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    Related Topics

    From Musculoskeletal System

    Ribs (12 Pairs)
    12 pairs of bones that form the sides of the thoracic cage.
    Pubis
    Part of the pelvis that joins with the opposite side to form the pubic symphysis.
    Acromioclavicular Joint
    The acromioclavicular joint connects the clavicle and scapula at the top of the shoulder, enabling smooth scapular motion and stability during arm movements.
    Frontal Bone
    Bone forming the forehead and upper part of the orbits.
    Acetabulum
    The acetabulum is the pelvic socket that connects with the femoral head to form the hip joint, vital for stability, movement, and weight-bearing.
    Buccinator
    Muscle that helps with chewing and blowing air out.
    Vertebral Column
    Spinal column consisting of vertebrae.
    Maxillae
    Upper jaw bones that house the teeth and form part of the orbit.
    Hinge Joints
    e.g., elbow, knee
    Gluteus Maximus
    Largest muscle in the buttocks responsible for hip extension.
    Brachioradialis
    Muscle responsible for forearm flexion.
    Skull
    Bony structure of the head that encases the brain.
    Thoracic Vertebrae (T1 - T12)
    Vertebrae in the upper and mid-back (T1-T12).
    Annular Ligament
    The annular ligament is a strong fibrous band encircling the head of the radius, stabilizing the proximal radioulnar joint and allowing smooth rotation of the forearm.
    Palatine Bones
    Bones forming part of the hard palate and nasal cavity.
    Coccygeus
    Pelvic floor muscle supporting the coccyx.
    Biceps Tendon
    Tendon that attaches the biceps muscle to the bone.
    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.
    Lumbar Vertebrae (L1 - L5)
    Vertebrae in the lower back (L1-L5).
    Sphenoid Bone
    Bone forming part of the base of the skull and sides of the orbits.
    Ball-and-Socket Joints
    e.g., shoulder, hip
    Sesamoid Bones
    e.g., patella, some found in hands/feet.
    Rotator Cuff Muscles
    Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.
    Metacarpals (5 bones)
    5 bones forming the palm of the hand.

    Ellipsoidal (Condyloid) Joints

    Reviewed by our medical team

    e.g., wrist

    1. Overview

    An ellipsoidal joint, also known as a condyloid joint, is a type of synovial joint that permits movement in two planes: flexion–extension and abduction–adduction. These biaxial joints have an oval-shaped condyle of one bone fitting into the elliptical cavity of another, allowing angular but not rotational movement. Ellipsoidal joints are essential for precise, controlled motion and are found in areas requiring coordinated mobility and stability.

    2. Location

    Ellipsoidal joints are present in several key areas of the body:

    • Wrist joint (radiocarpal joint): Between the distal radius and the scaphoid and lunate carpal bones.

    • Metacarpophalangeal joints (MCPs): Between the heads of metacarpal bones and bases of proximal phalanges in the fingers (knuckle joints).

    • Atlanto-occipital joint: Between the occipital condyles of the skull and the superior facets of the atlas (C1 vertebra).

    • Metatarsophalangeal joints (MTPs): Similar joints in the toes.

    3. Structure

    Ellipsoidal joints are structured for complex movement within a confined range:

    • Articular surfaces: One surface is an oval convex condyle, and the other is a reciprocally shaped concave surface.

    • Joint capsule: Encloses the joint and is lined by a synovial membrane that secretes synovial fluid.

    • Synovial fluid: Lubricates the joint, reduces friction, and nourishes articular cartilage.

    • Ligaments: Surround and stabilize the joint, preventing excessive or abnormal movement.

    • Articular cartilage: Covers the joint surfaces, allowing smooth, low-friction interaction between bones.

    4. Function

    Ellipsoidal joints allow a range of controlled, angular motions:

    • Flexion and extension: Movement in the sagittal plane, such as bending and straightening fingers.

    • Abduction and adduction: Movement in the coronal plane, such as spreading fingers apart or bringing them together.

    • Circumduction: A circular, conical motion combining flexion, extension, abduction, and adduction (but no axial rotation).

    5. Physiological role(s)

    Ellipsoidal joints play crucial roles in fine and gross motor function:

    • Manual dexterity: MCP joints are key to grasping, pinching, and manipulating objects with precision.

    • Postural alignment: Atlanto-occipital joint helps support head posture and balance.

    • Locomotion support: MTP joints contribute to propulsion and toe-off during walking and running.

    • Articulation balance: These joints enable complex joint interplay without compromising stability.

    6. Clinical Significance

    Several conditions can affect ellipsoidal joints and impair their function:

    • Osteoarthritis:

      • Degeneration of articular cartilage in MCP or wrist joints causes stiffness, pain, and loss of function.

    • Rheumatoid arthritis:

      • Commonly affects MCP joints with joint swelling, deformity (e.g., ulnar drift), and inflammation.

    • Atlanto-occipital dislocation:

      • A rare but life-threatening injury where the skull becomes dislodged from the spine, often due to trauma.

    • Joint contracture or stiffness:

      • Prolonged immobility or scarring may limit movement at ellipsoidal joints, particularly in the fingers.

    • Joint injections or aspiration:

      • Inflamed or swollen ellipsoidal joints, especially the wrist, may require corticosteroid injections or fluid removal for relief.

    Did you know? The clavicle is the only bone in the body that connects the arm to the body trunk.