ARTERIES OF BIRDS. 201 



forming several articular arteries around the joint, and communi- 

 cating vnth the other branch, and with the anterior tibial, and 

 the metatarsal branch of the plantar artery. 



' The articular arteries go off next from the artery in the ham ; 

 the two principal ones are deep-seated. One proceeds under the 

 vastus internus to the external part of the joint ; the other is 

 large, and situated upon the inside. It forms two vessels : one 

 is the true articular artery, and spreads upon the ligaments of the 

 joint ; the other is distributed in the substance of the flexor of 

 the heel, which is placed upon the inside and fore part of the leg, 

 and comes out upon the edge of this muscle to be lost in the 

 integuments. 



' The posterior tibial artery, fig. 94, 28, is extremely small ; it 

 only supplies muscular branches to the internal head of the 

 gastrocnemius, and some of the flexors of the toes ; it is lost on 

 the inside of the heel in anastomoses with the peroneal artery, 

 and other small superficial branches. 



' The trunk of the artery of the leg now gets upon the poste- 

 rior surface of the tibia, and sends off, through the deficiency left 

 between the tibia and fibula at the superior part, a branch which 

 is distributed to all the muscles upon the fore part of the leg. 

 The artery then creeps along the back of the bones for some 

 way, and passing between them above, where the fibula is anchy- 

 losed with the tibia, it reappears on the anterior part of the leg 

 in the situation of the anterior tibial artery ; at this place it 

 detaches some very small branches, which frequently divide and 

 unite again, to produce a most singular reticulation or plexus of 

 vessels, which closely adheres to the trunk of the artery, and is 

 continued with it as far as the articulation of the tibia with the 

 metatarsal bone, where it disappears without seeming to answer 

 any useful design. This plexus resembles in appearance exactly 

 the division of the arteries of the extremities, which has been 

 described by Mr. Carlisle in the tardigrade quadrupeds, but 

 differs from it in this circumstance, that the trunk of the artery 

 is preserved behind it, without suffering any material diminution 

 of its size. 



' The anterior tibial artery furnishes no branch of any impor- 

 tance during the time it is proceeding along the fore part of the 

 leg. It passes under the strong ligament which binds down the 

 tendons of the anterior muscles of the leg, and over the fore part 

 of the joint on the inside of the tendon of the tibialis anticus, at 

 which places it distributes some branches which inosculate Avith 

 the other arteries round the joint ; it then pursues its course in 



