The Sensory Pathways from the Shoulder Joint

T HE anatomy of the peripheral nervous system in man has been engaging increasing attention owing to the development of neurosurgerv during the last few decades. One of the reasons why I have taken up the question of the innervation of the shoulder joint for closer examination is the knowledge that a Swedish surgeon, Dr. H. Wahren, in the course of the last few years, has made operative cuts of nerve branches running to the joints, as a last resort in certain states of severe pain. That surgical operations on the nerves of the joints require a thorough knowledge of the anatomy of those nerves is self-evident. From other points of view also, such knowledge is desirable. Pains in the shoulder joint and arms involve many still rather obscure problems and, even if thes e problems lie mainly in the sphere of physiology and pathology, it seems essential that the normal neuromorphological conditions should be ascertained so far as possible. If we turn to standard textbooks on anatomy, we find there merely quite summary information on the origin and distribution of the articular nerves, and the same is true of even the large monographs on the peripheral nervous system by Hovelacque n and Clara. 4 The older textbooks, such as those by Cruveilhier, 5 I-Ienle, 9 Quain, 2~ and Poirier and Charpy, 19 give somewhat fuller accounts. The most detailed descriptions and illustrations of the artieular nerves, however, have been given by Rtidinger, 22 who, by minute dissections, followed the nerve branches to the joints as far as seems to have been possible. Unfortunately, however, he does not inform us on how large a material his description is based. A schematic representation of the innervation of the extremity joints, evidently based on Riidinger's account, can be found in an atlas of the peripheral nerves by Hasse. s By numerous histologic investigations it has been shown that nerve branches run to the articular capsules and their ligaments, to the articular menisci and disci and to the glenoidal labra. That the hyaline cartilages are devoid of nerves is a generally accepted view, which tallies with the observation made by Bloch, 1 Lennander, 14,15 and NystrSm 18 tha t hyaline cartilage is non-sensitive. As regards the structure of the articular nerves, Riidinger 2~ as far back as 1857 had suggested that the fibres of which they are eonsti tuted are of both encephalospinal and sympathetic origin. A more systematic investigation was made by Sherrington 27 on eats and monkeys, and by Sasaoka 2~,2t on eats. The principal facts brought to light by these investigations are that the medullated fibres in the articular nerves have a calibre similar to that of the slenderer nerve branches Co the skin, and that the articular nerves also