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(c) The inferior lateral genicular artery runs laterally, across the popliteus muscle and anterior to the plantaris and the lateral head of the gastrocnemius; then, turning forwards, it is joined by the inferior lateral genicular nerve, and passes to the medial side
N. plantaris medialis.
A. plantaris medialis--
A. plantaris lateralis.
of the fibular collateral ligament.
M. semitendinosus It terminates by anastomosing with its fellow of the opposite side and with the superior lateral genicular and anterior tibial recurrent arteries.
A. genu superior
A. genu inferior
M. flexor hallucis
Tendon of M.
(d) The inferior medial genicular artery passes medially, distal to the medial condyle of the tibia, along the proximal border of the popliteus and in front of the medial head of the gastrocnemius, to the medial side of the knee, where it turns forwards, between the bone and the tibial collateral ligament, and terminates anteriorly by anastomosing with its fellow of the opposite side, with the recurrent branch of the anterior tibial artery, and with the superior medial genicular artery.
(e) The arteria genu media passes directly forwards from the front of the popliteal artery, pierces the central part of the posterior surface of the capsule of the knee-joint, and enters the intercondylar fossa. It supplies branches to the crucial ligaments and to the synovial membrane, and is accompanied by the medial genicular branch of the tibial nerve, and sometimes by the genicular branch of the obturator
(3) Cutaneous branches are distributed to the skin over the M. peronæus brevis popliteal fossa. One of these, the superficial sural artery, runs along the middle of the back of the calf with the vena saphena parva.
M. flexor hallucis
ARTERIA TIBIALIS POSTERIOR.
The posterior tibial artery, the larger of the two terminal branches of the popliteal, commences at the distal border of the popliteus and terminates midway between the tip of the medial malleolus and the most prominent part of the heel, at the distal border of the laciniate ligament (O.T. internal annular). It ends by dividing into the medial and the lateral plantar arteries, which pass onwards to the sole of the foot.
The posterior tibial artery runs distally and medially, in the posterior part of the leg, between the superficial and deep layers of muscles and covered, posteriorly, by the deep intermuscular fascia which intervenes between them.
Relations. Anterior.-It is in contact anteriorly, and proximo-distally, with the tibialis posterior, the flexor digitorum longus, the posterior surface of the tibia, and the posterior ligament of the ankle-joint.
Posterior. The artery is crossed about 37 mm. (an inch and a half) distal to its origin by the tibial nerve. Elsewhere it is in contact with the intermuscular fascia which binds down the deep layer of muscles. More superficially the proximal half of the artery is covered by the fleshy parts of the soleus and gastrocnemius muscles, between which is the plantaris; the distal half of the artery is much nearer the surface, and is covered only by skin and fasciæ, except at its termination, where it lies deep to the laciniate ligament.
Lateral and Medial.—The artery is accompanied by two venæ comites, one on each side. The tibial nerve lies at first on the medial side of the vessel, then crosses posterior to it, and is continued distally on its lateral side. In the most distal part of its course the artery is separated from the medial malleolus by the tendons of the tibialis posterior and the flexor digitorum longus, whilst the tendon of the flexor hallucis longus lies postero-lateral to it. Branches. The posterior tibial gives off numerous branches, the largest of which, the peroneal, forms one of the chief arteries of the leg. The branches include
(1) Large muscular branches which are distributed to the soleus, the tibialis posterior, the flexor digitorum longus, and the flexor hallucis longus. They anastomose with the deep sural branches of the popliteal artery and the lower medial genicular artery. (2) A fibular branch passes laterally, to the neck of the fibula, where it anastomoses with the inferior lateral genicular and the deep sural arteries, and supplies the adjacent muscles.
(3) The peroneal artery (Fig. 781) is the largest branch of the posterior tibial. It arises about 25 mm. (an inch) below the distal border of the popliteus, curves laterally across the proximal part of the tibialis posterior to the medial crest of the fibula, along which it passes to the distal part of the interosseous space. About 25 mm. (an inch) proximal to the ankle-joint it gives off a perforating branch and then passes, posterior to the tibio-fibular syndesmosis and lateral malleolus, to the lateral side of the heel and the foot. It supplies the ankle, the tibio-fibular syndesmosis, and the talo-calcanean joint, and anastomoses with the medial calcanean branch of the lateral plantar artery, and with the tarsal and arcuate branches of the dorsalis pedis.
As the peroneal artery passes laterally from its origin it lies posterior to the tibialis posterior, and is covered posteriorly by the deep intermuscular fascia and by the soleus. As it descends along the medial crest of the fibula it lies in a fibrous canal between the tibialis posterior in front and the flexor hallucis longus behind. The peroneal artery is accompanied by two venæ comites, and is crossed anteriorly and posteriorly by communicating branches between them.
