102 DISSECTION OF THE DOG 



communes II, III, et IV), which run between the second and third, third 

 and fourth, and fourth and fifth metatarsal bones. 



N. plantabis lateralis. — This, the larger of the two terminal branches 

 of the tibial nerve, has been followed to its disappearance under the m. adductor 

 digiti quinti. It will now be seen to end in several branches about the proximal 

 third of the metatarsus. Some of these branches are distributed to the small 

 muscles of the sole ; three of them, the second, third, and fourth common plantar 

 digital nerves (nn. digitales plantares communes II, III, et IV), follow the 

 corresponding arteries of the same name. 



M. peeon^tts longt/s. — The tendon of the long peroneal muscle has been 

 foUowed as far as the lateral aspect of the tarsus. It can now be examined 

 as it lies in the groove in the cuboid bone and crosses the plantar aspect of 

 the tarsus to its insertion into the rudimentary first metatarsal bone (or, in 

 its absence, into the second bone). The tendon is enclosed in a strong fibrous 

 sheath which must be opened. 



Arttculatio genu. — This joint is formed by the condyles and patellar sur- 

 face of the femur, the patella, and the articular surface at the proximal end 

 of the tibia. Although the adaption of the bony surfaces is indifferent, the 

 joint, in virtue of the character and number of the ligaments in association 

 therewith, is strongly constituted. 



Dissection. — Clear away the remains of the muscles about the joint, but 

 leave the tendons of origin of the popliteus muscle and the long extensor 

 of the digits. Clean the surface of the joint-capsule and define the 

 collateral ligaments. 



Capsula articularis. — In describing the joint-capsule, it is convenient to 

 consider it as divided into two parts : (1) The anterior part is roomy and 

 attached to the condyles and about the margin of the patellar surface of the 

 femur and along the articular edge of the tibia. The patella may be regarded 

 as a bony island in this part of the capsule. On each side of the patella the 

 capsule is thickened ; the thickenings being connected with cartilaginous 

 extensions of the bone. (2) The posterior portion of the capsule is much less 

 roomy, and is attached about the articular margins of the femur and tibia. 

 Both parts of the joint-capsule are adherent to the edges of the menisci between 

 the femur and tibia, and are continuous with the collateral ligaments of the 

 joint. 



It will be observed that the origins of the popliteus muscle and long extensor 

 of the digits are within the capsule. 



Ligamentum patellcB. — The patellar ligament is a strong flattened band 

 extending from the patella to the tuberosity of the tibia. A pad of fat is 

 interposed between the ligament and the joint-capsule, and a small synovial 



