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What are the corpus cavernosum and corpus spongiosum?

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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 penis contains three cylindrical masses of erectile tissue that facilitate erection. These structures are bound together by fibrous tissue and contain spongelike networks that fill with blood during sexual excitation.12

Corpora Cavernosa

The two corpora cavernosa are identical, long cylindrical bodies located along the sides and upper portion of the penis. They consist of empty spaces divided by partitions of muscle, collagen, and elastic fiber. During an erection, these spaces fill with blood, which becomes temporarily trapped, causing the penis to enlarge and harden.12

Corpus Spongiosum

The corpus spongiosum is a single mass of tissue located below the corpora cavernosa. It surrounds the urethra and extends forward to form the glans penis. While also considered erectile tissue, it contains more fibrous tissue and less space than the corpora cavernosa. It does not become as rigid during an erection, as it maintains a constant blood flow to prevent the urethra from collapsing, thereby ensuring the passage of semen.12