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    Related Topics

    From Musculoskeletal System

    Tibialis Anterior
    Muscle that dorsiflexes and inverts the foot.
    Trapezius
    Muscle responsible for moving, rotating, and stabilizing the scapula.
    Sutures (in the skull)
    Fibrous joints between skull bones.
    Sesamoid Bones
    e.g., patella, some found in hands/feet.
    Adductors
    Muscles that bring the thighs toward the midline.
    Hinge Joints
    e.g., elbow, knee
    Posterior Longitudinal Ligament
    Spinal ligament running along the back of the vertebral column.
    Sartorius
    Longest muscle in the body responsible for hip flexion.
    Obliques (External and Internal)
    Muscles responsible for torso rotation.
    Quadriceps Tendon
    Tendon that connects the quadriceps to the patella.
    Patellar Tendon
    Tendon connecting the patella to the tibia.
    Iliolumbar Ligament
    Ligament connecting the ilium and lumbar vertebrae.
    Anterior Longitudinal Ligament
    Spinal ligament running along the front of the vertebral column.
    Pectoralis Major
    Chest muscle responsible for shoulder movement.
    Masseter
    Muscle that elevates the mandible.
    Pelvic Floor Muscles
    Muscles that support pelvic organs.
    Ellipsoidal (Condyloid) Joints
    e.g., wrist
    Interspinous Ligament
    Spinal ligament between adjacent vertebral spinous processes.
    Zygomaticus
    Muscle that raises the corners of the mouth.
    Metatarsals (5 bones)
    5 bones forming the mid-foot.
    Tarsals (7 bones)
    7 ankle bones.
    Palatine Bones
    Bones forming part of the hard palate and nasal cavity.
    Cervical Vertebrae (C1 - C7)
    Vertebrae in the neck region (C1-C7).
    Ligamentum Flavum
    Spinal ligament connecting the laminae of adjacent vertebrae.
    Coccyx
    Tailbone, the remnant of the tail in humans.

    Sacroiliac Ligaments

    Reviewed by our medical team

    Ligaments connecting the sacrum to the iliac bones.

    1. Overview

    The sacroiliac (SI) ligaments are a group of strong, fibrous structures that stabilize the sacroiliac joints—the articulations between the sacrum and the ilium of the pelvis. These ligaments are essential for maintaining pelvic integrity, distributing weight from the upper body to the lower limbs, and limiting excessive motion at the SI joint, which is mostly an immobile or slightly mobile joint.

    2. Location

    The sacroiliac ligaments are located in the posterior pelvis, surrounding the sacroiliac joints:

    • Connect: The sacrum (S1–S4 vertebrae) to the ilium of each hip bone.

    • Span: From the lateral sacral surface to the ilial auricular surface and iliac tuberosity.

    • Lie posterior to: The sacroiliac joint capsule and anterior pelvic organs.

    3. Structure

    There are several distinct sacroiliac ligaments, classified into anterior, interosseous, and posterior groups:

    • Anterior sacroiliac ligament:

      • A thin, broad band located on the anterior surface of the joint capsule.

      • Connects the anterior sacral ala to the ilium's auricular surface.

    • Interosseous sacroiliac ligament:

      • The strongest and deepest of the SI ligaments.

      • Occupies the space between the sacrum and the ilium posterior to the joint.

      • Provides the primary stabilization of the SI joint.

    • Posterior sacroiliac ligament:

      • Located on the dorsal surface of the sacrum and ilium.

      • Subdivided into short (horizontal) and long (oblique) portions.

      • Attaches from the sacral tubercles to the posterior superior iliac spine (PSIS) and iliac crest.

    These ligaments are composed of densely packed collagen fibers capable of resisting high tensile loads and shear forces.

    4. Function

    The sacroiliac ligaments provide essential structural and mechanical functions:

    • Stabilize the sacroiliac joint: Limit anterior and inferior movement of the sacrum relative to the ilium.

    • Distribute mechanical load: Transfer weight from the spine to the pelvic girdle and lower limbs.

    • Resist shear forces: Prevent displacement during twisting, lifting, or shifting motions.

    • Anchor pelvic structures: Support the connection between the axial and appendicular skeletons.

    5. Physiological role(s)

    Though passive in nature, sacroiliac ligaments contribute to:

    • Postural integrity: Maintain pelvic alignment during upright stance, walking, and load-bearing.

    • Shock absorption: Act as tension-bearing structures during spine and hip motion.

    • Pelvic movement regulation: Control minute joint glides (nutation and counternutation) needed for locomotion and childbirth.

    • Proprioception: Contain mechanoreceptors that help the nervous system regulate posture and movement.

    6. Clinical Significance

    Dysfunction or injury to the sacroiliac ligaments can lead to pain and mobility issues:

    • Sacroiliac joint dysfunction:

      • May result from ligamentous laxity, trauma, leg-length discrepancy, or poor biomechanics.

      • Presents as lower back or buttock pain, sometimes radiating to the thigh.

    • Sacroiliitis:

      • Inflammation of the SI joint, often involving the ligaments; associated with conditions like ankylosing spondylitis and other spondyloarthropathies.

    • Ligament strain or tear:

      • Can occur from sudden rotational forces, lifting injuries, or falls.

      • May cause acute localized pain, swelling, and tenderness over the SI joint.

    • Pregnancy-related pelvic pain:

      • Hormonal relaxation of the sacroiliac ligaments increases joint mobility, which can result in pain and instability.

    • Injection or surgical intervention:

      • SI joint injections target inflammation involving these ligaments.

      • Fusion surgery may be considered for chronic, treatment-resistant SI joint instability.

    Did you know? The human body has over 600 muscles.