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Beneath the skin, on the body of the penis,
the ordinary superficial fascia is very distinct ;
it is continuous with that of the groin, and
also with the dartos tissue of the scrotum.
Near the root of the organ there is in front a
dense band of fibre-elastic tissue, named the
suspensory ligament, lying amongst the fibres
of the superficial fascia ; it is triangular in

form ; its anterior border is free, its upper border is connected with the fore part
of the pubic symphysis, and below it runs down upon the dorsum of the penis.



The integuments of the penis are supplied with blood by branches of the dorsal
artery of the penis and external pudic ; the veins join the dorsal and external pudic
veins. Their nerves are derived from the dorsal and internal superficial perineal
branches of the pudic nerves.

The corpora cavernosa form the principal part of the body of the penis. They
are two cylindrical bodies placed side by side, flattened on their median aspects,
and closely united and in part blended together along the middle line in the
anterior three-fourths of their length ; whilst at the back part, in contact with the
symphysis pubis, they separate from each other in the form of two bulging and then
tapering processes named crura, which, extending backwards, are attached to the
pubic and ischial rami, and are invested by the erectores penis or ischio-cavernosi
muscles. The enlarged portions at the root, named by Kobelt the bulbs of the corpora
cavernosa, attain a much greater proportionate development in some quadrupeds
than in man. In front, the corpora cavernosa are closely bound together into a

S 3


1, glans penis ; 2, prepuce ; 3, urethra ; 4, fraenum of the prepuce.



1, glans penis ; 2, prepuce ; 3, urethra ; 5, corpus spongiosum ; 6, corpus cavernosum.



The outer outline indicates the integument surrounding the deeper parts ; the erectile tissues of the
corpora cavernosa and the septum pectiniforine are shown in section ; u, placed on the section of the
spongy body, below the urethra ; v, the single dorsal vein ; a, the dorsal artery, and n, the nerve of
one side.

blunt conical extremity, which is covered by the glans penis and firmly connected
to its base by fibrous tissue.

The under surface of the united cavernous bodies is marked by a longitudinal
groove, in which is lodged the corpus spongiosum. The upper or anterior surface
is also marked with a slight median groove in which the dorsal vein of the penis
is situated, and near the root is attached to the pubes by the suspensory ligament.

Structure. The median septum between the two corpora cavernosa is thick
and complete near the root of the penis ; but further forward it becomes thinner,
and only imperfectly separates their cavities, for it exhibits, particularly towards
the anterior extremity, numerous clefts, extending from the dorsal to the urethral
edge, and admitting of a free communication between the erectile tissue of the two
sides. From the direction of these slits, the intermediate white portions of the
septum resemble somewhat the teeth of a comb, and hence the partition has received
the name of septum pectiniforme.

The external fibrous investment of the cavernous structure is white and dense,
from one to two millimetres thick, and very strong and elastic. It is composed
for the most part of longitudinal bundles of shining white fibres, with numerous
well-developed elastic fibres, enclosing the two corpora cavernosa in a common



covering ; and internal to this, each corpus cavernosum is surrounded by a layer of
circular fibres, which enter into the formation of the septum.

From the interior of the fibrous envelope, and from the sides of the septum,
numerous lamellae, bands, and cords, composed of fibrous elastic and plain muscular
tissue, and named tmbeculce,, pass inwards, and run through and across the cavity iu



a, trabeculas of connective tissue
with many elastic fibres and bundles
of plain muscular tissue cut across (c);
6, venous spaces.

all directions, thus subdividing
it into a multitude of inter-
stices, and giving the entire
structure a spongy character.

The trabecula?, whether
lamelliform or cord-like, are
larger and stronger near the
circumference than along the
centre of each cavernous body,
and they also become gradually
thicker towards the crura.
The interspaces, conversely,
are larger in the middle than near the surface ; their long diameter is, in the latter
situation, placed transversely to that of the penis : and they become larger towards
the forepart of the penis. They are occupied by venous blood, being in reality large



M tiller).

a, a small artery supported by the larger
trabeculse, and branching out on all sides ;
c, the tendril-like arterial tufts or helicine
arteries of Miiller ; d, the areolar structure
formed by the finer trabecula. 1 .

cavernous veins, and are lined by a
layer of flattened epithelium similar
to that lining other veins.

