6. The Arteries of the Lower Extremity

The artery which supplies the greater part of the lower extremity is the direct continuation of the external iliac. It runs as a single trunk from the inguinal ligament to the lower border of the Popliteus, where it divides into two branches, the anterior and posterior tibial. The upper part of the main trunk is named the femoral, the lower part the popliteal. 1 a. The Femoral Artery

FIG. 545– Femoral sheath laid open to show its three compartments. (See enlarged image)

FIG. 546– Structures passing behind the inguinal ligament. (See enlarged image)

(A. Femoralis)

The femoral artery (Figs. 549, 550) begins immediately behind the inguinal ligament, midway between the anterior superior spine of the ilium and the symphysis pubis, and passes down the front and medial side of the thigh. It ends at the junction of the middle with the lower third of the thigh, where it passes through an opening in the Adductor magnus to become the popliteal artery. The vessel, at the upper part of the thigh, lies in front of the hip-joint; in the lower part of its course it lies to the medial side of the body of the femur, and between these two parts, where it crosses the angle between the head and body, the vessel is some distance from the bone. The first 4 cm. of the vessel is enclosed, together with the femoral vein, in a fibrous sheath—the femoral sheath. In the upper third of the thigh the femoral artery is contained in the femoral triangle (Scarpa’s triangle), and in the middle third of the thigh, in the adductor canal (Hunter’s canal). 2

FIG. 547– The relations of the femoral and abdominal inguinal rings, seen from within the abdomen. Right side. (See enlarged image) The femoral sheath (crural sheath) (Figs. 545, 546) is formed by a prolongation downward, behind the inguinal ligament, of the fasciæ which line the abdomen, the transversalis fascia being continued down in front of the femoral vessels and the iliac fascia behind them. The sheath assumes the form of a short funnel, the wide end of which is directed upward, while the lower, narrow end fuses with the fascial investment of the vessels, about 4 cm. below the inguinal ligament. It is strengthened in front by a band termed the deep crural arch (page 419). The lateral wall of the sheath is vertical and is perforated by the lumboinguinal nerve; the medial wall is directed obliquely downward and lateralward, and is pierced by the great saphenous vein and by some lymphatic vessels. The sheath is divided by two vertical partitions which stretch between its anterior and posterior walls. The lateral compartment contains the femoral artery, and the intermediate the femoral vein, while the medial and smallest compartment is named the femoral canal, and contains some lymphatic vessels and a lymph gland imbedded in a small amount of areolar tissue. The femoral canal is conical and measures about 1.25 cm. in length. Its base, directed upward and named the femoral ring, is oval in form, its long diameter being directed transversely and measuring about 1.25 cm. The femoral ring (Figs. 546, 547) is bounded in front by the inguinal ligament, behind by the Pectineus covered by the pectineal fascia, medially by the crescentic base of the lacunar ligament, and laterally by the fibrous septum on the medial side of the femoral vein. The spermatic cord in the male and the round ligament of the uterus in the female lie immediately above the anterior margin of the ring, while the inferior epigastric vessels are close to its upper and lateral angle. The femoral ring is closed by a somewhat condensed portion of the extraperitoneal fatty tissue, named the septum femorale (crural septum), the abdominal surface of which supports a small lymph gland and is covered by the parietal layer of the peritoneum. The septum femorale is pierced by numerous lymphatic vessels passing from the deep inguinal to the external iliac lymph glands, and the parietal peritoneum immediately above it presents a slight depression named the femoral fossa. 3

