To describe he knee joint, ligaments, structure & neurovascular supply To demonstrate the ankle joint anatomy To list the main features of other lower limb joints To list main groups of lymph nodes in the LL
The knee joint: This is the largest synovial joint in the body. It consists of: 1- The weight bearing tibio-femoral articulation. 2- The patello-femoral articulation which directs the pull of quadriceps tendon anteiorly on the tibia without tendon wear.
General characteristics: Basically the joint is a hinge joint that allows mainly flexion - extension movement, though the actual movements are more complex. Like all hinge joints, the knee joint is reinforced by two collateral ligaments. In addition, two very strong ligaments (the cruciate ligaments) interconnect the adjacent ends of the femur and tibia and maintain their opposition during movement
Two fibrocartilaginous menisci, between the femoral condyles and tibia accommodate changes in the shape of the articular surfaces during movements. Because the knee joint is involved in weight bearing, it has an efficient 'locking' mechanism to reduce the amount of muscle energy required to keep the joint extended when standing.
Articular surfaces: -Like all synovial joints, articular surfaces are covered by hyaline cartilage. -The major surfaces involved include: 1- Tibio-femoral articulation: A-The two femoral condyles; - The medial is longer, narrower & more concave - The lateral is more anteriorly projecting. B-The superior aspect of the tibial condyles.
2- Patello-femoral articulation: A-The patellar surface of the femur. B- Posterior surface of the patella, the lateral aspect is wider than the medial
Locking mechanism (screw-home movement): -When standing, the knee joint is 'locked' into position to reduce the amount of muscle work needed to maintain the standing position Iliotibial tract keeps this etended position
-This locking is provided by the element of medial rotation that accompanies extension during standing i.e; because of the shorter LFC it will stop moving before the MFC which will still rotating on the tibia till full locking of the joint occurs. Popliteus muscle unlocks the knee by initiating lateral rotation of the femur on the tibia
Don t be confused! The LFC in this view looks longer than the medial but this is because this is the full length of the articular surface of the LFC while there is more posterior articular surface is remaining for MFC for the locking mechanism
Fibrous membrane: -The fibrous capsule encloses the articular cavity and the intercondylar region. -Medially blends with the tibial collateral ligament and is attached to the medial meniscus. -Laterally it neither blends with fibular collateral ligament nor attached to the lateral meniscus
-Anteriorly, the capsule is attached to the margins of the patella -Popliteus tendon pierces the capsule to insert on the lateral femoral condyle. -Muscles contributing to the capsule are: 1- Vasti medialis & lateralis (patellar retinacula) 2- Semimembranosus (oblique popliteal ligament)
Synovial membrane: -This membrane attaches to the margins of the articular surfaces & to the outer margins of the menisci - The two cruciate ligaments, though within the capsule, they lie outside the articular cavity. -Anteriorly, the synovial membrane is separated from the patellar ligament by an infrapatellar fat pad.
Knee joint bursae: 1- Subpopliteus bursa; between popliteus tendon & lateral femoral condyle. 2- Suprapatellar bursa: between quadriceps tendon & the front of femoral haft. 3- Subcutaneous prepatellar bursa. 4- Deep and subcutaneous infra-patellar bursae 5- Semimembranosus bursa
Ligaments: 1- The patellar ligament: Is basically the continuation of the quadriceps femoris tendon inferior to the patella. 2- Fibular collateral L: a cord-like L attached superiorly to the lateral femoral epicondyle & Inferiorly to the lateral surface of the fibular head, it is NOT attached to the capsule 3-The tibial collateral L: a broad L extends between the medial femoral epicondyle & medial surface of the tibia, it is ATTACHED to the capsule
4- The cruciate ligaments: -The Anterior CL extends between the anterior part of the intercondylar area of the tibia & the lateral wall of the intercondylar fossa of the femur -The anterior cruciate ligament prevents anterior displacement of the tibia relative to the femur -Supplied by the middle genicular artery
-The Posterior CL extends between the posterior aspect of the intercondylar area of the tibia & the medial wall of the intercondylar fossa of the femur. -It restricts posterior displacement of tibia relative to femur -Supplied by the middle genicular artery
The menisci: -These are C-shaped, medial & lateral fibrocartilaginous structures -MM is semilunar while LL is almost circular - Both are attached at each end to the intercondylar region of the tibial plateau -Both are connected to each other anteriorly by the transverse ligament of the knee -Their function is to improve congruency between articular surfaces during movements MM ACL LM MM LM MM LM PCL
-MM is more liable to injury because it is fixed & can t be taken away from the moving femoral condyles -LM is less liable to injury because it is more mobile -Factors which predispose to mobility of the LM are: 1- No attachment to knee capsule 2- Attachment to popliteus which draws it back. 3- The posteriorly sloping lateral tibial condyle.
