Myology Myology of the Knee

Distal Femur Anatomy: Medial and lateral condyles: rounded portions of distal femur that articulate with the proximal tibia Medial and lateral epicondyles: blunt projections from the sides of the condyles Adductor tubercle: small projection above the medial epicondyle Intercondylar fossa: deep depression between condyles, location of the cruciate ligaments Patellar surface: area for articulation with patella

Anatomical Review: Distal Femur

Patella Small triangular bone Sesamoid bone that develops in the tendon of the quadriceps muscle Patella functions to increase the leverage of the tendon of the quadriceps muscle, to maintain the position of the tendon when the knee is flexed, and protect the knee joint. Anatomy: Base: broad superior end of the patella Apex: point inferior end of patella Articular surface: on posterior side of patella are two articular facets for medial and lateral condyles of the femur

Anatomical Review: Patella

Tibia Known as the shin bone Located medially in the leg Anatomy: Medial and lateral condyles: bulging prominences on the proximal tibia, upper surfaces are concave for articulation with femoral condyles Intercondylar eminence: upward projection on articular surface between condyles; point of ligamentous attachment Tibial tuberosity: projection on anterior midline surface Tibial crest: sharp ridge on anterior surface Medial malleolus: rounded downward projection of distal end of tibia Fibular notch: depression on lateral tibial for articulation with the fibula

Fibula Located parallel and lateral to tibia Anatomy: Head: rounded portion located on the proximal fibula; articulates with the inferior portion of the lateral condyle of the tibia Lateral malleolus: rounded prominence at distal end of fibula, forms prominence on the lateral surface of ankle.

Anatomical Review: Tibia and Fibula

Articular Anatomy: Knee Largest joint in the body; a modified hinge joint made up of 3 joints: Intermediate patello-femoral joint: between patella and the patellar surface of the femur Lateral tibio-femoral joint: between lateral condyle of the femur, lateral meniscus, and lateral condyle of the tibia Medial tibio-femoral joint: between medial condyle of the femur, medial meniscus, and medial condyle of the tibia

(See slide #12 for diagram) Soft Tissue of the knee (See slide #12 for diagram) Articular Capsule: composed of fibrocartilage and expansions of muscle tendons Medial and lateral patellar Retinaculae: fused tendons of the quadriceps muscles and the TFL that strengthen the anterior surface of the joint. Patellar Ligament: continuation of the common tendon of the quadriceps muscle extending from the patella to the tibial tuberosity Medial (Tibial) collateral ligament: broad flat ligament on the medial surface of the knee joint extending from the medial femoral condyle to the medial tibial condyle Lateral (Fibular) collateral ligament: strong rounded ligament on the lateral surface of the knee joint extending from the lateral femoral condyle to the lateral aspect of the fibular head. Anterior cruciate ligament (ACL): Intracapsular ligament extending from the anterior aspect of the tibia to the posteromedial aspect of the lateral femoral condyle. Functions to limit forward movement of the tibia on the femur and hyperextension of the knee Posterior cruciate ligament (PCL): Intracapsular ligament extending from the posterior aspect of the tibia to the anterolateral aspect of the medial femoral condyle. Functions to limit backward movement of the tibia on the femur.

Soft Tissue of the knee (cont..) (See slide #12 for diagram) Medial and Lateral Menisci: fibrocartilage discs located between the femoral and tibial condyles. They help to compensate for the irregular shape of the bones. Bursae: Prepatellar bursa: located between the patella and the skin; allows free movement of the skin over the patella Suprapatellar bursa: located between the inferior aspect of the femur surface and the quadriceps muscle; allows free movement of the quadriceps tendon over the femur. Deep infrapatellar bursa: located between the patellar tendon and the tibial tuberosity.

Knee Ranges of Motion Each student should be able to describe and demonstrate the following movements: Knee flexion Knee extension Knee medial Rotation Knee lateral Rotation Note: Rotation of the knee can only be performed when the knee joint is in the flexed position.

