Answer
1. When the penis is flaccid, most of its blood supply comes from the dorsal branch of the penile artery.
2. The blood that fills the lacunae and results in erection of the penis comes from the dilated deep branch of the penile artery.
Work Step by Step
The blood supply of the penis come from branches of the internal iliac arteries-- the internal pudendal or penile arteries; these enter the root of the penis and divide. Each penile artery gives rise to a superficial dorsal branch which supplies adjacent skin fascia and corpus spongiosum. The deep branch travels into the corpus spongiosum on each side and gives off branches that empty into the lacunae of these structures.
