Anatomy of the Knee Bony Structures Quad muscles - Tibia: proximal end forms tibial plateaus, tibial plateaus, articulates with Tendon femoral condyles. o Knee hinge joint flexion/extension Patellar tendon o Tibial plateaus separated by intercodylar tubercles . Medial and lateral tubercle Tibial tuberosity Lateral tibial plateau is smaller compare to medial . Tibial plateaus slope posteriorly o Cruciate ligaments and meniscus attach anterior and posterior to tubercles Fibular head o Distal to plateaus is tibial tuberosity . Common insertion for patellar tendon Lateral condyle o Distal and anterior to plateaus are lateral and medial condyles . Lateral condyle has facet that articulates with head of fibula IT Band Facet = extremely smooth surface of bone o Medial to lateral condyle is Gerdys tubercle o GERDYS tubercle – point of muscular attachment - Femur: medial/lateral condyle o Medial condyle is longer than lateral and slightly more distal o Slight external rotation at terminal (full) extension o Femoral condyles project more posterior than they do anterior o Groove between condyles, anteriorly is trochlear or patello- femoral groove o Posteriorly the condyles are separated by intercodylar notch (fossa) . Notch more narrow in women o Linea aspera: longitudinal ridge on posterior surface of femur (rough line) o Medial and lateral super condylar lines: lines running from each femoral condyle posteriorly to the linea aspera o Femur is longest and strongest bone o Directly superior to condyle is epicondyle (epi – above) o On medial side of medial epicondyle is adductor tubercle . Serves as point of attachment for adductor magnus muscle o Small groove present within medial and lateral condyle to accommodate the medial and lateral meniscus (very shallow) - Patella o Largest Sesamoid bone in body o Rounded, triangular bond and has only one articulation with femur o Can only dislocated laterally o Posterior surface has 3 facets . Odd . Medial articulateon trochlear groove . Lateral o As flexion increases in knee, contact with patella moves proximal . Contact beign and 10-20o flexion, distal contact . Full extension is 0o . 45 of flexion, contact in middle . 60 flexion, superior aspect . 90-135 flexion, odd facet contacts platello-femoral groove - Fibula does not have direct articulation with knee and is a non weight baring bone o Serves for ligamentous and muscular attachment Joints/Articulations of Knee - Tibio/femoral : femoral condyles sit on plateaus - Patello-femoral - Superior tibiofibular Nervous Innervation - Sciatic nerve provides most of motor and sensory innervation to lower extremity o Comes off of lumbrosacral plexus o Splits into common peroneal and tibial nerves at proximal popliteal space . Tibial pierces gastrocnemius muscles . Common peroneal wraps around fibular head o Branch of tibial nerve is known as surreal nerve . Innervation to skin of posterior lower leg and lateral foot o Common peroneal innervates knee and short head of biceps femoris muscle o Tibial also innervates knee and muscles of posterior lower leg . Tibial nerve is much larger than peroneal Hamstrings – posterior thigh - Biceps Femoris o Origin of long head: ischial tuberosity o Origin of short head: linea aspera and proximal 2/3 of lateral supercodylar line o Insertion: head of fibular, lateral condyle of tibia, deep fascia on lateral lower leg o Action: flexes knee, extends hip, externally rotates lower leg/hip . Short head does not extend hip or thigh o Nerve to long head: sciatic, tibial branch o Nerve to short head: peroneal branch o Artery: profunda femoris and popliteal - Semitendinosus o Origin: tendon of biceps femoris, ischial tuberosity o Insertion: upper anterior of medial tibial condyle (pes anserine) o Action: flexes knee/lower leg, extends hip, internal rotation of hip and lower leg o Nerve: tibial branch of sciatic o Artery: profunda femoris and popliteal o Pes anserine (not bony structure, tendon) insertion is common insertion for the semitendinosus, gracillis and Sartorius - Semimembranosus o Origin: ischial tuberosity o Insertion: posterior surface of medial condyle of tibia o Action: flexion of knee/lower leg, extension of thigh/hip, internal rotation of hip/lower leg o Nerve: tibial branch of sciatic o Artery: profunda femoris and popliteal (provide to all hamstrings) Vascular structures - Popliteal artery branches off of the femoral o Femoral runs through the adductor magnus m. - Lateral to the popliteal artery is the popliteal vein and lateral to the vein is the tibial nerve. - Popliteal braches off to form five different arteries in the knee: o Superior medial genicular: distal femur, knee joint, patella o Superior lateral genicular: distal femur, knee joint, patella o Inferior medial genicular: knee and proximal tibia o Inferior lateral genicular: knee joint and gastrocnemius o Middle genicular: ligaments of the knee and synovial membrane - Popliteal branches off then to form the anterior and posterior tibial arteries Synovium - Synovial membrane lines the joint cavity of the knee o Secretes synovial fluid for joint lubrication - Lubricates articular hyaline cartilage of bone ends o Creates smoother movements/motion within the knee - Knee is largest synovial joint in the body o Contains less than 1 ml of fluid (1 ml = to 1/3 oz) o Synovium however can expand to hold 80 ml of fluid - Synovial capsule is 2 finger widths superior to the patella, and posteriorly to the origin of the gastrocs o Lateral to the LCL and medially to the MCL - Synovial membrane is the innermost layer of the joint that houses the synovial fluid External Ligaments of the Knee - Lateral (fibular) collateral ligament(LCL) o Lateral epicondyle of the femur to the head of the fibula o Major lateral stabilizer of the knee o 2” long and rounded cord like structure o Easy to palpate o Directly under the tendon of the biceps femoris near the fibular attachment o Lateral side of the femoral condyle, LCL attachment is located between the gastroc and the popliteus o Rarely injured because it is protected by opposite extremity - Medial (tibial) collateral ligament (MCL) o Medial epicondyle of the femur to the medial condyle of tibia.