Latin synonyms: Ala ossis ilii/ Facies iliaca alae ossis ilium
The iliac fossa or fossa iliaca in Latin is the smooth internal cavity of the ilium, the largest of the three fused bones that form the hip (ilium, ischium, and pubis). It is positioned in an antero-superior direction, and is bounded by the iliac crest from above, the anterior border from the front, and the medial border, separating it from the sacropelvic surface, from behind.
The posterolateral wall of the greater pelvis is formed by this smooth and slightly concave fossa. Below, it is continuous with a wide shallow groove that lies in between the anterior inferior iliac spine and the iliopubic ramus. The converging fibers of the iliacus muscle occupy said groove laterally, while the tendon of the psoas major muscle do so medially. A bursa separates the tendon from the underlying bone.
The iliolumbar artery is the major supplier of the iliac fossa. Within the fossa, it divides into an iliac branch, which supplies the ilium and iliacus muscle, and a lumbar branch, which supplies the psoas major and quadratus lumborum muscles. The iliolumbar veins from the iliac fossa of the greater pelvis follow the same course as the arteries and then usually drain into the common iliac veins.
The right iliac fossa houses the caecum (the first part of the large intestine), the vermiform appendix, and the terminal ilium. The left iliac fossa on the other hand, contains the terminal part of the descending colon and the proximal sigmoid colon. Clinically, pain and tenderness in the right iliac fossa immediately raises the suspicion of appendicitis. Pain in the left iliac fossa is less common, and tends to affect older populations.
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