On reflecting the glutaus maximus the fol lowing parts are brought into view :—lst, several large branches of arteries and veins, which were divided in reflecting the muscle, and which passed into the substance of the great glutwus muscle; these are from the glutreal and isehiatie arteries, and appear principally at the upper and posterior part of the gliitteus medius; 2d, the whole of the glutaus medics, the pos terior two-thirds of which had been covered by the larger muscle ; 3d, at the posterior edge of the glu twos medius is the pyriformis muscle part ly concealed by it, and coming out of the supe rior sacro-sciatic foramen; 4th, next below the pyriformis lie the two gemelli, with the tendon of the obturator internus between them, and below these is the quadratus femoris, having underneath it the strong tendon of the obturator externus; Stli, the great sciatic nerve is seen emerging from the superior saero-sciatie fora men near the sciatic artery. Sometimes it comes out entirely below the pyriformis; some times it descends in two branches, one of which perforates that muscle, and they then unite. The trunk passes directly downwards, cross ing the rotator muscles of the hip, and pass ing between the projecting tuberosity of the ischium and the trochanter major. in this part of its course it is accompanied by the sciatic artery, which is seen about half an inch to the ioternal or sacral side of the nerve, and sends one considerable branch to supply the nerve, and runs tortuously imbedded in its neurilema. The course which the nerve and artery here take will be represented by a line drawn from the posterior superior spinous pro cess of the ilium to a spot midway between the tuber ischii and trochanter major. Lastly, in this view are exposed the bursa' sacs, of which there are several between the gluteus maximus and the subjacent parts. The most considerable is found between it and the external surface of the trochanter major. A consider able hut smaller one is placed between its broad tendinous expansion and the upper part of the vastus externus, and two smaller ones com monly between the muscle and the os femoris at the upper and back part of the thigh. The ischiatic artery at the commencement of its course is smaller than the glutwal, and comes down over the pyriformis muscle, and makes its exit from the pelvis through the lower part of the sciatic notch, between the pyriform and levator ani muscles, above the lesser sciatic ligament, and in front of the sciatic nerve; it sometimes passes between the roots of this nerve. On the dorsum of the pelvis the sciatic artery is covered by the gluteus maximus muscle, and may be seen by a similar dissec tion to that which exposes the glutwal artery, excepting that it is found about an inch and a half lower down than the last-named vessel.
The glutaal artery comes out of the pelvis at the upper part of the sciatic notch in com pany with the superior glutaal nerve and vein. It immediately winds upwards upon the dorsum ilii, keeping close to the bone, and shortly after its arrival upon the dorsum it divides into branches principally distributed to the glutwal muscles. To expose this artery and its branches in dissection, it is necessary to proceed as in the dissection of the gluteus maximus muscle.
Next divide this muscle in a line from the posterior superior spine of the ilium to the tuberosity of the ischium. In making this dis section several large arteries and veins must be injured. If the edges of the muscle be now separated and die subjacent cellular membrane removed, the glutwal artery, accompanied by one or two large veins and by the glutwal nerve, may be seen escaping from the sciatic notch above the pyriform muscle, between it and the glutaus mishits. This artery, as it escapes from the pelvis, lies three inches and a half from the mesian line, or from the spinous processes of the sacrum.
The glutreal and ischiadie arteries, as we have seen, are covered by the gluteus maximus mus cle, and lie at such a depth from the surface that they are not very liable to injury. Wounds, however, of this part do occasionally implicate these vessels, either in their large branches or even the trunks themselves, and they have been affected with aneurism, an instance of which is mentioned by Mr. J. Bell,* and which attained a considerable size. In the case of a wound, its direction will lead us to the situation of the artery ; and in the instance of aneurism just mentioned, Mr. Bell ventured to lay open the sac and thus reach the mouth of the glutreal artery, which he secured by liga ture, and this perhaps might be accomplished in a very emaciated person; hut generally speaking the artery lies so deep, and the vessels which must be wounded in making the neces sary incisions would by their bleeding so ob scure the operation, that the most experienced surgeons do not recommend the attempt under ordinary circumstances, but prefer the operation of tying the internal iliac. f As a guide, how ever, to the situation of the glutwal artery, whether in the examination of a wound or in operating upon it, its position on the dorsum of the pelvis may be ascertained by drawing a line from the posterior spinous process of the ilium to the middle of the space between the tuberosity of the isehium and trochanter major. If this line is divided into three, the glutreal artery will be found emerging from the pelvis at the juncture of its upper and middle thirds.] To return to the consideration of the anato mical structures which we expose in succession. We are struck with the difference in texture of the three glutei muscles. The fibres of the two smaller glutai are of moderate size and strength, while those of the larger glutmus are remarkable for their coarseness and large dimen sions. The relative situation of the three muscles is also important. The position and direction of the gluteus maximus isjust in that line in which the greatest vigour of action is required to erect the body by drawing the back part of the pelvis towards the trochanter major. in this operation it is assisted by the position of the glutaus medals and minimus, the posterior fibres of which are covered by the glutaus maxims. These anterior fibres have a different action, varying in the different posi tions of the body in relation to the thigh, and, according to this, consisting either in rotation inwards, abduction, or flexion of the femur, or, this bone being fixed, assisting in the various anterior movements of the pelvis upon the thigh.
