374 [HE HORSE. 
on each side with the two divisions of the flexor perforatus. In addition 
to these structures, and the synovial capsules lining them, the joint is pro-- 
tected by two lateral ligaments, and in front by the extensor tendon. 
Fic. 16.— EXTERNAL VIEW OF THE Pas- 
TERN JOINT. 
A. Tnferlor third of the large metacarpal 
one. 
B. External sesamoid bone. 
C. Suffragineal bone. 
D. Coronal bone. 
EK. Navicular bone. 
F. Pedal bone. 
1. One division of the suspensory liga- 
ment. 
2. Lateral sesamoideal ligament (external). 
3. Ligamentous fibres given to the ex- 
tensor pedis tendon by the suspen- 
sory ligament. 
Inferior superficial sesamoideal liga- 
ment. 
6. 7. Extensor pedis tendon. 
External lateral phalangio-pedal liga 
ment. 
. External lateral cartilage. 
i Ne 
The lateral gaments, thick and strong, take an oblique direction from 
above downwards, and from before backwards, one on each side of the joint. 
They arise from two depressions, just below the tubercles on the lateral 
parts of the os suffraginis, and terminate at the superior edge of the os 
corone. Their lowest fibres prolong themselves beyond this bone to gain 
the extremities of the os naviculare, and constitute the posterior lateral 
ligaments of the coffin joint. ; 
The synonal membrane lines the posterior surface of the extensor ten- 
dons anteriorly, the lateral ligaments, and the fibro-cartilage ; it forms 
posteriorly a cul de sac, which mounts up between this and the posterior 
surface of the os suffraginis. 
THE MOVEMENTS of this joint are simply of extension and flexion when 
the muscles are in action ; but when they are relaxed there is some slight 
lateral motion. 
THE COFFIN JOINT. 
THE COFFIN JOINT is made up of the lower end of the os corone, in- 
serted in the concavity of the pedal bone, and supported behind by the 
navicular bone. These are lined by one continuous synovial capsule, 
and protected by ligaments which may be divided into two sets. urs, 
those connecting the os corone to the os pedis. Secondly, that between 
the os naviculare and the os pedis, which is of an interosseous character, 
being short, and composed of very strong fibres; and thirdly, the liga- 
ment on each side connecting the os naviculare with the coronet. 
Fic. 17.—PosTERIoR VIEW OF 
THE COFFIN JOINT. 
A. Coronal bone. 
B. Navicular bone. 
C. Pedal bone. 
1. Corono-navicular ligament. 
2. 2. Lateral ligaments of the 
navicular bone. 
3. Pedo-navicular ligament. 
1. The corono-pedal ligaments are two on each side, one anterior and the 
other posterior. The former consist of two large, thick and short bundles 
of fibres attached above to the sides of the os corone, and below to the 
lateral edges of the cacumen corone of the pedal bone. (See page 341.) 
a 
