"It [the ligament] is very thick between the anterior inferior spine of the os ilium all the way to the small anterior tuberosity which unites, as it were, the basis of the great trochanter with the basis of the neck. It is likewise very thick between the same spine and the middle part of the oblique rough line observable between the tuberosity and the little trochanter; and here likewise it is strengthened by a bundle of fibres connected to the passage of the tendon of the iliac muscle and to the inferior portion of the oblique rough line. The disposition of the ligamentous fibres of which these two thick portions are composed forms a sort of triangle with the oblique rough line which terminates the basis of the neck."1 Weitbrecht, an excellent, perhaps the best, authority upon the ligaments, referring in this connection to Winslow, distinctly recognizes a forked arrangement, which he thus describes : "Partim anterius versus collum femoris et trochanterem minorem procedit, . . . partim vero lateraliter versus exteriora progreditur, et circa radicem trochanteris majoris in tuberculo laterali terminatur. Atque binae hae divaricationes, una cum linea obliconstituunt.": 2 qua, figuram . . . triangularem . . The Webers describe the ligament as triangular, laying stress upon its thickness, which, as they assert, is greater than that of the ligament of the patella or the tendo Achillis, and concluding thus: "With this great strength we should expect that every other part of the capsule would be ruptured before this ligament; and that even the bone itself would first yield." 8 1 An Anatomical Exposition of the Structure of the Human Body (sect. 2, pp. 138-139). By James Benignus Winslow. (Douglas's Translation.) London, 1776. 2 Syndesmologia, sive Historia Ligamentorum, etc. (p. 141). Josias Weitbrecht, D. M. Petropoli, 1742. 8 Traité d'Ostéologie, etc. (pp. 323, 324). S. P. Soemmerring, and G. and E. Weber. Paris, 1843. CAPSULE OF THE HIP. In a front view of the cleanly dissected capsule of the joint, the Y ligament is distinctly seen, the tissue occupying its fork being sometimes a mere membrane, and sometimes thicker. The external band hinders eversion, especially when the leg is extended. Both bands limit extension. In abducting the leg, a band is raised (pubo-femoral) between the bony ridge. above the thyroid foramen and the prominence at the inner part of the intertrochanteric line, hindering abduction in every position of the limb. Between this band and the Y ligament the capsule is comparatively thin; and here the primitive pubic dislocation doubtless occurs. Behind and inside the pubofemoral band, looking directly toward the thyroid foramen, is found the thinnest part of the capsule, which at this point resembles wet bladder, readily permitting the thyroid dislocation. Outside and behind the Y ligament, where the dorsal dislocations occur, the capsule is very strong, limiting adduction and rotation inward. There is also a fasciculus from the tuber ischii at its upper part to the upper part of the trochanter behind, arresting flexion and inversion. The principal ligamentous bands are the two first described, no part of the capsule comparing in strength with the Y ligament and the tissue which lies immediately behind it, beneath the tendon. of the obturator internus muscle. LIGAMENTUM TERES. Little can be added to the excellent paper of Mr. Struthers1 upon the function of this ligament. When the limb is bent upon the body, it hinders eversion,- thus opposing the action of the sartorius muscle, and hindering, in this position, dislocation upon the thyroid foramen. It is not, however, possessed of much strength; is ruptured in all the complete and 1 Edinburgh Medical Journal, November, 1858 (p. 434). sudden dislocations, and, according to Cruveilhier, is often undeveloped and sometimes wanting. OBTURATOR INTERNUS MUSCLE. It will hereafter be seen that this muscle, with which the gemelli are practically identified, is materially concerned in one variety of hip dislocation, and is important in relation to its reduction. There is a peculiarity of the obturator internus, hitherto undescribed, which explains its strength. Its muscular belly is, in some subjects, mingled with tendinous fibres. This may be verified in dissection by reflecting the muscle from its pulley so as to expose its internal and fibrous surface. The four or five tendinous divisions which wind round the lesser sacro-sciatic notch, and which seem to disappear in the thickness of the muscular tissue, may then be traced in part to a bony origin, some of their minute and ultimate fibres arising from the margin of the obturator foramen. The muscle, when extended, thus practically becomes a ligament, and by the attachment of its combined tissues acquires great strength. Again, the friction of the tendon over the pulley lessens the draft upon the extended muscle, and so increases its power of resistance that it is the strongest, as in relation to luxation it is the most important, of the small outward rotators of the hip. That portion of the capsule which lies directly beneath the tendon is also very strong; and while their fibres mutually reinforce one another, their mechanical action in the dorsal luxations is much the same. 1 The average weight required to rupture this and the adjacent muscles in four subjects is as follows: Pyriformis 10 lbs. Obturator internus 40 66 Obturator externus 36 lbs. In the only recent subject among these, the obturator internus on one side parted at 64 lbs. and on the other at 60 lbs., the obturator externus at 52 and 44 lbs., and the pyriformis at 16 lbs. Arising within the pelvis, the obturator internus emerges from the pelvic cavity at a point several inches behind the great trochanter, into the back and upper part of which it is inserted. By its contraction it draws the trochanter back ward, everting the thigh when straight, and abducting it if flexed. Upon the dead or etherized subject it is rendered tense in the extended limb by rotation inward, ad duction being then FIG. 2.1 more limited; but in the flexed limb, and especially in extreme flexion, it is relaxed; so that in reducing a backward dislocation, when this muscle is still entire, it might be advantageous to flex the limb as much as possible. A curious corroboration of the importance of this muscle, as well as of the external branch of the Y ligament, is seen in a preparation 2 of my own, the case having been one of old ununited fracture of the neck of the femur, in a subject the weight of whose body in walking had been suspended chiefly 1 Ununited fracture of the neck of the thigh-bone, showing the hypertrophied outer fasciculus of the ligament supporting the weight of the pelvis in walking. The inner fasciculus is seen below. 2 No. 2715, The Warren Anatomical Museum of Harvard University. between the outer branch of the Y ligament in front and the obturator internus behind (Figs. 2 and 3). This is probably the usual condition of patients after this injury, where the shaft of the femur moves freely upon the detached head of the bone. OTHER MUSCLES. It has already been stated that the restricted movements of the thigh in the various luxations are in part due to the active and passive resistance of several muscles which (like the psoas and iliacus) connect the femur with the pelvis, and become more or less tense by its displace ment; yet their action, in a practical point of view, is of FIG. 3.1 secondary importance, whether considered in relation to its direction or its extent. Without the powerful ligament and the muscle already described, the regular femoral luxations would lose much of their present distinctive character; and regard being had to the action of these fibrous bands, the dislocations can be reduced with little reference to the muscles. 1 Fig. 2 seen from behind, to show the tense obturator tendon bearing its share of the weight of the body. The inferior gemellus, hypertrophied, is seen below it. |