y///. 



803 



Fig. 373. 



can ]>erceive that it is essentially constituted by adipose tissue.) Numerous 

 Mood-vessels and nerves complete this structure. 



'B. THE KEKATOGENOUS MEMBHANE, OR SUBCOBNEUS INTEGUMENT. The 

 krrutogenous membrane envelops the extremity of the digit, by spreading 

 over the terminal expansion of the tendon of the extensor pedis, through the 

 mcilium of a fibrous fascia a dependency of the lateral cartilages; and also 

 over tin- inferior moiety of the external face of these cartilages, the bulbs of 

 tlic plantar cushion, pyramidal body, anterior part of the plantar face of tlie 

 third plialanx, and over the anterior surface of the same bone. It covers all 

 these parts like a sock, and the hoof incloses it. as a shoe does the human foot. 



Tliis membrane becomes continuous with the skin of the digital region 

 at a circular line that intersects the middle portion of the second phalanx, 

 and inclines obliquely downward from behind to before. Below this line, 

 in front and laterally, the subungular tissues form a semicylindrical pro- 

 tulx-rauce, covered with villi, and designated the " bourrelet." (This 

 clastic prominence has received several most inappropriate names from 

 Knglish farriers and hippotomists, such as "coronary ligament," "coronary 

 substance," " cutiduris," etc. From its function, structure, situation, and its 

 analogy to the plantar cushion. I have designated it the " coronary cushion.' ) 



On the plantar cushion and the lower face of the pedal bone, this mem- 

 brane is also a villous tunic the velvety tissue, which is continuous, towards 

 the bulbs, with the extremities of the coronary cushion. 



The portion spread over the anterior face 

 of the third phalanx constitutes the laminal 

 or " leafy tissue," so called because of the 

 lamina) or parallel leaves seen on its sur- 

 face. 



The three regions of the keratogenous 

 apparatus will be successively studied. 



1. CORONARY CUSHION. This part is the 

 matrix of the wall of the hoof, and is lodged 

 in a cavity excavated at the upper border of 

 this part of the horny case. It forms, ac- 

 cording to the expression employed by 

 M. Bouley, a rounded prominence, which 

 projeets like a cornice above the podo- 

 phvllous tissue. 



Its inferior border is separated by a white 

 zone from the upper extremity of the laminae, 

 which constitute this boundary. 



The superior border is limited by a 

 slightly projecting margin named the/.,//' 

 ODMC //;/;/, lu-cause it originates the horn of 

 the prriople. I Jet ween this margin and the 

 cushion is a sharply defined groove 



Tin: './//< niitii x, narrower than tin- middle 

 portion, on arriving at tin; bulbs of the 

 plantar cushion, bend downward* into the 

 lateral lacuna- of the pyramidal body, where 

 they become confounded with the vt-lv. ty 

 



The tttr/cwe of the organ shous filiform prolongations, a little constricted 

 1 named jHij>ilhi . rillo-fMif>Hf<i, rilli, and rill- . whoso 



LATKRAI. VIIIW 01 Till. II. HIM V i .HPI, 

 A I I Kit ItKMOVAI. OK Till: Hour. 



1, lViio|'lir riii, tlivi.l.-.l liy :i narrow 

 JI-.M.XI- iV-'tn tin- ori>ii:ir\ riishiiin. 

 _'. uli'.li i~ i-oiitimiiiiis witli 

 ]'l.int:ir i u>liinii, 4, .in. I juiiis 

 1 ii- l:iiiiin;i-, :'.. thri'iii,'li 

 medium of tin- liiti? zon. 



tin- 

 I In- 

 tlu- 



at their base, and 



3 r 2 