At the posterior edge of the middle glutaus is the pyriformis coming out of the upper open ing of the sciatic notch. as we have seen, the glutaal artery is also emerging from the pelvis and winding round the upper edge of the notch. This, therefore, will be the situa tion of an aneurism of this artery, and a pul sating tumour being detected in the situation just indicated by measure, as the seat of this vessel, will be a very strong ground for deciding both as to the disease and the vessel diseased. A ease lately came under our notice of a very obscure character in which a swelling was situated precisely in the position of the glutaal artery, but without pulsation or any other syrrt ptom of aneurism. The swelling was at first indistinct, but as the surrounding parts wasted under the effect of disease it became more pro minent. It was firm to the touch and rather moveable, and about the size of a hen's egg. But the principal part of the disease showed itself within the pelvis in a tumour consisting almost entirely of coagulum, as was proved by puncture, situated behind the rectum, and pressing it forward so as to occupy nearly the whole pelvis, and obstructing the passage both of faces and urine. As there was no decided symptom of aneurism no operation was at tempted for the relief of the case, and as the girl, who is eighteen years of age, still lingers, the nature of the disease is not yet cleared up. But this part also occasionally gives exit to a hernial tumour, part of the intestines or even the bladder or ovary becoming thus displaced and being lodged in the sae.* The superior opening of the sciatic notch is hounded above by the notch of the ilium, before by the de scending ramus of the ischium, and below and behind by the superior sacro-sciatic ligament; and so large is the opening thus left that we might expect to find the protrusion of some of the viscera of the pelvis much more frequently than we do. Yet so completely is this part covered and defended by the pyriform muscle, the plexus of nerves, the glutai maximus and medius, that this form of hernia is an extremely rare occurrence. When it does occur in the adult, the diagnosis is very difficult while the hernia is small, owing to the great depth at which it is situated. When, however, it is congenital, the nature of the swelling is larger in proportion to the size of the surrounding parts, and the depth of the superjacent parts less ; yet even here Professor Schreger did not at first detect the nature of the swelling. In fact nothing but the actual feeling of the guggling of the gas of the intestines under the finger seems sufficient to discriminate the case, and this is of course not to be expected when the gut is strangulated. Indeed, in Dr. Jones's case* the symptoms were not at all referred by the patient to the true seat of the disease, and the surgeon was in consequence never led to make any external examination of this part. It may be well to state here the anatomical relations of the hernial sac in this case, which was carefully dissected. " A small orifice in the side of the pelvis, anterior to but a little above the sciatic nerve and on the fore part of the pyriformis muscle, led into a bag situated under the gluteus maxi mus muscle, and this was the hernial sac, in which the portion of intestine had been stran gulated. The cellular membrane which con nects the sciatic nerve to the surrounding parts of the ischiatic notch had yielded to the pres sure of the peritoneum and viscera. The orifice of the hernial sac was placed anterior to the internal iliac artery and vein, below the obtura tor artery and above the obturator vein. Its neck was situated anterior to the sciatic nerve, and its fundus, which was on the outer part of the pelvis, was covered by the glutaus maxi mus. Anterior to but a little below the fundus of the sac, was situated the sciatic nerve, behind it the glutaal artery. Above, it was placed near the bone, and below appeared the muscles and ligaments of the pelvis." We must not conclude this article without a few words on the general form of the glutreal region as affording an important means of diagnosis in disease. In examining this re gion in a healthy person we observe, 1st, the thick rounded prominence of the nates, formed by the posterior and inferior margin of the glutaus maximus ; f..'cl, the projection of the trochanter major, only covered by the integu ments and the thin tendon of the last-named muscle; 3d, the projection of the crista forming the upper boundary of the region ; 4th, a depression, perpendicular in direction, between the nates and the trochanter major; 5th, another depression, slighter than the last and transverse in direction, between the tro chanter and crista Now almost all these points become altered in character and relation in disease. In dislo cation of the femur they of course are changed by the difference in position which the trochan ter assumes in common with the head of the bone; and according to the unnatural situation which this occupies, so will the alteration in the general form of the parts be modified. But we now speak particularly of the changes of disease. Even in the inflammatory stage of disease of the hip joint, it is surprising how great is the effect produced upon the nates. The roundness and fulness gradually go, the nates looks wasted, and the depression between this and the trochanter disappears. This wast ing, arising from interstitial absorption of the glutaus and parts adjacent, is the more striking as it occurs too rapidly upon the affection of the joint to be the effect of inaction of the muscle, as we have seen It occur In a marked degree in a rather severe attack of inflammation of the joint, which readily yielded to treat ment.• Then in the more advanced stages of disease of the joint, the depressions above mentioned are not only lost, but from morbid depositions in the neighbourhood of the hip they become elevated and swollen, and the sharp prominences of the trochanter lost in the general fulness of the part.
(A. T. S. Dodd.)