THE SENSORY NERVES OF THE HIP JOINT

Abstract

Nerve Supply to the Ventral Aspect of the Hip Joint 1. The articular branch of the obturator nerve to the ventral aspect of the coxofemoral joint is almost constant (98 per cent. ± 2). 2. The articular branches arise more frequently from the trunk of the obturator nerve (71.64 per cent. of the cases ± 6.4) than from either the posterior (23.37 per cent. ± 6.2) or the anterior branch (2.98 per cent. ± 2.4) of the obturator nerve. 3. The articular branch of the obturator nerve is single in 67.34 per cent. ± 6.7 of the cases in 28.57 per cent. ± 6.4 there are two articular branches, and in 4.08 per cent. ± 2.8 there are three. 4. The articular nerves may be of two types,—that is, capsular (penetrating the capsule), and acetabular (penetrating the incisure of the acetabulum). 5. The capsular branch is present in 93.87 per cent. of the cases; it was missing in only three of our specimens; only the acetabular branch was present in these. The acetabular branch is present in 59.18 per cent. ± 6.9 of the cases. It arises directly from the trunk or from the terminal branches of the obturator nerve in 14.28 per cent. ± 4.9 of the cases; from the nerve to the external obturator muscle in 18.36 per cent. ± 5.5; from the capsular branch in 26.53 per cent. ± 6.2. 6. A common origin of branches from the obturator nerve was found as follows: articular branch and nerve to the external obturator muscle, in 44.98 per cent. ± 7.1 of the cases capsular, acetabular, and muscular branches, in 12.24 per cent. ± 4.6; acetabular and muscular branches, in 20.4 per cent. ± 5.8; capsular and muscular branches, in 12.24 per cent. ± 4.6. 7. The origin of the articular branches of the obturator nerve is proximal to the obturator canal (that is, in the pelvic cavity) in 40.29 per cent. ± 7; at the level of the internal orifice of that canal, in 26.86 per cent. ± 6.3; within the canal, in 17.61 per cent. ± 5.4; at the level of its external orifice, in 14.42 per cent. ± 5.1. 8. When present, the accessory obturator nerve may or may not give off filaments to the coxofemoral joint. It was present in two of our specimens and contributed to the innervation of the joint in one case. 9. No direct articular branches from the femoral nerve were found. There are, however, nerve filaments arising from the nerve to the pectinaeus muscle, which follow the medial circumflex vessels, as well as twigs from the nerves to the vastus lateralis, intermedius, medical, and rectus femoris muscles, which follow the lateral femoral circumflex vessels. Innervation of the Dorsal Aspect of the Hip Joint 1. The dorsal aspect is supplied in all cases by one or more branches arising from the nerve to the musculus quadratus femoris and musculus gemellus inferior. We suggest for the latter the name musculo-articularis of the sacral plexus. In only two instances was there a concomitant branch directly from the sciatic nerve. 2. The nervus musculo-articularis originates most frequently from the sacral plexus (69.81 per cent. ± 6.3); next most frequently from the initial portion of the sciatic nerve (24.52 per cent. ± 5.9); or from the tibial branch of the sciatic nerve (5.66 per cent. ± 3.2), in cases of high division of the latter. 3. The nervus musculo-articularis arises from the anterior aspect of the transitional segment between the sacral plexus and the sciatic nerve, at a point in the transverse plane somewhere between the lateral and the medial margin. 4. The origin of the nervus musculo-articularis occurs most frequently proximal to the interior outline of the ischiatic foramen (37.73 per cent. ± 2.4); at its level, in 30.18 per cent. ± 6.3; distal to it, in 32.07 per cent. ± 6.4. The maximum distance between this origin (either proximal or distal) and the inferior outline of the ischiatic foramen was 25 millimeters. 5. The initial of the nervus musculo-articularis, from its origin down to the upper margin of the musculus gemellus superior, is the part most accessible to the surgeon and might be called its surgical segment. It may measure between 3 and 45 millimeters in length.