Ultimately, the cause for erectile dysfunction is that not enough nitric oxide NO is released by the vascular endothelium of the branches of the perineal artery , a branch of the internal pudendal artery. Book for Boys: Revised Edition. Hypothalamic—pituitary—gonadal axis Hypothalamic—pituitary—prolactin axis Andrology Hormone. Main article: Human penis size. Look up penis in Wiktionary, the free dictionary. For the similar arousal in females, see clitoral erection. Menarche Menstruation Follicular phase Ovulation Luteal phase.
Heidi. Age: 28.
Protrusion is not affected much by erection, but more by relaxation of the retractor penis muscle and straightening of the sigmoid flexure.
Mina. Age: 22.
An Investigation: What's Better – Curved Dicks or Straight Dicks?
Although many erect penises point upwards, it is common and normal for the erect penis to point nearly vertically upwards or nearly vertically downwards or even horizontally straight forward, all depending on the tension of the suspensory ligament that holds it in position. Socially, such erections can be embarrassing if they happen in public or when undesired. This may also become slightly engorged with blood, but less so than the corpora cavernosa. Given the small amount of erectile tissue in a bull's penis , there is little enlargement after erection.