Clinical Anatomy Quiz 3.2

The patella, also known as the kneecap, is the largest sesamoid bone in the body. Sesamoid bones are small, round bones that are embedded within tendons. The patella is located in front of the knee joint and plays a crucial role in the mechanics of the knee. It acts as a fulcrum, increasing the leverage of the quadriceps muscles and improving the efficiency of knee extension. The patella also helps protect the knee joint and provides stability during movements such as walking, running, and jumping.

In the screw home mechanism, the unlocking of the knee in an open chain occurs due to an internal rotation of the tibia on the femur. This means that the tibia rotates inwardly on the femur, allowing the knee joint to unlock and move freely. This internal rotation is an important component of knee movement and is necessary for activities such as walking and running.

The patella, also known as the kneecap, is a small bone that is embedded in the joint capsule of the knee. It is also connected to the quadriceps tendon, which helps to stabilize and move the knee joint. The patella acts as a protective shield for the knee joint and provides leverage for the quadriceps muscles to extend the leg.

The correct answer is "intersection". In a crossed 4-bar linkage system, the intersection point of the bars represents the instant center of rotation. This is because at this point, the bars are perpendicular to each other and can rotate freely. The instant center of rotation is the point where the motion of the bars can be considered as pure rotation.

During the last few degrees of extension in an open chain, the tibia rotates externally on the femur. This rotation is responsible for producing a locking of the knee.

The patella, also known as the kneecap, increases the moment arm for the quadriceps group by 50-60%. The moment arm refers to the perpendicular distance between the line of action of a force and the axis of rotation. In the case of the patella, it acts as a fulcrum, increasing the lever arm of the quadriceps tendon, which allows for greater torque production and more efficient movement of the knee joint. This increased moment arm provided by the patella enhances the mechanical advantage of the quadriceps muscles, enabling better force generation during activities such as walking, running, and jumping.

The lateral lip of the gutter of the patellofemoral joint is higher to prevent lateral dislocation of the patella. This is because the patella (kneecap) has a tendency to dislocate laterally, meaning it can move out of its normal position towards the outside of the knee. By having a higher lateral lip, it acts as a barrier and helps to keep the patella in place, reducing the risk of dislocation.

The term "circumferential displacement" refers to the movement of the articular surface of the patella from a posterior to a superior position during extension to flexion of the patellofemoral joint. This means that as the knee joint moves from a straightened position to a bent position, the patella shifts its orientation from facing backward to facing upward. This displacement is a normal and essential part of the patellofemoral joint's range of motion.

The q-angle refers to the angle formed between the quadriceps muscle and the line of pull of the patellar tendon. This angle is important in assessing the alignment and tracking of the patella (kneecap). The q-angle is influenced by various factors such as the width of the pelvis, the position of the femur, and the strength and balance of the muscles around the knee. By measuring the q-angle, healthcare professionals can evaluate the risk of certain knee conditions, such as patellar instability or patellofemoral pain syndrome.

The q-angle is used to determine proper alignment of the patella. The q-angle is the angle formed between the quadriceps muscle and the patellar tendon. It is measured by drawing two lines: one from the anterior superior iliac spine to the center of the patella, and another from the tibial tubercle to the center of the patella. The q-angle helps assess patellar tracking and can indicate any imbalances or abnormalities in the alignment of the patella.

The anterior transverse ligament connects the medial and lateral horns of the menisci. This ligament is located in the knee joint and helps to stabilize and support the menisci, which are C-shaped cartilage structures that sit between the femur and tibia bones. The anterior transverse ligament plays a crucial role in maintaining the proper alignment and function of the menisci during movement and weight-bearing activities.

During flexion, the menisci move posteriorly. This is because flexion refers to the bending of a joint, and in the case of the knee joint, flexion involves the movement of the lower leg towards the back of the thigh. As the knee flexes, the femur rolls and glides posteriorly on the tibia, causing the menisci (which are located between these two bones) to also move posteriorly. This movement helps to distribute and absorb the forces acting on the knee joint during flexion, providing stability and reducing the risk of injury.

