THE rOSTERIOR LIMBS. 



141 



Fig. 93. 



slightly roughened, serves for the attachment of the popliteus muscle ; the other 



inferior, much more extensive, is farrowed into numerous longitudinal crests, 



which give attachment to the perforaus muscle. On the limit of these two 



surfaces is remarked the nutrient foramen of the bone. 



The bordf^rs are distinguished as antnior, cxtfrnnJ., and 



internal. The ///-.s/ is rounded, and not very salient in its 



inferior two-thirds ; it forms, in its superior third, a 



curved crest, with the concavity external, which joins the 



anterior and superior tuberosity of the bone ; this has 



received tlie name of the tibi((l crest. The exteiiud border 



is very thick and concave above, where it constitutes, in 



common with the fibula, the tibial arch. The internal is 



also very thick, straight, and provided superiorly with some 



salient tubercles to which the popliteus is attached. 



Extremities. — The superior extremiti/., the most volumi- 

 noiLS, is formed by three tuberosities — an anterior and two 

 lateral, which are external and internal. The first., the 

 smallest, is a rugged process continuous with the tibial 

 crest, and separated from the external tuberosity by a 

 wide and deep groove, into which passes a tendinous cord ; 

 it is excavated, in front, by a vertically elongated fossa, 

 which lodges the middle ligament of the patella. The 

 external tuberosity, medium in size and the most detached, 

 has outwardly an articular facet for the head of the fibula. 

 The internal tuherositij, the largest and least detached, 

 presents : on the sides, ligamentous imprints ; behind, a 

 small tubercle which gives attachment to the posterior 

 crucial ligament of the femoro-tibial articulation. The 

 superior face of the two lateral tuberosities is occupied by 

 two large, irregular, and undulated articular surfaces, which 

 respond to the condyles of the femur, through the medium 

 of the two meniscus-shaped fibro-cartilages interposed 

 between the two bones. Of these two surfaces, the ex- 

 ternal is always the widest, because it serves, by its posterior 

 part, for the gliding movements of the popliteal tendon. 

 They are separated from each other by the tibial spine — a 

 conical articular eminence, divided into two lateral parts 

 by a groove for insertion excavated at its base ; and in front 

 by two lateral facets for the insertion, anteriorly, of the 

 two inter-articular cartilages ; it is bordered behind by 

 another fossa, which receives the posterior insertion of the 

 internal meniscus. 



The inferior extremiti/, flattened behind and before, ex- 

 hibits an articular surface moulded on the pulley of the 

 astragalus, and two lateral tuberosities. The articular 

 surface is formed by two deep cavities, oblique forwards and outwards, and 

 separated by a median tenon which terminates posteriorly by a very prominent 

 projection, on which the bone rests when it is made to stand vertically on a hori- 

 zontal plane. The external tuberosity ^ projects but little, and is traversed in its 



' The external malleolus of Man 

 12 



POSTERIOR VIF.W OF 

 RIGHT TIBIA. 



Tibial spine ; 2, fossa 

 for the insertion of the 

 internal meniscus ; 3, 

 eitei-n;il tuberosity 

 with articulation for 

 the fibula : 4, fos^a for 

 the insertion of exter- 

 nal meniscus ; 5, fibula, 

 forming with the tibia 

 the tibial arch ; 6, shaft, 

 or body of the tibia; 

 7, 8, exteinal and in- 

 ternal malleoli, inferior 

 tuberosities, or lateral 

 processes of the tibia; 

 9, articular trochleae 

 with a median ndge, 

 for articulation with 

 the astragalus. 