FIG. 548– Scheme of the femoral artery. (Poirier and Charpy.) (See enlarged image) The femoral triangle (trigonum femorale; Scarpa’s triangle) (Fig. 549) corresponds to the depression seen immediately below the fold of the groin. Its apex is directed downward, and the sides are formed laterally by the medial margin of the Sartorius, medially by the medial margin of the Adductor longus, and above by the inguinal ligament. The floor of the space is formed from its lateral to its medial side by the Iliacus, Psoas major, Pectineus, in some cases a small part of the Adductor brevis, and the Adductor longus; and it is divided into two nearly equal parts by the femoral vessels, which extend from near the middle of its base to its apex: the artery giving off in this situation its superficial and profunda branches, the vein receiving the deep femoral and great saphenous tributaries. On the lateral side of the femoral artery is the femoral nerve dividing into its branches. Besides the vessels and nerves, this space contains some fat and lymphatics. 4 The adductor canal (canalis adductorius; Hunter’s canal) is an aponeurotic tunnel in the middle third of the thigh, extending from the apex of the femoral triangle to the opening in the Adductor magnus. It is bounded, in front and laterally, by the Vastus medialis; behind by the Adductores longus and magnus; and is covered in by a strong aponeurosis which extends from the Vastus medialis, across the femoral vessels to the Adductores longus and magnus; lying on the aponeurosis is the Sartorius muscle. The canal contains the femoral artery and vein, the saphenous nerve, and the nerve to the Vastus medialis. 5

FIG. 549– The left femoral triangle. (See enlarged image) Relations of the Femoral Artery.—In the femoral triangle (Fig. 549) the artery is superficial. In front of it are the skin and superficial fascia, the superficial subinguinal lymph glands, the superficial iliac circumflex vein, the superficial layer of the fascia lata and the anterior part of the femoral sheath. The lumboinguinal nerve courses for a short distance within the lateral compartment of the femoral sheath, and lies at first in front and then lateral to the artery. Near the apex of the femoral triangle the medial branch of the anterior femoral cutaneous nerve crosses the artery from its lateral to its medial side. 6 Behind the artery are the posterior part of the femoral sheath, the pectineal fascia, the medial part of the tendon of the Psoas major, the Pectineus and the Adductor longus. The artery is separated from the capsule of the hip-joint by the tendon of the Psoas major, from the Pectineus by the femoral vein and profunda vessels, and from the Adductor longus by the femoral vein. The nerve to the Pectineus passes medialward behind the artery. On the lateral side of the artery, but separated from it by some fibers of the Psoas major, is the femoral nerve. The femoral vein is on the medial side of the upper part of the artery, but is behind the vessel in the lower part of the femoral triangle. 7

FIG. 550– The femoral artery. (See enlarged image) In the adductor canal (Fig. 550) the femoral artery is more deeply situated, being covered by the integument, the superficial and deep fasciæ, the Sartorius and the fibrous roof of the canal; the saphenous nerve crosses from its lateral to its medial side. Behind the artery are the Adductores longus and magnus; in front and lateral to it is the Vastus medialis. The femoral vein lies posterior to the upper part, and lateral to the lower part of the artery. 8 Peculiarities.—Several cases are recorded in which the femoral artery divided into two trunks below the origin of the profunda, and became reunited near the opening in the Adductor magnus, so as to form a single popliteal artery. One occurred in a patient who was operated upon for popliteal aneurism. A few cases have been recorded in which the femoral artery was absent, its place being supplied by the inferior gluteal artery which accompanied the sciatic nerve to the popliteal fossa. The external iliac in these cases was small, and terminated in the profunda. The femoral vein is occasionally placed along the medial side of the artery throughout the entire extent of the femoral trangle; or it may be split so that a large vein is placed on either side of the artery for a greater or lesser distance. 9 Collateral Circulation.—After ligature of the femoral artery, the main channels for carrying on the circulation are the anastomoses between—(1) the superior and inferior gluteal branches of the hypogastric with the medial and lateral femoral circumflex and first perforating branches of the profunda femoris; (2) the obturator branch of the hypogastric with the medial femoral circumflex of the profunda; (3) the internal pudendal of the hypogastric with the superficial and deep external pudendal of the femoral; (4) the deep iliac circumflex of the external iliac with the lateral femoral circumflex of the profunda and the superficial iliac circumflex of the femoral, and (5) the inferior gluteal of the hypogastric with the perforating branches of the profunda. 10

Branches.—The branches of the femoral artery are: 11

Superficial Epigastric.		Deep External Pudendal.
Superficial Iliac Circumflex.		Muscular.
Superficial External Pudendal.		Profunda Femoris.
Highest Genicular.

