2 functional components: Pelvic girdle & bones of the free lower limb Body weight is transferred Vertebral column (Sacroiliac joints) Pelvic girdle (Hip joints) Femurs Femurs (L. femora)

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. HIP JOINT Iliofemoral ligament [body's strongest ligament] Y Iliofemoral ligament [body's strongest ligament] Y anterior inferior iliac spine & acetabular rim proximally & intertrochanteric line distally prevents hyperextension of the hip joint during standing by screwing the femoral head into the acetabulum Pubofemoral ligament Pubofemoral ligament arises from the obturator crest of the pubic bone prevents overabduction of the hip joint Ischiofemoral ligament [weakest of the three] Ischiofemoral ligament [weakest of the three] arises from the ischial part of the acetabular rim spirals around the femoral neck, medial to the base of the greater trochanter

. Ligament of the head of the femur  a synovial fold conducting a blood vessel.  weak and of little importance in strengthening the hip joint.  attaches to the margins of the acetabular notch & fovea for the ligament of the head.

. iliofemoral ligament During extension of the hip joint, the fibrous layer of the joint capsule, especially the iliofemoral ligament, is tense; therefore, the hip can usually be extended only slightly beyond the vertical except by movement of the bony pelvis (flexion of lumbar vertebrae). From the anatomical position, the range of abduction of the hip joint is usually greater than for adduction. About 60° of abduction is possible when the thigh is extended, and more when it is flexed. Lateral rotation is much more powerful than medial rotation. MOVEMENTS OF THE HIP JOINT

. Patellar ligament Patellar ligament patella to the tibial tuberosity. Collateral ligaments of the knee stabilize the hinge-like motion of the knee. tense when the knee is fully extended, contributing to stability while standing. As flexion proceeds, increasingly loose, permitting and limiting (serving as check ligaments for) rotation at the knee. Fibular collateral ligament from lateral epicondyle of femur to lateral surface of the fibular head Tibial collateral ligament from medial epicondyle of femur to medial condyle & superior part of medial surface of tibia weaker than the FCL, is more often damaged. As a result, the TCL and medial meniscus are commonly torn during contact sports such as football.

. Oblique popliteal ligament arises posterior to medial tibial condyle and passes superolaterally toward lateral femoral condyle. Arcuate popliteal ligament arises from posterior aspect of fibular head, and spreads over the posterior surface of the knee joint. strengthens the joint capsule posterolaterally.

. Intracapsular (internal) ligaments of the knee joint 1.1. Anterior cruciate ligament (ACL) weaker of the two cruciate ligaments. from anterior intercondylar area of tibia to medial side of the lateral condyle of the femur. 1.limits posterior rolling (turning and traveling) of the femoral condyles on the tibial plateau during flexion. 2.prevents posterior displacement of the femur on the tibia 3.prevents hyperextension of the knee joint.

. Intracapsular (internal) ligaments of the knee joint 1.2. Posterior cruciate ligament (PCL) stronger of the two cruciate ligaments. from posterior intercondylar area of the tibia to lateral surface of medial condyle of femur 1.limits anterior rolling of the femur on the tibial plateau during extension. 2.prevents anterior displacement of the femur on the tibia 3.prevents posterior displacement of the tibia on the femur 4.helps prevent hyperflexion of the knee joint. In the weight-bearing flexed knee, the PCL is the main stabilizing factor for the femur (e.g., when walking downhill).

. Intracapsular (internal) ligaments of the knee joint 2.1. Medial meniscus 2.1. Medial meniscus is C shaped, anterior end (horn) is attached to the anterior intercondylar area of the tibia, anterior to the attachment of the ACL. posterior end is attached to the posterior intercondylar area, anterior to the attachment of the PCL. Because of its widespread attachments laterally to the tibial intercondylar area and medially to the TCL, the medial meniscus is less mobile on the tibial plateau than is the lateral meniscus Lateral meniscus 2.2. Lateral meniscus is nearly circular, smaller, and more freely movable than the medial meniscus.

. The stability of the knee joint depends on: (1) the strength and actions of the surrounding muscles and their tendons (2) the ligaments that connect the femur and tibia. The erect, extended position is the most stable position of the knee.

JOINT TYPE MOVEMENT Hip Hip Ball and socket flexion-extension, abduction- adduction, medial-lateral rotation, and circumduction Knee Knee Hingeflexion-extension combined with gliding and rolling and with rotation about a vertical axis Superior tibiofibular Planeslight movement during dorsiflexion Inferior tibiofibular SYNDESMOSIS Ankle Ankle Hingedorsiflexion and plantarflexion

Iliofemoral ligament Ischiofemoral ligament Ligament of the head of the femur Pubofemoral ligament Extracapsular (external) ligaments Patellar ligament Fibular collateral ligament (lateral collateral ligament) Tibial collateral ligament (medial collateral ligament) Oblique popliteal ligament Arcuate popliteal ligament Intracapsular (internal) ligaments Anterior and posterior cruciate ligaments Lateral and medial menisci Anterior and posterior ligaments of the fibular head Hip joint Knee joint Superior tibiofibular joint Anterior talofibular ligament Posterior talofibular ligament Calcaneofibular ligament Ankle joint