Knee Extension PDF

# 22^th lecture. Theoretical Part: Knee Extension ## Objectives: At the end of this lecture the student will be able to: 1. Identify the primary muscles involved in knee extension. 2. Identify the range of motion of knee extension. 3. Describe effect of weakness of knee extension. 4. Des...

# 22^th lecture. Theoretical Part: Knee Extension ## Objectives: At the end of this lecture the student will be able to: 1. Identify the primary muscles involved in knee extension. 2. Identify the range of motion of knee extension. 3. Describe effect of weakness of knee extension. 4. Describe effect of contracture of knee extension. ## Content: 1. Primary muscles involved in knee extension. 2. Range of motion of knee extension. 3. Effect of weakness of knee extension. 4. Effect of contracture of knee extension. ## Knee Extension ### Primary Muscles: #### Quadriceps: * **a.** *Rectus femoris*. * **b.** *Vastus lateralis*. * **c.** *Vastus intermedius*. * **d.** *Vastus medialis*. ### Range of Motion: - The range of motion of complete extension of the knee is from 120-130 degrees of flexion to 0. degree ### Factors Limiting Motion: 1. Tension of hamstring muscle. ### Anatomy of rectus femoris muscle. #### Origin: * **Straight head:** anterior inferior iliac spine. * **Reflected head:** ilium above acetabulum (Fig. 1). #### Insertion: * **a.** Quadriceps tendon to patella. * **b.** Via ligamentum patellae into tubercle of tibia. #### Action: * **a.** Extends knee. * **b.** Flexes hip. #### Nerve: Femoral nerve. ### Anatomy of Vastus lataralis muscle. #### Origin: * **a.** Upper intertrochanteric line. * **b.** Base of greater trochanter. * **c.** Lateral linea aspera. * **d.** Llateral supracondylar ridge and lateral intermuscular septum (Fig.2). #### Insertion: * **a.** Lateral quadriceps tendon to patella. * **b.** Via ligamentum patellae into tubercle of tibia. #### Action: Extends knee. #### Nerve: Femoral nerve. ### Anatomy of Vastus intermedius muscle. #### Origin: - Anterior and lateral shaft of femur (Fig. 3). #### Insertion: * **a.** Quadriceps tendon to patella. * **b.** Via ligamentum patellae into tubercle of tibia. #### Action: Extends knee. #### Nerve: Femoral nerve. ### Anatomy of Vastus medialis muscle. #### Origin: * **a.** Lower intertrochanteric line. * **b.** medial linea aspera. * **c.** medial intermuscular septum (Fig.4). #### Insertion: * **a.** Medial quadriceps tendon to patella and directly into medial patella. * **b.** Via ligamentum patellae into tubercle of tibia. #### Action: * **a.** Extends knee. * **b.** Stabilizes patella. #### Nerve: Femoral nerve. ### Effects of weakness: * **a.** Weakness of these muscles interferes with the functions of going up and down stairs and incline as well as getting up and down from a sitting position. * **b.** The weakness result in knee hyper extension: weak quadriceps requires that the patient lock the knee joint by slight hyperextension. * **c.** Continuous push suddenly by force thrust in the direction of hyperextension in growing children may result in a very marked degree of deformity. ### Effects of shortness or contracture: * **a.** Shortness or contracture of knee extensor muscles will produce restriction of the knee flexion. * **b.** A shortness of the rectus femoris part of the quadriceps results in a restriction of the knee flexion when the hip is extended or a restriction of the hip extension when the knee is flexed. The document consists of six pages, each with an image and text accompanying it. The content is summarized above. The images are depictions of the human leg and describe the musculature involved in knee extension.