The intertrabecular spaces thus
form a labyrinth of intercommuni-
cating venous areolas divided by the
trabecular tissue, and opening freely
from one corpus cavernosum to the
other through the septum, especially
in front. The blood is carried away

from these spaces by two sets of veins, the one set joining the prostatic plexus and
pudenda!, veins ; the others passing into the dorsal vein. Of these last some issue
from between the corpus cavernosum and the spongy body of the urethra, encircling
the penis nearly at right angles, while others pass more directly into the dorsal vein
from the upper surface.

The principal arteries of the corpora cavernosa are the cavernous branches of the
pudic arteries (profundse penis), of the right and left sides ; but the dorsal artery of



the penis also sends small twigs through the fibrous sheath of the corpora cavernosa,
along the upper surface, especially in the fore part of the penis._ Within the
cavernous tissue, the numerous branches of arteries are supported by the trabecula)
in the middle of which they run, and terminate in branches of capillary minuteness
which open into the intertrabecular spaces ; some of the arterial twigs project
into the spaces, and form peculiar curling and somewhat dilated vessels, which


THE PKNIS (Henle).

On the left is seen the fibrous tissue ; at *, a section of the arteria profunda penis.

were named by J. Mu'ller, helicine arteries. These are usually bound down by small
fibrous bands (fig. 259,* *), and it appears to be due to this circumstance that these
projecting vessels acquire a looped or tortuous aspect when distended with injection.
The helicine arteries are most abundant in the posterior part of the corpora
cavernosa, and are found in the corresponding part of the corpus spongiosum also ;


A and B, from the corpus cavernosnm penis ; D, from
the corpus spongiosum urethra ; C, transverse section
of one of the helicine arteries ; in this and the other
figures the smaller lateral prolongations of the arterial
vessels into the sheath are shown ; * *, fasciculi of
connective tissue passing off from the summit of two of
the sheaths.

but they have not been feen in the glans
penis. They are more distinct in the human
subject than in animals, where they are often
missed. Small capillary branches pass from
them to supply the tissue of the enclosing

In addition to the blood which passes
into the venous spaces from the capillary
network of the sheath and trabeculse some
small arteries are said by C. Langer to open
directly into the larger venous spaces.

The corpus spongiosum urethras com-
mences below the triangular ligament of the
perineum, where it is placed between the diverging crura of the corpora cavernosa.
and somewhat behind their point of junction. The enlarged and rounded posterior
extremity is named the bulb, and projects backwards somewhat beyond the urethra.
It extends forwards as a cylindrical, or slightly tapering body, lodged in the groove
on the under side of the united cavernous bodies, as far as their blunt conical
anterior extremity, over which it expands so as to form the glans penis already
described. In the whole of this extent it encloses the urethra.

VOL. III., FT. 4. B,



The posterior bulbous part, or bulb of the urethra, varies in size in different
subjects. It receives an investment from the triangular ligament on which it rests,
and is embraced by the ejaculator urinae, or bulbo-cavernosus muscle. The posterior
extremity of the bulb exhibits, more or less distinctly, a subdivision into two lateral
portions or lobes, separated by a slight f arrow on the lower surface, and by a slender
fibrous partition within, which extends for a short distance forwards ; in early
infancy this is more marked. It is above this part that the urethra, having pierced
the triangular ligament, enters the bulb, surrounded obliquely by a portion of the
spongy tissue, named by Kobelt the collwulm bulbi, from which a layer of venous




1, fibrous tunic of the corpus spon-
giosum ; 2, mucous membrane of the
urethra ; 3, section of a lacuna of the
mucous membrane ; 4, section of an

erectile tissue passes back upon
the membranous and prostatic
portions of the urethra to the
neck of the bladder, lying closely
beneath the mucous membrane.
At first the urethra is nearer the
upper than the lower part of the
corpus spongiosum, but it soon
gains and continues to occupy
the middle of that body.

