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    Related Topics

    From Musculoskeletal System

    Extensor Tendons
    Tendons that help extend the fingers and toes.
    Quadriceps Tendon
    Tendon that connects the quadriceps to the patella.
    Pelvic Floor Muscles
    Muscles that support pelvic organs.
    Adductors
    Muscles that bring the thighs toward the midline.
    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.
    Biceps Brachii
    Muscle responsible for elbow flexion.
    Clavicle
    Collarbone connecting the arm to the body.
    Ellipsoidal (Condyloid) Joints
    e.g., wrist
    Occipital Bone
    Bone forming the back and base of the skull.
    Glenohumeral Ligaments
    Shoulder ligaments that stabilize the shoulder joint.
    Hinge Joints
    e.g., elbow, knee
    Carpals (8 bones)
    8 wrist bones.
    Lacrimal Bones
    Bones forming part of the eye socket and housing the tear ducts.
    Sacrum
    Triangular bone at the base of the spine.
    Vomer Bone
    Bone forming the nasal septum.
    Maxillae
    Upper jaw bones that house the teeth and form part of the orbit.
    Lateral Collateral Ligament (LCL)
    Knee ligament that stabilizes the outer knee.
    Sartorius
    Longest muscle in the body responsible for hip flexion.
    Sesamoid Bones
    e.g., patella, some found in hands/feet.
    Ethmoid Bone
    Bone forming part of the nasal cavity and the orbit.
    Zygomatic Bones
    Cheekbones that form part of the orbit.
    Coracoacromial Ligament
    Ligament that connects the acromion to the coracoid process.
    Radius
    Forearm bone on the thumb side.
    Tibialis Anterior
    Muscle that dorsiflexes and inverts the foot.
    Ribs (12 Pairs)
    12 pairs of bones that form the sides of the thoracic cage.

    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 bones make up only 15% of your body weight.