« PrécédentContinuer »
ved into a hollow in the base of the glans. The skin covering the body of penis is thin, delicate, and freely movable, and, except near the root of the a, is free from hairs; on the urethral aspect of the penis the skin is marked
median raphe, continuous with the raphe of the scrotum. Traced towards base of the glans, the skin forms a free fold called the præputium, or prepuce,
overlaps the glans to a variable extent. From the deep surface of the ace the skin is reflected on to the terminal part of the penis, along a line just mal to the corona glandis, and is continued over the entire glans to the mal urethral orifice. A small median fold, the frenulum præputii, passes to the surface of the prepuce from a point immediately below the orificium urethræ num. The skin covering the glans is firmly attached to the underlying e tissue, and here, as well as on the deep surface of the prepuce, it presents resemblance to mucous membrane. netimes minute sebaceous glands, glandulæ præputiales, are found in very variable 's on the glans and inner surface of the prepuce; the secretion from these when e present may help to form the smegma præputii, which tends to collect in the between the glans and the prepuce. The main source of the smegma is to be n the desquamated and broken-down epithelial cells derived from the surface of
ns and prepuce.
the radix penis, or root, the three component parts of the organ separate Le another (Fig. 1018). orpora cavernosa
diverging from her laterally, at first
somewhat swollen, , gradually tapering,
Corpus caverfirm, fibrous attach
-nosum penis he periosteum on the
Urethra urface of the pubic
-Corpus caverhese diverging parts
hosum urethræ orpora cavernosa are ne crura penis, and covered by the corgischio-cavernosus The corpus caverethræ lying between
becomes enlarged, a somewhat spheriwhich receives the
Bulb of urethra bus urethræ. The
urogenital diaphragm s much in size in
Corpus cavernosum penis ndividuals, and is co the under sur- FIG. 1018.-STRUCTURES COMPOSING THE RADIX PENIS. fascia inferior of
The corpus penis is seen in section. enital diaphragm, nich it rests. The posterior part and under surface of the bulb usually lian notch or groove—an indication that the bulb is originally composed nmetrical portions, which during development have become fused in the
These two portions are termed the hemispheria bulbi urethræ, and een in subjects whose tissues have been hardened by intravascular A slightly marked median septum, situated within the bulb tissue, n a deeper plane the line along which fusion has taken place. The urethra, piercing the fascia inferior of the urogenital diaphragm, enters liquely a short distance in front of its posterior extremity (Fig. 1024). e superficial surface of the bulb is the bulbo-cavernosus muscle. what triangular band of strong fibrous tissue, called the ligamentum penis, is attached to the front of the symphysis pubis, and extends is capsule of the penis, with which it becomes continuous (Fig. 1017).
Structure of the Penis. — Each corpus cavernosum penis is enclosed by a denst white fibrous coat- tunica albuginea corporum cavernosorum, which, fusing with the corresponding coat of the opposite side, forms a median septum penis. The septum is very incomplete, especially near the terminal part of the penis, where it is interrupted by a number of nearly parallel slit-like perforations; hence the term “septun pectiniforme” is often applied to it (Figs. 1019 and 1020). Through these openings the erectile tissue of the corpora cavernosa of opposite sides is continuous.
The fibrous coat contains some elastic fibres, and may be divided into an outer layer of longitudinally directed fibres and an inner layer of circular fibres, some of which latter are continued into the septum. Numerous fibrous strands, called trabeculæ corporum cavernosorum, proceed from the deep surface of the tunica albuginea, and stretching across the interior of the corpus cavernosum, form a fine sponge-like framework whose interspaces communicate freely with one another, and are filled with blood. These blood-containing spaces lead directly into the veins of the penis, and, like the veins, have a lining of flat endothelial cells. The size of the penis varies with the amount of blood in this cavernous tissue. The structure of the corpus cavernosum urethræ resembles that of the corpora cavernosa penis, but the fibrous coat is much thinner and more elastic, and the trabeculæ are finer (Fig. 1019).
The glans penis is also composed of cavernous tissue which communicates by a rich venous plexus, situated on the ventral aspect of the urethra, with the corpus spongiosum urethræ. No strongly marked tunica albuginea is present, and the erectile tissue is practically bounded by the firmly adherent skin. Surrounding the urethra, which in this part of the penis is represented by a laterally compressed slit-like passage, is a mass of fibro-elastic tissue which forms a kind of median septum within the glans. This septum
FIG. 1019.-TRANSVERSE SECTION THROUGH THE
BODY OF THE PENIS.
FIG. 1020.-A LONGITUDINAL SECTION OF THE
TERMINAL PORTION OF THE PENIS.
is continued backwards to join the sheath of the conical end of the corpora cavernosa, and ventrally it gives attachment to the frenulum of the prepuce. It imperfectly divides the erectile tissue of the glans into right and left portions, which, however, freely communicate dorsally. From the septum, trabeculæ pass out in all directions into the tissue of the glans
Loosely surrounding the corpora cavernosa penis and the corpus cavernosum urethra is a fibrous sheath containing numerous elastic tissue fibres. This sheath is termed the fascia penis, and reaches as far as the base of the glans, where it becomes fixed to the floor of the groove limited by the corona glandis. În its proximal part the sheath gives insertion to many of the fibres of the bulbo-cavernosus and ischio-cavernosus muscles.
