Lesson # 34
Topography and distribution of branches of femoral and popliteal arteries. Arteries of leg and foot.
Anastomoses between the arterial branches of lower extremity. Superficial and deep veins and lymphatic nodes and vessels of lower extremity
Theme 1. Topography and distribution of branches of femoral and popliteal arteries. Arteries of leg and foot. Anastomoses between the arterial branches of lower extremity
Femoral artery is continuation of external iliac artery, which passes under inguinal ligament through lacuna vasorum laterally from femoral vein. Then femoral artery runs downward in iliopectineal sulcus and anterior femoral sulcus. It enters into adductorial canal and exits from canal in popliteal fossa where contines into popliteal artery.
Femoral artery gives off:
· superficial epigastric artery passes on anterior abdominal wall and supplies a inferior portion of external oblique muscle aponeurosis and skin;
· superficial circumflexа iliac artery passes laterally and ramifies in muscles and skin near superior anterior iliac spina;
· deep femoral artery gives off medial circumflex femoral artery and lateral circumflexа artery, three perforating arteries, that supply posterior group of thigh muscles;
· descending genu artery begins from femoral artery in adductorial canal, passes through the tendinous hiatus of this canal and passes down together with saphenus nerve to knee-joint, where takes hand in formation of articulate knee net (rete articulare genus).
The femoral artery.
Popliteal artery is continuation of femoral artery, passes in advance of tibial nerve and popliteal vein and on level of inferior margin of popliteal muscle divides into anterior tibial artery and posterior tibial artery.
Popliteal artery gives off the following branches:
· superior medial and lateral genu arteries;
· middle genu artery;
· inferior medial and lateral genu arteries.
All these arteries participate in feeding of knee-joint and muscles around it.
Circumpatellar anastomosis.
Posterior tibial artery continues from popliteal artery, passes in cruropopliteal canal, under musculus soleus, behind medial malleolus, passes in separate fibrous canal under flexors tendom retinaculum on sole, where subdivides into medial plantar artery and lateral plantar artery.
The popliteal, posterior tibial, and peroneal arteries.
Branches of posterior tibial artery:
· fibular artery passes in inferior musculоfibular channel, supplies peroneal muscles and behind lateral malleolus divides into lateral maleolar branches and calcaneal branches;
· medial malleolar branches take hand in formation of medial maleolar rete;
· muscular branches supply deep and superficial muscles of posterior group in shin;
· fibular circumflexа branch runs laterally from beginning of tibial artery and rounding a head of fibula joins to articulate knee net;
· lateral plantar artery is a terminal branch of posterior tibial artery, lies in lateral plantar sulcus, passes medially and, anastomosing with deep plantar branch (from dorsal pedis artery), forms plantar arc. Lateral plantar artery gives off four plantar metatarsal arteries, which continue into common plantar digital arteries. Last subdivide into two proper plantar digital arteries, which supply skin of both sides of each finger on sole;
· medial plantar artery is second terminal branches of posterior tibial artery (has a deep branch and superficial branch), lies into medial plantar sulcus and supplies muscles of medial plantar group, anastomosing with first dorsal metatarsal artery.
The plantar arteries. Superficial view.
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Anterior tibial artery begins from popliteal artery in popliteal fossa, runs at cruropopliteal canal and makes perforating in superior portion of interossea membrane. Artery lies on anterior surface of interossea membrane between muscles of anterior shin group and, passing under retinaculum of extensor muscles, continues on foot under name of dorsal pedis artery.
Anterior tibial artery gives off the following branches:
· posterior recurrent tibial artery takes hand in formation of articulate knee net;
· anterior recurrent tibial artery takes hand in formation of articulate knee net;
· muscular branches supply anterior shin muscles group;
· anterior medial maleolar artery takes hand in formation medial maleolar net;
Anterior tibial and dorsalis pedis arteries.
Superficial and deep veins and lymphatic nodes and vessels of lower extremity
The Veins of the Lower Extremity
Just as with the upper extremity, the veins of the lower extremity are divided into deep and superficial, or subcutaneous, veins, which pass independently of the arteries (Fig. 63).
The deep veins of the foot and crus are binary and they accompany arteries of the same name. V. poplitea, which is comprised of all the deep veins of the crus, constitutes a single trunk lying in the popliteal fossa posteriorly and somewhat laterally of the artery of the same name. V. femoralis is single; it originates laterally of the femoral artery but, then, passes gradually to the posterior surface of the artery, and as it rises higher, it passes onto the medial surface. From this position the vein runs under the inguinal ligament into the lacuna vasorum. The veins flowing into v. femoralis are all binary.
