1172 SURGICAL AND TOPOGRAPHICAL ANATOMY 



this part lying on the periosteum of the last i)liahinx. The synovial sheaths, as 

 they pass beneatli the annular htrament. are sonu-what eonstricted. 



Deeper down are the articular synovial sacs, tive in number: (1) Between 

 the interarticular cartilage and the head of the ulna; (2) between the radius and 

 the interarticular cartilage above, and the scai)hoid, and semilunar and cuneiform 

 V)elow; (3) between the trapezium and first metacarpal bone; (4) between the jusi- 

 form and the cuneiform bone; (5) between the two rows of carpal bones, sending two 

 processes upwards between the three bones of the upper row, and three downwards 

 lietween the four of the lower row; these three processes being also continued below 

 into the inner four carpo-metacarpal and three intermetacarpal joints. 



Beneath the palmar fascia covering the thenar eminence are the following struc- 

 tures: — Superticialis volw, abductor pollicis, opponens pollicis, radial head of short 

 flexor, tendon of long flexor, ulnar head of short flexor, princeps polli(,-is, and 

 radialis indicis arteries, metacarpal bone of the thumb, with the tendon of the 

 flexor carpi radialis and trapezium. 



Beneath the central part of the palmar fascia are the superficial arch and its 

 digital branches; the ulnar and median nerves, with their branches; the flexors, 

 superficial and deep, Avith their synovial sheath; and the lumbricales; then a layer 

 of connective tissue (the only structure which prevents matter pent in by the palmar 

 fascia from making its way back out through the dorsum), the deep arch, the 

 interossei, and the metacarpal bones. 



In the hypothenar eminence under the fascia are part of the ulnar artery and 

 nerve, the abductor and flexor brevis minimi digiti, the opponens, the deep branch 

 of the ulnar artery and nerve, and the fifth metacarpal bone. 



The back of the wrist and hand. — The posterior annular ligament has already 

 been described with the anterior. On the outer side is the so-called ' snuff-box 

 space' (tabatlere anatomique of Cloquet), a triangular hollow, bounded towards 

 the radius by the two first extensors of the thumb, and tow'ards the ulna by the 

 extensor secundi internodii. The scaphoid and trapezium, with their dorsal liga- 

 ments, form the floor. In the roof lie the radial vein and branches of the radial 

 nerve. More deeply is the artery following a line from the apex of the styloid pro- 

 cess to the back of the interosseous space. The different tendons have already been 

 given. Between the first two metacarpal bones is the first dorsal interosseous 

 muscle, which forms a fleshy projection against the radial side of the index meta- 

 carpal, when the thumb and index are pressed together. On its palmar aspect is 

 the adductor pollicis. Wasting of the former muscle is a ready indication of injury 

 or disease of the ulnar nerve. 



TIIi: LOWER EXTREMITY 



THE THIGH 



Bony landmarks. — Many of these, such as the anterior superior spine of 

 the ilium and the spine of the pubes, have already l)een mentioned. 



The head and shaft of the femur are well covered in, save in the emaciated. 

 The head lies just below Poui)art's ligament, under the ilio-psoas and a little to the 

 outer side of the centre of that ligament. The outline of the condyles can be 

 traced when the knee is flexed, and. on the outer side, a small portion of the 

 shaft is accessible between the biceps and vastus externus. 



Trochanter major. — This most valuable landmark is most ])rominent when 

 the limb is rotate*! inwards or adducted; it lies at the bottom of a depression when 

 the femur is everted. The only structures of importance Ix'tween it and the skin 

 are the expanded insertion of the gluteus maximus and the bursa beneath the 

 muscle. This is often multilocular. The top of the great trochanter is about 



