Changes

The '''cranial branch of the saphenous vein''' passes through the tarsus to become the '''common digital vein''' in the region of the metatarsus.  This vein runs across the third metatarsus (cannon bone) to unite with the medial plantar vein.  The '''caudal branch of the medial saphenous vein and artery''' run distally in a groove cranial to the common calcaneal tendon.  The '''medial saphenous vein''' anastamoses with the '''caudal tibial vein''' and '''lateral saphenous vein''' proximal to the hock, subsequently dividing into the medial and lateral plantar veins. The '''saphenous artery''' anastamoses with the '''caudal tibial artery''', giving rise to the '''medial and lateral plantar arteries'''.  

The '''cranial branch of the saphenous vein''' passes through the tarsus to become the '''common digital vein''' in the region of the metatarsus.  This vein runs across the third metatarsus (cannon bone) to unite with the medial plantar vein.  The '''caudal branch of the medial saphenous vein and artery''' run distally in a groove cranial to the common calcaneal tendon.  The '''medial saphenous vein''' anastamoses with the '''caudal tibial vein''' and '''lateral saphenous vein''' proximal to the hock, subsequently dividing into the medial and lateral plantar veins. The '''saphenous artery''' anastamoses with the '''caudal tibial artery''', giving rise to the '''medial and lateral plantar arteries'''.  

The '''femoral vessels''' give rise to the '''descending artery and vein of the stifle''', as well as other small vessels to that joint, in the distal third of the thigh.  Some of the smaller vessels to the stifle joint arise from the '''popliteal vessels''' which are continuations of the femoral vessels. The '''femoral vessels''' also branch to form the '''lateral saphenous vein'''.  The lateral saphenous vein runs distally along the caudal border of the ''gastrocnemius'' and anastamoses with the '''caudal branch of the medial saphenous vein''' and '''caudal tibial vein''' proximal to the hock.

The caudal branches of the '''saphenous artery and medial saphenous vein''' continue as the '''lateral and medial plantar vessels''', running with the deep digital flexor tendon, over the sustentaculum tali, to the level of the metatarsus. The vein lies superficial to the corresponding artery.  In the digit, the medial and lateral digital veins, arteries and nerves lie next to each other in a dorsal to plantar arrangement; this can be remembered as VAN (vein, artery, nerve).  

The '''popliteal vessels''' bifurcate to form '''cranial and caudal tibial vessels''' at the level of the fibular head. The '''cranial tibial vessels''' pass between the tibia and fibula, then follow the tibia to the level of the hock; at this point they become the '''short pedal vessels'''. The '''pedal artery''' continues to become the '''dorsal metatarsal artery'''.  The dorsal metatarsal artery passes over the lateral surface of the third metatarsal (cannon bone) and fourth metatarsal (lateral splint) plantarodistally. It then receives the '''plantar metatarsal arteries''' which run on the plantar aspect of the third metatarsal.

The '''medial and lateral plantar vessels''' enter the metatarsus to give rise to the '''deep plantar arterial and venous arches'''; from which the '''medial and lateral metatarsal vessels''' originate. The medial and lateral metatarsal arteries join the '''medial and lateral digital arteries''', which result from the bifurcation of the '''dorsal metatarsal artery''', close to the fetlock. The dorsal metatarsal artery continues as the '''short dorsal pedal artery''', which subsequently forms the '''cranial tibial artery''' on the dorsal hock.  The cranial tibial, dorsal pedal and dorsal metatarsal arteries supply the digit and hoof.

 

The '''dorsal common digital vein''' crosses the medial surface and the '''dorsal metatarsal artery''' crosses the lateral surface of the third metatarsus (cannon bone) obliquely. The dorsal common digital vein joins the medial plantar vein in the distal third of the cannon bone.  The '''medial plantar vein''' then becomes the '''medial digital vein''' at the level of the metacarpophalangeal (fetlock) joint. At this level, the medial plantar vein anastamoses with the '''lateral plantar vein''' via the '''distal deep plantar arch'''.

 

The '''medial and lateral digital arteries''' run on their corresponding sides of the digit, forming '''dorsal and plantar branches''' to the proximal and middle phalanx. These branches anastamose with each other to form '''arterial circles''' around the proximal and middle phalanges.

 

The '''dorsal branch of the lateral and medial digital arteries''' arises at the level of the distal phalanx. It runs though the foramen/notch in the plantar process of the distal phalanx into the parietal groove.  The digital arteries continue to the solar surface and enter the solar foraminae on either side to anastamose within the bone, forming the '''terminal arch'''.  Branches of the terminal arch run in osseous canals to the parietal surface, where they supply the laminar dermis. Some branches also emerge close to the solar margin and anastamose to form an artery that follows this margin.

 

'''Digital veins''' are satellite to the arteries down to and into the distal phalanx, but not all the branching arteries are accompanied by veins.  There is a dense '''venous plexus''' in the coronary and laminar dermis of the sole which drains into the '''medial and lateral digital veins''' via many smaller veins.  Most of these veins lie subcutaneously, just proximal to the hoof, others run directly to the digital veins from the axial surface of the ungual cartilages.