6. The =plantar arteries=, internal and external (A. plantaris medialis,
lateralis), are the small terminals of the posterior tibial. They
descend along the sides of the tarsal sheath of the deep flexor with the
plantar nerves to the proximal part of the metatarsus, where they unite
with the perforating tarsal artery to form the =plantar arch= (Arcus
plantaris). Four =plantar metatarsal arteries= proceed from this arch.
The two slender =superficial plantar metatarsal arteries= (A. metatarsea
plantaris superficialis medialis, lateralis) descend on either side of
the deep flexor tendon with the plantar nerves and unite with the great
metatarsal or with the corresponding digital artery. The two =deep= or
=interosseous plantar metatarsal arteries= (A. metatarsea plantaris
profundus medialis, lateralis) descend between the suspensory ligament
and the corresponding small metatarsal bone and unite near the fetlock
with the great metatarsal. The inner artery is the larger of the two and
usually appears to be the continuation of the perforating tarsal. It
supplies the nutrient artery of the large metatarsal bone. In other
cases it is the direct continuation of the internal plantar artery, the
external artery only uniting with the perforating tarsal.
[Illustration:
FIG. 458.—DISSECTION OF LEG AND HOCK OF HORSE, INNER VIEW. (After
Schmaltz, Atlas d. Anat. d. Pferdes.)
]