The patellar network (

circulatory anastomosis A circulatory anastomosis is a connection (an anastomosis) between two blood vessels, such as between arteries (arterio-arterial anastomosis), between veins (veno-venous anastomosis) or between an artery and a vein (arterio-venous anastomosi ...

around the

knee-joint In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the hu ...

, patellar anastomosis, genicular anastomosis, articular vascular network of knee or rete articulare genus) is an intricate network of blood vessels around and above the

patella The patella (: patellae or patellas), also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in m ...

, and on the contiguous ends of the

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

and

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

, forming a

superficial Superficial may refer to: *Superficial anatomy, is the study of the external features of the body *Superficiality, the discourses in philosophy regarding social relation * Superficial charm, the tendency to be smooth, engaging, charming, slick and ...

and a

deep Deep or The Deep may refer to: Places United States * Deep Creek (Appomattox River tributary), Virginia * Deep Creek (Great Salt Lake), Idaho and Utah * Deep Creek (Mahantango Creek tributary), Pennsylvania * Deep Creek (Mojave River tributary ...

plexus In anatomy, a plexus (from the Latin term for 'braid') is a branching network of blood vessels, lymphatic vessels, or nerves. The nerves are typically axons outside the central nervous system. The standard plural form in English is plexuses. Al ...

. * The ''superficial plexus'' is situated between the fascia and skin around about the patella, and forms three well-defined arches: one, above the upper border of the patella, in the loose connective tissue over the

quadriceps femoris The quadriceps femoris muscle (, also called the quadriceps extensor, quadriceps or quads) is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the sole List of extensors of the human body#Knee, exte ...

; the other two, below the level of the patella, are situated in the fat behind the

patellar ligament The patellar tendon is the distal portion of the common tendon of the quadriceps femoris, which is continued from the patella to the tibial tuberosity. It is also sometimes called the patellar ligament as it forms a bone to bone connection when ...

. * The ''deep plexus'', which forms a close net-work of vessels, lies on the lower end of the femur and upper end of the tibia around their articular surfaces, and sends numerous offsets into the interior of the joint. The

genicular arteries The genicular arteries (from Latin ''geniculum'', "knee") are six arteries in the human leg, five of which are branches of the popliteal artery, that anastomose in the knee region in the patellar network or ''genicular anastomosis''. They supply ...

which form this plexus are the medial inferior and medial superior genicular arteries, the lateral inferior and lateral superior genicular arteries, the

descending genicular artery The descending genicular artery (also known as the highest genicular artery) arises from the femoral artery just before its passage through the adductor hiatus. The descending geniculate artery immediately divides into two branches: a saphenous br ...

, the descending branch of lateral femoral circumflex artery, and the anterior tibial recurrent artery.

Clinical relevance

The genicular anastomosis provides collateral circulation to supply the leg when the knee is fully flexed. When the knee suffers a popliteal

aneurysm An aneurysm is an outward :wikt:bulge, bulging, likened to a bubble or balloon, caused by a localized, abnormal, weak spot on a blood vessel wall. Aneurysms may be a result of a hereditary condition or an acquired disease. Aneurysms can also b ...

, if the

femoral artery The femoral artery is a large artery in the thigh and the main arterial supply to the thigh and leg. The femoral artery gives off the deep femoral artery and descends along the anteromedial part of the thigh in the femoral triangle. It enters ...

has to be ligated surgically, blood can still reach the

popliteal artery The popliteal artery is a deeply placed continuation of the femoral artery opening in the distal portion of the adductor magnus muscle. It courses through the popliteal fossa and ends at the lower border of the popliteus muscle, where it branche ...

distal to the ligation via the genicular anastomosis. However, if flow in the

of a normal leg is suddenly disrupted, blood flow distally is rarely sufficient. The reason for this is the fact that the genicular anastomosis is only present in a minority of individuals and is always undeveloped when disease in the

is absent. Illustrations of the genicular anastomosis in textbooks all appear to have been derived from the idealized image, shown in the sidebox, produced first by

Gray's Anatomy ''Gray's Anatomy'' is a reference book of human anatomy written by Henry Gray, illustrated by Henry Vandyke Carter and first published in London in 1858. It has had multiple revised editions, and the current edition, the 42nd (October 2020 ...

in 1910. Neither the 1910 illustration, nor any subsequent version, was made of an anatomical dissection but rather from the writings of

John Hunter (surgeon) Sir John Hunter (13 February 1728 – 16 October 1793) was a Scottish people, Scottish surgery, surgeon, one of the most distinguished scientists and surgeons of his day. He was an early advocate of careful observation and scientific methods ...

and

Astley Cooper Sir Astley Paston Cooper, 1st Baronet (23 August 176812 February 1841) was a British surgeon and anatomist, who made contributions to otology, vascular surgery, the anatomy and pathology of the mammary glands and testicles, and the pathology ...

which described the genicular anastomosis many years after ligation of the

for popliteal

. The genicular anastomosis has not been demonstrated even with modern imaging techniques such as

X-ray computed tomography An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

angiography Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is perfo ...

References

External links

Definition of Genicular Anastomosis
at medilexicon.com {{Authority control Knee