According to the observations of Retterer, which are founded mainly upon a study of
the development of the organ, the glans penis is only formed as to the part immediately
encircling the urethra by true corpus spongiosum, the greater portion being developed
from integumental tissue, which has become very vascular and cavernous, and which
has united with the anterior ends both of the corpora cavernosa and of the corpus
spongiosum ; the vascular connection with the latter being however by far the most

Structure. This is essentially the same as that of the corpora cavernosa, but
with a much less developed fibrous framework. Like the corpora cavernosa, it is
distended with blood during erection, but it never acquires the same rigidity. The
fibrous tunic (fig. 260, 1) is much thinner, is less white in colour, and contains more
elastic tissue ; the trabeculse are finer and more equal in size ; the areolse are smaller,
more uniform, and directed for the most part with their long diameter in the line of
that of the penis ; in the glans, the meshes are smallest and most uniform. Plain
muscular fibres immediately surround the canal of the urethra, and also form part of
the external coat of the spongy substance.

Blood-vessels. Arteries. A considerable artery derived from the internal
pudic enters the bulb on each side, and supplies the greater part of the spongy body,
sending branches as far as the glans penis, but this part is chiefly supplied by
branches from the arteria dorsalis. Besides these, there is another but much smaller
branch of the pudic artery, entering the bulb on the upper surface, about an inch
from its posterior extremity, and running forwards in the corpus spongiosum to the
glans (Kobelt). The arteries open into the venous spaces chiefly if not entirely by
the intervention of capillaries. Veins issue from the glans and adjoining part of
the spongy body, to end in the vena dorsalis penis ; those of the rest of the spongy
body for the most part pass backwards through the bulb, and end in the prostatic


and pudic venous plexuses ; some emerge from beneath the corpora cavernosa,
anastomose with their veins, and end partly in the cutaneous veins ^ the penis and
scrotum, and partly in the pudic and obturator veins.

The lymphatics of the penis form a dense network on the skin of the glans
and prepuce, and also underneath the mucous lining of the urethra. They pass
chiefly into the inguinal glands. Deep-seated lymphatics are also described as
issuing from the cavernous and spongy bodies, and passing under the pubic arch
with the deep veins, to join the lymphatic plexuses in the pelvis.

The nerves of the penis are derived from the dorsal and superficial perineal
branches of the pudic nerve and from the hypogastric plexus of the sympathetic.
The former are distributed to the skin and mucous membrane, the latter entirely
to the cavernous and spongy bodies. Simple and compound end-bulbs (genital
corpuscles) occur numerously on the nerves of the penis, and Pacinian bodies have
been found on the nerves of the glans (see Yol. I., Part 2, p. 338).


The male urethra extends from the neck of the bladder to the extremity of the
penis. Its total length when moderately stretched is about 8| inches (20.4 c.m.),
but it varies with the length of the penis, and the condition of that organ. Except
during the passage of urine or semen the walls of the canal are in close apposition,
the outline of the urethral cleft being vertical in the glans penis, transverse in the
body of the penis, and crescentic about the middle of the prostatic part. Its
diameter when moderately distended differs at different parts, as will be stated more
particularly hereafter. The tube consists of a continuous mucous membrane,
supported by an outer layer of submucous tissue connecting it with the several parts
through which it passes. In the submucous tissue there are, throughout the whole
extent of the urethra, two layers of plain muscular fibres, the inner fibres disposed
longitudinally, and the outer in a circular direction. The urethra may be divided
into two parts, a urinary and a uro-genital. The urinary portion is about half an
inch in length and extends from the vesical orifice to the openings of the common
ejaculatory ducts. The uro-genital part, as its name implies, serves as a channel
for both the urine and the spermatic fluid. It comprises the remaining and much
the longer division of the urethra.

More commonly, however, the urethra is described under the three divisions of
the prostatic, membranous or muscular, and spongy or penile portions.

