The Knee Joint and its Components

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Questions and Answers

What is the main function of the menisci in the knee joint?

To facilitate flexion and extension of the knee joint

To supply nerves to the capsule of the knee joint

To provide stability to the joint by deepening the socket for the femoral condyles (correct)

To rotate the tibial plateau on the femoral condyles

What is the normal range of flexion of the knee joint?

135-140 degrees (correct)

90-100 degrees

150-155 degrees

120-125 degrees

What is the purpose of the medial rotation of the femur on the tibia during the final stages of extension?

To adjust ligament tension (correct)

To deepen the socket for the femoral condyles

To facilitate hyperextension of the knee

To rotate the tibial plateau on the femoral condyles

What is the consequence of hyperextending the knee in individuals with normal knees?

It puts the ligaments at risk of rupture Signup and view all the answers

What is the movement of the tibia during the final stages of extension?

The tibia remains stationary Signup and view all the answers

How many nerves supply the capsule of the knee joint?

4 Signup and view all the answers

What is the shape of the menisci?

Wedge-shaped Signup and view all the answers

What is the extent of internal rotation of the knee joint?

10 degrees Signup and view all the answers

What is the function of the posterior cruciate ligament in the knee joint?

To prevent excessive forward movement of the femur Signup and view all the answers

Why is the posterior cruciate ligament thicker than the anterior cruciate ligament?

Because it plays a more crucial role in preventing femur movement Signup and view all the answers

What happens to the posterior cruciate ligament during flexion of the knee joint?

Only part of it becomes taut Signup and view all the answers

Why is the anterior cruciate ligament more prone to injury than the posterior cruciate ligament?

Because it is thinner and more delicate Signup and view all the answers

What is the consequence of a ruptured cruciate ligament?

Swelling and pain in the joint Signup and view all the answers

When is the posterior cruciate ligament most active?

During flexion of the knee joint Signup and view all the answers

What is the role of the quadriceps femoris muscle in preventing femur movement?

It resists the tendency to flex the joint Signup and view all the answers

When are the cruciate ligaments most susceptible to injury?

During sudden twisting movements Signup and view all the answers

What is the primary function of the popliteus muscle in the knee joint?

To laterally rotate the femur and unlock the joint Signup and view all the answers

What is the result of the medial rotation of the femur on the tibia in the final 15 degrees of extension?

Tightening of all the ligaments of the joint, putting it into a 'close-packed' position Signup and view all the answers

What is the difference between the medial and lateral femoral condyles?

The medial condyle is larger and more curved Signup and view all the answers

What happens to the femoral condyles during the movement from flexion to extension?

They move anteriorly and glide forwards Signup and view all the answers

What is the purpose of the arcuate ligament in the knee joint?

To provide additional stability to the joint Signup and view all the answers

What happens to the lateral femoral condyle during extension?

It uses up its articular surface quicker than the medial condyle Signup and view all the answers

During which phase of gait is the knee joint in extension?

During the stance phase Signup and view all the answers

What is the significance of the 'close-packed' position of the knee joint?

It puts the joint into a solid stable entity Signup and view all the answers

What is the primary reason for the patella to dislocate laterally in patients with a wasting of the vastus medialis?

The vastus medialis muscle is weakened, causing the patella to shift laterally. Signup and view all the answers

What is the average Q-angle in women?

17 degrees Signup and view all the answers

Which of the following conditions can increase the Q-angle?

Genu valgum Signup and view all the answers

What is the consequence of a high Q-angle on the patella?

Enormous strain on the patella, leading to dislocation Signup and view all the answers

What is the primary cause of an abnormal Q-angle in some individuals?

Mal-positioned patella Signup and view all the answers

What is the purpose of measuring the Q-angle?

To assess the risk of patellar dislocation Signup and view all the answers

What is the relationship between the Q-angle and patellar dislocation?

An increase in the Q-angle is associated with an increased risk of patellar dislocation Signup and view all the answers

What is the method of measuring the Q-angle?

Drawing two lines and measuring the angle of intersection using a protractor Signup and view all the answers

What degree of knee bend is required to relax the hamstrings?

30 degrees Signup and view all the answers

Which ligament is not at risk of injury during twisting of the body upon full extension?

Lateral collateral ligament Signup and view all the answers

What type of tackle is likely to tear both the anterior cruciate and medial collateral ligament?

Sideways tackle Signup and view all the answers

Who first described the 'unhappy triad' of injuries?

O'Donoghue Signup and view all the answers

What is the result of a valgus or varus bending in full extension?

Tearing of multiple ligaments, including the collateral ligaments Signup and view all the answers

What is attached to the medial meniscus?

Medial collateral ligament Signup and view all the answers

What is the term for the common association of injuries involving the anterior cruciate ligament, medial collateral ligament, and medial meniscus?

Unhappy triad Signup and view all the answers

What is the focus of the final part of the lecture on the knee joint?

Bursae of the knee Signup and view all the answers

Study Notes

The Knee Joint

The knee joint is a modified synovial hinge joint that is capable of flexion by 135-140 degrees, but cannot extend beyond 0 degrees in the normal knee.
The joint has some rotation at the extremes of flexion and extension, allowing the tibial plateau to rotate on the femoral condyles.

Menisci

The knee joint has two intra-synovial articular discs called menisci: medial meniscus and lateral meniscus.
The menisci are wedge-shaped semi-circular discs that help to deepen the socket for the femoral condyles and provide added support to the joint.

Muscles Crossing the Knee Joint

The stability of the knee joint is added to by the tone of the muscles of the thigh and leg that cross it.

Neurovasculature of the Knee Joint

The capsule of the knee joint is supplied by four nerves: femoral nerve, obturator nerve, tibial nerve, and common fibular nerve.
The nerves supply the joint anteriorly and medially (femoral nerve and obturator nerve) and posteriorly and laterally (tibial nerve and common fibular nerve).

Q-Angle

The Q-angle is the angle created by the quadriceps muscle pulling along the mechanical axis rather than the anatomical one, due to the femur being angled.
The Q-angle is measured by drawing two lines: one from the anterior superior iliac spine to the center of the patella, and another from the tibial tuberosity to the center of the patella.
The Q-angle is greater in women (about 17 degrees) than in men (about 14 degrees) due to wider hips.

Popliteus Muscle

The popliteus muscle laterally rotates the femur to unlock the knee joint when it is locked in full extension.
The muscle arises from the triangular area in the back of the tibia, just proximal to the soleal line, and inserts onto the lateral femoral epicondyle.

Cruciate Ligaments

The anterior cruciate ligament prevents excessive forward movement of the femur.
The posterior cruciate ligament performs the opposite action to the anterior one, preventing excessive backward movement of the femur.
The posterior cruciate ligament is about three times the thickness of the anterior one and is only part of it is taut in extension.

Cruciate Ligament Injury

The anterior cruciate ligament is more prone to injury than the posterior one due to its thinner structure.
Rupture of the cruciate ligaments may cause bleeding inside the joint capsule, leading to swelling, discoloration, and pain.

The Unhappy Triad

The unhappy triad is a common association of injuries that occurs when there is a twisting of the body upon full extension, resulting in tears to the anterior cruciate ligament, medial collateral ligament, and medial meniscus.
The injuries are often seen in contact sports, such as rugby or football, where the foot is fixed firmly on the ground and the momentum of the trunk twists and tears the ligaments.

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Description

Learn about the anatomy and stability of the knee joint, including the menisci and muscles that support it.