Superficial to the fascia penis is a layer of extremely lax areolar tissue, and more superficial still is a prolongation of the tunica dartos of the scrotum, covered by the delicate skin of the penis. Numerous sebaceous glands are present in the skin, especially on the urethral aspect of the penis. In some mami
mmals, such as the walrus, dog, bear, baboon, etc., a bone called the os penis s developed in the septum which intervenes between the corpora cavernosa penis. Vessels
and Nerves of the Penis. — The penis receives its arterial supply from branches of the internal pudendal artery. The erectile tissue of the corpora cavernosa penis is supplied chiefly by the deep arteries of the penis, while that of the corpus cavernosum urethræ receives its arterial supply from the artery to the bulb. Branches of the dorsal artery of the penis piercing the fibrous coat of the corpora cavernosa penis furnish additional twigs to the erectile tissue of these structures. The glans receives its chief blood-supply from branches of the dorsal artery. capillaries, into which they lead, open directly into the cavernous venous spaces. As the lie in the finer trabeculæ the smaller branches often present a peculiar twisted appearance. and hence the name arteriæ helicinæ is sometimes applied to them.
with which the cavernous spaces communicate, carry the blood, for the most part, ly into the pudendal plexus, or into the dorsal vein and so to the pudendal plexus. ein of the penis begins in tributaries from the glans and prepuce, and lies in the en the corpora cavernosa penis as it ascends to pass beneath the arcuate ligament to join the pudendal plexus. On each side of it lies the dorsal artery, and still the median plane lies the dorsal nerve (Fig. 1019), ph-vessels of the penis are arranged in a deep and superficial series, and end in the As of the inguinal group of lymph-glands. e-supply of the penis is derived from the pudendal nerve and from the hypopelvic plexuses. The branches of the pudendal are the dorsal nerve of the penis, s from the perineal nerves. These supply the cutaneous structures of the penis, ympathetic filaments from the hypogastric and pelvic plexuses, which reach the gh the prostatic nerve plexus, end in the erectile tissue.
costata, or prostate, is a partly glandular, partly muscular organ of a dark
colour which surrounds the beginning of the urethra in the male. It 1 the pelvis behind the pubes, and is enclosed by a dense sheath derived
pelvic fascia. Through the various connexions of this sheath the s firmly fixed within the pelvic cavity. The ejaculatory ducts traverse ate in their course downwards and forwards to join the urethra as it
Lig. um. Seminal
umbilical area of bladder
Lateral aspect of
Infero-lateral „Urethra prostate
area of bladder
Drawn from specimens hardened in situ.
s through the gland (Fig. 1023). The size of the prostate varies cony in different individuals, but its transverse, or longest, diameter is usually e and a quarter to one and a half inches; its antero-posterior diameter hree-quarters of an inch ; and its vertical diameter about one and a quarter
Superficially the prostate is separated from the bladder by deep wide grooves directed downwards and forwards, and by a narrow posterior groove s horizontal. connexion with the prostate, we describe an apex which is directed downa base looking upwards, a posterior, and two lateral surfaces. The general
of the organ has been often compared with that of a Spanish chestnut. per surface, or basis prostatæ, is directed upwards against the inferior aspect bladder, in the neighbourhood of its urethral opening. The greater part of rface is structurally continuous with the bladder wall, only a narrow portion s free on each side, and forms the lower limit of the deep groove which the separation of the bladder and prostate (Fig. 1021). The lateral surfaces prostate are convex and prominent, especially in their posterior and upper s, and rest against the fascia covering the levator ani muscle. They are ed for the most part laterally, downwards, and somewhat forwards, and meet er in front in a rounded anterior border, sometimes called the "anterior 2," or "facies anterior," of the prostate. Posteriorly the prostate presents a ed somewhat triangular posterior surface, directed backwards and downwards
against the anterior wall of the rectum, from which it is separated by a layer of the pelvic fascia. This flattened facies posterior is separated on each side from the lateral surfaces by a rounded border which, beginning above at the prominent lateral part of the prostate, ends below at the apex of the organ. The apex prostatæ points downwards, and is in relation to the sphincter urethræ membranaceæ muscle, from which it is separated by the fascia superior of the urogenital diaphragm. From the apex the rounded anterior border, which separates the lateral surfaces, passes upwards in the median plane behind the symphysis pubis and retropubic pad of fat." This border is interrupted in its lower part by the passage of the urethra.
When the sheath formed by the pelvic fascia is stripped off the prostate the organ has a more rounded outline, and the surfaces just described are not so clearly defined. The anterior border may now appear to be rather a surface than a border, and the antero-posterior diameter of the whole organ is considerably reduced.
