Intra-articular ligaments
The cruciate ligaments (ligamenta cruciata genus) are located deep within the joint cavity and provide secure fixation between the femur and tibia.
This group includes two main structures:
- Anterior cruciate ligament (ligamentum cruciatum anterius). Originates from the inner surface of the lateral femoral condyle. From there, its fibers run downward and attach to the tibia in the region of the anterior intercondylar area (area intercondylaris anterior tibiae).
- Posterior cruciate ligament (ligamentum cruciatum posterius). Originates from the inner surface of the medial femoral condyle. Its fixation site is the posterior intercondylar area of the tibia (area intercondylaris posterior).
Structures of the posterior capsule
The posterior part of the fibrous capsule of the knee joint is reinforced by a robust complex of extra-articular ligaments and adjacent muscle tendons.
The lateral regions are supported by collateral ligaments: the tibial collateral ligament (ligamentum collaterale tibiale) is located medially, and the fibular collateral ligament (ligamentum collaterale fibulare) is located laterally.
The following ligaments and muscular elements are distinguished on the posterior surface of the joint:
| Structure | Latin name | Anatomical feature |
|---|---|---|
| Oblique popliteal ligament | Lig. popliteum obliquum | Is part of the semimembranosus tendon, weaving into the capsule |
| Arcuate popliteal ligament | Lig. popliteum arcuatum | Has its own retinaculum (retinaculum lig. arcuati) |
| Semimembranosus tendon | Tendo m. semimembranosi | Gives off fibers to form the oblique popliteal ligament |
| Adductor magnus tendon | Tendo m. adductoris magni | Participates in reinforcing the posterior complex |
In addition, the popliteus muscle (musculus popliteus), plantaris muscle (musculus plantaris), as well as the medial and lateral heads of the gastrocnemius muscle (caput mediale et laterale musculi gastrocnemii) are adjacent to the posterior surface of the capsule.
Relationship to the synovial membrane
The topography of the synovial membrane (membrana synovialis) is a key aspect for understanding the pathways of pathological processes in the joint.
Despite the fact that the cruciate ligaments are located inside the fibrous capsule, they lie partially outside the synovial membrane (extrasynovially).
The course of the synovial membrane follows strict patterns:
- The membrane passes from the femoral condyles onto the anterior surface of the cruciate ligaments.
- It tightly covers these ligaments only anteriorly and laterally.
- The posterior parts of the cruciate ligaments remain completely uncovered by the synovial membrane.
Clinical significance of topography
The complex spatial relationship between the synovial membrane and the cruciate ligaments creates unique anatomical conditions that play a crucial role in operative surgery and the treatment of purulent arthritis.
- Separation of compartments. The lateral and medial compartments of the knee joint are anatomically isolated from each other by synovial recesses.
- Division of the cavity. The cruciate ligaments themselves physically divide the general joint cavity into two isolated parts: anterior and posterior.
- Barrier function. Such a cellular, compartmental structure of the joint performs a vital protective function. It serves as a mechanical barrier that prevents the rapid penetration of pus from one part of the joint to another during acute inflammatory processes.
Briefly: answers to topical questions
To which bone structures does the arcuate popliteal ligament attach?
The arcuate popliteal ligament (lig. popliteum arcuatum / arcuate ligament) is part of the posterolateral corner complex of the knee joint. In the source, it is listed among the structures attaching to the head of the fibula. It also has a retinaculum (retinaculum lig. arcuati).
What intra-articular ligaments of the knee joint exist besides the cruciate ligaments?
Sources indicate the transverse ligament of the knee (lig. transversum genus). This is a fibrous band connecting the anterior horns of the menisci.
From which arteries do the cruciate ligaments of the knee joint receive their blood supply?
The cruciate ligaments of the knee joint receive blood supply from the middle genicular artery.
- Middle genicular artery (a. media genus) is an unpaired artery that branches off from the popliteal artery slightly inferior to the superior arteries.
It heads directly forward and branches within the cruciate ligaments, as well as in the posterior wall of the knee joint capsule.
Class and exam questions
Where do the cruciate ligaments originate and attach?
The anterior cruciate ligament runs from the inner surface of the lateral femoral condyle to the anterior intercondylar area of the tibia. The posterior ligament originates from the medial femoral condyle and attaches to the posterior intercondylar area.
How are the cruciate ligaments covered by the synovial membrane?
They lie within the capsule, but are partially extrasynovial: the synovial membrane covers them only anteriorly and laterally, leaving the posterior parts uncovered.
What is the barrier function of the ligamentous apparatus?
The ligaments and synovial recesses divide the joint cavity into anterior and posterior parts, and also separate the medial and lateral compartments. This prevents the rapid spread of pus in purulent arthritis.
Which ligaments reinforce the posterior part of the fibrous capsule?
The posterior capsule is reinforced by the oblique popliteal ligament (part of the semimembranosus tendon) and the arcuate popliteal ligament, which has its own retinaculum.
What else to study on this topic
- Anatomy of the knee collateral ligaments
- Connection of the semimembranosus tendon with the joint capsule
- Synovial recesses of the knee joint
- Pathways of pus spread in knee arthritis
- Retinaculum of the arcuate popliteal ligament
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