TALIPES. 149 



shoulder-joint, even when inflammation is present, is rarely 

 well marked. 



In addition to the above natural bursse, certain exposed bony 

 points which are prone to receive intermittent pressure may have 

 adventitious bursae developed over them. The most common 

 example of this is the bursal sac which forms over the inner 

 side of the head of the first metatarsal bone and the first 

 metatarso-phalangeal joint, particularly in cases of hallux valgus, 

 constituting what is ordinarily called a bunion. Chronic or 

 acute inflammation of this bursa is by no means infrequent. If 

 suppuration occur, pus may find its w r ay into the subjacent joint 

 and lead to acute septic arthritis. 



Haemorrhage into Bursae. Bursal sacs may become distended 

 with blood as the result of falls or blows upon them. This is 

 particularly liable to occur in the case of the pre-patellar and the 

 olecranon bursae. 



TALIPES. 



Flat-foot (Talipes valgus). Flat-foot is a very common 

 complaint. The longitudinal arch of the foot is made up of a 

 posterior and an anterior pillar. The posterior is the shorter 

 and more vertical of the two, and consists of the whole of the 

 os calcis and all of the astragalus except the anterior part of its 

 head, namely that portion which is received into the cup-like 

 depression on the posterior surface of the navicular. The 

 anterior pillar consists of the tarsus and metatarsus, but readily 

 falls into two portions, an inner, made up of the navicular, the 

 three cuneiforms and the three inner metatarsals, and an outer 

 composed of the cuboid and the two outer metatarsals. The 

 phalanges take no share in forming the arch. 



The conformation of the bones, particularly the articulating 

 surfaces of the head of the astragalus and the posterior facet of 

 the navicular, is one of the factors in the preservation of the 

 longitudinal arch. 



In close contact with the bones are the ligaments, the second 



