Iliac CrestEdit
The iliac crest is the thick, curved superior border of the ilium, one of the three bones that make up the pelvic girdle. It forms a prominent ridge along the upper edge of the pelvis and can be felt through the skin on the flank. Running from the anterior superior iliac spine to the posterior superior iliac spine, the crest marks the transition between the inner and outer aspects of the pelvis and serves as an important muscular attachment site as well as a readily palpable clinical landmark.
In life, the crest provides attachment for several abdominal and hip muscles and plays a role in shaping the contour and function of the pelvic region. Because it is a clear surface on which soft tissue can be anchored, it is frequently referenced in clinical exam and imaging. The crest is part of the larger ilium, which in turn contributes to the stability and mobility of the hip joint and the trunk. For orientation, clinicians often relate the crest to nearby landmarks such as the anterior superior iliac spine anterior superior iliac spine and posterior superior iliac spine posterior superior iliac spine.
Anatomy
Structure and boundaries
The iliac crest forms the superior margin of the ilium, extending along the outer surface of the bone. It is a robust, palpable ridge that can be traced from the front to the back of the pelvis. The crest serves as a dividing line between the inner and outer aspects of the pelvic wall and overhangs the gluteal region.
Attachments and relationships
Numerous structures arise from or attach to the crest. Notable muscular connections include: - the gluteus medius muscle, which originates from the outer lip of the crest and the broader surface of the ilium; - the external oblique muscle, with its aponeurosis attaching to the iliac crest as part of the abdominal wall; - the internal oblique and transversus abdominis muscles also have origins that involve the region around the crest.
The crest is also a key anchor for fascia and connective tissue in the region and helps define the boundary between the abdomen and the thigh. In imaging and surgical contexts, the crest serves as a reliable reference point for locating underlying structures, including the lumbar spine and hip joint.
Development and variation
During growth, the ilium and its apophyses develop in a coordinated pattern. The iliac crest features an apophysis in adolescence that fuses with the main bone over time. The crest can differ in prominence and orientation among individuals, and its contour may be influenced by habitual posture and muscular development.
Clinical landmarks and imaging
In medical practice, the posterior aspect of the crest aligns with important landmarks used during procedures and assessments. One well-known reference is the line that roughly corresponds to the level of the L4-L5 intervertebral space, commonly used to guide lumbar procedures in combination with palpation of the iliac crest. The crest thus functions as both a surface landmark and a functional attachment site in the musculoskeletal system.
Clinical significance
Palpation and procedures
Because it is a prominent and stable surface, the iliac crest is routinely palpated during physical examination and used to orient imaging studies (X-ray, CT, MRI) of the pelvis and lower spine. It is often referenced when describing the location of injuries, surgical plans, and graft donor sites.
Hip pointer and athletic injuries
Direct trauma to the iliac crest, such as a blow to the hip, can cause a hip pointer injury— a painful contusion to the crest region. Such injuries are common in contact sports and can limit movement and weight-bearing for a period of time.
Bone grafting and reconstructive surgery
The iliac crest is a widely used donor site for autografts in orthopedic and maxillofacial procedures. The combination of cortical and cancellous bone in the crest makes it suitable for grafting material in spinal fusions, reconstructive surgery, and dental implant augmentation. Harvesting bone from the crest must be weighed against potential donor-site morbidity and patient factors.
Fractures and developmental issues
Fractures of the iliac crest are uncommon compared with other pelvic injuries but may occur after high-energy trauma. In adolescents, the crest can be involved in apophyseal injuries, which may present with localized tenderness and swelling. Imaging helps distinguish these from more serious pelvic injuries.