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    Related Topics

    From Musculoskeletal System

    Palatine Bones
    Bones forming part of the hard palate and nasal cavity.
    Ellipsoidal (Condyloid) Joints
    e.g., wrist
    Pelvic Floor Muscles
    Muscles that support pelvic organs.
    Humerus
    Upper arm bone connecting the shoulder to the elbow.
    Hyoid Bone
    U-shaped bone in the neck that supports the tongue.
    Ethmoid Bone
    Bone forming part of the nasal cavity and the orbit.
    Thoracic Cage
    Ribs and sternum forming the protective cage for the heart and lungs.
    Deltoid
    Shoulder muscle responsible for arm abduction.
    Occipital Bone
    Bone forming the back and base of the skull.
    Interspinous Ligament
    Spinal ligament between adjacent vertebral spinous processes.
    Masseter
    Muscle that elevates the mandible.
    Medial Collateral Ligament (MCL)
    Knee ligament that stabilizes the inner knee.
    Pectoralis Major
    Chest muscle responsible for shoulder movement.
    Vomer Bone
    Bone forming the nasal septum.
    Gomphoses
    Fibrous joints where a peg fits into a socket (e.g., teeth in jaw).
    Sacrum
    Triangular bone at the base of the spine.
    Nasal Bones
    Bones forming the bridge of the nose.
    Patellar Tendon
    Tendon connecting the patella to the tibia.
    Flexor Tendons
    Tendons that help flex the fingers and toes.
    Hinge Joints
    e.g., elbow, knee
    Coracoacromial Ligament
    Ligament that connects the acromion to the coracoid process.
    Rotator Cuff Muscles
    Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.
    Symphyses
    Cartilaginous joints where bones are connected by fibrocartilage.
    Radius
    Forearm bone on the thumb side.
    Saddle Joints
    e.g., thumb joint

    Posterior Cruciate Ligament (PCL)

    Reviewed by our medical team

    Knee ligament that stabilizes the joint.

    1. Overview

    The posterior cruciate ligament (PCL) is one of the key stabilizing ligaments of the knee joint. It connects the femur (thigh bone) to the tibia (shin bone) and resists posterior displacement of the tibia relative to the femur. Although less commonly injured than the anterior cruciate ligament (ACL), the PCL is equally important for maintaining knee stability during dynamic activities like walking, running, and jumping.

    2. Location

    The PCL is located deep within the knee joint, in the intercondylar region:

    • Origin: Anterolateral aspect of the medial femoral condyle (inside the femoral notch).

    • Insertion: Posterior intercondylar area of the tibia.

    • Orientation: Runs obliquely downward, backward, and slightly medially from femur to tibia.

    • Position: Lies posterior to the anterior cruciate ligament (ACL), forming a crisscross configuration with it.

    3. Structure

    The PCL is a thick, strong, intra-articular but extrasynovial ligament:

    • Length: Approximately 30–38 mm.

    • Width: Around 13 mm, though broader near its femoral origin.

    • Bundles:

      • Anterolateral bundle: Taut in flexion; primary stabilizer.

      • Posteromedial bundle: Taut in extension; provides secondary restraint.

    • Composition: Dense collagen fibers oriented for high tensile strength.

    • Blood supply: Primarily from the middle genicular artery.

    • Innervation: From the posterior articular branch of the tibial nerve, contributing to proprioception.

    4. Function

    The PCL serves multiple mechanical functions critical to knee joint integrity:

    • Prevents posterior tibial translation: Stops the tibia from sliding backward relative to the femur, especially in flexion.

    • Maintains knee stability: Works with the ACL to stabilize the knee in both static and dynamic postures.

    • Guides knee motion: Helps maintain proper alignment and articulation during knee flexion and extension.

    • Secondary restraint to varus, valgus, and external rotation: Especially when other ligaments are compromised.

    5. Physiological role(s)

    Though passive in nature, the PCL indirectly supports broader physiological processes:

    • Proprioception: Contains mechanoreceptors that provide feedback on knee position and movement to coordinate neuromuscular control.

    • Energy efficiency in gait: Stabilizes the knee during stance phase, reducing muscular demand during walking and running.

    • Joint integrity: Minimizes abnormal shearing forces on the articular cartilage, helping prevent degenerative changes.

    6. Clinical Significance

    Injury to the PCL, while less common than ACL tears, can significantly impair knee function:

    • PCL injuries:

      • Often caused by a direct blow to the anterior tibia (e.g., “dashboard injury” in car accidents) or hyperflexion of the knee.

      • Classified by grade:

        • Grade I: Mild sprain.

        • Grade II: Partial tear.

        • Grade III: Complete rupture, often with other ligament injuries.

    • Symptoms:

      • Posterior knee pain, swelling, instability, difficulty walking downhill or descending stairs.

    • Diagnosis:

      • Posterior drawer test, posterior sag sign, and MRI for confirmation and grading.

    • Treatment:

      • Grade I–II typically managed conservatively with bracing and rehabilitation.

      • Grade III or chronic instability may require surgical reconstruction using autograft or allograft tissue.

    • Rehabilitation:

      • Focuses on strengthening the quadriceps, improving proprioception, and avoiding posterior tibial stress in early stages.

    • Long-term implications:

      • Chronic PCL deficiency may contribute to early onset osteoarthritis of the medial or patellofemoral compartments.

    Did you know? Sesamoid bones are bones that form within tendons, like the patella.