Vascular supply (anastomosis around the knee): Ten arteries share in the formation of this anastomosis which supplies the knee joint & surrounding structures: 1) The genicular arteries 2) Descending branch of LFCA 3) Descending genicular artery 4) Fourth perforator artery 5) Anterior & posterior tibial recurrents 6) Circumflex fibular artery -The knee joint is innervated by branches from the obturator, femoral, tibial, and common fibular nerves.
Movements: - Extension: Quadriceps femoris - Flexion: Hamstrings, gracilis, sartorius and popliteus. - Lateral rotation: Biceps femoris. - Medial rotation: semimembranosus, semitendinosus, gracilis, sartorius and popliteus. Lateral and medial rotation can only occur when the knee is flexed (if the knee is not flexed, the medial/lateral rotation occurs at the hip joint).
Proximal TF joint: - An arthrodial (synovial) plane joint between the lateral condyle of the tibia and the head of the fibula. - The contiguous surfaces of the bones present flat, oval facets covered with cartilage and connected together by an articular capsule and by anterior and posterior ligaments.
Ankle joint: 1- Ankle proper (Mortise joint, Talocrural joint) 2- Inferior tibiofibular 3- Subtalar
The ankle joint proper: -The anchored distal ends of the fibula & tibia create a deep bracket-shaped socket for the upper expanded part of the body of the talus -The roof of the socket is formed by the inferior surface of the distal end of the tibia -Medial & lateral sides are formed by the corresponding malleoli -The ankle joint is a hinge-like synovial joint which involves the talus of the foot and the tibia and fibula of the leg -It mainly allows dorsiflexion & plantarflexion
-When viewed from above, the articular surface of the talus is much wider anteriorly than it is posteriorly. -As a result, the bone fits tighter into its socket when the foot is dorsiflexed & therefore most stable in this position. -The articular cavity is enclosed by a synovial membrane, which attaches around the margins of the articular surfaces & reflects on the inside of the capsule.
Medial (deltoid) ligament: -A large, strong & triangular in shape. Its apex is attached to the medial malleolus and its broad base is attached below. Lateral ligament: - The lateral ligament of the ankle is composed of three separate ligaments, anterior talofibular, posterior talofibular & calcaneofibular ligaments.
Subtalar joint: The talus is oriented slightly obliquely on the anterior surface of the calcaneus. There are two points of articulation between the two bones, anterior & posterior In both, the concavity on talus receives a convexity of calcaneus 4 talocalcaneal ligaments support the joint It is involved in inversion-eversion movement
Tibiofibular joints: Distal TF joint: - Syndesmotic (fibrous) plane joint - Formed by the rough, convex surface of the medial side of the distal fibula with the rough concave surface on the lateral side of the tibia. - These surfaces are smooth, and covered with cartilage continuous with that of the ankle-joint. - The ligaments are: Anterior ligament of the lateral malleolus Posterior ligament of the lateral malleolus Interosseous membrane of leg
Lymphatic drainage of the lower limb: -Superficial lymphatics drain everything superficial to deep fascia & accompany veins -Deep lymphatics drain deeper structures & accompany arteries
Superficial LN: -The vertical group of superficial inguinal LN drains the lower limb & are arranged around the termination of great saphenous vein (vs deltopectoral) -Popliteal LN drain the heel, lateral leg & foor & arranged around the termination of small saphenous vein (vs supratrochlear) Deep LN: Deep inguinal node lies in the femoral canal (vs axillary)
Superficial lymphatics Accompany veins Deep lymphatics Accompany arteries Internal iliac LN From gluteal region Along G saphenous v. Structures superficial to fascia lata except lateral foot, heel & back of leg From lateral foot, heel & back of leg External iliac LN SILN Vertical group Superficial Pop. LN DILN Deep Pop. LN Along gluteal arteries From deep structures of the lower limb Along S saphenous v.