1 . The first, or prostatic portion, is the part which passes through the prostate
gland. It is about 1|- inches in length, is the widest part of the canal, and is wider
in the middle than at either end : at the neck of the bladder its diameter is nearly
one-third of an inch, in the next part it widens a little, so as to be rather more than-
this (in old persons nearly half an inch), farther on it diminishes, until, at its
inferior limit, it is smaller than at its commencement. Its direction is vertical or
very nearly so. Though enclosed in the firm glandular substance, it is more dilatable
than any other part of the urethra ; but immediately at the neck of the bladder, it
is much more resistant. The transverse section of the urethra, as it lies in the
prostate, is curved with the convexity forwards.

The lining membrane of the prostatic portion of the urethra is thrown into
longitudinal folds, when not distended by fluid. Towards the neck of the bladder,
a slight elevation on the posterior surface passes back into the uvula vesicse. Some-
what in advance of this, and continued from it along the floor of the passage,
projects a narrow median ridge, about three quarters of an inch in length, and one
eighth of an inch in its greatest height ; this ridge gradually rises into a peak, and
sinks down again at its anterior or lower end ; it is formed by an elevation of the

R 2



mucous membrane and subjacent tissue. This is the crest of the urethra (crista
urethras), which also receives the names of colliculus seminalis, caput gallinaginis and
verumontanum. On each side of this ridge the surface is slightly depressed, so as to
form a longitudinal groove, named the prostatic sinus, the floor of which is pierced
by numerous foramina, the orifices of the prostatic ducts. Through these a viscid
fluid oozes out on pressure ; the ducts of the middle lobe open above the urethral



ABOVE. (Allen Thomson. )

A portion of the wall of the bladder
and the anterior part of the prostate
gland have been removed, the corpora
cavernosa penis have been separated
in the middle line and turned to the
side, and the urethra has been slit
up ; the bulb is left entire below, and
upon and behind it the glands of
Cowper with their ducts have been
exposed, t, placed in the middle of
the trigonum vesicee ; u, u, oblique
apertures of the ureters ; from these
an elevation of the wall of the bladder
is shown running down to u v, the
uvula vesicle ; I, the longitudinal
muscular fibres of the bladder passing
down upon the prostate ; s v, the
circular fibres of the sphincter ; p,
the glandular part of the prostate ;
p', the prostatic portion of the urethra
from the uvula vesicse a median ridge
is seen descending to the caput gal-
linaginis, in which s indicates the
opening of the prostatic utricle, and
d, that of one of the ejaculatory
ducts ; m, the commencement of the
membranous portion of the urethra ;
b, the bulb of the spongy body ; &',
the bulbous part of the urethra ; c,
one of Cowper's glands ; c d, c d,
course and orifice of its duct lying
upon the bulb, and passing forward
between the spongy body and the
urethra, into which along with its
fellow it opens ; c c, one of the corpora

crest, and some others open below it. The prostatic urethral mucous membrane is
covered by a laminated epithelium like that of the bladder.

At the fore part of the most elevated portion of the crest, and exactly in the
middle line, is the orifice of a blind recess, upon or within the lateral margins of
which are placed the slit-like openings of the common seminal or ejaculatory ducts,
one at each side. This median opening leads into the prostatic utricle, which has
been named also sinus pocularis, vesicula prostatica or uterus masculinus. It was
first described by Morgagni, and corresponds with the vagina and uterus in the
female, its prominent lateral lips being supposed to represent the hymen.

The vesicle forms a cul-de-sac running upwards or backwards, for a distance of
from a quarter to half an inch (6 to 12 mm.). Its orifice forms a longitudinal cleft
about 2 or 3 mm. in length, but the vesicle increases somewhat in diameter towards its
farther end or fundus. The narrow portion runs in the urethral crest, and its
fundus lies behind and beneath the middle lobe, and in some cases reaches to the
posterior surface of the prostate gland. Its parietes, which are distinct, and of



pome thickness, are composed of fibrous tissue and mucous membrane, together with
a fe\v muscular fibres, and enclose on each side the ejaculatory duct ; numerous


BL., bladder ; P.S., pubic symphysis ; F. , fat ; p, p', prostate ; BU, bulb of corpus spongiosum ; M,
membranous portion of urethra ; s, spongy portion ; G. glans penis. For other references see p. 114.


small ramified and convoluted glands open on its inner surface. The epithelium is
columnar and is by some authors stated to be ciliated. There are small glands
opening into its cavity near the entrance into the urethra. The caput gallinaginis
contains some well-marked erectile and plain muscular tissue, and it has been
supposed that this eminence, when distended with blood, may offer an obstacle to
the passage of the semen backwards into the bladder.

