THE KXEE-JOIXT 



'J.OI 



of the head of the tibia. It is strengthened superficially between the femur and 

 patella by an expansion from the subcrureus, and is separated from the fibrous 

 expansion of the extensor tendon by a layer of fatty tissue. The synovial mem- 

 brane lines its deep surface, and holds it against the borders of the semilunar 

 cartilages; it is also attached to the coronary ligaments. 



Internal Ligaments 



The anterior crucial ligament (figs. 246 and 247) is strong and cord-like. It 

 is attached to the inner half of the fossa in front of the spine of the tibia, and to 

 the outer border of the inner articular facet as far back as the inner tubercle of the 

 spine. It passes upwards, backwards, and outwards to the liack part of the internal 

 surface of the external condyle. To the tibia, it is fixed behind the anterior 

 extremity of the internal semilunar cartilage. Behind and to the outer side it has 

 the anterior extremity of the external semilunar cartilage, a few fibres of which 

 blend with the outer edge of the ligament. Its anterior fibres at the tibial end are 

 strongest and longest, being fixed highest on the femur; while the posterior, 

 springing from the spine, are shorter and more oblique. Near the spine, a s\i\> is 

 sometimes given off to the posterior crucial. 



The posterior crucial ligament (figs. 246, 247, and 248) is stronger and less 



Fig. 247. — STRrcTiRES lying ox the Head of the Tibia. (Eight knee.) 



Ligamentura patellas 



Expansion from quadriceps 

 extensor tendon 



Transverse ligamen 



External semilunar fibro- 

 cartilage 

 Anterior crucial 



Internal semilunar flbro- 

 eartilage 



Posterior crucial 

 ligament 



Tendon of biceps 

 External lateral ligament 



ol)lique than the anterior. It is fixed lielow to the greater portion of the fossa 

 Ix'hind the spine of the tibia, especially the outer and posterior portion, and then 

 inwards and upwards along the popliteal notch ; being joined by fibres which arise 

 Vtetween the tubercles of the spine, it ascends to the anterior part of the outer 

 surface of the inner condyle, having a Avide crescentic attachment more than half 

 an inch (1 -o cm. ) in extent just above the articular surface. Behind, it is connected 

 at the tibia directly with the posterior ligament, and a little higher up by means 

 of a quantity of interposed areolar tissue. In front it rests upon the posterior 

 horn of the internal semilunar cartilage, and receives a large slip from the external 

 cartilage, which ascends along it either in front, or behind to the femur; higher 

 up in front it is connected with the anterior crucial ligament. 



Until they rise above the spine of the tibia the two crucial ligaments are closely 

 bound together, so that no interspace exists between their tibial attachments and 

 the point of decussation; the only space between them is therefore a V-shaped 

 one corresponding to the upper half of their X-shaped arrangement, and this is a 

 mere chink in the undissected state, and can be seen from the front only, owing to 

 the fatty tissue beneath the synovial membrane which surrounds their femoral 

 attachment. 



The interarticular or semilunar fibro-cartilages (figs. 246 and 247) are two 

 crescentic jjlates resting upon the circumferential ] tortious of the articular facets of the 

 17 



