292 THE ARTICULATIONS OR JOINTS. 
surface behind the spine of the tibia and close to the popliteal notch. Its fibres 
pass obliquely upwards, forwards, and inwards, to be inserted into the outer non- 
articular surtace of the inner condyle, far forwards towards the anterior margin of 
the intercondyloid notch. It is rendered tense in the position of flexion. 
The semilunar interarticular fibro-cartilages are two in number—an inner and an 
outer—placed horizontally between the articular surfaces of the femur and tibia. 
In general outline they correspond to the circumferential portions of the tibial 
facets upon which they rest. Kach has a thick, convex, fixed border in relation to 
the periphery of the joint, and a thin, concave, free border directed towards the 
interior of the joint. Neither of them is sufficiently large to cover the whole of the 
tibial articular surface upon which it rests. The upper and lower surfaces of each 
semilune are smooth and free, and each cartilage terminates in an anterior and a 
posterior fibrous horn or cornu. 
The. internal semilunar fibro-cartilage (meniscus medialis, Fig. 225) forms very 
nearly a semicircle. It is attached by its anterior horn to the non-articular surface 
on the head of the tibia, in front of the tibial attachment of the anterior crucial | 
ligament, and by its posterior horn to the non-articular surface immediately in 
front of the tibial attachment of the posterior crucial hgament. The deep or hinder 
part of the internal lateral heament is attached to its periphery. 
The external semilunar fibro-cartilage (meniscus lateralis, Fig. 225) is attached 
by its anterior horn to the non-articular surface of the tibia in front of the tibial 
Spine, where it is 
Anterior cornu of external placed to the 
semilunar cartilage outer side, and 
partly under 
Gover ‘OL ;qule 
Anterior tuberosity 
Transverse ligament of tibia 
5 
Anterior cornu of internal 
semilunar cartilage ~ 
External ee > 
semilunar tibial end of the | 
. ibro-¢ar- D = 
Anterior tilmco «6 @terior crucial 
crucial ete) . ° 
ligament ligament. By its 
eer spine ot PoSterior horn it 
tibia is attached to the 
@ (outer ‘ 
tubercle) Interval between 
the two tubereles 
which surmount : 
the tibial spine, © 
2.e. in front of the 
attachment of — 
Posterior comu of exter- the poster@r harm 
\ nal semilunar cartilage z ‘ if 
'Fasciculus from external semilunar ot the internal 
Posterior crucial ligament cartilage to posterior crucial ligament semilunar cartil- ‘ 
Fig. 225.—Urrer END oF TIBIA, WITH SEMILUNAR CARTILAGES AND ATTACHED age. This fibro- . 
q 
tibia | 
(inner FF 
tubercle) 
Internal 
semilunar 
tibro- 
cartilage 
Posterior cornu 
of internal semi- ~ 
lunar cartilage 
PORTIONS OF CRUCIAL LIGAMENTS. : : : 
cartilage, with its 
two horns, therefore forms almost a complete circle. Posteriorly it is attached by 
its periphery to the posterior hgament, but on the outer side it is separated from 
the external lateral ligament by the tendon of the popliteus muscle, and on this 
aspect its periphery is tree. 
The two horns of the external semilune are embraced by the two horns of the 
internal one, and, while the anterior crucial hgament has its tibial attachment almost 
between the anterior horns of the two semilunes, the tibial attachment of the posterior — 
crucial ligament is situated behind the posterior horns of the two semilunes. 
Both semilunes possess certain accessory attachments. Thus the external semilune 
sends a large bundle of fibres from its convex posterior border to augment the posterior 
aspect of the posterior crucial hgament, by which these fibres are conducted to the 
femur. Again, the convex or peripheral margins of each semilune possess certain 
attachments to the deep surface of the capsule on its inner and posterior aspects, as 
has already been explained, but, in addition, they are attached to the non-articular 
circumference of the tibial head by short fibrous bands known as the ligamenta 
coronaria. Lastly, a rounded band which varies in strength, the transverse liga- 
ment (lig. transversum genu, Figs. 223 and 225), stretches between the anterior 
