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    From Musculoskeletal System

    Carpals (8 bones)
    8 wrist bones.
    Symphyses
    Cartilaginous joints where bones are connected by fibrocartilage.
    Quadriceps Tendon
    Tendon that connects the quadriceps to the patella.
    Phalanges (14 bones)
    14 bones forming the toes.
    Flexor Tendons
    Tendons that help flex the fingers and toes.
    Acromioclavicular Ligament
    Ligament that connects the acromion to the clavicle.
    Metatarsals (5 bones)
    5 bones forming the mid-foot.
    Anterior Longitudinal Ligament
    Spinal ligament running along the front of the vertebral column.
    Tibia
    Shin bone, the larger bone in the lower leg.
    Metacarpals (5 bones)
    5 bones forming the palm of the hand.
    Mandible
    Lower jawbone that houses the teeth.
    Diaphragm
    Primary muscle for breathing.
    Patellar Tendon
    Tendon connecting the patella to the tibia.
    Biceps Brachii
    Muscle responsible for elbow flexion.
    Palatine Bones
    Bones forming part of the hard palate and nasal cavity.
    Pubis
    Part of the pelvis that joins with the opposite side to form the pubic symphysis.
    Gluteus Maximus
    Largest muscle in the buttocks responsible for hip extension.
    Ulna
    Forearm bone on the pinky side.
    Sacroiliac Ligaments
    Ligaments connecting the sacrum to the iliac bones.
    Pectoralis Major
    Chest muscle responsible for shoulder movement.
    Rotator Cuff Muscles
    Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.
    Ribs (12 Pairs)
    12 pairs of bones that form the sides of the thoracic cage.
    Biceps Tendon
    Tendon that attaches the biceps muscle to the bone.
    Pelvic Floor Muscles
    Muscles that support pelvic organs.
    Soleus
    Calf muscle responsible for plantarflexion of the foot.

    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? Bones in the feet form arches that provide balance and flexibility.