The largest of the subcutaneous veins of the lower extremity are two trunks: v. saphena magna and v. saphena parva. The long saphenous vein (vena saphena magna) originates on the dorsal surface of the foot from rete venosum dorsale pedis and the arcus venosus dorsalis pedis. Having received a few small branches from the side of the sole, it passes upward along the medial side of the crus and femur. In the upper one-third of the femur, it bends onto the anteromedial surface and, lying on the broad fascia, runs toward the hiatus saphenus. At this point, it drains into the femoral vein, passing over the lower horn of the crescent-shaped edge. V. saphena magna
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quite often is binary with both its trunks draining separately into the femoral vein. Among the other subcutaneous veins flowing into the femoral vein, mention should be made of v. epigastrica superficialis, v. circumflex a ilium superficialis, and vv. pudendae externae, which accompany arteries of the same name. Some of them drain directly into the femoral vein; others drain into v. saphena magna as it flows into the region of the hiatus saphenus. The short saphenous vein (v. saphena parva) originates on the lateral side of the dorsal surface of the foot, passes below and behind the lateral malleolus, and then rises along the posterior surface of the crus. At first it runs along the lateral edge of Achilles’ tendon and then proceeds upward along the middle of the posterior segment of the crus corresponding to the groove between the heads of mm. gastrocnemii. When it reaches the lower angle of the popliteal fossa, v. saphena parva drains into the popliteal vein. V. saphena parva is joined by branches to v. saphena magna.
DISTRIBUTION OF THE VEINS
1. In the veins the blood flows through the greater part of the body (the trunk and limbs) against the force of gravity and, therefore, slower than in the arteries. The balance in the heart is achieved because most of the venous bed is much wider than the arterial bed. The greater width of the venous bed is the result of the following anatomical adaptations: the larger calibre of the veins, their greater number, the paired attendance of the arteries, the presence of veins not accompanying arteries, the greater number of anastomoses, the denser venous network, the formation of venous plexuses and sinuses, and the presence of a portal system in the liver. Because of this, venous blood flows to the heart along three large vessels (two venae cavae and the coronary sinus, in addition to the small veins running to the heart), while from the heart blood flows only along the aorta.
2. Deep veins accompanying the arteries (venae commitantes) are distributed according to the same laws as the arteries they accompany (see p. 93). Moreover, most of them accompany the arteries in pairs. Where the venous outflow is most hampered, i.e., in the extremities, the veins are mainly paired, since this arrangement is the result of evolution in four-legged animals whose torsos are horizontal, while both pairs of limbs are perpendicular to the ground.
3. Many superficial veins lying under the skin accompany the nerves of the skin, although a significant number form subcutaneous venous plexuses with no connection to either the nerves or the arteries.
4. Venous plexuses are mainly encountered in internal organs that change in volume in cavities with inflexible walls. The plexuses facilitate the flow of venous blood when the organs increase in size and are compressed by the walls. This explains the abundance of venous plexuses around the organs of the small pelvis (urinary bladder, uterus, rectum), in the vertebral canal, where the pressure of the cerebrospinal fluid constantly fluctuates, and in similar places.
5. In the cranial cavity where the slightest impediment to the venous outflow has an immediate effect on brain functions, there are, besides the veins, venous sinuses with inflexible walls formed by the dura mater. These spherical adaptations lie mainly where the processes of the dura mater are
attached to the bones of the skull (at the seams of tegmental bones and bone sulci of analogous sinuses).
6. Among the special adaptations are the diploic veins, venae diploicae.
HAEMATO-LYMPHATIC RELATIONS
As stated above, the thoracic duct drains into the left jugular vein or into the angle of its confluence with .the left subclavian vein (angulus venosus sinister), while the right lymphatic duct drains into the right subclavian vein. Lymph flowing through these ducts, therefore, mixes with the blood flowing in the veins so that a mixture of venous blood and lymph flows into the heart.
According to the latest data, lymph flows into the venous paths not only where the lymphatic ducts join the large veins running to the heart, but also in the lymph nodes.
An exchange of fluid between blood and lymph occurs in the nodes. Forty per cent of the lymph (afferent) flowing into the node transfers into the venous paths of the lymph nodes. In phlebohypertonia the reverse phenomenon is observed in the drained organs: part of the blood plasma flows into the lymphatic sinuses of the nodes. This reverse flow serves as one of the compensatory mechanisms in venous hypertension.
THE DEVELOPMENT OF LYMPHATIC VESSELS
The development of the lymphatic system in the process of phylogenesis is closely related to the development of blood circulation, which, in turn, is determined by the adaptation of the respiratory organs to the environment (Fig. 76).
In aquatic fauna (fish which breathe with gills and have a dual-chamber venous heart), iymph is propelled by the pulsations of the lymphatic heart, a dilated lympthatic vessel that propels lymph into the venous bed. Fish have no lymph nodes, and the lymphatic tissue is diffuse. In amphibians the number of lymphatic hearts increases, and they are situated in pairs on the border between the trunk and the extremities (anterior and posterior pairs). The diffuse lymphatic tissue becomes concentrated in follicles located in the mucous membranes.
When gills are finally replaced by lungs in terrestrial animals and pulmonary circulation develops in addition to systemic circulation, the movement of lymph is facilitated by the throbbing of the heart. As a result the role of lymphatic hearts diminishes, and they gradually disappear to be preserved only in a single (posterior) pair. At the same time the overall number of lymphatic vessels increases.
