Chapter IV: Surgical Anatomy

It is essential for the Mohel to possess a knowledge of the structure of the organ on which he operates.

The skin of the penis is continuous on the upper surface with the skin of the abdomen, and on the under surface with that of the scrotum. On drawing forward the prepuce or foreskin it is very easy to include the skin of the scrotum in the grasp of the fingers unless due care is taken. If the traction on the foreskin is too forcible and the skin of the scrotum is therefore pulled up tightly, there is a danger of the scrotal skin being slit up to some extent. The intimate connection of the skin of the penis and scrotum must always be kept well in mind.

Under the foreskin and continuous with it at its free margin there is a membrane which rising from the neck or constriction below the glans envelops the latter entirely up to the opening of the urethra. Here it leaves the glans and joins the outer skin. The name given to this structure is _mucous membrane_, and the method of dealing with it constitutes the principal portion of the art of circumcision.

This mucous membrane is the whitish glistening structure which appears after the removal of the skin.

It is important to note the disposition of this mucous membrane, as revealed after the amputation of the prepuce.

1) It usually _covers over the glans right up to the orifice of
the urethra_.

2) It may be reflected off the glans before reaching this point,
and become continuous with or adherent to the skin lining. In
this case the glans will not be completely covered by the mucous
membrane, because a small portion will have been cut off in the
first stage of the operation. In those cases the membrane missing
from the upper part of the glans will be found on the inside of
the amputated foreskin.

3) In other cases this inner mucous membrane is very deficient
covering only three quarters or less of the surface of the glans,
the remaining portion being adherent to the inner surface of the
foreskin.

The _consistence of this membrane_ is such that it can be easily torn through but,

1) It may be elastic so that it stretches without tearing.

2) It may be so thin that it is liable to be pushed down by the
nails instead of being torn.

3) It may be so thick as to necessitate the use of the scissors
to cut it.

It may be loosely applied to the glans so that the thumb nails are easily inserted beneath it, or it may be so adherent that great difficulty is experienced in tearing it through and peeling it off the glans.

An important fold of this membrane, triangular in shape is attached to the under surface of the glans below its base reaching almost up to the opening of the urethra. This is called the _Frænum_, and it is fully exposed during the second stage of the operation.

The body of the penis itself is composed of three parts. On the upper surface behind the glans are the two _Corpora Cavernosa_, united firmly together, but leaving a hollow on their under surface for the _Corpus Spongiosum_ which is prolonged beyond them in an enlarged extremity known as the _glans_. The constriction beneath the glans is called the _Cervix or Neck_, while the projecting rim of the glans above this is called the _Corona_. Occasionally there are found here small masses of soft creamy material, which is the natural secretion of the part.

The canal of the urethra runs in the corpus spongiosum. Each of these three corpora is firmly united to the pubic bone behind.

They are constructed of an outer sheath from the inner surface of which numerous fine membranous partitions stretch, dividing the whole up into numerous small compartments. These compartments are lined with a fine network of veins, which are able to expand with blood and to distend and fill up these spaces. When this occurs the whole organ swells and becomes firm and the tension of the fibrous material forming the main structure is called into play so that the process assumes the form of an erection. The veins which should drain the penis of blood are compressed by the action of certain muscles and this adds to the engorgement of the organ.

When the penis of an infant is in a state of erection the operation of circumcision can be more easily performed and the dressing more efficiently applied. The manipulation of the organ necessary to grasp the prepuce is generally sufficient to stimulate the increased blood supply requisite for an erection. The skin of the penis does not share with the rest of the organ, a greater amount of blood during this state. It stretches by its own elasticity.

All the arteries and veins of the penis run in the deep structures previously alluded to, so that circumcision, in an infant at any rate, can never wound a blood vessel. The _Frænum is freely supplied with blood_, and if cut will produce troublesome hæmorrhage, but a circumcision in no way interferes with this part.