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ANATOMY
OF
THE
PENIS
AND
RELATED
AREAS
Overview
The penis is the male organ of reproduction and urinary
elimination, located on the midline of the front lower abdomen
at the level of the pubic bone, above the
scrotum. It develops in the male embryo from a small mass of
tissue that also forms the clitoris in the female embryo.
The Penis
The penis is actually made of three separate cylinders (two on
top and one on bottom) of a special type of erectile tissue
that are capable of filling with blood and becoming rigid.
Each of the three cylinders is covered with a thin layer of
thin but tough connective
tissue, as well as being bound together as a group with that
same type of thin tissue. The two top cylinders are called the
“corpora cavernosa” because of the thousands of tiny caverns,
or open spaces in the tissue
that fill with blood during erection. The bottom cylinder is
called the “corpora spongiosum” because it is composed of soft
and spongy tissue; it has the “urethra” or urinary passage
tube running through it from the bladder, and ends at the tip
of the penis. As the corpora spongiosum nears the end of the
penis, it flares out to form the “glans” or head of the penis
that looks like a mushroom or cap on top of the two corpora
cavernosa.
If you are interested in learning about PD, then you must
understand the special connective tissue layers below the skin
surface of the penis. This particular tissue that is so
important in any discussion of PD is a very thin membrane, called the
tunica albuginea. It is made of connective tissue and it covers
or wraps around
the two corpora cavernosa cylinder bodies. Under the
microscope it is possible to see that the tunica albuginea is
not a solid structure but it is a laminated, or multilayered
structure like pages of a book or layers of an onion. The
tunica albuginea not only covers the penis structure once with
this laminated tissue, it covers it twice.
The first deep layer, shaped like a tube, encloses each of the
two corpora cavernosa. Since the corpora cavernosa are located
closely side-by-side, where the two cylinders touch along the
midline the inner layer forms a band of tissue called a
septum. The second layer of the tunica albuginea, also shaped
like a tube but twice as large, goes around the pair of the
corpora cavernosa. (Think of it this way: the two corpora
cavernosa are like two hot dogs, side by side; each hot dog
has a casing or cover on it; the two hot dogs and their
casings are held together with another layer of casing to bind
them together in a pair. Where the two hot dogs and casings
touch each other, the two casings fuse to make the septum; the
septum fuses also to the second casing layer to make a very
strong and secure structure.) Back to the penis: The septum of
the deep inner layer attaches along the midline to the top and
bottom section of the superficial outer layer, creating a
structure that is almost like an I-beam. In addition, there is
another or third layer of connective tissue around the two
corpora cavernosa that is even more superficial than the
tunica albuginea. It is another tubular layer of tissue,
called Buck’s fascia, that gives the penis added rigidity when
the corpora cavernosa fill with blood during erection. There
are no nerve endings in the tunica albuginea, but there are
nerve endings in Buck’s fascia. Any pain associated with PD
comes from stretching or inflammation of Buck’s fascia, not
the tunica albuginea.
The blood supply to the penis, by way of the internal pudendal
artery, is abundant. Good blood circulation is required for
the corpora cavernosa and corpora spongiosum to produce an
erection. However, not all parts of the penis have or need a
good supply of blood. As is typical of most connective tissue
in the body, the tunica albuginea does not have a good blood
supply – it doesn’t need it for the most part, although this
poor blood supply works against it. When injured, the poor
blood flow to the tunica albuginea causes it to heal slowly or
poorly in some cases. The limited blood supply to the tunica
is an important aspect of the anatomy of the penis that
affects the outcome of Peyronie’s disease. Therefore, keeping
the blood flow to the penis as full as possible is vital to
the health of this tissue and improves chances for its
recovery after injury; lack of blood flow favors scar
development.
It is perhaps no coincidence that a study showed that out of
76 cases of PD 36% had arterial disease and 59% had obstructed
venous drainage in the blood circulation to the penis.(1) Other research has also shown a mixture of circulation
problems with the arteries and veins of men with PD.(2,3) For these very important reasons,
PDI treatment
recommendations strongly emphasize therapy that will increase
blood circulation to and from the penis. No where else have we
found any authority to draw attention to, or correlate, this
important anatomical or therapeutic factor.
Please refer to Figure 1, below, for details of normal penis
anatomy, as well as detail of a scar (plaque) in the
tunica albuginea that is shown to be distorting the penis.
Figure 1
...and
This is How It Works...
With a better understanding of the anatomy of the male organ
of reproduction, it should be easier to understand how the
male anatomy "comes to attention" when erect. If you
wish to understand how this complicated, but
fascinating, process of erection occurs, click on
How an
Erection Happens.