In birds lymphatic hearts are present only in the foetus, and the number of lymphatic vessels increases. Valves appear inside the vessels, preventing the reverse flow of lymph. Several lymph nodes make their appearance. With the appearance of a muscular diaphragm in mammals and the further development of the heart and blood vessels as well as the skeletal musculature, the movement of lymph is eased by the suction action of the thoracic cage and the contraction of the heart, blood vessels, and muscles. There is no longer any need for the lymphatic hearts, and they disappear completely. At the same time, the number of lymphatic vessels, in which many valves develop, increases. The lymph ducts passing along the aorta merge into a large unpaired trunk, the ductus thoracicus. The number of lymph nodes increases sharply, particularly in primates.
Since human beings walk erect, the number of valves in the lymphatic vessels of human extremities increases, particularly in the lower limbs. Humans have the greatest number of lymph nodes of any species, which testifies to the increased importance of the lymphatic system in limiting the spread of pathological processes. A Soviet scientist Zhdanov maintains that the increase of lymph nodes in man (even, in comparison with monkeys) is connected with diet.
There are two theories regarding the embryonic development of the lymphatic system. According to the centrifugal development theory, as the first theory is called, the lymphatic system develops out of the venous system. The second, theory contends that the system originates separately out of the mesenchyme and only later joins the veins; this theory is called the theory of centripetal development. Most authors currently recognize the latter theory, according to which the lymphatic system develops independently of the system of blood circulation and establishes connections with the venous system secondarily. The lymphatic system originates as detached germs, which grow, branch out, and form canals,
or lymph capillaries. Expanding and merging, these capillaries, in their second month, form six lymph sacs: two by the jugular veins, one retroperitoneal at the base of the mesentery, near the adrenals, one neighbouring the preceding one (this is the cisterna chyli), and two by the iliac veins.
The lymphatic vessels of the head, neck, and upper extremity (these last from supplementary sacs occurring by the subclavian veins) develop from jugular sacs. The retroperitoneal S3C gives rise to vessels of the mesentery collecting lymph from the intestine. The iliac sacs are the source for vessels of the lower limbs and pelvis. Moreover, the jugular sacs grow in the direction of the thoracic cavity and join in a single trunk, which meets the growing cisterna chyli. As a result a thoracic duct uniting the systems of the iliac, retroperitoneal and jugular sacs is formed. Thus, a single system of lymphatic vessels is created, which makes contact with the venous system only near the jugular sacs at the confluence of the jugular and subclavian veins on both sides of the body.
The initially symmetrical structure of the lymphatic system is disturbed later, however, because the left duct (thoracic) develops to a greater extent than the right. This greater development is explained by the asymmetrical position of the heart and large veins which creates more favourable conditions for the flow of lymph and blood through the left side in the region of the left venous angle. On the right side, because of the proximity to the venous half of the heart, there is a greater periodical increase of pressure in the vena cava superior as the result of heart contractions, which hampers the stream of lymph from freely joining the flow of venous blood. This functional difference in the circulation through the right and left main lymph trunks of the body also explains their unequal development. A dual thoracic duct, common in lower vertebrates, is sometimes preserved as a developmental variant in humans. Besides the lymphatic vessels and sacs, the lymph nodes also develop, but somewhat later (in the third month).
THE LYMPHATIC SYSTEM IN VARIOUS PARTS OF THE BODY
The lymphatic vessels of the trunk, head, and limbs (i.e., of the soma) are divided into superficial and deep vessels, separated by the deep fascia of the given region. Thus, the lymphatic vessels of the skin, subcutaneous tissue, and part of the fascia, are superficial, while all other vessels, i.e., the lymphatic vessels lying under the fascia, are deep. The deep lymphatic system of the soma is built as follows.
The deep lymphatic vessels arising from the capillary lymph networks of joint capsules, muscles, tendons, fasciae, nerves, and so on run, at first, as components of the neurovascular bundles of these organs and then drain into the lymph collectors of the given part of the body. In their turn the lymph collectors accompany large arterial and venous trunks and drain into the regional lymph nodes.
THE LOWER EXTREMITY
The lymph nodes of the lower extremity are located in the following places (Fig. 77).
1. Popliteal fossa—popliteal lymph glands (nodi lymphatici poplitet).
2. Inguinal region—inguinal lymph glands (nodi lymphatici inguinales). They lie immediately under the inguinal ligament and are divided into superficial and deep inguinal lymph glands.
a) superficial inguinal glands (nodi lymphatici inguinales superficiales) are located on the wide fascia of the femur below its perforation by v. saphena magna;
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b)deep inguinal glands (nodi lymphatici.inguinales profundi) are locatea in the same region as the superficial glands although under the wide fascir.
The superficial lymphatic vessels drain into two groups of collect os running the length of v. saphena magna to the medial group of the superficial inguinal nodes and along v. saphena parva to the popliteal nodes of the posterolateral group.
The posterolateral group of collectors and the popliteal nodes, receive lymph from the skin, subcutaneous tissue, and superficial fasciae of a small region of the leg (the fourth and fifth toes, the lateral edge of the foot, the inferior lateral surface of the crus, and the lateral part of the gastrocnemius region). From all other parts of the leg, the lymph flows into the medial group of collectors and then into the inguinal nodes without interruption in the popliteal nodes.
This explains the reaction of the inguinal nodes (tumescence and tenderness) in purulent inflammation of the skin of the ungual phalanx of the big toe, for example. The superficial lymphatic vessels of the upper one-third of the thigh drain into the inguinal nodes, which also receive the superficial vessels of the gluteal region, the anterior abdominal wall, and the external sexual organs.
The deep lymphatic vessels of the foot and crus, including the articular sac of the knee joint, drain into the popliteal nodes. From there the lymph flows through the deep collectors attendant to the femoral artery until it reaches the deep inguinal nodes. These same collectors also receive lymph from the deep tissues of the thigh. As a result, the large group of nodes located in the inguinal region collects lymph from the entire lower limb, the anterior wall of the abdomen (below the navel), the gluteal region, the perineum and external sexual organs, and partly from the internal sexual organs (uterus).
The efferent vessels of the inguinal nodes run the length of the external iliac artery and vein to the iliac lymph nodes from where the lymph passes into the truncus lumbalis.
THE PELVIS
In the pelvis the lymph nodes are mainly located along the blood vessels, as well as on the surface of the internal organs. The following groups are found there: 1) external and common iliac lymph glands (nodi lymphatici iliaci externi and commune) along the external artery and the common iliac artery; their efferent ducts are directed towards nodi lymphatici lumbales; 2) internal iliac lymph glands (nodi lymphatici iliaci interni) (9-12) on the lateral wall of the pelvic cavity; their efferent ducts pass to the nodes located along the common iliac artery; 3) sacral lymph glands (nodi lymphatici sac- rales), small nodes along a. sacralis mediana; their efferent ducts run towards nodi lymphatici iliaci, located near the promontorium. The efferent lymphatic vessels of the organs of the minor pelvis drain into these nodes (see also the section on splanchnology) (Fig. 77).
External iliac vein is continuation of femoral vein and receives blood from all veins of lower limb. Inferior epigastric vein and deep circumflexа ilei vein empties into external iliac vein under inguinal ligament.
The veins of lower limb subdivide into superficial and deep. Deep veins are double and accompany same name artery (only a popliteal vein and femoral vein are odd).
Follow veins belong to superficial veins of lower limb:
1. Vena saphena magna has numerous valves, starts in front of medial malleolus, where receives influxes from plantar surface of foot, passes along saphenus nerve on medial leg surface upward, than on medial surface on thigh to saphaenus hiatus, where transfixes cribriform fascia and empties into femoral vein. Vena saphena magna has the numerous subcutaneous tributaries from anteromedial surface of leg, thigh and external genitals.
2. Vena saphena parva has the numerous valves and collects blood from dorsal venous arch of foot, passes behind lateral malleolus, lies into sulcus between lateral and medial heads of gastrocnemius muscle and in popliteal fossa empties into popliteal vein.
The great saphenous vein and its tributaries at the fossa ovalis.
3.
Follow vessels belong to deep veins of lower limb:
· femoral vein;
· deep femoral vein;
· popliteal vein;
· anterior tibial veins;
· posterior tibial veins;
· fibular veins.
The Superficial Veins of the Lower Extremity
The superficial veins of the lower extremity are the great and small saphenous veins and their tributaries.
On the dorsum of the foot the dorsal digital veins receive, in the clefts between the toes, the intercapitular veins from the plantar cutaneous venous arch and join to form short common digital veins which unite across the distal ends of the metatarsal bones in a dorsal venous arch. Proximal to this arch is an irregular venous net-work which receives tributaries from the deep veins and is joined at the sides of the foot by a medial and a lateral marginal vein, formed mainly by the union of branches from the superficial parts of the sole of the foot.
On the sole of the foot the superficial veins form a plantar cutaneous venous arch which extends across the roots of the toes and opens at the sides of the foot into the medial and lateral marginal veins. Proximal to this arch is a plantar cutaneous venous net-work which is especially dense in the fat beneath the heel; this net-work communicates with the cutaneous venous arch and with the deep veins, but is chiefly drained into the medial and lateral marginal veins.
The great saphenous vein (v. saphena magna;
internal or long saphenous vein) (581), the longest vein in the body, begins in the medial marginal vein
of the dorsum of the foot and ends in the femoral vein about
Tributaries.—At the ankle it receives branches from the sole of the foot through the medial marginal vein; in the leg it anastomoses freely with the small saphenous vein, communicates with the anterior and posterior tibial veins and receives many cutaneous veins; in the thigh it communicates with the femoral vein and receives numerous tributaries; those from the medial and posterior parts of the thigh frequently unite to form a large accessory saphenous vein which joins the main vein at a variable level. Near the fossa ovalis (580) it is joined by the superficial epigastric, superficial iliac circumflex, and superficial external pudendal veins. A vein, named the thoracoepigastric, runs along the lateral aspect of the trunk between the superficial epigastric vein below and the lateral thoracic vein above and establishes an important communication between the femoral and axillary veins.
The valves in the great saphenous vein vary from ten to twenty in number; they are more numerous in the leg than in the thigh.
The small saphenous vein (v. saphena parva; external or short saphenous vein) (582) begins behind the lateral malleolus as a continuation of the lateral marginal vein; it first ascends along the lateral margin of the tendocalcaneus, and then crosses it to reach the middle of the back of the leg. Running directly upward, it perforates the deep fascia in the lower part of the popliteal fossa, and ends in the popliteal vein, between the heads of the Gastrocnemius. It communicates with the deep veins on the dorsum of the foot, and receives numerous large tributaries from the back of the leg. Before it pierces the deep fascia, it gives off a branch which runs upward and forward to join the great saphenous vein. The small saphenous vein possesses from nine to twelve valves, one of which is always found near its termination in the popliteal vein. In the lower third of the leg the small saphenous vein is in close relation with the sural nerve, in the upper two-thirds with the medial sural cutaneous nerve.
The Deep Veins of the Lower Extremity
The deep veins of the lower extremity accompany the arteries and their branches; they possess numerous valves.
The great saphenous vein and its tributaries.
The small saphenous vein.
The plantar digital veins (vv. digitales plantares) arise from plexuses on the plantar surfaces of the digits, and, after sending intercapitular veins to join the dorsal digital veins, unite to form four metatarsal veins; these run backward in the metatarsal spaces, communicate, by means of perforating veins, with the veins on the dorsum of the foot, and unite to form the deep plantar venous arch which lies alongside the plantar arterial arch. From the deep plantar venous arch the medial and lateral plantar veins run backward close to the corresponding arteries and, after communicating with the great and small saphenous veins, unite behind the medial malleolus to form the posterior tibial veins.
The posterior tibial veins (vv. tibiales posteriores) accompany the posterior tibial artery, and are joined by the peroneal veins.
The anterior tibial veins (vv. tibiales anteriores) are the upward continuation of the venæ comitantes of the dorsalis pedis artery. They leave the front of the leg by passing between the tibia and fibula, over the interosseous membrane, and unite with the posterior tibial, to form the popliteal vein.
The Popliteal Vein (v. poplitea) (583) is formed by the junction of the anterior and posterior tibial veins at the lower border of the Popliteus; it ascends through the popliteal fossa to the aperture in the Adductor magnus, where it becomes the femoral vein. In the lower part of its course it is placed medial to the artery; between the heads of the Gastrocnemius it is superficial to that vessel; but above the knee-joint, it is close to its lateral side. It receives tributaries corresponding to the branches of the popliteal artery, and it also receives the small saphenous vein. The valves in the popliteal vein are usually four in number.
The femoral vein (v. femoralis) accompanies
the femoral artery through the upper two-thirds of the thigh. In the lower part
of its course it lies lateral to the artery; higher up, it is behind it; and at
the inguinal ligament, it lies on its medial side, and on the same plane. It
receives numerous muscular tributaries, and about
The Deep Femoral Vein (v. profunda femoris) receives tributaries corresponding to the perforating branches of the profunda artery, and through these establishes communications with the popliteal vein below and the inferior gluteal vein above. It also receives the medial and lateral femoral circumflex veins.
The popliteal vein.
The Veins of the Abdomen and Pelvis (585, 586, 587)
The external iliac vein (v. iliaca externa), the upward continuation of the femoral vein, begins behind the inguinal ligament, and, passing upward along the brim of the lesser pelvis, ends opposite the sacroiliac articulation, by uniting with the hypogastric vein to form the common iliac vein. On the right side, it lies at first medial to the artery: but, as it passes upward, gradually inclines behind it. On the left side, it lies altogether on the medial side of the artery. It frequently contains one, sometimes two, valves.
Tributaries.—The external iliac vein receives the inferior epigastric, deep iliac circumflex, and pubic veins.
The Inferior Epigastric Vein (v. epigastrica
inferior; deep epigastric vein) is formed by the union of the venæ
comitantes of the inferior epigastric artery, which communicate above with the
superior epigastric vein; it joins the external iliac about
The Deep Iliac Circumflex Vein (v. circumflexa
ilium profunda) is formed by the union of the venæ comitantes of the
deep iliac circumflex artery, and joins the external iliac vein about
The Pubic Vein communicates with the obturator vein in the obturator foramen, and ascends on the back of the pubis to the external iliac vein.
The hypogastric vein (v. hypogastrica; internal iliac vein) begins near the upper part of the greater sciatic foramen, passes upward behind and slightly medial to the hypogastric artery and, at the brim of the pelvis, joins with the external iliac to form the common iliac vein.
The femoral vein and its tributaries.
