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    Related Topics

    From Musculoskeletal System

    Pectoralis Major
    Chest muscle responsible for shoulder movement.
    Tarsals (7 bones)
    7 ankle bones.
    Sacroiliac Ligaments
    Ligaments connecting the sacrum to the iliac bones.
    Synchondroses
    Cartilaginous joints where bones are connected by hyaline cartilage.
    Temporalis
    Muscle involved in closing the jaw.
    Acetabulum
    The acetabulum is the pelvic socket that connects with the femoral head to form the hip joint, vital for stability, movement, and weight-bearing.
    Facial Bones
    Bones forming the structure of the face.
    Anterior Cruciate Ligament (ACL)
    Knee ligament that stabilizes the joint.
    Maxillae
    Upper jaw bones that house the teeth and form part of the orbit.
    Phalanges (14 bones)
    14 bones forming the toes.
    Quadriceps
    Rectus Femoris, Vastus Medialis, Vastus Lateralis, Vastus Intermedius.
    Sacrum
    Triangular bone at the base of the spine.
    Zygomatic Bones
    Cheekbones that form part of the orbit.
    Rotator Cuff Tendons
    Tendons of the rotator cuff muscles.
    Femur
    Thigh bone, the longest and strongest bone in the body.
    Glenohumeral Ligaments
    Shoulder ligaments that stabilize the shoulder joint.
    Frontal Bone
    Bone forming the forehead and upper part of the orbits.
    Posterior Longitudinal Ligament
    Spinal ligament running along the back of the vertebral column.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Coccygeus
    Pelvic floor muscle supporting the coccyx.
    Pubis
    Part of the pelvis that joins with the opposite side to form the pubic symphysis.
    Pivot Joints
    e.g., atlanto-axial joint
    Gliding (Plane) Joints
    e.g., between carpals
    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.
    Pelvic Floor Muscles
    Muscles that support pelvic organs.

    Syndesmoses

    Reviewed by our medical team

    Fibrous joints where bones are connected by ligaments.

    1. Overview

    Syndesmoses are a type of fibrous joint in which two bones are connected by a sheet or bundle of dense connective tissue, primarily collagen. Unlike sutures, which are immobile, syndesmoses allow for slight but important movement (amphiarthroses). These joints provide strength, stability, and shock absorption, particularly in long bones of the limbs.

    2. Location

    Syndesmoses are found in areas where bones are spaced apart but need to be firmly connected. Common examples include:

    • Distal tibiofibular joint: Between the distal ends of the tibia and fibula in the lower leg.

    • Interosseous membrane of the forearm: Connects the shafts of the radius and ulna.

    • Interosseous membrane of the leg: Runs between the tibia and fibula along their lengths.

    3. Structure

    Syndesmoses are composed primarily of dense fibrous connective tissue:

    • Interosseous membrane or ligament: A strong, flexible sheet of collagen fibers that links the bones.

    • Articulating bones: Are not in direct contact but are held at a fixed distance.

    • Vascularity: These structures are relatively avascular, which slows healing when injured.

    • Innervation: Supplied by nerves that may also relay proprioceptive signals.

    The collagen fiber orientation is often oblique or crisscrossed to optimize force transmission and prevent displacement.

    4. Function

    Syndesmoses have multiple mechanical and supportive functions:

    • Stabilize long bones: Prevent separation and provide strength to the limb skeleton.

    • Transmit force: Distribute mechanical loads between bones during motion (e.g., from the radius to the ulna or from the fibula to the tibia).

    • Permit limited movement: Allow for rotation and gliding motions necessary for daily limb function (e.g., forearm pronation/supination).

    • Maintain joint alignment: Keep articulating bones properly oriented during dynamic activities.

    5. Physiological role(s)

    Beyond structural support, syndesmoses play roles in coordination and functional integration of limb movement:

    • Enhance joint congruency: Allow bones to move together as a unit without dislocation.

    • Provide sensory feedback: Contain mechanoreceptors that contribute to limb proprioception and coordination.

    • Support muscle efficiency: Serve as stable anchors for adjacent muscle attachments.

    6. Clinical Significance

    Injury or dysfunction of syndesmoses can affect limb stability and function:

    • High ankle sprain (syndesmotic sprain):

      • Involves injury to the distal tibiofibular syndesmosis.

      • Common in athletes, causing pain above the ankle, difficulty bearing weight, and prolonged recovery.

    • Interosseous membrane rupture:

      • Can occur due to trauma or fracture (e.g., Essex-Lopresti injury of the forearm).

      • Leads to instability between the radius and ulna, affecting grip and rotation.

    • Surgical implications:

      • Stabilization of distal tibiofibular syndesmosis is often required with screws or suture buttons in fracture repair.

    • Chronic syndesmotic injuries:

      • If untreated, can lead to joint instability, arthritis, and altered gait mechanics.

    • Diagnostic imaging:

      • MRI and stress radiographs are often used to assess ligament integrity in syndesmotic joints.

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