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How does the corpus spongiosum relate to the urethra?

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Front view anatomical diagrams of the male and female reproductive systems, with labeled organs including penis, testis, prostate gland, uterus, ovary, and vagina. — human reproductive system Organs and structures of the male and female reproductive systems.

The corpus spongiosum is a single mass of erectile tissue that plays a critical role in protecting the urethra during sexual activity. Anatomically, it lies in a midline groove on the undersurface of the two corpora cavernosa and directly surrounds the urethra throughout the length of the penis.12

The relationship between these structures is essential for reproductive function:

Structural Support: The corpus spongiosum contains the urethra, which serves as a passage for both urine and semen.12
Prevention of Collapse: Unlike the corpora cavernosa, the corpus spongiosum does not become as rigid during an erection. Because it maintains a continual outflow of blood, the tissue does not compress the urethra, ensuring the passage remains open for the release of semen.2
Extension: The corpus spongiosum extends beyond the corpora cavernosa to form the glans penis, where the urethra terminates at the external opening.12