Chapter 9 - Section 9.3 - Study Guide - Assess Your Learning Outcomes - Page 305: 5

The knee is a complex hinge joint that allows for bending (flexion) and straightening (extension) of the leg. It consists of two main joints: the tibiofemoral joint and the patellofemoral joint. Additionally, there are several ligaments, menisci, and bursae that contribute to its stability and function. Here are the key features of the knee: **Tibiofemoral Joint:** 1. **Femur (Thigh Bone):** The distal end of the femur forms the upper part of the tibiofemoral joint. It has two condyles (medial and lateral) that articulate with the tibia. 2. **Tibia (Shin Bone):** The proximal end of the tibia forms the lower part of the tibiofemoral joint. It has two corresponding condyles that articulate with the femoral condyles. 3. **Menisci:** There are two menisci in the knee joint, one on the medial (inner) side and one on the lateral (outer) side. These are C-shaped wedges of fibrocartilage that sit between the femoral and tibial condyles. They provide cushioning, stability, and help distribute weight and reduce friction within the joint. 4. **Cruciate Ligaments:** - **Anterior Cruciate Ligament (ACL):** The ACL is located within the knee joint and crosses from the posterior aspect of the femur to the anterior aspect of the tibia. It helps prevent the tibia from moving too far forward in relation to the femur and plays a crucial role in stabilizing the knee during rotational movements. - **Posterior Cruciate Ligament (PCL):** The PCL is also situated within the knee joint and crosses from the anterior aspect of the femur to the posterior aspect of the tibia. It prevents excessive backward movement of the tibia in relation to the femur. **Patellofemoral Joint:** 1. **Patella (Kneecap):** The patella is a small, triangular bone that sits in front of the knee joint. It acts as a fulcrum, improving the leverage of the quadriceps muscles as they extend the leg. 2. **Femur (Femoral Trochlea):** The patella glides within a groove at the lower end of the femur called the femoral trochlea. 3. **Patellar Ligament/Tendon:** The patella is connected to the tibia by the patellar ligament, which transitions into the patellar tendon as it attaches to the tibial tuberosity. **Bursae Around the Patella:** There are several bursae (fluid-filled sacs) around the patella to reduce friction and provide cushioning: a. **Suprapatellar Bursa:** Located between the quadriceps tendon and the femur, above the patella. b. **Prepatellar Bursa:** Positioned between the patella and the skin at the front of the knee. c. **Infrapatellar Bursa (Subdivided into two bursae):** - **Subcutaneous Infrapatellar Bursa:** Located just beneath the skin and above the patellar ligament. - **Deep Infrapatellar Bursa:** Situated between the patellar ligament and the tibia. The knee is highly vulnerable to injury and degenerative conditions due to its weight-bearing nature and complex structure. Injuries to the ligaments, menisci, or bursae can result in pain, instability, and reduced mobility, requiring medical evaluation and often rehabilitation or surgical intervention for treatment.

The knee is a complex hinge joint that allows for bending (flexion) and straightening (extension) of the leg. It consists of two main joints: the tibiofemoral joint and the patellofemoral joint. Additionally, there are several ligaments, menisci, and bursae that contribute to its stability and function. Here are the key features of the knee: **Tibiofemoral Joint:** 1. **Femur (Thigh Bone):** The distal end of the femur forms the upper part of the tibiofemoral joint. It has two condyles (medial and lateral) that articulate with the tibia. 2. **Tibia (Shin Bone):** The proximal end of the tibia forms the lower part of the tibiofemoral joint. It has two corresponding condyles that articulate with the femoral condyles. 3. **Menisci:** There are two menisci in the knee joint, one on the medial (inner) side and one on the lateral (outer) side. These are C-shaped wedges of fibrocartilage that sit between the femoral and tibial condyles. They provide cushioning, stability, and help distribute weight and reduce friction within the joint. 4. **Cruciate Ligaments:** - **Anterior Cruciate Ligament (ACL):** The ACL is located within the knee joint and crosses from the posterior aspect of the femur to the anterior aspect of the tibia. It helps prevent the tibia from moving too far forward in relation to the femur and plays a crucial role in stabilizing the knee during rotational movements. - **Posterior Cruciate Ligament (PCL):** The PCL is also situated within the knee joint and crosses from the anterior aspect of the femur to the posterior aspect of the tibia. It prevents excessive backward movement of the tibia in relation to the femur. **Patellofemoral Joint:** 1. **Patella (Kneecap):** The patella is a small, triangular bone that sits in front of the knee joint. It acts as a fulcrum, improving the leverage of the quadriceps muscles as they extend the leg. 2. **Femur (Femoral Trochlea):** The patella glides within a groove at the lower end of the femur called the femoral trochlea. 3. **Patellar Ligament/Tendon:** The patella is connected to the tibia by the patellar ligament, which transitions into the patellar tendon as it attaches to the tibial tuberosity. **Bursae Around the Patella:** There are several bursae (fluid-filled sacs) around the patella to reduce friction and provide cushioning: a. **Suprapatellar Bursa:** Located between the quadriceps tendon and the femur, above the patella. b. **Prepatellar Bursa:** Positioned between the patella and the skin at the front of the knee. c. **Infrapatellar Bursa (Subdivided into two bursae):** - **Subcutaneous Infrapatellar Bursa:** Located just beneath the skin and above the patellar ligament. - **Deep Infrapatellar Bursa:** Situated between the patellar ligament and the tibia. The knee is highly vulnerable to injury and degenerative conditions due to its weight-bearing nature and complex structure. Injuries to the ligaments, menisci, or bursae can result in pain, instability, and reduced mobility, requiring medical evaluation and often rehabilitation or surgical intervention for treatment.