its deeper aspect this ligament is closely adherent to the anterior border of the 
276 THE ARTICULATIONS OR JOINTS. 
by one end to the tip of the styloid process of the radius, and by the other toa 
rough area at the base of the tubercle of the scaphoid bone, 7.¢. external to its 
radial articular surface. 
The internal lateral ligament (Fig. 216) is also a distinct rounded structure, 
having one end attached to the tip of the styloid process of the ulna and the other to 
the rough non-articular 
border of the cuneiform 
bone, some of its fibres 
being prolonged to the 
pisiform bone. 
The anterior ligament 
(Fig. 216) is attached 
External lateral superiorly to the anterior 
ligament 5 > j 
margin of the lower end — 
Tubercle of seaphoia Of the radius, as well as ¥ 
bone, slightly to the base of — 
ee ee the styloid process of the 
4 ulna. Some transverse 
; 
Anterior radio- 
ulnar ligament { 
Internal lateral {\'} 
Pisiform bone j 
Os magnum, with 
ligaments radiat- 
ing from it 
Trapezium fibres may be seen, but 
the greater number pass 
obliquely downwards and 
inwards to the palmar 
non-articular surfaces 
of the scaphoid, semi- 
lunar, and cuneiform 
bones, while some of 
them may even be con- 
tinued as far as the os 
magnum. Those fibres — 
Fic. 216.—LIGAMENTS ON ANTERIOR ASPECT OF RADIO-CARPAL, from the ulna run 
CARPAL, AND CARPO-METACARPAL JOINTS, : 
obliquely outwards. On 
Unciform process j 
| Mal Mf 
ps 
pe 
triangular fibro-cartilage of the inferior radio-ulnar articulation. . 
The posterior ligament extends from the posterior margin of the lower end 
of the radius, obliquely downwards and inwards, to the dorsal non-articular 
areas on the proximal row of the carpal bones. The slip to the latter assists in 
forming the fibrous sheath through which the tendon of the extensor carpi ulnaris 
muscle travels to its insertion. The principal bundle of fibres is connected with — 
the cuneiform bone. 
The synovial membrane (Fig. 217) is simple, and is confined to the articulation, — 
except in those cases in which the triangular fibro-cartilage is perforated, or in which 
one of the interosseous ligaments between the carpal bones of the first row is absent. 
Movements at the Radio-carpal Joint.—The radio-carpal joint affords an excellent example 
of a biaxial articulation, in which a long transverse axis of movement is situated more or less at 
right angles to a short axis placed in the antero-posterior direction. The nature of the move- 
ments which are possible about these two axes is essentially the same in both cases, viz. flexion 
and extension. The movements about the longer transverse axis are anterior or palmar flexion, 
extension, and its continuation into dorsi-flexion, About the shorter antero-posterior axis we get 
movements which result from combined action by certain flexor and extensor muscles, whereby — 
the radial or ulnar borders of the hand may be approximated towards the corresponding borders 
of the forearm. Lateral movement may also be possible to a slight extent. The range of moyve- 
ment in connexion with either of the principal axes is largely a matter of individual peculiarity, 
for, with the exception of the lateral ligaments, there is no serious obstacle to the cultivation of — 
greater mobility at the radio-carpal joint. 
CARPAL JOINTS. 
The articulations subsisting between the individual carpal bones (articulationes | 
intercarpee) are all diarthroses, and although the total amount of movement 
throughout the series is considerable, yet the extent of movement which is possible 
