By flexion of the elbow to the utmost, the circulation through the brachial artery can be arrested; but the position is painful, and can be tolerated only for a short time.
Lymphatic gland.—There is a small lymphatic gland just above the inner condyle, in front of the intermuscular septum. It is the first to take alarm in poisoned wounds of the hand.
THE FOREARM AND WRIST.
139. Ulna.—The edge of the ulna can be felt subcutaneous from the olecranon to the styloid process (in supination). Any irregularity could be easily detected. The styloid process of the ulna does not descend so low as the styloid process of the radius, or it would impede the free abduction of the hand. Its apex is on a level with the radio-carpal joint. The head of the ulna is plainly felt and seen projecting at the back of the wrist, especially in pronation of the forearm. It then lies between the tendons of the extensor carpi ulnaris and extensor minimi digiti. There is often a subcutaneous bursa over it.
140. Radius.—The upper half of the shaft of the radius is so covered by muscles that we cannot feel it; the lower half is more accessible to the touch, especially just above and just below the part where it is crossed by the extensors of the thumb. Its styloid process is readily felt, and made all the more manifest by being covered by the first two extensor tendons of the thumb. It descends lower, and lies more to the front than the corresponding process of the ulna. The relative positions of these styloid processes can be best examined by placing the thumb on one and the forefinger on the other.
Feel for the little bony pulley on the back of the radius near the wrist, which keeps in place the third extensor tendon of the thumb. This and the bone just above it is the place which we examine for a suspected fracture (termed Colles’s) near the lower end of the radius.
141. Carpus.—Below the styloid process of the radius, just on the inner side of the extensors of the thumb, we feel the tubercle of the scaphoid bone. Between the styloid process and the tubercle is the level of the radio-carpal joint. A little lower we feel the trapezium.
Just below the ulna on the palm of the hand we feel the pisiform bone; and on the inner side of this, the cuneiform.
There are several transverse furrows on the palmar aspect of the wrist. The lowest of these, which is slightly convex downwards, corresponds with the upper edge of the anterior annular ligament and the intercarpal joint. The line of the radio-carpal joint, as already stated, is on a level with the apex of the styloid process of the ulna.
In forcible flexion of the wrist, the tendon of the flexor carpi radialis and that of the palmaris longus come up in relief. On the outer side of the first-named tendon we feel the pulse, the radial artery here lying close to the radius.