Tributaries.—With the exception of the fetal umbilical vein which passes upward and backward from the umbilicus to the liver, and the iliolumbar vein which usually joins the common iliac vein, the tributaries of the hypogastric vein correspond with the branches of the hypogastric artery. It receives (a) the gluteal, internal pudendal, and obturator veins, which have their origins outside the pelvis; (b) the lateral sacral veins, which lie in front of the sacrum; and (c) the middle hemorrhoidal, vesical, uterine, and vaginal veins, which originate in venous plexuses connected with the pelvic viscera.
The Lymphatics of the Lower Extremity
The superficial and deep vessels are distinguished in lower limb. The superficial vessels are situated over superficial fascia and deep vessels positioned closely to deep blood vessels. Popliteal nodes and inguinal nodes are distinguished in lower limb. Last one subdivide into deep inguinal nodes and superficial inguinal nodes. Superficial inguinal nodes dispose along inguinal ligament and lie on superficial sheet of fascia lata femoris. Their efferent vessels pass to external iliac nodes, which accompany same name artery.
The superficial vessels of lower limb formed from capillary skin networks and subcutaneous cellular tissue and form medial, lateral and posterior vessel groups.
Medial group of superficial vessels formed in skin of I, II and III fingers, medial part of foot and medial surface of shin. These vessels run along vena saphena magna and empty into superficial inguinal nodes.
Lateral group of superficial vessels of lower limb formed laterally in area of fingers in dorsal foot surface and lateral surface of shin. These vessels beneath knee join to medial group.
Posterior group of superficial vessels of lower limb starts in skin of heel and plantar surface of lateral foot margin, passes along the vena saphaena parva and runs into popliteal lymphatic nodes.
Deep vessels of lower limb drainage muscles, joints, synovial sheaths, bones, nerves, accompany deep arteries and veins and empty into deep inguinal nodes.
The Veins of the Lower Extremity
Just as with the upper extremity, the veins of the lower extremity are divided into deep and superficial, or subcutaneous, veins, which pass independently of the arteries .
The deep veins of the foot and crus are binary and they accompany arteries of the same name. V. poplitea, which is comprised of all the deep veins of the crus, constitutes a single trunk lying in the popliteal fossa posteriorly and somewhat laterally of the artery of the same name. V. femoralis is single; it originates laterally of the femoral artery but, then, passes gradually to the posterior surface of the artery, and as it rises higher, it passes onto the medial surface. From this position the vein runs under the inguinal ligament into the lacuna vasorum. The veins flowing into v. femoralis are all binary.
The largest of the subcutaneous veins of the lower extremity are two trunks: v. saphena magna and v. saphena parva. The long saphenous vein (vena saphena magna) originates on the dorsal surface of the foot from rete venosum dorsale pedis and the arcus venosus dorsalis pedis. Having received a few small branches from the side of the sole, it passes upward along the medial side of the crus and femur. In the upper one-third of the femur, it bends onto the anteromedial surface and, lying on the broad fascia, runs toward the hiatus saphenus. At this point, it drains into the femoral vein, passing over the lower horn of the crescent-shaped edge. V. saphena magna
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quite often is binary with both its trunks draining separately into the femoral vein. Among the other subcutaneous veins flowing into the femoral vein, mention should be made of v. epigastrica superficialis, v. circumflex a ilium superficialis, and vv. pudendae externae, which accompany arteries of the same name. Some of them drain directly into the femoral vein; others drain into v. saphena magna as it flows into the region of the hiatus saphenus. The short saphenous vein (v. saphena parva) originates on the lateral side of the dorsal surface of the foot, passes below and behind the lateral malleolus, and then rises along the posterior surface of the crus. At first it runs along the lateral edge of Achilles’ tendon and then proceeds upward along the middle of the posterior segment of the crus corresponding to the groove between the heads of mm. gastrocnemii. When it reaches the lower angle of the popliteal fossa, v. saphena parva drains into the popliteal vein. V. saphena parva is joined by branches to v. saphena magna.
1. In the veins the blood flows through the greater part of the body (the trunk and limbs) against the force of gravity and, therefore, slower than in the arteries. The balance in the heart is achieved because most of the venous bed is much wider than the arterial bed. The greater width of the venous bed is the result of the following anatomical adaptations: the larger calibre of the veins, their greater number, the paired attendance of the arteries, the presence of veins not accompanying arteries, the greater number of anastomoses, the denser venous network, the formation of venous plexuses and sinuses, and the presence of a portal system in the liver. Because of this, venous blood flows to the heart along three large vessels (two venae cavae and the coronary sinus, in addition to the small veins running to the heart), while from the heart blood flows only along the aorta.
2. Deep veins accompanying the arteries (venae commitantes) are distributed according to the same laws as the arteries they accompany (see p. 93). Moreover, most of them accompany the arteries in pairs. Where the venous outflow is most hampered, i.e., in the extremities, the veins are mainly paired, since this arrangement is the result of evolution in four-legged animals whose torsos are horizontal, while both pairs of limbs are perpendicular to the ground.
