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    From Musculoskeletal System

    Anterior Cruciate Ligament (ACL)
    Knee ligament that stabilizes the joint.
    Vomer Bone
    Bone forming the nasal septum.
    Lacrimal Bones
    Bones forming part of the eye socket and housing the tear ducts.
    Hamstrings
    Biceps Femoris, Semitendinosus, Semimembranosus.
    Diaphragm
    Primary muscle for breathing.
    Maxillae
    Upper jaw bones that house the teeth and form part of the orbit.
    Carpals (8 bones)
    8 wrist bones.
    Achilles Tendon
    Tendon connecting the calf muscle to the heel bone.
    Coccyx
    Tailbone, the remnant of the tail in humans.
    Mandible
    Lower jawbone that houses the teeth.
    Facial Bones
    Bones forming the structure of the face.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Deltoid
    Shoulder muscle responsible for arm abduction.
    Tarsals (7 bones)
    7 ankle bones.
    Gomphoses
    Fibrous joints where a peg fits into a socket (e.g., teeth in jaw).
    Sutures (in the skull)
    Fibrous joints between skull bones.
    Gastrocnemius
    Calf muscle responsible for plantarflexion of the foot.
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    Temporal Bones
    Bones forming the lower sides of the skull and housing the ears.
    Anterior Longitudinal Ligament
    Spinal ligament running along the front of the vertebral column.
    Pelvic Floor Muscles
    Muscles that support pelvic organs.
    Ribs (12 Pairs)
    12 pairs of bones that form the sides of the thoracic cage.
    Hinge Joints
    e.g., elbow, knee
    Iliolumbar Ligament
    Ligament connecting the ilium and lumbar vertebrae.
    Skull
    Bony structure of the head that encases the brain.

    Synchondroses

    Reviewed by our medical team

    Cartilaginous joints where bones are connected by hyaline cartilage.

    1. Overview

    Synchondroses are a type of cartilaginous joint where two bones are joined by hyaline cartilage. These joints are typically immovable (synarthroses) and are primarily found during growth and development stages. Some synchondroses are temporary and fuse over time, while others persist throughout life, serving structural and functional roles in the axial skeleton.

    2. Location

    Synchondroses occur in various regions, particularly in growing bones and parts of the thoracic and cranial base. Common examples include:

    • Epiphyseal plates (growth plates): Between the epiphysis and diaphysis of long bones during development.

    • First sternocostal joint: Between the first rib and the manubrium of the sternum (permanent synchondrosis).

    • Spheno-occipital synchondrosis: Between the sphenoid and occipital bones in the cranial base (fuses in adolescence).

    • Intra-pelvic synchondroses (in infants): Found temporarily between parts of developing hip bones.

    3. Structure

    Synchondroses are structurally simple yet biomechanically significant:

    • Connecting tissue: Hyaline cartilage unites the two bones.

    • Bone surfaces: Covered by smooth cartilage without a synovial cavity.

    • No joint capsule: Unlike synovial joints, synchondroses lack a surrounding fibrous capsule.

    • Vascularity: Limited blood supply in the cartilage; most nourishment comes via diffusion.

    In growing bones, synchondroses are often part of the growth mechanism and later undergo ossification (endochondral fusion).

    4. Function

    Synchondroses provide both temporary and permanent mechanical functions:

    • Allow bone growth: Epiphyseal plates enable longitudinal growth in long bones during childhood and adolescence.

    • Provide stability: In permanent synchondroses like the first sternocostal joint, they ensure rigid yet slightly flexible connections.

    • Transmit forces: Act as force-transmitting interfaces between adjacent skeletal elements (e.g., ribs and sternum).

    5. Physiological role(s)

    Synchondroses support critical physiological functions:

    • Facilitate development: Essential in endochondral ossification during skeletal growth.

    • Maintain thoracic shape: Provide slight flexibility to the upper rib cage for breathing while maintaining stability.

    • Cranial base formation: Contribute to the alignment and shape of the skull during early development.

    6. Clinical Significance

    Though less commonly injured, synchondroses are involved in several clinical scenarios:

    • Growth plate fractures:

      • In children and adolescents, trauma can damage epiphyseal synchondroses (Salter-Harris fractures), potentially affecting bone growth.

    • Premature closure:

      • Early fusion of epiphyseal plates can lead to limb length discrepancies or skeletal deformities.

    • Spheno-occipital fusion issues:

      • Abnormal fusion may contribute to craniofacial anomalies or interfere with cranial base development.

    • Costochondritis (rarely involving first rib synchondrosis):

      • Inflammation near the first sternocostal synchondrosis may cause localized chest pain, though most costochondritis affects synovial joints of other ribs.

    • Ossification and aging:

      • Many synchondroses ossify with age, reducing thoracic flexibility and contributing to skeletal rigidity in elderly individuals.

    Did you know? The sternum is connected to the ribs by cartilage.