Introduction: Anatomy of the Knee Joint
The knee joint anatomy is a complex topic. It is a hinge joint located between the thigh bone (femur) and the shin bone (tibia). It is one of the human body’s largest and most complex joints and is essential for movement and support. This post will explore the main structures that make up the knee joint and their functions.
Bones of the Knee Joint
There are three bones that make up the knee joint anatomy: the femur, the tibia, and the patella.
The femur is the long bone in the thigh that extends from the human hip to the knee. It is the strongest bone in the body and is responsible for bearing the majority of the body’s weight.
The tibia, also known as the shin bone, is the larger of the two bones in the lower leg. It is located on the leg’s medial (inner) side and articulates with the femur at the knee joint.
The patella, or knee cap, is a small bone in front of the knee joint. It helps to protect the joint and also helps to increase the leverage of the quadriceps muscles, which are responsible for extending the leg.
Ligaments of the Knee Joint
Ligaments are strong, fibrous bands that connect bones to each other and help to stabilize joints and thus help the anatomy of the knee joint. There are several ligaments in the knee joint, including the collateral and cruciate.
The collateral ligaments are located on the knee joint’s sides and help stabilize the joint from lateral (sideways) movement. There are two collateral ligaments: the medial collateral ligament (MCL) on the inner side of the joint and the lateral collateral ligament (LCL) on the outer side.
The cruciate ligaments are located within the joint and help to stabilize the joint from front to back and rotational movement. There are two cruciate ligaments: the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). The ACL is located in the front of the joint, and the PCL is in the back.
Tendons of the Knee Joint
Tendons are strong, fibrous cords that connect muscles to bones. In the knee joint, there are two main tendons: the quadriceps tendon and the patellar tendon. These are very important in the anatomy of the knee joint
The quadriceps tendon is a large tendon that connects the quadriceps muscles (located on the front of the thigh) to the patella. It helps to extend the leg and is responsible for the majority of the power when pushing off the ground, such as when jumping or running.
The patellar tendon is a strong tendon that connects the patella to the tibia. It helps to extend the leg and is also responsible for transmitting forces from the quadriceps muscles to the tibia.
Cartilage and Menisci of the Knee Joint
Cartilage is a smooth, cushioning tissue that covers the ends of bones and helps to reduce friction within joints. In the knee joint, the articular cartilage is located on the ends of the femur and tibia. It helps to absorb shock and allows the bones to move smoothly against each other.
The menisci are two crescent-shaped pieces of cartilage located on the tibia. The medial meniscus is on the joint’s inner side, and the lateral meniscus
is on the outer side. The menisci help to distribute weight evenly across the joint and also help to absorb shock.
Muscles of the Joint
There are several muscles that play a role in the movement and stability of the knee joint. The quadriceps muscles, located on the front of the thigh, are responsible for extending the leg. whereas, hamstrings muscles, located on the back of the thigh, are responsible for flexing the leg. The calf muscles, located in the lower leg, also play a role in turning the leg.
Function of the Joint
The primary function of the knee joint is to allow for leg movement. It allows for extension and flexion of the leg, as well as some limited rotation and lateral movement. The knee joint also plays a vital role in shock absorption, helping to protect the bones and other structures of the leg from impact.
Common Injuries and Conditions of the Knee Joint
Like any joint, the knee is prone to injury and can be affected by various conditions. Some common injuries and conditions of the knee joint include sprains and strains (damage to the ligaments or muscles), fractures (breaks in the bones), arthritis (degeneration of the joint cartilage), and meniscal tears (injury to the menisci). Proper care and treatment of the knee joint can help to prevent or manage these conditions.
Anatomy of Knee Joint (Exam Question-Answer Type)
Question : Describe knee joint under the following headings: (a)
classification, (b) ligaments and menisci, (c) relations, (d)
movements and muscles producing them, and (e) applied
anatomy.
Knee joint
- Classification
- Compound synovial joint
- Two components:
- Condylar joint (modified hinge joint) between medial and lateral condyles of femur and tibia
- Saddle joint between femur and patella
Ligaments and menisci
- Capsular ligament
- Attached to margins of articular surfaces except anteriorly (deficient, supplemented by extensor apparatus of knee joint including quadriceps tendon, patella, and ligamentum patellae)
- Posterolaterally, it prevents opening for passage of tendon of popliteus
- Medial (tibial) collateral ligament
- Superficial and deep parts
- External part attached above to epicondyle of femur, below to upper part of medial border of tibia
- Deep part firmly attached to medial meniscus
- Lateral (fibular) collateral ligament
- Attached above to epicondyle of femur, below to head of fibula
- Lies away from meniscus
- Cruciate ligaments (anterior and posterior)
- Intracapsular
- Anterior cruciate ligament extends from anterior part of intercondylar area of tibia to medial side of lateral femoral condyle
- Prevents hyperextension and resists
Ligaments and menisci (continued)
- Cruciate ligaments (anterior and posterior) (continued)
- Posterior cruciate ligament extends from posterior part of intercondylar area of tibia to lateral side of medial femoral condyle
- Becomes taut in hyperflexion and resists posterior displacement of tibia on femur
- Menisci (semilunar cartilages)
- Semilunar fibrocartilaginous plates on articular surfaces of superior surface of tibia
- Medial meniscus larger and ‘C’-shaped, lateral meniscus smaller and ‘O’-shaped
- Attached to tibial intercondylar area by horns (anterior and posterior) and peripherally by coronary ligaments
Relations
- Anterior portion: patella, quadriceps tendon, patellar tendon, anterior cruciate ligament (ACL), articular cartilage, menisci
- Posterior portion: posterior cruciate ligament (PCL), hamstrings muscles, calf muscles, articular cartilage, menisci
- Medial portion: medial collateral ligament,
- Lateral portion: lateral collateral ligament, articular cartilage, menisci
Movements and muscles producing them
- Flexion: produced by hamstrings muscles and calf muscles
- Extension: produced by quadriceps muscles
- Medial and lateral rotation: produced by muscles that cross the knee joint
Applied anatomy
- Knee joint plays essential role in support and movement of body
- Damage to joint structures can lead to pain, instability, and impaired function
- Treatment may include medications, physical therapy, and surgery
Conclusion
The knee joint is a complex and essential structure that allows us to move and support our bodies. Understanding the knee joint’s main structures and functions can help us better care for and protect this critical joint. If you experience pain or discomfort in your knees, be sure to speak with a healthcare professional for proper evaluation and treatment.
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