The superficial epigastric artery (a. epigastrica superficialis) arises from the front of the femoral artery about 1 cm. below the inguinal ligament, and, passing through the femoral sheath and the fascia cribrosa, turns upward in front of the inguinal ligament, and ascends between the two layers of the superficial fascia of the abdominal wall nearly as far as the umbilicus. It distributes branches to the superficial subinguinal lymph glands, the superficial fascia, and the integument; it anastomoses with branches of the inferior epigastric, and with its fellow of the opposite side. 12 The superficial iliac circumflex artery (a. circumflexa ilium superficialis), the smallest of the cutaneous branches, arises close to the preceding, and, piercing the fascia lata, runs lateralward, parallel with the inguinal ligament, as far as the crest of the ilium; it divides into branches which supply the integument of the groin, the superficial fascia, and the superficial subinguinal lymph glands, anastomosing with the deep iliac circumflex, the superior gluteal and lateral femoral circumflex arteries. 13 The superficial external pudendal artery (a. pudenda externa superficialis; superficial external pudic artery) arises from the medial side of the femoral artery, close to the preceding vessels, and, after piercing the femoral sheath and fascia cribrosa, courses medialward, across the spermatic cord (or round ligament in the female), to be distributed to the integument on the lower part of the abdomen, the penis and scrotum in the male, and the labium majus in the female, anastomosing with branches of the internal pudendal. 14 The deep external pudendal artery (a. pudenda externa profunda; deep external pudic artery), more deeply seated than the preceding, passes medialward across the Pectineus and the Adductor longus muscles; it is covered by the fascia lata, which it pierces at the medial side of the thigh, and is distributed, in the male, to the integument of the scrotum and perineum, in the female to the labium majus; its branches anastomose with the scrotal (or labial) branches of the perineal artery. 15 Muscular branches (rami musculares) are supplied by the femoral artery to the Sartorius, Vastus medialis, and Adductores. 16 The profunda femoris artery (a. profunda femoris; deep femoral artery) (Fig. 550) is a large vessel arising from the lateral and back part of the femoral artery, from 2 to 5 cm. below the inguinal ligament. At first it lies lateral to the femoral artery; it then runs behind it and the femoral vein to the medial side of the femur, and, passing downward behind the Adductor longus, ends at the lower third of the thigh in a small branch, which pierces the Adductor magnus, and is distributed on the back of the thigh to the hamstring muscles. The terminal part of the profunda is sometimes named the fourth perforating artery. 17 Relations.—Behind it, from above downward, are the Iliacus, Pectineus, Adductor brevis, and Adductor magnus. In front it is separated from the femoral artery by the femoral and profunda veins above and by the Adductor longus below. Laterally, the origin of the Vastus medialis intervenes between it and the femur. 18 Peculiarities.—This vessel sometimes arises from the medial side, and, more rarely, from the back of the femoral artery; but a more important peculiarity, from a surgical point of view, is that relating to the height at which the vessel arises. In three-fourths of a large number of cases it arose from 2.25 to 5 cm. below the inguinal ligament; in a few cases the distance was less than 2.25 cm.; more rarely, opposite the ligament; and in one case above the inguinal ligament, from the external iliac. Occasionally the distance between the origin of the vessel and the inguinal ligament exceeds 5 cm. 19 Branches.—The profunda gives off the following branches: 20

Lateral Femoral Circumflex.		Perforating.
Medial Femoral Circumflex.		Muscular.