3. Many superficial veins lying under the skin accompany the nerves of the skin, although a significant number form subcutaneous venous plexuses with no connection to either the nerves or the arteries.
4. Venous plexuses are mainly encountered in internal organs that change in volume in cavities with inflexible walls. The plexuses facilitate the flow of venous blood when the organs increase in size and are compressed by the walls. This explains the abundance of venous plexuses around the organs of the small pelvis (urinary bladder, uterus, rectum), in the vertebral canal, where the pressure of the cerebrospinal fluid constantly fluctuates, and in similar places.
5. In the cranial cavity where the slightest impediment to the venous outflow has an immediate effect on brain functions, there are, besides the veins, venous sinuses with inflexible walls formed by the dura mater. These spherical adaptations lie mainly where the processes of the dura mater are
attached to the bones of the skull (at the seams of tegmental bones and bone sulci of analogous sinuses).
6. Among the special adaptations are the diploic veins, venae diploicae.
HAEMATO-LYMPHATIC RELATIONS
As stated above, the thoracic duct drains into the left jugular vein or into the angle of its confluence with .the left subclavian vein (angulus venosus sinister), while the right lymphatic duct drains into the right subclavian vein. Lymph flowing through these ducts, therefore, mixes with the blood flowing in the veins so that a mixture of venous blood and lymph flows into the heart.
According to the latest data, lymph flows into the venous paths not only where the lymphatic ducts join the large veins running to the heart, but also in the lymph nodes.
An exchange of fluid between blood and lymph occurs in the nodes. Forty per cent of the lymph (afferent) flowing into the node transfers into the venous paths of the lymph nodes. In phlebohypertonia the reverse phenomenon is observed in the drained organs: part of the blood plasma flows into the lymphatic sinuses of the nodes. This reverse flow serves as one of the compensatory mechanisms in venous hypertension.
THE DEVELOPMENT OF LYMPHATIC VESSELS
The development of the lymphatic system in the process of phylogenesis is closely related to the development of blood circulation, which, in turn, is determined by the adaptation of the respiratory organs to the environment (Fig. 76).
In aquatic fauna (fish which breathe with gills and have a dual-chamber venous heart), iymph is propelled by the pulsations of the lymphatic heart, a dilated lympthatic vessel that propels lymph into the venous bed. Fish have no lymph nodes, and the lymphatic tissue is diffuse. In amphibians the number of lymphatic hearts increases, and they are situated in pairs on the border between the trunk and the extremities (anterior and posterior pairs). The diffuse lymphatic tissue becomes concentrated in follicles located in the mucous membranes.
When gills are finally replaced by lungs in terrestrial animals and pulmonary circulation develops in addition to systemic circulation, the movement of lymph is facilitated by the throbbing of the heart. As a result the role of lymphatic hearts diminishes, and they gradually disappear to be preserved only in a single (posterior) pair. At the same time the overall number of lymphatic vessels increases.
In birds lymphatic hearts are present only in the foetus, and the number of lymphatic vessels increases. Valves appear inside the vessels, preventing the reverse flow of lymph. Several lymph nodes make their appearance. With the appearance of a muscular diaphragm in mammals and the further development of the heart and blood vessels as well as the skeletal musculature, the movement of lymph is eased by the suction action of the thoracic cage and the contraction of the heart, blood vessels, and muscles. There is no longer any need for the lymphatic hearts, and they disappear completely. At the same time, the number of lymphatic vessels, in which many valves develop, increases. The lymph ducts passing along the aorta merge into a large unpaired trunk, the ductus thoracicus. The number of lymph nodes increases sharply, particularly in primates.
Since human beings walk erect, the number of valves in the lymphatic vessels of human extremities increases, particularly in the lower limbs. Humans have the greatest number of lymph nodes of any species, which testifies to the increased importance of the lymphatic system in limiting the spread of pathological processes. A Soviet scientist Zhdanov maintains that the increase of lymph nodes in man (even, in comparison with monkeys) is connected with diet.
There are two theories regarding the embryonic development of the lymphatic system. According to the centrifugal development theory, as the first theory is called, the lymphatic system develops out of the venous system. The second, theory contends that the system
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originates separately out of the mesenchyme and only later joins the veins; this theory is called the theory of centripetal development. Most authors currently recognize the latter theory, according to which the lymphatic system develops independently of the system of blood circulation and establishes connections with the venous system secondarily. The lymphatic system originates as detached germs, which grow, branch out, and form canals,
or lymph capillaries. Expanding and merging, these capillaries, in their second month, form six lymph sacs: two by the jugular veins, one retroperitoneal at the base of the mesentery, near the adrenals, one neighbouring the preceding one (this is the cisterna chyli), and two by the iliac veins.
