The penis becomes rigid as a result. The glans penis, the expanded cap of the corpus spongiosum, remains more malleable during erection because its tunica albuginea is much thinner than elsewhere in the penis.
The penis hardens as a consequence. The glans penis, the expanded head of the corpus spongiosum, remains more pliable during erection because its tunica albuginea is much thinner than elsewhere in the penis.