SENSITIVE STRUCTURES OF THE FOOT. 



551 



villi of which secrete the horny frog ; below this is a layer of 

 capillary blood-vessels ; its substance is made up of connective 

 tissue, intermixed with yellow-fibro-cellular tissue of a peculiar 

 elastic nature, which used to be described as fat. 



The Coronary substance, or coronary band, formerly called 

 the coronary ligament, is that vascular structure Avhich occupies 

 the cutigeral groove on the superior border of the wall. It 

 consists of a dense fibrous mesh or band, which is connected with 

 the coffin bone and extensor tendon by the medium of dense 

 cellular tissue, Keposing on this is a plexus of blood-vessels, 

 which is covered by a modification of the true skin, containing 

 numerous papillae, which enter the 

 funnel-shaped openings in the crust, 

 the horn of which is thus secreted. 



The coronary band presents along 

 its upper border a narrow" lip or 

 process — the periojMc ring — which 

 secretes the horn of the periople. 



The Sensitive lamina (podo- 

 phyllous tissue) are the continua- 

 tion of the coronary substance, and 

 are attached to the coffin bone by a 

 dense fibrous membrane, in which 

 ramifies the vascular plexus emana- 

 ting from the bone. These highly- 

 organised plates are interposed 

 between, and firmly attached to, the 

 homy lamine3 on the wall, and are 

 covered by minute papillae, which 

 secrete the horny laminae ; on their 

 inferior extremity are a few papillae, which help to secrete the 

 homy sole. 



The Sensitive sole, continuous with the sensitive laminae 

 and frog, is firmly attached to the coffin bone ; like the sensitive 

 laminas, it is made up of a fibro-vascular membrane, clothed by 

 a continuation of the corium, which is covered by the villi which 

 secrete 'the horny sole. 



For the circulation of the foot, see pp. 417, 439; for its 

 nerves, pp. 511, 514. 



Sensitive foot— lateral view, a, Corc- 

 nary band ; 6, Podophyllous tissue. 



