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    Related Topics

    From Musculoskeletal System

    Coccygeus
    Pelvic floor muscle supporting the coccyx.
    Ribs (12 Pairs)
    12 pairs of bones that form the sides of the thoracic cage.
    Sternum
    Breastbone located in the center of the chest.
    Zygomatic Bones
    Cheekbones that form part of the orbit.
    Clavicle
    Collarbone connecting the arm to the body.
    Skull
    Bony structure of the head that encases the brain.
    Thoracic Vertebrae (T1 - T12)
    Vertebrae in the upper and mid-back (T1-T12).
    Sphenoid Bone
    Bone forming part of the base of the skull and sides of the orbits.
    Hyoid Bone
    U-shaped bone in the neck that supports the tongue.
    Anterior Scalene Muscle
    The anterior scalene muscle is a deep neck muscle that elevates the first rib during inspiration and aids in neck flexion and stability, located between key neurovascular structures.
    Gastrocnemius
    Calf muscle responsible for plantarflexion of the foot.
    Deltoid
    Shoulder muscle responsible for arm abduction.
    Sartorius
    Longest muscle in the body responsible for hip flexion.
    Hinge Joints
    e.g., elbow, knee
    Patella
    Knee cap, protecting the knee joint.
    Sutures (in the skull)
    Fibrous joints between skull bones.
    Thoracic Cage
    Ribs and sternum forming the protective cage for the heart and lungs.
    Synchondroses
    Cartilaginous joints where bones are connected by hyaline cartilage.
    Rotator Cuff Muscles
    Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.
    Gomphoses
    Fibrous joints where a peg fits into a socket (e.g., teeth in jaw).
    Buccinator
    Muscle that helps with chewing and blowing air out.
    Wormian Bones
    Sutural bones in the skull.
    Trapezius
    Muscle responsible for moving, rotating, and stabilizing the scapula.
    Biceps Brachii
    Muscle responsible for elbow flexion.
    Sesamoid Bones
    e.g., patella, some found in hands/feet.

    Symphyses

    Reviewed by our medical team

    Cartilaginous joints where bones are connected by fibrocartilage.

    1. Overview

    A symphysis is a type of cartilaginous joint where two bones are joined together by a pad of fibrocartilage. These joints are amphiarthrotic, meaning they allow limited movement while maintaining strong structural integrity. Symphyses are found in the axial skeleton and serve important roles in absorbing shock and providing stability to the body’s midline.

    2. Location

    Symphyses are located along the midline of the body, primarily in the axial skeleton. Major examples include:

    • Pubic symphysis: Between the two pubic bones of the pelvis.

    • Intervertebral discs: Between the vertebral bodies from C2 to the sacrum.

    • Manubriosternal joint: Between the manubrium and the body of the sternum (may ossify with age).

    3. Structure

    Symphyses are composed of:

    • Articulating bones: Covered with a thin layer of hyaline cartilage.

    • Fibrocartilaginous disc: A strong, compressible pad of fibrocartilage situated between the bones.

    • No synovial cavity: Unlike synovial joints, symphyses do not contain a joint capsule or synovial fluid.

    • Limited vascularity: Fibrocartilage has a poor blood supply, especially in central areas.

    Despite their simplicity, symphyses are durable and adaptable, with a structure optimized for both stability and resilience.

    4. Function

    Symphyses serve key mechanical and supportive functions:

    • Shock absorption: The fibrocartilage discs cushion forces transmitted between bones, especially during weight-bearing activities.

    • Limited movement: Allow slight movement for flexibility, such as vertebral bending or expansion of the pelvis during childbirth.

    • Joint stability: Provide firm articulation in regions where strength and minimal mobility are required.

    5. Physiological role(s)

    Symphyses play roles beyond mechanical function:

    • Spinal flexibility: Intervertebral symphyses allow bending, twisting, and compression of the vertebral column while protecting the spinal cord.

    • Pelvic expansion: The pubic symphysis loosens under the influence of hormones like relaxin during pregnancy, allowing safe passage during childbirth.

    • Height maintenance: Intervertebral discs contribute to overall height and slightly compress throughout the day with activity.

    6. Clinical Significance

    Symphyses are involved in several clinical conditions:

    • Degenerative disc disease:

      • Intervertebral discs may lose hydration and elasticity with age, leading to pain, reduced flexibility, and nerve compression.

    • Herniated disc:

      • Protrusion of the nucleus pulposus through the annulus fibrosus in intervertebral symphyses, potentially compressing spinal nerves.

    • Symphysis pubis dysfunction (SPD):

      • Common during pregnancy due to increased ligament laxity; causes pain in the pubic area and difficulty with walking or climbing stairs.

    • Ankylosis:

      • Fusion of the symphysis, either due to age (e.g., manubriosternal joint) or disease (e.g., ankylosing spondylitis).

    • Inflammatory conditions:

      • Symphysitis or inflammation of a symphysis joint can cause localized pain, such as osteitis pubis seen in athletes or post-surgery patients.

    Did you know? Your hand has 5 metacarpal bones.