THE METACARPUS — THE LARGE METACARPAL BONE 



87 



THE METACARPUS 

 Three metacarpal bones (Ossa metacarpalia) are present in the horse. Of 

 these only one, the third or large metacarpal bone, is fully developed and carries a 

 digit; the other two, the second and fourth, are much reduced, and are commonly 

 called the internal and external small metacarpal or "spHnt" bones. 



Tuberosity -^r:^.:^^-'^ 



^f,h 'W^ Head of small 



>^ 



Groove for 



suspensory 

 ligament 



metacarpal 

 bone 



Nutrient 

 foramen 



Distal ends of 

 small meta- 

 carpal bones 



Sesamoid 

 bones 



First phalanx 



Second 

 pJialanx 



Fig. 56. — Distal Row of Carpal Bones, Metacar- 

 pus, First .\nd Second Ph.\langes, .a.nd 

 Proximal Sesamoid Bones of Horse; Pos- 

 terior View, Left Side. 

 The fourth (external) metacarpal bone is wrongly 



numbered as I. (After Schmaltz, Atlas, d. Anat. d. 



Pferdes.) 



- Metacarpal 

 tuberosity 



Head of 

 small 

 metacar- 

 pal bone 



Distal 

 ends of 

 small 

 metacar- 

 pal bones 



Second phalanx 



Lateral 

 cartilage ' J /- 



Dorsal Wall 



groove sur- 

 face of 

 third 

 phalanx 



Fig. 57. — Left Metacarpal .\xd Digital Bones of 

 Horse, Internal View, (.\fter Schmaltz, 

 Atlas d. Anat. d. Pferdes.) 



The Large Metacarpal Bone 

 This (Os metacarpal tertium) is a very strong long bone, placed vertically 

 between the carpus above and the first phalanx below. It consists of a shaft and 

 two extremities. 



