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    Related Topics

    From Musculoskeletal System

    Ethmoid Bone
    Bone forming part of the nasal cavity and the orbit.
    Sternocleidomastoid
    Muscle that rotates and flexes the neck.
    Ball-and-Socket Joints
    e.g., shoulder, hip
    Synchondroses
    Cartilaginous joints where bones are connected by hyaline cartilage.
    Acromioclavicular Ligament
    Ligament that connects the acromion to the clavicle.
    Masseter
    Muscle that elevates the mandible.
    Scapula
    Shoulder blade providing attachment for muscles of the upper limb.
    Extensor Tendons
    Tendons that help extend the fingers and toes.
    Trapezius
    Muscle responsible for moving, rotating, and stabilizing the scapula.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Gliding (Plane) Joints
    e.g., between carpals
    Coccygeus
    Pelvic floor muscle supporting the coccyx.
    Triceps Brachii
    Muscle responsible for elbow extension.
    Rectus Abdominis
    Abs muscle that flexes the trunk.
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    Phalanges (14 bones)
    14 bones forming the toes.
    Iliolumbar Ligament
    Ligament connecting the ilium and lumbar vertebrae.
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    Hyoid Bone
    U-shaped bone in the neck that supports the tongue.
    Anterior Longitudinal Ligament
    Spinal ligament running along the front of the vertebral column.
    Latissimus Dorsi
    Back muscle responsible for arm adduction and extension.
    Hinge Joints
    e.g., elbow, knee
    Sacrum
    Triangular bone at the base of the spine.
    Tarsals (7 bones)
    7 ankle bones.
    Sesamoid Bones
    e.g., patella, some found in hands/feet.

    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? The sternocleidomastoid muscle helps rotate the head.