The lymphatic vessels of the head, neck, and upper extremity (these last from supplementary sacs occurring by the subclavian veins) develop from jugular sacs. The retroperitoneal S3C gives rise to vessels of the mesentery collecting lymph from the intestine. The iliac sacs are the source for vessels of the lower limbs and pelvis. Moreover, the jugular sacs grow in the direction of the thoracic cavity and join in a single trunk, which meets the growing cisterna chyli. As a result a thoracic duct uniting the systems of the iliac, retroperitoneal and jugular sacs is formed. Thus, a single system of lymphatic vessels is created, which makes contact with the venous system only near the jugular sacs at the confluence of the jugular and subclavian veins on both sides of the body.
The initially symmetrical structure of the lymphatic system is disturbed later, however, because the left duct (thoracic) develops to a greater extent than the right. This greater development is explained by the asymmetrical position of the heart and large veins which creates more favourable conditions for the flow of lymph and blood through the left side in the region of the left venous angle. On the right side, because of the proximity to the venous half of the heart, there is a greater periodical increase of pressure in the vena cava superior as the result of heart contractions, which hampers the stream of lymph from freely joining the flow of venous blood. This functional difference in the circulation through the right and left main lymph trunks of the body also explains their unequal development. A dual thoracic duct, common in lower vertebrates, is sometimes preserved as a developmental variant in humans. Besides the lymphatic vessels and sacs, the lymph nodes also develop, but somewhat later (in the third month).
THE LYMPHATIC SYSTEM IN VARIOUS PARTS OF THE BODY
The lymphatic vessels of the trunk, head, and limbs (i.e., of the soma) are divided into superficial and deep vessels, separated by the deep fascia of the given region. Thus, the lymphatic vessels of the skin, subcutaneous tissue, and part of the fascia, are superficial, while all other vessels, i.e., the lymphatic vessels lying under the fascia, are deep. The deep lymphatic system of the soma is built as follows. The deep lymphatic vessels arising from the capillary lymph networks of joint capsules, muscles, tendons, fasciae, nerves, and so on run, at first, as components of the neurovascular bundles of these organs and then drain into the lymph collectors of the given part of the body. In their turn the lymph collectors accompany large arterial and venous trunks and drain into the regional lymph nodes.
THE LOWER EXTREMITY
The lymph nodes of the lower extremity are located in the following places (Fig. 77).
1. Popliteal fossa—popliteal lymph glands (nodi lymphatici poplitet).
2. Inguinal region—inguinal lymph glands (nodi lymphatici inguinales). They lie immediately under the inguinal ligament and are divided into superficial and deep inguinal lymph glands.
a)superficial inguinal glands (nodi lymphatici inguinales superficiales) are located on the wide fascia of the femur below its perforation by v. saphena magna;
b)deep inguinal glands (nodi lymphatici.inguinales profundi) are locatea in the same region as the superficial glands although under the wide fascir.
The superficial lymphatic vessels drain into two groups of collect os running the length of v. saphena magna to the medial group of the superficial inguinal nodes and along v. saphena parva to the popliteal nodes of the posterolateral group.
The posterolateral group of collectors and the popliteal nodes, receive lymph from the skin, subcutaneous tissue, and superficial fasciae of a small region of the leg (the fourth and fifth toes, the lateral edge of the foot, the inferior lateral surface of the crus, and the lateral part of the gastrocnemius region). From all other parts of the leg, the lymph flows into the medial group of collectors and then into the inguinal nodes without interruption in the popliteal nodes. This explains the reaction of the inguinal nodes (tumescence and tenderness) in purulent inflammation of the skin of the ungual phalanx of the big toe, for example. The superficial lymphatic vessels of the upper one-third of the thigh drain into the inguinal nodes, which also receive the superficial vessels of the gluteal region, the anterior abdominal wall, and the external sexual organs.
The deep lymphatic vessels of the foot and crus, including the articular sac of the knee joint, drain into the popliteal nodes. From there the lymph flows through the deep collectors attendant to the femoral artery until it reaches the deep inguinal nodes. These same collectors also receive lymph from the deep tissues of the thigh. As a result, the large group of nodes located in the inguinal region collects lymph from the entire lower limb, the anterior wall of the abdomen (below the navel), the gluteal region, the perineum and external sexual organs, and partly from the internal sexual organs (uterus).
The efferent vessels of the inguinal nodes run the length of the external iliac artery and vein to the iliac lymph nodes from where the lymph passes into the truncus lumbalis.
THE PELVIS
In the pelvis the lymph nodes are mainly located along the blood vessels, as well as on the surface of the internal organs. The following groups are found there: 1) external and common iliac lymph glands (nodi lymphatici iliaci externi and commune) along the external artery and the common iliac artery; their efferent ducts are directed towards nodi lymphatici lumbales; 2) internal iliac lymph glands (nodi lymphatici iliaci interni) (9-12) on the lateral wall of the pelvic cavity; their efferent ducts pass to the nodes located along the common iliac artery; 3) sacral lymph glands (nodi lymphatici sac- rales), small nodes along a. sacralis mediana; their efferent ducts run towards nodi lymphatici iliaci, located near the promontorium. The efferent lymphatic vessels of the organs of the minor pelvis drain into these nodes.
