This
section describes the visible parts which
make up a man's sexual organs: the penis and
scrotum. There are actually quite a lot of
parts which have to work together smoothly
to make sex possible and satisfying. Knowing
a little about these parts will give you
more understanding of your own body and how
your sexual response works.
The
penis
The
penis is a very individual organ.
Penis shape, size, color and thickness
vary from man
to man. Looking at it, one can distinguish a
long shaft with a tip, called the glans, at
the end. The shaft and glans are separated
by the corona, or coronal rim, which runs
like a ring around the penis just at the
base of the glans. On the underside, the
corona is traversed by the frenulum, a
little piece of skin which joins up the
shaft and the foreskin. This area contains a
lot of nerve endings, which makes it one of
the most sensitive areas on the penis. The
outer skin of the penis, towards the end,
normally fits loosely and usually covers the
glans of the penis in the flaccid state.
This part of the skin is called the foreskin
or prepuce; it is often removed during
circumcision. At the top of the glans you
find the opening of the urethra, through
which urine and semen (ejaculatory fluid)
are passed to the outside.
The
base of the penis is attached in three parts
to the internal skeleton and muscles of the
hip region. Two suspensory ligaments which
run from the base of the penis to the
internal structure of the hip help to keep
the penis at an upright angle when it's
erect.
The
inside of the penis mostly consists of three
spongy bodies, which run parallel to each
other down the whole length of the penis.
During an erection, these spongy areas fill
with blood and allow the penis to go hard.
If
you look at a cross section of the penis,
the two major spongy bodies are called the
corpora cavernosa, or cavernous bodies. They
lie side by side. Along their underside runs
the third spongy body, the corpus
spongiosum. This spongy area is thinner, but
through its length runs the urethra, the
tube through which you pass urine. At the
tip of the penis, the corpus spongiosum
expands to form the whole of the body of the
glans. At the top of the two cavernous
bodies run the deep dorsal vein and in the
middle of it are the dorsal artery and
penile nerves. Additionally, the cavernosal
arteries run along the length of the
cavernous bodies, bringing a rich blood
supply to the penis. As an erection results
from more blood coming into the penis than
going out, all of these blood vessels are
essential for the penis to function
correctly.
Another
essential part of the penis are the
membranes which surround each of the spongy
bodies and the whole structure. Each spongy
body is surrounded by a fascia, the tunica
albuginea. The whole structure of the three
spongy bodies is surrounded by the Buck's
fascia. This layer also contains the deep
dorsal vein and the dorsal artery and nerve.
Then a third layer holds the penis together,
the superficial or Colles fascia, which
contains another blood vessel, the
superficial dorsal vein.
Graphic of
a penis going from soft (flaccid) to erect
(click on the image to make it bigger).
The
scrotum
The
word scrotum literally means bag. It's the
supporting structure which holds the
testicles, the organs which produce sperm
and testosterone. The scrotum itself is made
up of loose skin, fascia and muscle and it
hangs underneath the end of the penis
attached to the abdominal wall. Along its
midline runs the raphe (or seam), which
shows where, internally, a septum divides
the scrotum into two areas, each containing
one of the testicles. The scrotum contains
smooth muscle fibers, the dartos muscle,
which runs into the smooth subcutaneous
muscles of the abdominal wall. Under certain
conditions such as cold temperatures, or
during exercise, fear or sexual intercourse,
the dartos muscle contracts and pulls the
testicles closer to the body. When it's
warm, or under loose clothing, or in older
men, the dartos muscle tends to be more
relaxed and the
scrotum hangs quite low.
This allows the testicles to be kept away
from the body and remain cooler than normal
body temperature. This reduction in
temperature is believed to help sperm
production. One of the testicles, normally
the left one, hangs a bit lower in the
scrotum, which makes it easier for a man to
walk without squeezing his balls. It's also
quite normal for one testicle to be bigger
than the other.
Read
more about the internal parts of your sexual
equipment:
