634 
NAVICULAR DISEASE. 
disease in the tendon bursa formed by the perforans tendon at the posterior 
surface of the navicular bone just before its insertion, which Eichbaum 
named “ bursa podotrochlearis/’ 
Anatomy. At the posterior surface of the navicular bone, over which it 
glides, surrounded by a sheath, and just above its insertion into the os pedis, 
the perforans tendon becomes expanded, forming a tendon sheath, which 
sometimes suffers from acute or chronic inflammation. Acute inflammation 
is most commonly the result of some mechanical injury to the hoof, either by 
picked-up nails or by stones becoming fixed under the shoe. In the case of 
picked-up nails, the bursa podotrochlearis is either directly wounded or 
Fig. 248.— Preparation illustrating navicular disease. 1, Os pedis ; 2, flexor pedis perforans 
tendon drawn downwards ; 3, lower (gliding) surface of the navicular bone ; 4, coronet 
bone ; a and b, roughened, abraded spots on the flexor perforans tendon ; c, eroded spots 
on the navicular bone ; d, proliferations from periosteum on the upper margin of the os 
pedis. 
inflammation extends to it from the sensitive frog. Such acute conditions 
are described under “ Diseases of the Hoof.” 
The conditions included under the title to this section are all chronic, and 
vary greatly in origin, intensity, and extent. As, however, there is no 
satisfactory method of clinically separating them, we are forced to regard 
them under the one head, which therefore includes all aseptic inflammations 
in this position, and especially those of a chronic character. 
Pathology and Causation. 
The following structures are affected :— 
(1) The navicular bone. 
(2) The perforans tendon. 
(3) The bursa podotrochlearis. 
