9 2 OSTEOLOGY. 



the broadest of the three, presents on its superior third a 

 triangular and rather smooth portion, to which the popliteus 

 muscle is attached, the remaining two-thirds being strongly- 

 marked by a number of longitudinal ridges, and giving attach- 

 ment to the deep flexor muscles of the foot ; the nutrient 

 foramen is in the upper third of this surface. 



The anterior border is rounded, and indistinctly marked, 

 except in its upper third, where we find the prominent tibial 

 ridge, which is curved outwards, and joins the anterior 

 tuberosity of the proximal extremity. The external border is 

 thick and concave above, so that with the fibula it forms the 

 tibial arch. The internal border is also thick, and at its upper 

 part has a small tubercle, to which the popliteus muscle is 

 attached. 



The proximal extremity is-' much more • expanded than the 

 distal, and presents two large, smooth, somewhat . undulated, 

 articular surfaces, divided by a roughened conical process, the 

 tibial spine, on the outer side of which is an irregular excava- 

 tion for the insertion of one of the crucial ligaments. The semi- 

 lunar cartilages are interposed between these surfaces and the 

 condyles of the femur. Anteriorly a tuberosity, concave exter- 

 nally and convex internally, joins the tibial ridge, and presents 

 a vertical notch in front for the middle straight ligament of the 

 patella. At the sides are two processes, to which the lateral 

 ligaments are attached, the external being the largest, and 

 presenting also an articular facet for the head of the fibula. 

 Between this process and the anterior tuberosity is a deep groove, 

 for the passage of the tendinous part of the flexor metatarsi 

 muscle. 



The distal extremity, much smaller than the proximal, and 

 flattened transversely, presents two smooth, deep articular 

 grooves, which run obliquely backwards and inwards, the internal 

 being the deepest, and the external the widest ; also three pro- 

 jections, the middle one forming a division between the groves, 

 being articular and continuous with them, while the others, which 

 form the lateral processes or Tnalleoli, are roughened outside for 

 the reception of ligaments. The articular surface corresponds to 

 the trochlea of the astragalus articulating with it. The internal 

 malleolus is the most prominent, and the external the widest, 

 being grooved for the passage of the tendon of the peroneus 

 muscle. 



