crura

Crura, plural of crus, are elongated, leg‑like structures used in anatomy to describe several distinct anchor points or bases within organs. The term comes from Latin crura, meaning “legs,” and is applied across systems to denote paired, structural supports that connect proximal parts of an organ to surrounding bones or brain regions.

Diaphragmatic crura are paired tendinous bands that arise from the upper lumbar vertebrae. The right crus typically originates from L1 to L3 and the left from L1 to L2; they ascend to form part of the diaphragmatic muscle. The crura surround openings through which major structures pass: the esophagus is enclosed by fibers of the right crus to form the esophageal hiatus, while the aorta passes between the crura at the aortic hiatus, with the median arcuate ligament contributing anteriorly. These crura help stabilize the esophagogastric junction and maintain diaphragmatic function. Pathologies such as hiatal hernia involve alterations in this region.

Crura cerebri, or the cerebral peduncles, are two prominent bundles of descending motor fibers on the ventral aspect of the midbrain. Each crus carries corticospinal, corticobulbar, and other projection fibers from the cerebral cortex toward the brainstem and spinal cord. The crura are separated by the interpeduncular fossa and are visualized on the brain’s ventral surface; lesions here can produce contralateral motor deficits depending on the tract involved.

Penile and clitoral crura are the proximal roots of the corpora cavernosa that anchor the respective organ to the pubic rami. In the penis, the crura arise from the ischiopubic rami and extend toward the body, forming part of the erectile tissue together with the corpora cavernosa. The clitoral crura are homologous structures that contribute to erection. Both sets of crura are supplied by cavernous arteries and autonomic nerves, and their engorgement during arousal aids in erection.