THE LOWER LlMS 545 



such an extent as to be overlapped by the second toe. Under these 

 circumstances the inner part of the head of the first metatarsal 

 bone and the inner part of the proximal end of the first phalanx 

 give rise to a prominence on the inner aspect of the metatarso- 

 phalangeal joint of the great toe. Over this prommence a synovial 

 bursa is formed, and, when this bursa becomes enlarged, the most 

 common form of bun ion is the result. I f suppuration should ensue, the 

 metatarso-phalangeal joint of the great toe may become involved. 



The filth metatarsal bursa is situated over the plantar aspect of 

 the head of the fifth metatarsal bone, which supports the phalanges 

 of the httle toe. This bursa is of small size, and is due to the fact 

 that the external pillar of the longitudinal arch of the foot is nearer 

 the ground than the internal pillar. 



Another fifth metatarsal bursa is sometimes formed over the 

 prominent tuberosity on the outer surface of the base or proximal 

 end of the fifth metatarsal bone. This occurs in cases of talipes 

 varus, in which the inner border of the foot is raised. 



The navicular bursa is not common. It may be formed over the 

 tuberosity of the navicular or scaphoid bone, about ij inches in 

 front of the internal malleolus — e.g., in cases of talipes valgus, in 

 which the outer border of the foot is raised. 



The tendon-sheath of the peroneus longus invests the tendon of 

 that muscle as it traverses the fibro-osseous canal formed by the 

 long plantar ligament and the peroneal groove on the plantar sur- 

 face of the cuboid bone. It is deeply placed. 



Plantar Fascia or Aponeurosis. — The plantar fascia is connected 

 to the skin by fibrous processes, which enclose and support the 

 lobules of the superficial fascia, and it presents two longitudinal 

 grooves, along the course of which intermuscular septa pass deeply 

 into the sole. These grooves indicate the division of the plantar 

 fascia into three portions — central and two lateral. 



The central division covers the flexor brevis digitorum, and is of 

 considerable strength. It is triangular, being somewhat pointed 

 behind and expanded in front. Posteriorly, where it is narrow 

 and thick, it is attached to the inner tubercle on the plantar aspect 

 of the tuber calcis. From this point the fibres pass forwards 

 towards the toes, the central division meanwhile widening out and 

 becoming thinner. At the heads of the metatarsal bones it divides 

 into five digital processes, one for each toe. The direction of its 

 fibres is longitudinal — that is to say, they nm from heel to toes, 

 but towards the balls of the toes transverse fibres make their 

 appearance. Moreover, in the webs of the toes there are other 

 superadded transverse fibres, which constitute the superficial 

 transverse ligament. This ligament arch«s over the digital vessels, 

 nerves, lumbricales muscles, and digital processes. Each of the 

 five digital processes forms an arch over the flexor tendons as 

 I these are about to pass to the plantar aspects of the toes. The 

 1 final disposition of each process is as follows : (i) it is attached 

 superficially to the skin ; (2) it joins the vaginal hgament of the 

 ' 35 



