The =external iliac artery= has the same course as in the horse. The
circumflex iliac artery is large. A branch from it emerges between the
abdominal and lumbar muscles near the external angle of the ilium and
ramifies like the terminals of the ilio-lumbar artery of the horse.
The =femoral= and =popliteal arteries= pursue a similar course to those
of the horse. The chief differences in their branches are as follows:
1. The =external pudic artery= is distributed chiefly to the scrotum in
the male. In the cow it is usually termed the =mammary= and is very
large, especially during lactation. Each divides at the base of the
mammary gland into two branches which are distributed to the anterior
and posterior parts (“quarters”) of the gland. A small branch
accompanies the subcutaneous abdominal vein to the xiphoid region.
2. The =deep femoral artery= gives off an obturator branch which passes
up through the obturator foramen to supply the obturator internus and
compensates otherwise for the absence of the obturator artery.
3. The =anterior femoral artery= is large. It often gives off the
=external circumflex artery= of the thigh, which perforates the proximal
end of the quadriceps, gives branches to that muscle, the iliacus,
glutei, and tensor fasciæ latæ.
4. The =saphenous artery= is large. It descends in front of the
homonymous vein to the postero-internal surface of the hock, where it
divides into two plantar branches. The =internal plantar artery= (A.
plantaris medialis) is the direct continuation of the saphenous. It
descends at first along the inner border of the superficial flexor
tendon and is continued as the =internal superficial plantar metatarsal
artery= along the inner side of the deep flexor tendon with the internal
plantar nerve. It anastomoses at the proximal end of the metatarsus with
the perforating metatarsal artery, assisting in the formation of the
proximal plantar arch. Near the fetlock it concurs with the perforating
branch of the dorsal metatarsal artery in the formation of the distal
plantar arch. Below this it is continued as the =internal digital
artery=. The =external plantar artery= (A. plantaris lateralis) is
small. It descends along the outer border of the deep flexor tendon with
the external plantar nerve, concurs with the perforating tarsal and the
internal plantar arteries in the formation of the proximal plantar arch,
and gives branches to the rete tarsi dorsale. Continuing downward along
the deep flexor tendon as the =external superficial plantar metatarsal
artery=, it assists in forming the distal plantar arch and becomes the
=external digital artery=.
[Illustration:
FIG. 476.—ARTERIES OF DISTAL PART OF RIGHT HIND LIMB OF OX, ANTERIOR
VIEW.
_a_, Anterior tibial artery; _b_, proximal perforating metatarsal
artery; _c_, dorsal metatarsal artery; _d_, dorsal common digital
artery; _e_, _e′_, dorsal proper digital arteries.
]
[Illustration:
FIG. 477.—ARTERIES OF DISTAL PART OF RIGHT HIND LIMB OF OX, POSTERIOR
VIEW.
_e_, Saphenous artery; _f_, _f′_, internal and external plantar
arteries; _g_, _g′_, internal and external superficial plantar
metatarsal arteries; _h_, deep plantar metatarsal artery; _i_, _j_,
internal and external plantar digital arteries; _k_, plantar common
digital artery; _l_, _l′_, internal and external plantar digital
arteries.
]
The =posterior tibial artery= is relatively small and is distributed
chiefly to the muscles on the posterior surface of the tibia. Lower down
it is replaced by the saphenous artery as described above.
The =anterior tibial artery= has the same course as in the horse. It is
continued down the groove on the front of the metatarsal bone as the
=dorsal metatarsal artery=. This is the chief artery of the region and
is accompanied by two veins. It detaches the proximal perforating
metatarsal artery, which passes through the proximal foramen of the
metatarsal bone and concurs with the superficial plantar arteries in
forming the proximal plantar arch. Near the distal end of the metatarsal
bone it gives off the distal perforating metatarsal artery which passes
back through the distal metatarsal foramen and assists in forming the
distal plantar arch. The two arches are connected by the small =deep
plantar metatarsal artery= which lies in the groove on the posterior
face of the large metatarsal bone.
The =dorsal common digital artery= is the direct continuation of the
dorsal metatarsal. It divides into two branches which unite in the
interdigital space with the corresponding branches of the plantar common
digital to form the proper digital arteries.
The =plantar common digital artery= descends from the distal plantar
arch, anastomoses in the interdigital space with the internal and
external digitals, and divides into two branches which join those of the
dorsal common digital artery as before mentioned.
The foregoing is a brief statement of the more common arrangement of the
vessels in the distal part of the limb, but minor variations are very
common.