82 OSTEOLOGY. 



which presents numerous depressions and foramina, the latter 

 being for the passage of blood-vessels and nerves, and the former 

 for the attachment of soft structures. Anteriorly it is surmounted 

 by the coronal or pyramidal process, which gives insertion to 

 the tendon of the extensor pedis muscle, and prevents the os 

 coronas from slipping too far forwards ; a ligament is inserted in 

 an excavation on each side of this process. The inferior edge of 

 the wall is serrated or notched, the notches opening into various 

 foramina ; and its declivity increases in degree, but decreases in 

 extent as it proceeds backwards. At each side is the preplantar 

 groove, which originates posteriorly in the large foramen of the 

 same name, and along which the lateral laminal artery passes. 



The sole, or inferior surface, which lies on the sensitive or 

 vascular sole, is slightly excavated and half-moon shaped, and, 

 excepting the articular surface, is the smoothest part of the 

 bone ; it is bounded externally by the inferior edge of the wall, 

 and at its postero-intcrnal part by an uneven semicircular ridge, 

 the semilunar ridge, which separates it from the tendinous 

 surface. 



The tendinous surface is the roughened portion placed imme- 

 diately behind the sole ; it presents a triangular roughened 

 depression on its middle and anterior part, where the tendon of 

 the flexor pedis perforans muscle becomes inserted, and on each 

 side a groove, the plantar groove, which terminates in the large 

 plantar foramen, along which passes the artery and nerve pro- 

 ceeding to the interior of the bone. The posterior .part of this 

 surface is roughened for the attachment of the inferior navicular 

 ligament. The articular surface presents two glenoid cavities, 

 separated by a slight eminence which terminates in the coronal 

 process ; this part of the surface articulates with the inferior 

 extremity of the os coronas. Behind the cavities, a flattened, 

 narrow triangular surface articulates with the os naviculare. 



The alee, or ivings, are the irregular protuberances on the 

 posterior part of the wall ; they are bifid, being divided by a 

 fissure or notch, the preplantar fissure, which in old animals is 

 converted into the preplantar foramen, through which the lateral 

 laminal artery passes to gain the groove on the wall. The 

 inferior and posterior portion of the ala, the more bulky of 

 the two, is the retrossal process ; and the superior portion, thin, 

 and giving attachment to the lateral cartilage, is the basilar 

 process. 



