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    Related Topics

    From Musculoskeletal System

    Gastrocnemius
    Calf muscle responsible for plantarflexion of the foot.
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    Maxillae
    Upper jaw bones that house the teeth and form part of the orbit.
    Femur
    Thigh bone, the longest and strongest bone in the body.
    Frontal Bone
    Bone forming the forehead and upper part of the orbits.
    Lumbar Vertebrae (L1 - L5)
    Vertebrae in the lower back (L1-L5).
    Soleus
    Calf muscle responsible for plantarflexion of the foot.
    Masseter
    Muscle that elevates the mandible.
    Rotator Cuff Tendons
    Tendons of the rotator cuff muscles.
    Anterior Cruciate Ligament (ACL)
    Knee ligament that stabilizes the joint.
    Fibula
    Smaller bone in the lower leg, located alongside the tibia.
    Tibialis Anterior
    Muscle that dorsiflexes and inverts the foot.
    Pivot Joints
    e.g., atlanto-axial joint
    Ligamentum Flavum
    Spinal ligament connecting the laminae of adjacent vertebrae.
    Clavicle
    Collarbone connecting the arm to the body.
    Temporalis
    Muscle involved in closing the jaw.
    Wormian Bones
    Sutural bones in the skull.
    Brachioradialis
    Muscle responsible for forearm flexion.
    Sacrum
    Triangular bone at the base of the spine.
    Sesamoid Bones
    e.g., patella, some found in hands/feet.
    Hyoid Bone
    U-shaped bone in the neck that supports the tongue.
    Sartorius
    Longest muscle in the body responsible for hip flexion.
    Saddle Joints
    e.g., thumb joint
    Sutures (in the skull)
    Fibrous joints between skull bones.
    Zygomaticus
    Muscle that raises the corners of the mouth.

    Medial Collateral Ligament (MCL)

    Reviewed by our medical team

    Knee ligament that stabilizes the inner knee.

    1. Overview

    The medial collateral ligament (MCL) is a broad, flat band of connective tissue located on the inner side of the knee. It is one of the four major ligaments that stabilize the knee joint, alongside the ACL, PCL, and LCL. The MCL is particularly responsible for resisting valgus stress (forces that push the knee inward) and plays a critical role in maintaining medial knee stability during movement and weight-bearing.

    2. Location

    The MCL is found on the medial (inner) aspect of the knee:

    • Proximal attachment: Medial epicondyle of the femur.

    • Distal attachment: Medial surface of the tibia, approximately 5–7 cm below the joint line.

    • Medially: Lies deep to the sartorius muscle and over the pes anserinus tendons.

    • Adjacent structures: Lies superficial to the joint capsule and medial meniscus, with deeper fibers merging with both.

    3. Structure

    The MCL is a flat, broad, and layered ligament with two distinct parts:

    • Superficial MCL:

      • Primary stabilizer against valgus stress.

      • Runs from the medial femoral epicondyle to the medial tibia.

    • Deep MCL:

      • Shorter and thicker, located deep to the superficial layer.

      • Firmly attached to the medial meniscus and joint capsule.

    The ligament is composed of densely packed collagen fibers aligned parallel to resist tensile forces, with limited elasticity.

    4. Function

    The medial collateral ligament plays a key role in knee stability and biomechanics:

    • Resists valgus stress: Prevents the knee from collapsing inward, especially when the foot is planted and a lateral force is applied.

    • Limits external rotation: Helps stabilize the knee during twisting motions.

    • Stabilizes medial joint line: Supports the integrity of the joint during walking, running, and side-to-side movements.

    • Assists in controlling knee flexion-extension motion: Acts in concert with other ligaments and muscles.

    5. Physiological role(s)

    The MCL contributes to several physiological and functional processes:

    • Proprioception: Contains sensory receptors that provide feedback on joint position and motion, aiding balance and coordination.

    • Force distribution: Helps dissipate forces across the knee joint, especially during high-load activities.

    • Joint capsule reinforcement: The deep fibers of the MCL blend with the joint capsule, contributing to passive stabilization.

    • Protection of medial meniscus: Prevents excessive gapping that could injure the meniscus.

    6. Clinical Significance

    The MCL is commonly injured, particularly in athletes and during contact sports:

    • MCL sprain:

      • Occurs when the knee is subjected to valgus stress; classified into grades:

        • Grade I: Mild sprain with no instability.

        • Grade II: Partial tear with some laxity.

        • Grade III: Complete rupture, often with joint instability.

    • Mechanism of injury:

      • Usually from a blow to the lateral knee or sudden directional changes.

    • Symptoms:

      • Medial knee pain, swelling, bruising, tenderness along the inner knee, and instability during walking or pivoting.

    • Diagnosis:

      • Clinical valgus stress test, MRI for detailed grading and assessment of associated injuries (e.g., medial meniscus or ACL).

    • Treatment:

      • Most MCL injuries (Grades I–II) are treated non-surgically with rest, bracing, physical therapy.

      • Grade III tears may require surgical repair, especially if combined with ACL injury.

    • Rehabilitation:

      • Includes strengthening, proprioception exercises, and progressive return to activity.

    Did you know? The sternocleidomastoid muscle helps rotate the head.