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    Related Topics

    From Musculoskeletal System

    Coracoacromial Ligament
    Ligament that connects the acromion to the coracoid process.
    Coccyx
    Tailbone, the remnant of the tail in humans.
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    Ethmoid Bone
    Bone forming part of the nasal cavity and the orbit.
    Gliding (Plane) Joints
    e.g., between carpals
    Fibula
    Smaller bone in the lower leg, located alongside the tibia.
    Sacrum
    Triangular bone at the base of the spine.
    Clavicle
    Collarbone connecting the arm to the body.
    Medial Collateral Ligament (MCL)
    Knee ligament that stabilizes the inner knee.
    Phalanges (14 bones)
    14 bones forming the toes.
    Ischium
    Part of the pelvis that supports weight while sitting.
    Femur
    Thigh bone, the longest and strongest bone in the body.
    Diaphragm
    Primary muscle for breathing.
    Levator Ani
    Pelvic floor muscle responsible for lifting the anus.
    Thoracic Cage
    Ribs and sternum forming the protective cage for the heart and lungs.
    Glenohumeral Ligaments
    Shoulder ligaments that stabilize the shoulder joint.
    Sternocleidomastoid
    Muscle that rotates and flexes the neck.
    Sutures (in the skull)
    Fibrous joints between skull bones.
    Extensor Tendons
    Tendons that help extend the fingers and toes.
    Rotator Cuff Muscles
    Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.
    Hinge Joints
    e.g., elbow, knee
    Ball-and-Socket Joints
    e.g., shoulder, hip
    Buccinator
    Muscle that helps with chewing and blowing air out.
    Annular Ligament
    The annular ligament is a strong fibrous band encircling the head of the radius, stabilizing the proximal radioulnar joint and allowing smooth rotation of the forearm.
    Soleus
    Calf muscle responsible for plantarflexion of the foot.

    Lateral Collateral Ligament (LCL)

    Reviewed by our medical team

    Knee ligament that stabilizes the outer knee.

    1. Overview

    The lateral collateral ligament (LCL) is a strong, cord-like ligament located on the outer side of the knee joint. It connects the femur (thigh bone) to the fibula (the smaller bone of the lower leg) and is essential for maintaining lateral knee stability. The LCL resists varus stress, which occurs when the knee is pushed outward. It is one of the four major ligaments that stabilize the knee, alongside the ACL, PCL, and MCL.

    2. Location

    The LCL is located on the lateral (outer) side of the knee:

    • Superior attachment: Lateral femoral epicondyle (posterior and superior to the popliteus tendon origin).

    • Inferior attachment: Head of the fibula.

    • Runs: Vertically and slightly posteriorly, superficial to the popliteus tendon.

    • Adjacent structures: Lies outside the knee joint capsule and is separated from the lateral meniscus and joint cavity.

    3. Structure

    The LCL is a cord-like, extracapsular ligament with the following structural characteristics:

    • Shape: Narrow and round in cross-section, unlike the flat, broad MCL.

    • Length: Approximately 5–6 cm long in adults.

    • Composition: Dense regular connective tissue primarily composed of collagen type I fibers.

    • Blood supply: Supplied by branches of the lateral inferior genicular artery.

    • Innervation: Provided by the common fibular (peroneal) nerve, which runs nearby and may be at risk in lateral injuries.

    4. Function

    The LCL performs several key mechanical functions:

    • Resists varus stress: Prevents the knee from bowing outward under load.

    • Stabilizes the knee laterally: Works with other ligaments and muscles to maintain joint alignment during movement.

    • Limits excessive external rotation: Particularly important during knee flexion.

    • Supports functional activities: Crucial for walking, running, pivoting, and cutting motions in sports.

    5. Physiological role(s)

    Though primarily a mechanical stabilizer, the LCL contributes to several physiological roles:

    • Joint proprioception: Contains mechanoreceptors that provide sensory feedback on knee position and movement.

    • Coordination with neuromuscular control: Works in concert with lateral hamstring and quadriceps muscles to maintain dynamic joint stability.

    • Load distribution: Helps absorb lateral forces and distribute stress across the lateral aspect of the knee.

    6. Clinical Significance

    LCL injuries and dysfunctions can lead to lateral knee instability and other complications:

    • LCL sprain or tear:

      • Caused by a direct blow to the medial side of the knee or excessive varus stress; may be graded I (mild) to III (complete rupture).

      • Symptoms include pain, swelling, instability, and difficulty walking or pivoting.

    • Posterolateral corner (PLC) injury:

      • The LCL is part of the PLC, which includes the popliteus tendon and arcuate ligament; combined injuries often lead to significant instability and require complex surgical repair.

    • Common fibular nerve injury:

      • Located near the fibular head; LCL injuries may be associated with nerve damage, causing foot drop or paresthesia in the lateral leg.

    • Reconstruction surgery:

      • Complete LCL ruptures, especially when combined with other ligament injuries, often require surgical reconstruction using grafts (autograft or allograft).

    • Rehabilitation:

      • Post-injury recovery involves physical therapy to restore strength, proprioception, and controlled motion; bracing may be used to limit varus stress.

    Did you know? Bones become stronger when stressed by exercise.