Soft Tissue of
the Pelvis
“Soft tissue” is a general anatomy term that refers to a broad
group of supporting and connecting tissues of the skeleton
that are not hard: skin, muscle, tendon, ligament and fascia
(a thin delicate membrane of connective tissue found
throughout the body that surrounds and covers internal organs,
muscles and related soft tissue structures, almost like Saran
plastic wrap ) .
In particular, this discussion is most concerned with the soft
tissue directly or indirectly associated with the penis. These
soft tissues are the various layers of muscles, tendons,
ligaments and fascia of the lower pelvic floor, inguinal or
groin region and the lower abdominal wall around the pubic
bone especially. Please refer to Figure 2, below, for a
general idea of these different tissues, and their
relationship to the male genital organ. What makes these soft
tissues so important to PD is their influence on the blood
supply and the lymphatic drainage (see below) to the genital
area.
Figure 2
Lymphatic
Drainage of the Pelvis
Simply, the lymph system is the sewer system of the body. It
consists of a large network of lymph vessels (much like
veins), that carry a clear fluid called lymph (much like
plasma). Along the pathway of these lymph vessels, from place
to place, there are small bean-shaped bodies of tissue (called
lymph nodes) that serve as filters. Refer to figure 3, below, to
see how all of this is connected. These are the same type of lymph
nodes that become tender and swollen under your jaw when you
have a sore throat.
Lymph nodes are distributed
throughout the
body, including the groin and deep in the lower pelvis where
you cannot touch them. The purpose of the lymph system is to
remove infection, cellular debris and toxins from every part
of the body. The final destination of the lymph fluid in the
lymph vessels is to enter into the liver for final disposal
and elimination via the gall bladder. Every part of the body
needs a full and uninterrupted movement of lymph fluid in both
directions, in and out. If there is poor movement or flow of
lymph, then toxins accumulate and fluid starts to collect,
like a backed-up sewer. The lymph fluid is moved along in the
lymph vessels by gravity and by internal massage and pressure
from those tissues that lay along side the lymph vessels.
Spasm, contraction and shortening of various soft tissues can
constrict the lymph vessels and cause backing up and
stagnation of lymph – again much like a backed up sewer.
For any tissue, organ or area of the body to be healthy – the
penis included – a good lymph circulation must service it,
just like your house needs a good sewer system. With poor
lymph circulation, tissue becomes easily diseased and does not
heal well. Figure 3, below, illustrates the
abundant lymphatic supply to the lower pelvis and genital
region.
Figure 3
Summary
The tunica albuginea normally has a limited blood flow, and
therefore poor oxygen supply because it is more like a tendon
in nature; tendons generally don't need and don’t have a huge blood supply. This is
critical in understanding how the scar develops in the tunica in
first place and how treatment should proceed. Like all parts
of the body, if the blood supply and lymphatic drainage of the
lower pelvis and penis are not correct, trouble can start.
PDI
treatment suggestions take these things into account.
Various therapies are suggested in this website that improve
the oxygen content and oxygen carrying capacity of the blood,
improve blood supply and lymphatic drainage, increase nutrient
support to the soft tissue structures of the genital area, and
improve the capacity of the body to heal and repair damaged
tissue. This is the connection of the anatomy and the therapy
that is offered for your review.
In the 14-part
"Treatment Options" section you will find many different
therapies that attempt to support and benefit the
blood and lymphatic supply to and from the lower pelvis.
With a better understanding of the structure and complexity
of this area of your body, you should be able to participate
in your treatment plan with a far better appreciation of
your problem and your purpose in following your treatment
plan.
==================================
With a better understanding of the anatomy of the penis, its
blood and lymphatic supply, and other soft tissue, you can now
think of PD in a different way. You now know the penis is made
of several unique tissues, and these are directly affected in
PD. Recall that specialized tissue of the penis has spaces
like “caves” and one area is like a “sponge”, both of which
fill with blood to create an erection. Even though the
cavernosa and the spongiosum have a huge blood supply, right
next to them is the tunica albuginea with a poor blood supply.
Throughout this website we will refer over and over again to
the tunica albuginea, the corpora cavernosa, the corpora
spongiosum, lymphatic flow, and connective tissue.
Understanding this anatomy will help you to later understand
the unique therapies we suggest for Peyronie’s disease. Now
you know.
________________________________________
1. Levine LA,
Coogan CL: Penile vascular assessment using color duplex
sonography in men with Peyronie’s disease. J Urol, 155:
1270-1273, 1996.
2. Lopez JA, Jarow JP: Penile vascular evaluation of men with
Peyronie’s disease. J Urol, 149: 53-55, 199
3. Burford CE, Glen JE, Burford EH: Fibrous cavernositis:
further observation with report of 31 additional cases. J Urol,
49: 350-356, 1943.
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