The correct answer is 10-15; 20. From full extension, the femoral condyles roll without sliding. The medial condyle rolls first for 10-15 degrees of flexion, while the lateral condyle rolls the first 20 degrees of flexion. This means that the medial condyle starts rolling before the lateral condyle, but the lateral condyle rolls further in the initial stages of flexion.

sliding movement becomes greater, so that by the end of flexion, femoral condyles are primarily sliding (if they kept rolling, they would roll off!)

The menisci are loosely attached to their respective tibial plateau via coronary ligaments. The term "coronary" refers to the anatomical position of these ligaments, which are located on the periphery of the menisci and help to stabilize them within the knee joint. These ligaments play a crucial role in maintaining the integrity and function of the menisci during joint movement and weight-bearing activities.

During extension, the menisci move anteriorly. This means that they slide forward or towards the front of the knee joint. The menisci are C-shaped cartilage structures located between the femur and tibia bones in the knee. They act as shock absorbers and help to distribute the load evenly across the joint. During extension, as the knee straightens, the menisci shift forward to maintain proper alignment and stability of the joint. This movement helps to prevent excessive stress on the joint surfaces and maintain smooth movement during extension.

NO single point of intersection

The articularis genu muscle is responsible for pulling the superapatellar bursa superiorly in the patellofemoral joint. This action helps to prevent pinching of the bursa and ensures smooth movement of the joint.

A normal q-angle is 15°. The q-angle is the angle formed by the intersection of two lines: one drawn from the anterior superior iliac spine to the center of the patella, and the other drawn from the tibial tubercle to the center of the patella. This angle is used to assess the alignment of the quadriceps muscles and the patella. A q-angle of 15° is considered normal, indicating proper alignment of these structures.

pulls patella laterally

The statement is true because the entire posterior surface of the patella, also known as the kneecap, is indeed covered with articular cartilage. Articular cartilage is a smooth, slippery tissue that covers the ends of bones in a joint, allowing them to glide smoothly over each other. In the case of the patella, this cartilage covers the back surface, which helps it to move smoothly against the femur (thigh bone) when the knee is bent or straightened. This arrangement helps to reduce friction and allows for proper joint function.

Proper function of patellofemoral joint is REQUIRED for optimal function of the tibiofemoral joint.

The patellofemoral joint is formed by the patellar articular surface of the femur and another structure. This structure is called the intercondylar notch. The intercondylar notch is a groove located between the condyles of the femur. It provides stability and allows for smooth movement of the patella within the joint.

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The statement is true because the medial and lateral menisci, which are located in the knee joint, are indeed asymmetrical and wedge-shaped. These structures serve to provide stability to the knee joint, distribute weight, and absorb shock during movement. The medial meniscus is larger and more C-shaped, while the lateral meniscus is smaller and more circular. This anatomical difference allows for better accommodation of the rounded shape of the femur and tibia, contributing to the overall function and biomechanics of the knee joint.

The statement is true because the menisci, which are C-shaped cartilages in the knee joint, serve to deepen the tibial plateaus. This helps to improve the stability of the knee joint by increasing the surface area for weight-bearing and reducing the stress on the articular cartilage. The acetabular labrum, on the other hand, is a ring of cartilage in the hip joint that deepens the socket and provides stability. While the menisci and acetabular labrum are not exactly the same in structure, they both serve a similar purpose of deepening the joint surfaces.

They are all on the posterior side.

At different points it will be in different positions of articulation.
For example it barely touches at full flexion (only lateral and odd facets)

During rotation, the menisci follow the motion of the femoral condyles and the femoral motion. This is because the menisci are located between the femoral condyles and the tibial plateau, and they act as shock absorbers and provide stability to the knee joint. As the femur rotates, the menisci move along with it to maintain proper alignment and distribution of forces within the knee joint. Therefore, the menisci follow the motion of the femoral condyles and the femur during rotation.

The screw home mechanism occurs when the medial femoral condyle is larger than the lateral femoral condyle. This size difference causes the tibia to externally rotate during knee extension, resulting in a locking mechanism that enhances stability of the knee joint.

The correct answer is coronary and anterior transverse. The menisci ligaments are structures in the knee joint that provide stability and help to distribute forces. The coronary ligaments are located on the outer edges of the menisci and attach them to the tibia bone. The anterior transverse ligament is located at the front of the knee joint and connects the two menisci together. Therefore, both the coronary and anterior transverse ligaments are important in maintaining the stability and function of the knee joint.

the lateral meniscus is the most mobile, doesn't get torn nearly as much.

The pes anserinus group and semimembranosus serve as dynamic stability for the medial knee. The pes anserinus group is a combination of the sartorius, gracilis, and semitendinosus tendons, which attach to the medial aspect of the tibia. These tendons help stabilize the medial knee during movement. The semimembranosus is one of the hamstring muscles, which also provides stability to the medial knee. Together, these structures help prevent excessive medial movement and provide support to the knee joint.

The PCL (Posterior Cruciate Ligament), OPL (Oblique Popliteal Ligament), and APL (Arcuate Popliteal Ligament) serve as static stability for the posterior knee. These ligaments provide stability by preventing excessive posterior translation of the tibia (shin bone) relative to the femur (thigh bone). They work together to maintain the integrity and alignment of the knee joint, ensuring proper function and preventing injuries.

The extensor retinacula and quadriceps serve as dynamic stability for the anterior knee. The extensor retinacula are fibrous bands that help to hold the patella in place and prevent it from dislocating. The quadriceps, which are a group of muscles at the front of the thigh, help to stabilize the knee joint and provide strength for extension movements. Both of these structures play a role in maintaining stability and proper function of the anterior knee.

The medial collateral ligament (MCL) and the posterior cruciate ligament (PCL) serve as static stability for the medial knee. These ligaments provide stability by preventing excessive side-to-side and backward movement of the knee joint. The MCL is located on the inner side of the knee and helps to prevent the knee from bending inward, while the PCL is located at the back of the knee and helps to prevent the tibia from sliding too far backward in relation to the femur. Together, these ligaments play a crucial role in maintaining stability and preventing injuries in the medial knee region.

The ACL (anterior cruciate ligament), MCL (medial collateral ligament), and LCL (lateral collateral ligament) serve as static stability for the anterior knee. These ligaments help to prevent excessive forward or sideways movement of the knee joint, providing stability and support to the knee.

doesn't move too much superior

The external medial meniscus attachments include the ACL, MCL, semimembranosus, and quadriceps via the meniscopatellar ligament. These structures connect to the medial meniscus and help stabilize and support the knee joint. The ACL (anterior cruciate ligament) and MCL (medial collateral ligament) provide important stability to the knee, while the semimembranosus is a muscle that attaches to the meniscus. The quadriceps muscle also attaches to the meniscus via the meniscopatellar ligament. These attachments play a crucial role in maintaining the integrity and function of the knee joint.

The external lateral meniscus attachments include the quadriceps via the meniscopatellar ligament, PCL, and popliteus. These structures are all connected to the external lateral meniscus and play a role in stabilizing and supporting the knee joint. The quadriceps muscle, through the meniscopatellar ligament, helps to maintain the position and movement of the meniscus. The PCL and popliteus also contribute to the stability of the meniscus by providing additional support and preventing excessive movement or displacement.

The hamstrings, gastroc, and popliteus muscles serve as dynamic stability for the posterior knee. These muscles work together to provide support and stability to the knee joint during movement. The hamstrings are responsible for flexing the knee and preventing excessive forward movement of the tibia, while the gastroc and popliteus help to control rotational movements of the knee. By contracting and providing tension, these muscles help to stabilize the knee and prevent injury.