece of the Adductor brevis muscle, between the Pectineus and the Adductor longus muscles.
5. A portion of the Vastus internus muscle below.
6. The Crural sheath covering in about the upper two inches of the Femoral vessels, and the ordinary areolar sheath below it. This, however, will most probably be taken away in cleaning the triangle, if not, it should now be removed. It will then be seen that the sheath is divided into three compartments by two fascial septa, the outermost one of which contains the Femoral artery, the middle the Femoral vein, and the innermost, which is only half an inch in length, contains a lymphatic gland.
7. The Femoral artery is seen giving off the Superficial Pudic, Epigastric, and Circumflex Iliac arteries, at the upper part, and lower down the Inferior External Pudic twig, which crosses inwards over the Pectineus muscle. The Profunda branch arises from one to two inches below Poupart's ligament on the outer side, but is exceedingly variable in its place of origin, and may come off at any point between Poupart's ligament and four inches below it. The Internal and External Circumflex branches of the Profunda artery may be seen at their origins, the former passing backwards between the Psoas and Pectineus muscles, the latter running out between the Superficial and Deep divisions of the Anterior Crural nerve. These last two branches, however, are also very variable in origin, and are often found arising from the Common Femoral trunk. Muscular branches of the Femoral artery are also displayed.
8. The Femoral vein is seen receiving branches similar to those of the main artery, except that the twigs corresponding to the Superficial Pudic, Epigastric, and Circumflex Iliac arteries run into the Long Saphenous vein, which also is seen to join the Femoral vein quite at its upper part. The Femoral vein at Poupart's ligament lies internal to the artery, but at the apex of Scarpa's triangle is beneath it; the Profunda vein is superficial to its artery, so that in Scarpa's triangle these two large veins lie between the Superficial and Deep Femoral arteries.
9. The Anterior Crural nerve is displayed lying between the Psoas and Iliacus muscles, about half an inch to the outer side of the Femoral artery. The Middle and Internal Cutaneous, and the Internal Saphenous offsets are traceable from it. Parallel with the last nerve, but external to it, a large nerve to the Vastus internus muscle may be seen. The Middle Cutaneous branch is found supplying the Sartorius muscle, and the two small nerves to the Pectineus muscle, which pass beneath the Femoral artery, may be followed. The distribution of the other muscular branches to the Rectus and Vastus externus muscles cannot be traced, but they are seen at their origins. 10. By separating slightly the Pectineus from the Adductor longus muscles, the Superficial division of the Obturator nerve is seen lying upon the small portion of the Adductor brevis muscle which is exposed. A slender twig of this nerve which runs along the inner border of the Adductor longus muscle may now be found. It is distributed to the Obturator plexus, but the ending cannot now be traced.
Divide now the Sartorius muscle at the lower part of the dissection, and turn it outwards and inwards. Beneath it is found the aponeurotic covering of Hunter's canal, which should be taken away. In addition there will now be seen—
1. Further portions of the Femoral artery and vein, the latter passing to the outer side of the artery. The Anastomotica Magna branch of the artery, coming off at the lower part of the canal.
2. More of the Long Saphenous nerve. It may lie on the outer side of the artery throughout the extent of the canal, or it may cross from the outer to the inner side, over it.
3. The branch of the Obturator nerve to the plexus of the same name may now be traced to its communication with the Inner branch of the Internal Cutaneous nerve.
4. Both Anterior and Inner branches of the Internal Cutaneous nerve will be seen, the former lying upon the artery, the latter to its inner side. A communication between the Inner branch and the Saphenous nerve is traceable, thus completing the so-called Obturator plexus.
a. Hook outwards the Anterior Crural nerve dividing the Internal Cutaneous and Long Saphenous branches.
b. Cut through the Femoral artery at its lowest part, and hook the ends upwards and downwards, dividing at the same time its muscular offsets.
c. Remove the Femoral and Profunda veins.
d. Divide the tendinous insertion of the Adductor longus muscle, and pull the muscle inwards. There will now be exposed—
1. The lower part of the Adductor magnus muscle, at its attachment to the Femur.
2. The whole length of the Profunda Femoris artery, and the origin of its branches, viz., the Internal and External Circumflex, and the four Perforating ; the upper two of which pierce the Adductor brevis muscle, the third and fourth (which last is the termination of the artery) passing to the back of the thigh through the Adductor magnus muscle.
The Adductor magnus muscle must be divided at its Femoral attachment, behind the opening for the Femoral artery, to follow out the terminal or fourth Perforating twig.