20. By this, 1st, The movements of the arm being entirely impeded, they cannot have any influence on those of the shoulder; hence, in this respect, the fragments are suffered to remain in contact. 2dly, The serratus-major and teres-major muscles, being kept in a state of habitual relaxation, can no longer draw the inferior fragment forward, which cannot, therefore, be separated from the body of the bone. 3dly, Nor can the body of the bone, being permanently held in this situation, be removed from the fragment; whence, in both respects, a displacement will be effectually prevented. This threefold advantage is not possessed by any of the different kinds of apparatus hitherto proposed, such as the sling and cross-bandage, employed by Petit, which have the fault of suffering the arm to move backward, of allowing the scapula to be easily separated from its insulated angle, of retarding by that means the cure, and even of preventing it entirely, while, by the process just described, it is usually completed by the thirtieth day. MEMOIR V. ON THE FRACTURES OF THE UPPER END OR NECK OF THE HUMERUS.[10] [10] For a very important improvement made by Dr. Physic in the treatment of an old fracture of the os humeri, and which may be applied also to similar fractures of other bones, see Article I. of the Appendix. TRANS. 1. The language of the surgeon differs, in this case, from that of the anatomist, and by the expression, “fracture of the neck of the humerus,” is here meant not that of the slight circular depression, which separates the head from the tuberosities of the bone, but rather that of the contracted or diminished portion of the bone, which commences at the tuberosities above, and being continued down the body of the bone, receives at its lower end the insertion of the tendons of the pectoralis major, the latissimus dorsi, and the teres major. Many practitioners consider this neck or contracted portion as extending even to the insertion of the deltoid muscle. 2. Several facts, the truth of which it is difficult to call in question, attest the possibility of a fracture of the neck of the bone, so called in anatomical language. I have myself seen, in the humerus of a young man, aged seventeen years, the head of the bone exactly separated from its body, by a division which had but slightly affected the upper extremity of the tuberosities. But the examples of this nature which occur in the annals of surgery are too few, to enable us to lay down any general principles for the treatment of such fractures. § II. OF THE VARIETIES AND THE CAUSES. 3. The operation of external bodies, active, when they are thrown against the shoulder, passive, when the shoulder, or the arm, is forcibly driven against them, is always the cause of a fracture of the neck of the humerus. From the mechanism of the part, the division is sometimes direct, and sometimes the effect of a counter-stroke.