ARTICULATIONS 17 



Structures on the Head of the Tibia in the middle line from 

 before backwards : 



1. Transverse ligament. 



2. Anterior extremity of in- 



ternal semilunar cartilage. 



3. Anterior crucial ligament. 



4. Anterior extremity of ex- 



ternal semilunar cartilage. 



5. The spine of tibia. 



6. Posterior extremity of ex- 



ternal semilunar cartilage. 



7. Posterior extremity of in- 



ternal semilunar cartilage. 



8. Posterior crucial ligament. 



The transverse ligament is a band of fibres which passes 

 between the anterior extremities of the semilunar cartilages. 



The coronary ligaments bind down the circumferences of 

 the semilunar cartilages to the head of the tibia. 



The synovial membrane is the largest in the body. It ex- 

 tends 2 inches above the articular end of femur under the 

 extensors ; thence it passes over the crucial ligaments to the 

 head of the tibia, where it covers both surfaces of the semi- 

 lunar cartilages, and lastly it lines the capsule. It also gives 

 a covering to the popliteus tendon, where it lies within the 

 capsule, and usually communicates with a bursa under the 

 inner tendon of the gastrocnemius and between this tendon 

 and that of the semi-membranosus. 



The ligamentum mucosum is a triangular fold of the 

 synovial membrane, attached to the intercondyloid notch, 

 and reaching to the patella. 



The ligamenta alaria are two fringes of the synovial mem- 

 brane, seen on either side of the ligamentum mucosum. 



III. THE TIBIO-FIBULAR ARTICULATIONS. 



(a) The Superior Tibio-fibular Articulations (arthrodial). 

 The anterior superior ligament passes from the head of 



the fibula upwards and inwards to the external tuberosity of 

 the tibia. 



The posterior superior ligament passes from the back part 

 of the head of the fibula to the back part of the external 

 tuberosity of the fibula. 



A synovial membrane lines the joint. 



(b) The Middle Tibio-fibular A rticulation consists of the inter- 

 osseous membrane, the fibres passing down from the tibia 

 to the fibula, being attached to the interosseous ridges on the 

 bones. Superiorly, there is an opening for the anterior tibial 

 vessels ; and inferiorly, one for the anterior peroneal vessels. 



(c) The Inferior Tibio-fibular Articulation. 



The inferior interosseous ligament passes between the 

 contiguous rough surfaces of the tibia and fibula, and is con- 

 tinuous above with the interosseous membrane. 



