You frequently hear ignorant persons (and the greater number of persons are lamentably ignorant of the structure of their own body) speaking of the _small bones_ of the shoulder, or the _small bones_ of the elbow. You may think this a matter of no importance, and that it does not concern you and people generally to have any knowledge of human anatomy. But I will tell you what is very often happening, and will leave you to judge whether such complete ignorance on this subject is not attended with some practical disadvantage. A man meets with an injury, falls and hurts his shoulder. The immediate effects of the injury subside; but he does not quickly recover the use of the part; he still cannot raise his elbow, or put his hand upon his head, or put it behind him. Soon he begins to think that something more is wrong than has been suspected; and the notion creeps over his mind, and gradually takes possession of it, that some small bone is displaced. Not content with the assurances of his medical man, he resorts to a quack, called a “bone-setter.” The latter, taking advantage of the popular fallacy, gratifies the patient with the information that his fears are correct, affirms that “a small bone is out,” and proceeds forthwith to employ the requisite forcible measures for putting the said “small bone” in. I need not say with what result. Every year, in this civilized country, many persons are maimed for life by these attempts to put imaginary small bones in. I beg you, therefore, particularly to observe that _there is no small bone_ either at the shoulder or at the elbow. The only small bones are at the wrist; and these are so well fitted to one another, and so firmly bound together, that nothing short of a crushing force suffices to displace them. This remark respecting the small bones of the wrist is true of nearly all the small bones in other parts of the body. So that, in fact, small bones are very rarely dislocated; and when you hear it asserted that a small bone is out, you may pretty confidently conclude that the speaker does not know what he is talking about. I have said that the upper limbs resemble the lower in their general construction. There are, however, some important differences; and one of the chief of these is the greater variety and freedom of the movements in the upper limbs. _Strength_, for the purpose of carrying the body, is the object in the lower limbs. _Mobility_ is the requisite in the upper limbs. Of this one example has already been given in the instance of the thumb as compared with the great toe. _Movements at the Shoulder._ An equally striking example is afforded by the shoulder. In the first place, the “Shoulder-blade” itself can be moved in several directions--upwards, downwards, backwards and forwards;--whereas the “Pelvis,” i. e. the part which bears to the lower limb the same relation that the shoulder-blade does to the upper-limb, is immoveably fixed.