144. ‘=Tabatière anatomique.=’--On the outer side of the wrist we can distinctly see and feel, when in action, the three extensor tendons of the thumb. Between the second and third there is deep depression, at the root of the thumb, which the French humorously call the ‘tabatière anatomique.’ In this depression we can make out--1, the relief of the superficial radial vein; 2, the radial artery, in its passage to the back of the hand; 3, the upper end of the metacarpal bone of the thumb. 145. =Tendons on back of wrist.=--The relative positions of the several extensor tendons of the wrist and fingers, as they play in their grooves over the back of the radius and ulna, can all be distinctly traced when the several muscles are put in action. The length of their synovial sheaths should be remembered. They vary from one inch and a half to two inches and a half. The longest of all are those of the extensors of the thumb. When these sheaths are inflamed and swollen, the motion of the tendons becomes painful and gives rise to a feeling of crepitus, called ‘tenalgia crepitans’ by some writers. It is said to be met with sometimes in pianists. 146. =Lines of arteries.=--The course of the radial artery corresponds with a line drawn from the outer border of the tendon of the biceps at the bend of the elbow down the front of the forearm to the front of the styloid process of the radius. In the upper third of its course the artery is overlapped by the supinator longus. To make allowance for this, the incision for the ligature of the artery in this situation should be made, not precisely in the line of its course, but rather nearer the middle of the forearm. The line of the ulnar artery runs from the middle of the bend of the elbow (slightly curving inwards) to the outer side of the pisiform bone. The radial and ulnar arteries can, in most cases, be effectually commanded by pressure well applied at the wrist, in wounds of the palmar arch. Before we make incisions along the forearm, it is always desirable to ascertain whether the ulnar artery, which usually runs under the superficial muscles, may not run abnormally over them; in which case its pulsations can be felt all down the forearm. _THE HAND._ 147. It is beside the purpose here to examine the question whether the hand can tell more than the arm, the leg, or any other part of the body, about the physical constitution of its owner, and to what use it has been put. Those who are interested in this subject should read a very elaborate treatise by Carus,[11] ‘On the Reason and Meaning of the Different Forms of the Hand.’ Still less would I indulge curiosity by inquiring whether the professors of chiromancy, relying on the text ‘erit signum in manu tua et quasi monumentum ante oculos tuos,’ can advance any reasonable pretensions for their assertion that they can read in the furrows of the palm the future destiny of its master.