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.
As a result of this process, the penis becomes stiffened. In contrast, the glans penis, which is the enlarged crown of the corpus spongiosum, retains some flexibility during an erection due to its relatively thin tunica albuginea compared to other areas of the penis.