Branches. (a) Muscular branches are distributed to the soleus, tibialis posterior, flexor hallucis longus, and the peroneal muscles. Some pass through the interosseous membrane and supply the anterior muscles of the leg.
(b) A nutrient branch enters the nutrient foramen of the fibula.
(c) A communicating branch passes across the back of the distal end of the shaft of the tibia, about 25 mm. (an inch) above the tibio-fibular syndesmosis, to anastomose with the posterior tibial artery.
(d) The perforating branch passes forwards at the junction of the distal border of the interosseous membrane and the interosseous tibio-fibular ligament, and runs, in front of the ankle, to the dorsum of the foot, where it anastomoses with the lateral malleolar branch of the anterior tibial artery and with the tarsal branch of the dorsalis pedis; it also supplies branches to the tibio-fibular syndesmosis, to the ankle-joint, and to the peronæus tertius.
(4) The nutrient branch, the largest of the nutrient group of arteries to long bones, springs from the proximal part of the posterior tibial, pierces the tibialis posterior, and enters the nutrient foramen on the posterior surface of the tibia. In the interior of the bone it divides into proximal and distal branches, the former passing towards the proximal extremity of the bone, and the latter towards the distal extremity. Before entering the tibia the nutrient artery gives small muscular branches.
(5) A communicating branch unites the posterior tibial to the peroneal artery about 25 mm. (an inch) above the tibio-fibular syndesmosis. It passes posterior to the shaft of the tibia and anterior to the flexor hallucis longus.
(6) Cutaneous branches are distributed to the skin of the medial and posterior part of the leg.
(7) A posterior medial malleolar branch is distributed to the medial surface of the medial malleolus, anastomosing with a corresponding branch of the anterior tibial artery.
(8) The medial and lateral plantar arteries are the terminal branches of the posterior tibial artery. They arise, under cover of the origin of the ligamentum laciniatum, midway between the tip of the medial malleolus and the most prominent part of the medial side of the os calcis (Figs. 781, 782).
Arteria Plantaris Medialis.-The medial plantar artery is the smaller of the two terminal branches of the posterior tibial artery. It passes forwards, along the
medial side of the foot, in the interval between the abductor hallucis and the flexor digitorum brevis, to the head of the first metatarsal bone, where it terminates by uniting with the plantar digital branch of the dorsalis pedis, which is distributed to the medial side of the great toe. In its course forwards it
Quadratus plantæ gives off a superficial branch, which ramifies on the superficial surface of the abductor hallucis; branches to the adjacent muscles and articulations, and to the subjacent skin; it also gives three digital branches which anasto
mose, at the roots of the three medial interdigital
Transverse head clefts, with the medial
plantar metatarsal arteries. Some of the cutaneous branches of the medial plantar artery anastomose, round the medial border of the foot, with the medial cutaneous branches of the dorsalis pedis artery.
Arteria Plantaris Lateralis.-The lateral plantar artery is the larger of the two terminal branches of the posterior tibial artery. It runs forwards and laterally, first between the flexor digitorum brevis superficially and the quadratus plantæ deeply, and then, in the interval between the flexor digitorum brevis and the abductor digiti quinti, to the medial side of the base of the fifth metatarsal bone, where it turns abruptly medially and, gaining a deeper plane, passes across the bases of the metatarsal bones and the origins of the interossei, and above the oblique head of the adductor of the great toe, to the lateral side of the base of the first metatarsal bone, where it terminates by anastomosing with the dorsalis pedis artery. The last part of the artery is convex forwards and forms the plantar arch, which is completed by the profunda branch of the dorsalis pedis.
Branches. Between its origin and the base of the fifth metatarsal the lateral
plantar artery gives off (a) the medial calcanean branch, which is distributed to the skin and the subcutaneous tissue of the heel.
(6) Muscular branches to the abductor hallucis, flexor digitorum brevis, quadratus plantæ, and abductor digiti quinti.
(c) Cutaneous branches to the skin of the lateral side of the foot.
Between the base of the fifth metatarsal bone and the first interosseous space it forms the plantar arch, and gives off (d) four plantar metatarsal branches; (e) three posterior perforating arteries to the dorsal metatarsal arteries; and (ƒ) articular branches to the tarsal joints.
