Knee anatomy: bones and ligaments

what are the 2 bundles of the ACL?

Anteromedial bundle Posterolateral bundle

what is the Anteromedial bundle ?

Attachment of tibia Is more anterior and medial Tight when knee is flexed

what is the bursae of the patella?

Burse= fluid sac that reduces friction Patellar bursae occur at 3 different locations: o Prepatellar o Suprapatellar o Infrapatellar

what is the medial and lateral patellar retinacula?

fused tendons of insertion of the quadriceps femoris muscle and fascia of thigh. Strengthens anterior surface of the knee joint

what are the 2 menisci at the knee joint?

medial and lateral menisci

what are the 2 main knee joints ?

1. Patellofemoral joint = Gliding joint between patella and femur 2. Tibiofemoral joint = Hinge joint rotates in the sagittal pane causing flexion/extension

what is the Posterolateral bundle?

Attachment of tibia is more posterior lateral Tight when knee is extended

what is a condyle?

Condyle = large prominence of bone forming part of a joint with another bone. Condyles form tibial part of knee joint.

what is the fibula?

The fibula is the thinner and more lateral of the two bones of the leg

what is the leg supported by and where do they articulate?

The leg is supported by the tibia and fibula. The tibia articulates with the femur at the knee joint and distally the tibia and fibula articulate with the talus at the ankle joint.

what s the patella?

The patella is the largest sesamoid bone in the body. It is embedded in the tendon of quadriceps femoris muscle, and is located anterior to the knee joint.

what is the tibia?

The tibia is the thicker and more medial of the two bones of the leg.

what is the patellar ligament?

continuation of tendon of insertion on quadriceps femoris muscle that extends from the patella to the tibial tuberosity. It strengthens anterior surface of knee joint. Posterior surface of ligament Is separated from the synovial membrane of joint by an infrapatellar fat pad

what is the Oblique popliteal ligament?

extends from intercondylar fossa and lateral condyle of the femur to the head and medial condyle of the tibia. Strengthens the posterior surface of the joint

What are the intracapsular ligaments?

ligaments within the capsule connecting tibia and femur. The anterior and posterior cruciate ligaments named based off their origins relative to intercodylar area of tibia. From origins, they cross on their way to their insertions on femur

what is the articular cartilage?

no complete, independent capsule unites the bones of the knee joint. The ligamentous sheath surrounding joint consists mostly of muscle tendons and their expansions

what is the meniscus at the knee joint?

2 fibrocartilage discs between tibial and femoral condyles help compensate for irregular shapes of bones and circulate synovial fluid - Crescent shaped cartilage tissues - Sits between articular surfaces of tibia and femur - Separated into medial and lateral menisci - Disperses pressure from body weight across the joint - Increases contact area decreasing wear and tear - Adds to the structural integrity of the knee

what are the features of the tibia?

Anterior border -Located on the front of the tibial shaft, it is commonly referred to as the 'shin bone'. Intercondylar eminence - A raised area in the central part of the intercondylar area of the tibial plateau. Lateral condyle - A prominent, proximal, and lateral mass that articulates with the femur. Medial condyle - A prominent, proximal, and medial mass that articulates with the femur. Medial malleolus - A thick process formed by the distal, expanded medial end of the tibia. Tuberosity - A bony prominence on the anterior aspect of the upper end of the tibial shaft for the insertion of the patellar ligament.

what are the ligaments at the knee joint?

Anterior cruciate ligament (ACL) Posterior cruciate ligament (PCL) Medial collateral ligament (MCL) Lateral collateral ligament (LCL)

what are the features fo the patella?

Apex= pointed inferiorly Articular facets= the posterior aspect of the patella is covered with articular cartilage for articulation with the medial and lateral femoral condyles. The medial aspect of the posterior surface only comes into contact with the femur during extreme flexion of the knee.

what is the Lateral collateral ligament (LCL)?

Attaches from lateral femoral epicondyle to the head of the femur Primarily resists Varus forces (acting to push knee laterally). Strengthens lateral aspect of joint. Ligament is covered by tendon of biceps femoris.

what is the Medial collateral ligament (MCL)?

Attaches from proximal to the medial femoral epicondyle to distal to medial tibial condyle Primarily resists valgus forces (acting to push knee medially). Tendons of Sartorius, gracilis and semitendinosus muscles, all of which strengthen the medial aspect of the joint, cross the ligament. Firmly attached to the medial meniscus

how are the anterior surfaces of medial and lateral menisci connected?

Connected by the transverse ligament the knee and to margins of head of tibia by the coronary ligaments.

what is the Posterior cruciate ligament (PCL)?

Extends anteriorly and medially from a depression on posterior intercondylar area to tibia and lateral meniscus to anterior, lateral surface of medial condyle of femur. Prevents posterior sliding of tibia when knee is flexed

what is the Anterior cruciate ligament (ACL)?

Extends posteriorly and laterally from a point anterior to intercondylar area of tibia to posterior, medial surface of lateral condyle of femur. It limits hyperextension of knee and prevents anterior sliding of tibia on femur. Helps stabilise joint, particularly resisting anterior translation of the tibia.

what are the features of the fibula?

Head - The expanded proximal end that articulates with the lateral condyle of the tibia. Styloid process - an upward projection of the head Lateral malleolus - The distal, expanded and somewhat flattened end, articulating with the talus bone of the ankle.

what occurs at the patellofemoral joint?

It articulates with the trochlear groove of the femur and increases the leverage of the quadriceps muscles at the knee

What are the 2 collateral ligaments?

Medial collateral ligament (MCL) Lateral collateral ligament (LCL)

how does the patellofemoral joint aid patella & quadriceps leverage?

Muscles generated a pulling force to rotate bones. By increasing the distance between the line of pull and the point of rotation, the effect of that force is increased. The patella increases the distance (lever arm) of the quads tendon to the knee.

what is the lateral meniscus?

Nearly circular piece of fibrocartilage. Anterior end attached anteriorly to intercondylar eminence of tibia and laterally and posteriorly to the ACL. Posterior end attaches posteriorly to intercondylar eminence of tibia and anteriorly to posterior end of medial meniscus.

what happens at the proximal and distal ends of the fibula?

Proximal end of fibula = Fibula head forming a joint with proximal end of the tibia - proximal tibiofibular joint Distal end of fibula = reach lateral malleolus = bony prominence ALSO have distal tibiofibular joint.

name the 3 joints between the tibia and fibula and where do they occur?

Proximal tibiofibular joint: • Between lateral tibial condyle and fibula head Distal tibiofibular • Between fibular notch and medial surface of fibula Interosseous membrane • forms a fibrous joint and separates the anterior and posterior compartments

what is the medial meniscus?

Semi-circular piece of fibrocartilage = c shaped. Its anterior end attached to anterior intercondylar fossa of tibia, anterior to ACL. Posterior end attached to posterior intercondylar fossa of tibia between attachments of PCL and lateral meniscus.

what is the Arcuate popliteal ligament?

extends from later condyle of femur to styloid process of head of fibula. Strengthens lower lateral part of the posterior surface of the joint

what are the motions available at the knee?

flexion, extension, internal and external rotation

what is the tibiofemoral joint?

hinge joint between lateral condyle of the femur, lateral meniscus and lateral condyle of the tibia Allows flexion and extension at the knee joint **Very important attachment site for quadriceps muscle

in-between the tibia and fibula, what runs down the length of it?

interosseous membrane