2. The membranous portion of the urethra comprises the part between the
apex of the prostate and the bulb of the corpus spongiosum. It is three quarters of
an inch (18 mm.) long, but about half an inch of its posterior surface is covered by
the bulb of the corpus cavernosum which projects backwards over it. This
membranous portion is the narrowest division of the urethra. In the middle its
diameter is one-fifth of an inch (5 mm.) : at the end not quite so much. It is
directed downwards and slightly forwards beneath the pubic arch, the anterior
slightly concave surface being distant nearly an inch from the pubic symphysis,
leaving an interval, occupied by the dorsal vessels and nerves of the penis, by
areolar tissue, and some muscular fibres. Its posterior convex surface is turned
towards the rectum. It lies between the two layers of the triangular ligament, and
both these fibrous membranes are prolonged upon it, the one backwards and the
other forwards. Between these two layers the urethra is surrounded by erectile
tissue, by some veins, and also by plain muscular tissue, and the fibres of the com-
pressor urethras muscle. On each side are Cowper's glands. The plain muscular
fibres of this portion of the urethra are continued over the outer and inner surfaces
of the prostate into the muscular fibres of the bladder posteriorly, and into those of
the spongy portion of the urethra anteriorly (Hancock).

3. The spongy portion of the urethra, by far the longest and most variable in
length and direction, includes the remainder of the canal, or that part which is
surrounded by the erectile tissue of the corpus spongiosum. Its length is about six-
inches (150mm.). The direction of the spongy portion of the urethra varies in different
parts of its course and under different conditions. Thus it inclines forwards and
downwards for a short distance in front of the superficial layer of the triangular
ligament, and then turns forwards and somewhat upwards to about the middle of
its length, where in the flaccid condition of the penis it usually bends sharply
downwards to the external nieatus. During erection of the penis or when this
organ is drawn forwards, as in passing a catheter, this temporary curve is obliterated
and the spongy part is straight frcni the external meatus to the neighbourhood of
the bulb. The part contained within the bulb, sometimes distinguished as the
bulbous portion, or sinus, is somewhat dilated. The succeeding portion, as far as the
glans, is of uniform diameter, being intermediate in this respect between the bulbous
and membranous portions. The cross section of its canal appears like a transverse
slit. The canal of the urethra in the glans has, on the contrary, when seen in a
cross section, the form of a vertical slit ; in this part, which is from one-third to
half an inch in length, the canal is again dilated, forming what is named the

fossa navicularis.

Lastly, at its orifice, which is a vertical fissure from one-fifth to oue-fourth of an
inch (5 to 6 mm.) in extent, and bounded by two small lips, the urethra is again
contracted and reaches its narrowest dimensions. From the resistant nature of the
tissues at its margin, this opening does not admit so large a sound or catheter as
even the membranous portion of the canal.

The mucous membrane of the urethra possesses a lining of epithelium, of
which the superficial cells are long and columnar, except for a short distance (5 to
8 mm.) from the orifice, where they are squamous, and where the subjacent
membrane is beset with papillae. The epithelium rests on a basement membrane.
Outside the mucous membrane, there is a layer of convoluted vascular structure, and


external to that a layer of circular plain muscular fibres separating it from the
proper substance of the spongy body.

The whole lining membrane of the urethra, except near the orifiCE,Ts beset with
small racemose mucous glands and follicles, commonly named the glands of
Littre, the ducts of which pass obliquely forwards through the membrane. They

Online LibraryJones QuainQuain's Elements of anatomy (Volume 3:4) → online text (page 30 of 44)