The fifth or most lateral metatarsal branch runs along the lateral side of the little toe, supplying the skin, joints, and the flexor tendons with their synovial sheaths. The three medial plantar metatarsal branches, second, third, and fourth, run forwards on the plantar surfaces of the interossei, the medial two lying dorsal to the oblique head of the adductor of the great toe, and all three passing dorsal to the transverse head of the adductor. At the bases of the interdigital clefts the second, third, and fourth plantar metatarsal arteries divide into plantar digital arteries which run along the plantar aspects of adjacent toes, and supply skin, joints, and the flexor tendons and sheaths. Opposite the last phalanx of each toe the digital arteries of opposite sides of the toe anastomose together.
The posterior perforating arteries are three in number; they pass dorsalwards through the three lateral intermetatarsal spaces, between the heads of the dorsal interosseous muscles, and terminate by uniting with the corresponding dorsal metatarsal arteries. Anterior perforating branches which communicate with the dorsal metatarsal arteries are given off from two or three of the plantar metatarsal arteries just before they divide. The articular branches are numerous and irregular; they supply the joints and ligaments of the tarsus on its plantar aspect.
ARTERIA TIBIALIS ANTERIOR.
The anterior tibial artery, the smaller of the two terminal divisions of the popliteal, commences opposite the distal border of the popliteus muscle, and terminates in front of the ankle, where it is continued into the dorsal artery of the foot.
Course and Relations. From its origin, at the back of the leg, the artery passes anteriorly, between the two slips of the proximal part of the tibialis posterior and above the proximal border of the interosseous membrane. It then runs distally, resting, in the proximal two-thirds of its course, against the anterior surface of the interosseous membrane and, subsequently, on the distal part of the tibia and the anterior ligament of the ankle-joint. In the proximal third of the anterior compartment of the leg it lies between the extensor digitorum longus laterally and the tibialis anterior medially; in the middle third it is between the extensor hallucis longus and the tibialis anterior; in the distal third the extensor hallucis longus crosses in front of the artery and reaches its medial side, and the most distal part of the vessel lies between the tendon of the extensor hallucis longus on the medial side and the most medial tendon of the extensor digitorum longus on the lateral side.
The deep peroneal nerve (O.T. anterior tibial) is at first well to the lateral side. of the artery, but it soon passes in front of the vessel, and it lies in front of the middle third of the artery; more distally the nerve is usually found on the lateral side again, and at the ankle it intervenes between the artery and the most medial tendon of the extensor digitorum longus.
Two venæ comites, with numerous intercommunications, accompany the artery. Obviously the anterior tibial artery is, at least in its proximal part, deeply placed; moreover, its lateral muscular boundaries overlap it. In the distal two-thirds of its extent it is, however, easily accessible from the surface; and beyond being covered by the nerve and crossed by the tendon, as already described, is only covered, in addition, by skin, fascia, and the transverse crural ligament.
Branches.--Close to its origin the artery gives off fibular and posterior tibial recurrent branches; after it reaches the front of the leg it gives off anterior tibial recurrent, muscular, cutaneous, medial malleolar, and lateral malleolar branches.
(1) The fibular branch is a small vessel which may arise separately from the anterior tibial artery, or by a common stem with the posterior tibial recurrent; occasionally it springs from the lower end of the popliteal artery, or from the posterior tibial.
It runs upwards and laterally, behind the neck of the fibula and through the fibres of the soleus, and it terminates in branches which supply the soleus, the peronæus longus, and the skin of the proximal and lateral part of the leg. It anasto moses with the inferior lateral genicular artery.
(2) The posterior tibial recurrent branch, also small, and not always present, runs upwards, anterior to the popliteus muscle, to the back of the knee-joint. It anastomoses with the inferior genicular branches of the popliteal, and gives branches to the popliteus muscle and the proximal tibio-fibular articulation.
(3) The anterior tibial recurrent branch arises from the anterior tibial artery in front of the interosseous membrane. It runs proximally and medially, between the proximal part of the tibialis anterior and the lateral condyle of the tibia, accompanied by the recurrent articular branch of the common peroneal nerve, and, after supplying the tibialis anterior and the proximal tibio-fibular articulation, it pierces the deep fascia of the leg; it is connected with the anastomoses round the knee-joint, formed by the genicular branches of
Extensor digitorum the popliteal artery, the de
scending branch of the lat eral circumflex artery, and the arteria genu suprema. (4) The muscular branches are distributed to the muscles of the front of the leg, and a few small branches also pass backwards to the deep surface of the tibialis posterior muscle.
(5) The cutaneous branches supply the skin of the front of the leg. (6) The medial anterior malleolar branch arises from the lower part of the anterior tibial artery, and is smaller than its companion on the lateral side. It runs medially, posterior to the tibialis anterior tendon, ramifies over the medial malleolus, anastomosing with branches of the posterior tibial artery, and is distributed to the skin and to the ankle-joint.