The urethra enters the prostate at a point near the middle of its upper surface, and leaves it at a point situated on its anterior border, just above and in front of the apex. As it descends, the urethra describes a curve which is concave forwards, and in median section it is seen to lie, on the whole, nearer to the posterior surface than to the anterior border of the gland.
The ejaculatory ducts, entering a slit-like interval, or hilum, situated just in front of the border which separates the base from the posterior surface of the prostate,
run downwards, medially, and forwards, to open into the prostatic portion of the urethra very close to one another.
The somewhat wedge-shaped portion Infero-lateral of the prostate, which lies between
these ducts and the posterior aspect
of the urethra, receives the name of Urethra
lobus medius (Fig. 1023). The base of
this middle lobe projects upwards Ureter against the bladder, and is continuous
with the part of the bladder wall lying
immediately behind the urethral orifice. Duetus When hypertrophied, as it often is in
old people, the middle lobe of the Posterior surface of prostate
prostate may cause a considerable
elevation in the cavity of the bladder, Fig. 1022.—PROSTATE, URINARY BLADDER, AND to which the term uvula vesicæ is SEMINAL VESICLES SEEN FROM BELOW.
applied. This elevation possesses conDrawn from a specimen hardened in situ. The lateral siderable surgical interest (p. 1277).
surfaces of the prostate are seen one on each side of the urethra and in front of the posterior surface.
The rest of the prostate is described
as being composed of two large lateral lobes, which are, however, not. marked off from one another superficially.
In front of the prostate, between it and the pubis, is a rich venous plexus-plexus pudendalis—in which the dorsal vein of the penis terminates. This plexus is continued backwards, on each side, round the lateral aspect of the prostate, and joins the large thin-walled veins which are collected for the most part in the deep sulcus between the bladder wall and the prostate, and form the prostatico-vesical plexus. Most of the veins forming this plexus lie partly within and partly outside the dense fibrous sheath of the prostate, which is derived from the visceral pelvic fascia (Figs. 1023 and 1024).
Fibrous Sheath of the Prostate. The sheath of the prostate is formed by the visceral pelvic fascia, and closely invests the gland on its lateral and posterior aspects. Inferiorly at the apex of the prostate the sheath becomes continuous with the fascia superior of the urogenital diaphragm, which lies above the sphincter urethrae membranaceæ muscle, and is attached to the pubic arch. In front two thickened bands pass forwards from the anterior aspect of the sheath, one on each side of the median plane, to reach the back of the lower part of the pubis, where
are attached to the periosteum. These constitute the pubo-prostatic ligas, and contain smooth muscle fibres, as well as dense connective tissue. of the muscle fibres in connexion with the pubo-prostatic ligaments, passing rds as well as backwards, gain the bladder wall, and are spoken of as the vesical muscles. Below the pubo-prostatic ligaments the medial edges of vatores ani muscles pass medially and almost meet together in front of the of the prostate. When followed backwards, the medial edges of these muscles en to closely embrace the apex of the prostate. This layer forms a part of all of the retro-pubic space which lies in front of the prostate and below the er (Fig. 1024). tween the pubo-prostatic ligaments there is a shallow fossa, or depression, the f which is formed by a thin layer of fascia connecting the anterior aspect of eath of the prostate with the back of the pubis. On each side of the body eral aspect of the sheath of the prostate is continuous with the strong fascia covers the pelvic surface of the levator ani muscle. When the fibrous sheath prostate is traced upwards beyond the level of the upper margin of the gland mes thinned out and joins the fascial covering of the bladder. Posteriorly the
prolongation of the sheath is continuous with the fascial layers which he ampullæ of the ductus deferentes and the seminal vesicles, and it is
to the peritoneum of the recto-vesical pouch. In this position it is often f as the recto-vesical fascia. cture of the Prostate.—Beneath the fibrous sheath of the gland the part of the prostate is seen to be largely composed of matted interlacing smooth muscle and connective tissue fibres, which form a kind of capsule for r parts of the organ. This layer, or capsule of the prostate, is not sharply ut from its deep aspect fibrous and muscular strands pass inwards, converging ne posterior wall of the urethra, to become continuous with the mass of smooth tissue which surrounds this canal as it traverses the prostate. These somewhat rranged strands divide the prostate into a number of incompletely defined which there appear to be about fifty. The yellowish-coloured glandular tissue, glandulare, which forms the lobules is composed of minute, slightly branched ve walls of which in certain places show numerous saccular dilatations. In the tion of the gland the tubules are slightly dilated and shorter than in the lower e they are longer and more convoluted. The glandular tubules lead into the ostatic ducts, which open into the urethral canal as it traverses the prostate. s prostatici number about twenty or thirty, and open for the most part into 1 each side of the median elevation, or crista urethralis, in the posterior wall hra (Fig. 1023 A). lk of the glandular tissue is situated at the sides of and behind the urethra. f the upper part of the prostatic portion of the urethra there is a mass of