The articular capsule of the knee joint (commonly referred to as the capsular ligament) is the wide and lax joint capsule of the

knee 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 ...

. It is thin in front and at the side, and contains the

patella The patella, 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 many tetrapods, such as ...

ligament A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal l ...

s, menisci, and bursae of the knee.Platzer (2004), p 206 The capsule consists of an inner

synovial membrane The synovial membrane (also known as the synovial stratum, synovium or stratum synoviale) is a specialized connective tissue that lines the inner surface of capsules of synovial joints and tendon sheath. It makes direct contact with the fibrous ...

, and an outer fibrous membrane separated by fatty deposits anteriorly and posteriorly.Platzer (2004), p 210

Synovial membrane

Anteriorly, the reflection of the synovial membrane lies on the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates ...

; located at some distance from the cartilage because of the presence of the suprapatellar bursa. Above, the reflection appears lifted from the bone by underlying periosteal

connective tissue Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...

. In a standing posture, the suprapatellar bursa is seemingly redundant. It is however also referred to as the ''suprapatellar synovial recess'' as it gradually unfolds as the knee is flexed; to open up completely when the knee is flexed 130 degrees.''Thieme Atlas of Anatomy'', pp 400-401 The suprapatellar bursa is prevented from being pinched during extension by the articularis genus muscle. On the

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

, the anterior reflection and attachment of the synovial membrane is located near the cartilage. Anteriorly, the infrapatellar fat pad is inserted below the patella and between the two membranes. It extends from the lower margin of the patella above, to the infrapatellar synovial fold below. With its free upper margin, this fold extends dorsally through the joint space to surround the two cruciate ligaments from the front, thus dividing the surrounding joint space into two chambers. Laterally of this are a pair of alar folds. Posteriorly, the femoral attachment of the synovial membrane is located at the cartilaginous margin of the

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction * Lateral cricoarytenoid muscle * Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

and medial femoral condyles, where the joint space has two dorsal extensions. Between these, the synovial membrane passes in front of the

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...

and posterior cruciate ligaments, why these ligaments are both intracapsular and extra-articular with their tibial attachment located exactly on the cartilage margin. Both the

and medial meniscus are, however, located within the synovial capsule.

Fibrous membrane

It is a thin, but strong, fibrous membrane which is strengthened in almost its entire extent by bands inseparably connected with it. Above and in front, beneath the tendon of the Quadriceps femoris, it is represented only by the synovial membrane. Its chief strengthening bands are derived from the

fascia lata The fascia lata is the deep fascia of the thigh. It encloses the thigh muscles and forms the outer limit of the fascial compartments of thigh, which are internally separated by the medial intermuscular septum and the lateral intermuscular sep ...

and from the

tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

s surrounding the joint.

Bursae

The numerous bursae surrounding the knee joint can be divided into the ''communicating'' and the ''non-communicating'' bursae: * Communicating bursae: ** The suprapatellar bursa, the largest bursa, extends the joint space anteriorly and proximally. ** The subpopliteal recess and

semimembranosus bursa The semimembranosus muscle () is the most medial of the three hamstring muscles in the thigh. It is so named because it has a flat tendon of origin. It lies posteromedially in the thigh, deep to the semitendinosus muscle. It extends the hip jo ...

are located posteriorly and are much smaller ** The

and medial subtendinous bursae of gastrocnemius are located at the origin of the two heads of the

gastrocnemius muscle The gastrocnemius muscle (plural ''gastrocnemii'') is a superficial two-headed muscle that is in the back part of the lower leg of humans. It runs from its two heads just above the knee to the heel, a three joint muscle (knee, ankle and subtalar ...

. * Non-communicating bursae: ** The

subcutaneous prepatellar bursa The prepatellar bursa is a frontal bursa of the knee joint. It is a superficial bursa with a thin synovial lining located between the skin and the patella. Pathology Prepatellar bursitis, also known as housemaid's knee, is a common cause of s ...

is located in front of the patella. ** The eep infrapatellar bursa is located under the patella, between the patellar ligament and the fibrous membrane of the joint capsule. It is communicating with the joint space in particular cases. ** Other less regularly present bursae include the subfascial prepatellar, the subtendinous prepatellar, and the

e. Adding to the complex structure of the knee space, there are remnants of three embryonic septal divisions of the knee space called synovial plicae:Burgener (2002), p 390 * The ''suprapatellar plica'' dividing the suprapatellar recess * The ''infrapatellar plica'', in front of the

anterior cruciate ligament The anterior cruciate ligament (ACL) is one of a pair of cruciate ligaments (the other being the posterior cruciate ligament) in the human knee. The two ligaments are also called "cruciform" ligaments, as they are arranged in a crossed formati ...

, reaches from the intercondylar notch to the infrapatellar fat pad * The ''medial patellar plica'', located adjacent to the patella's medial facet, runs vertically along the medial joint capsule

Additional images

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Notes

References

* * *

External links

*
knee/ligaments/ligamen2
at the

Dartmouth Medical School The Geisel School of Medicine at Dartmouth is the graduate medical school of Dartmouth College in Hanover, New Hampshire. The fourth oldest medical school in the United States, it was founded in 1797 by New England physician Nathan Smith. It is o ...

's Department of Anatomy {{Joints of lower limbs Animal anatomy Knee