Like the lower portion of the forearm, the wrist is compressed antero-posteriorly, and presents for examination anterior and posterior surfaces. The styloid processes of radius and ulna form prominent landmarks, separating these surfaces from one another, the styloid of the radius lying anterior to and ½ inch below that of the ulna. Three furrows can frequently be observed on the anterior skin surface, the superior corresponding to the level of the styloid of the ulna, the middle to the wrist-joint, and the inferior to the midcarpal joint and the upper border of the anterior annular ligament. From without inwards the following structures are met with at the front of the wrist : First, the radial artery, which is accompanied by its venae comités, and by the superficial volar when that vessel is given off high up (' double pulse ') ; then the tendon of the flexor carpi radialis, inserted into the bases of the second and third metacarpals, followed by the median nerve, which cannot be distinguished, and the tendon of the palmaris longus, which is absent in 10 per cent, of cases, and which, when present, is best rendered prominent by extending the fingers and flexing the wrist, and either closely approximating or widely separating the thenar and hypothenar eminences. The flexor sublimis digitorum lies immediately beneath the palmaris longus. Next comes the ulnar artery, with its venas comités ; then the ulnar nerve, which grooves the radial side of the pisiform bone ; and then the flexor carpi ulnaris, which is inserted into the pisiform bone, and is rendered prominent by forcibly flexing the little finger into the palm, and slightly flexing the wrist.
On the dorsal aspect, commencing externally beyond the radial artery, there are two tendons close together, the first being the extensor ossis, and the second the extensor primi internodii pollicis, separated by a slit-like interval. About ½ inch farther round lies the tendon of the extensor secundi internodii pollicis (extensor longus pollicis). These tendons are rendered prominent by abducting and extending the thumb. Between the two first and the third of these tendons lies a shallow triangular depression-the tabatière ana-tomique-which is crossed superficially by the dorsal vein of the thumb (cephalic) and branches of the radial nerve, and deeply by the radial artery running from the wrist to the posterior extremity of the first interosseous space. The floor of the area is formed by the scaphoid, trapezium, and base of the first metacarpal bone, and the tendons of the extensor carpi radialis longior and brevior cross the base of the triangle, to be inserted into the bases of the second and third metacarpal bones respectively. If the tendon of the extensor longus pollicis be followed up to the radius, a small bony tubercle is met, marking the outer border of its osseous groove. Here the tendon marks the centre of the posterior surface of the radius, and roughly the interval between the scaphoid and semilunar bones. Beyond the tendon of the extensor longus pollicis comes that of the extensor communis digitorum. Further to the ulnar border lies the tendon of the extensor minimi digiti, which can be felt ; then comes the head of the ulna, which is prominent when the hand is pronated ; and, lastly, there is the tendon of the extensor carpi ulnaris, which is inserted into the base of the fifth metacarpal. The styloid process of the ulna becomes most distinct on supination, lying to the ulnar side of the external carpi ulnaris tendon. Its tip corresponds to the line of the wrist-joint.
The palmar surface of the hand is roughly quadrilateral in outline and concave centrally, where the skin is adherent to the*-palmar fascia. This central depression is surrounded by the thenar and hypothenar eminences. At the upper extremity of the thenar eminence is a bony prominence, due to the tubercle of the scaphoid and ridge of the trapezium, while at the upper extremity of the hypothenar eminence is another bony prominence, due to the pisiform bone, with the unciform hook below it. The anterior annular ligament takes attachment from these points. The opponens and abductor pollicis take origin from the ridge of the trapezium, and the flexor carpi ulnaris is inserted into the pisiform and hook of the unciform. The abductor minimi digiti arises from the pisiform.
Three of the creases traversing the palm are of importance : The superior, starting from a point about 1 inch above the base of the index-finger, curves up and inwards, and demarcates the thenar eminence. The middle, starting from the same point, crosses the palm obliquely, to end over the hypothenar eminence, and indicates roughly the position of the superficial palmar arch, whose summit almost touches it in the line of tire third metacarpal. The deep palmar arch is about ½ inch nearer the wrist. The third furrow commences ¾ inch above the base of the little finger, and runs across toward the radial border of the palm, indicating the upper limit of the synovial flexor tendon sheaths of the three outer ringers. The metacarpophalangeal joints lie below this crease, and ¾ inch above the webs of the fingers, and about the same level the palmar fascia divides into four slips for the four fingers. Between these slips and opposite the webs of the fingers three small elevations, corresponding to the fatty tissue between the fasciar slips, may be seen, particularly when the first phalanges are extended and the other two are flexed. The transverse creases corresponding to the metacarpophalangeal joints lie ¾ inch below the joints. Those at the first interphalangeal joints are exactly opposite the joints, while those at the second interphalangeal joints are a little above the joints.
The superficial palmar arch may be represented by a curved line running from the pisiform down to the middle crease opposite the third metacarpal, and then up to. the tubercle of the scaphoid ; while the deep arch may be represented by a line from the base of the fifth to that of the second metacarpal, its centre corresponding to the apex of the hollow of the palm. The digital arteries bifurcate about ½ inch above the webs of the fingers.