The Lateral Femoral Circumflex Artery (a. circumflexa femoris lateralis; external circumflex artery) arises from the lateral side of the profunda, passes horizontally between the divisions of the femoral nerve, and behind the Sartorius and Rectus femoris, and divides into ascending, transverse, and descending branches. 21 The ascending branch passes upward, beneath the Tensor fasciæ latæ, to the lateral aspect of the hip, and anastomoses with the terminal branches of the superior gluteal and deep iliac circumflex arteries. 22 The descending branch runs downward, behind the Rectus femoris, upon the Vastus lateralis, to which it gives offsets; one long branch descends in the muscle as far as the knee, and anastomoses with the superior lateral genicular branch of the popliteal artery. It is accompanied by the branch of the femoral nerve to the Vastus lateralis. 23 The transverse branch, the smallest, passes lateralward over the Vastus intermedius, pierces the Vastus lateralis, and winds around the femur, just below the greater trochanter, anastomosing on the back of the thigh with the medial femoral circumflex, inferior gluteal, and first perforating arteries. 24 The Medial Femoral Circumflex Artery (a. circumflexa femoris medialis; internal circumflex artery) arises from the medial and posterior aspect of the profunda, and winds around the medial side of the femur, passing first between the Pectineus and Psoas major, and then between the Obturator externus and the Adductor brevis. At the upper border of the Adductor brevis it gives off two branches: one is distributed to the Adductores, the Gracilis, and Obturator externus, and anastomoses with the obturator artery; the other descends beneath the Adductor brevis, to supply it and the Adductor magnus; the continuation of the vessel passes backward and divides into superficial, deep, and acetabular branches. The superficial branch appears between the Quadratus femoris and upper border of the Adductor magnus, and anastomoses with the inferior gluteal, lateral femoral circumflex, and first perforating arteries (crucial anastomosis). The deep branch runs obliquely upward upon the tendon of the Obturator externus and in front of the Quadratus femoris toward the trochanteric fossa, where it anastomoses with twigs from the gluteal arteries. The acetabular branch arises opposite the acetabular notch and enters the hip-joint beneath the transverse ligament in company with an articular branch from the obturator artery; it supplies the fat in the bottom of the acetabulum, and is continued along the round ligament to the head of the femur. 25 The Perforating Arteries (Fig. 544), usually three in number, are so named because they perforate the tendon of the Adductor magnus to reach the back of the thigh. They pass backward close to the linea aspera of the femur under cover of small tendinous arches in the muscle. The first is given off above the Adductor brevis, the second in front of that muscle, and the third immediately below it. 26 The first perforating artery (a. perforans prima) passes backward between the Pectineus and Adductor brevis (sometimes it perforates the latter); it then pierces the Adductor magnus close to the linea aspera. It gives branches to the Adductores brevis and magnus, Biceps femoris, and Glutæus maximus, and anastomoses with the inferior gluteal, medial and lateral femoral circumflex and second perforating arteries. 27 The second perforating artery (a. perforans secunda), larger than the first, pierces the tendons of the Adductores brevis and magnus, and divides into ascending and descending branches, which supply the posterior femoral muscles, anastomosing with the first and third perforating. The second artery frequently arises in common with the first. The nutrient artery of the femur is usually given off from the second perforating artery; when two nutrient arteries exist, they usually spring from the first and third perforating vessels. 28 The third perforating artery (a. perforans tertia) is given off below the Adductor brevis; it pierces the Adductor magnus, and divides into branches which supply the posterior femoral muscles; anastomosing above with the higher perforating arteries, and below with the terminal branches of the profunda and the muscular branches of the popliteal. The nutrient artery of the femur may arise from this branch. The termination of the profunda artery, already described, is sometimes termed the fourth perforating artery. 29 Numerous muscular branches arise from the profunda; some of these end in the Adductores, others pierce the Adductor magnus, give branches to the hamstrings, and anastomose with the medial femoral circumflex artery and with the superior muscular branches of the popliteal. 30 The highest genicular artery (a. genu suprema; anastomotica magna artery) (Fig. 550) arises from the femoral just before it passes through the opening in the tendon of the Adductor magnus, and immediately divides into a saphenous and a musculo-articular branch. 31 The saphenous branch pierces the aponeurotic covering of the adductor canal, and accompanies the saphenous nerve to the medial side of the knee. It passes between the Sartorius and Gracilis, and, piercing the fascia lata, is distributed to the integument of the upper and medial part of the leg, anastomosing with the medial inferior genicular artery. 32 The musculo-articular branch descends in the substance of the Vastus medialis, and in front of the tendon of the Adductor magnus, to the medial side of the knee, where it anastomoses with the medial superior genicular artery and anterior recurrent tibial artery. A branch from this vessel crosses above the patellar surface of the femur, forming an anastomotic arch with the lateral superior genicular artery, and supplying branches to the knee-joint. 33

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