CHAPTER VIII. 



LAMENESS IN THE PHALANGEAL REGION. 



Anatomy. — The bones of the phalangeal region are : 



1. Os suffracjinis, also called first or metacarpal phalanx 

 and large pastern bone, with the two sesamoid bones. 



2. Os coronae, also known as second phalanx or small 

 pastern bone. 



3. Os 2^(^18, also called third phalanx, pedal or coffin 

 bone, with the navicular bone. 



These bones form three joints : 



1. Fetlock joint : This is a perfect hinge joint. Its 

 capsular ligament is reinforced by fibrous bands laterally. 

 It also has two lateral sesamoidal ligaments, which, 

 strengthened by the crossed iignments, unite the sesamoids 

 with the cannon bone and fir.-t ]ihalanx. Between the 

 sesamoid bones is the inter^esanjoidal ligament, which is of 

 a fibro-cartilaginous nature. This ligament, together with 

 the posterior face of the sesamoid bonos, forms the groove 

 for the flexor tendons to glide in. The KU])Prior jind inferior 

 sesamoidal ligaments inhibit excessive dorsal flrxion of the 

 fetlock-joint. The infei'ior sesamoidal ligament, situated at 

 the posterior face of the ds suffiaginis, is divided into three 

 separate branches : (a) The superior arises from the middle 

 of the fibro-cartilaginous mass behind the superior articular 

 surface of the os coronae, runs up behind the first phalanx 

 and is inserted into the base of the sesamoids, being 