Palpation of the knee Patella: Supine, with the knee extended. Locate the patella on the anterior knee and palpate its round Surface and edges. Gently shift the patella up and down and then side to side (remember the patella is the largest sesamoid bone in the body). Tibial tuberosity: Seated, again locate the patella and then slide your finger three to four inches inferiorly. You will feel a large tuberosity which serves at the attachment of the quadriceps group. Tibial shaft: from the tibial tuberosity continue down and palpate the shaft of the tibia. The shaft the tibia can be palpated down to the medial malleolus. Head of the Fibula: Seated, locate the tibial tuberosity and then move your fingers laterally three to four inches (toward the outside of the leg). The fibular head is slightly below the lateral tibial condyle. Note the wide tip of the fibular head. Pes Anserine attachment site: Pes anserine is the common insertion of the sartorius, gracilis, and semitendinosis tendons on the superior medial aspect of the knee. Have your partner seated with the knee flexed. Locate the tibial tuberosity and slide medially one inch and explore the flat surface of the pes anserine and any palpable tendons coming into it.

Palpation of the knee (cont.) Femoral condyles: Supine with the knee fully extended. Locate the patella and shift it medially onto the medial condyle. Palpate the edge of the lateral femoral condyle which is now exposed. Epicondyles of the Femur: Supine, with the knee flexed. Locate the patella and then slide directly lateral from the patella to the outside of the knee (be sure to be proximal to the head of the fibula). This is the lateral epicondyle. Return to the patella and then slide to the medial epicondyle on the inside of the knee Adductor tubercle: Supine with the knee flexed. Find the medial epicondyle and slide superiorly along the medial side of the femur. As the outline of the femur drops off into soft tissue, explore for the small point of the tubercle.

Muscles that move the knee Sartorius Rectus Femoris Vastus Lateralis Quadriceps Vastus Medialis Group Vastus Intermedius Biceps Femoris Semitendinosus Hamstring Group Semimembranosus

Sartorius O: ASIS I: Pes Anserine (proximal anteromedial aspect of the tibia A: Hip: Flexion, lateral rotation, and abduction of the thigh. Knee: Flexion and medial rotation of the leg. Pelvis: Anteriorly tilts the pelvis N: Femoral nerve Pes Anserine: common insertion of the Sartorius, Semitendinosus, and Gracilis

Rectus Femoris O: AIIS and superior brim of the acetabulum I: Tibial tuberosity via the patellar ligament A: Flexion of the femur and extension of the knee. **Reversed muscle action results in anterior tilting of the pelvis N: Femoral nerve

Vastus Lateralis O: Posterior aspect of the mid-shaft of the femur (linea aspera) I: Tibial tuberosity via the patellar ligament A: Extension of the knee N: Femoral nerve

Vastus Medialis O: Posterior aspect of the mid-shaft of the femur (linea aspera) I: Tibial tuberosity via the patellar ligament A: Extension of the knee N: Femoral nerve

Vastus Intermedius O: Anterior shaft and the linea aspera I: Tibial tuberosity via the patellar ligament A: Extension of the knee N: Femoral nerve

Biceps Femoris O: Long Head: Ischial tuberosity Short Head: Linea aspera I: Fibular head and lateral tibial condyle A: Hip: Extends, laterally rotates, and adducts (long head) the thigh Knee: Flexion and lateral rotation of the leg when the knee is flexed **Reversed muscle action results in a posterior tilt of the pelvis. N: Sciatic nerve

Semitendinosus O: Ischial tuberosity I: Pes anserine (proximal anteromedial aspect of the tibia A: Hip: Extension and medial rotation of the thigh Knee: Flexion and medial rotation of the leg when the knee is flexed. **Reversed muscle action results in a posterior tilt of the pelvis. N: Sciatic nerve

Semimembranosus O: Ischial tuberosity I: Medial tibial condyle A: Hip: Extension and medial rotation of the thigh Knee: Flexion and medial rotation of the leg when the knee is flexed. **Reversed muscle action results in a posterior tilt of the pelvis. N: Sciatic nerve