The tunica vaginalis communis is inseparably united with the parietal
layer of the tunica vaginalis propria. Where the spermatic cord passes
from the abdominal wall to the scrotum it is covered by integument and
cremasteric fascia on its ventral surface only, but is entirely
surrounded by the tunica vaginalis propria and tunica vaginalis
communis. The canal by which the spermatic cord passes through the body
wall is known as the =inguinal canal=. The end by which it opens into
the abdominal cavity is the =internal inguinal ring=, and the opposite
end is called the =external inguinal ring=.
The =internal inguinal ring= is merely the point of connection between
the proximal tubular portion of the tunica vaginalis propria and the
abdominal cavity. It is circular, and is situated close against the
lateral side of the lateral ligament of the bladder at its middle.
The =external inguinal ring= is an oval opening in the aponeurosis of
insertion of the external oblique muscle. The aponeurosis of this muscle
ends caudally in a free border along the cranial edge of the pubis, from
the ilium to the pubic tubercle. The external ring is just craniad of
the end of this aponeurosis.
The =inguinal canal= between these rings lies along the lateral border
of the rectus muscle. It is one to one and a half centimeters long. Its
medial wall rests on the rectus muscle; its dorsal wall on the fat
contained within the lateral ligament of the bladder. The lateral and
ventral walls lie on the transversus muscle proximally, on the internal
oblique near the distal end. The wall itself is composed of tunica
vaginalis propria and communis. As it passes within the caudal border of
the internal oblique muscle it receives some aponeurotic fibres from it.
A thin aponeurosis is also continued from the border of the external
ring onto the tunica vaginalis propria.
[Illustration: FIG. 110.--TESTIS.
_a_, testis; _b_, caput epididymis; _c_, epididymis; _d_, cauda
epididymis; _e_, vas deferens; _f_, spermatic cord.]
The =testes= (Fig. 110) are the organs which produce the spermatozoa.
They lie one in each compartment of the scrotal sac, enveloped in the
membranes or tunics described when treating of the scrotum. Each is
attached to the dorsal wall of its peritoneal pouch by a mesenteric
fold. The testis is surrounded by the visceral layer of the tunica
vaginalis propria, and within this, by a dense fibrous covering, =the
tunica albuginea=, which sends septa into its interior. Within the
fibrous covering it is made up of numerous coils of seminiferous tubules
which are readily seen by the naked eye.
The =epididymis= (Fig. 110, _c_) is the beginning of the efferent duct
of the testis. It appears as a flat band with a broad rounded end which
lies on the medial surface of the testis at its cranial end (_b_). From
this point it passes about the cranial end of the testis from its medial
to its lateral surface, forming thus a semicircle with the convexity
ventrad. Thence it passes as a narrower band (_c_) along the dorsal
side of the testis, laterad of the suspending mesentery, to the caudal
end of the testis (_d_). At the caudal end of the testis it is enlarged,
passes from its lateral to its medial surface, and turns at the same
time craniad to become continuous with the vas deferens (_e_).
The enlarged cranial end is the =caput epididymis= (_b_); the enlarged
caudal end the =cauda epididymis= (_d_). The whole epididymis is encased
in a tough fibrous covering similar to that of the testis. The fibrous
covering (albuginea) of the testis and that of the epididymis are
connected by fibrous tissue. Within the fibrous covering the head of the
epididymis is made up of tubules which pass from the testis into its
end: these are the =vasa efferentia testis=. The vasa efferentia unite
within the caput into a single vessel which passes in a very tortuous
course to the cauda. Its numerous windings form the cauda, from the end
of which it passes craniad as the =vas deferens= (_e_).
The =vas deferens= (Fig. 110, _e_; Fig. 111, _c_) is a slender tube much
convoluted at its beginning. It passes from the cauda epididymis (_d_)
along the mesenterial fold of the testis on its medial side, to the
spermatic cord (Fig. 111, _d_). It leaves the spermatic cord at the
internal inguinal ring and, curving over the ureter (Fig. 111, _b_),
bends craniad and approaches the vas deferens of the opposite side
dorsad of the neck of the bladder (Fig. 111, _f_). The two vasa
deferentia pass caudad together as far as the cranial border of the
pubis. There they enter the prostate gland (_g_), pierce the dorsal wall
of the neck of the bladder, and open close together on the inner
surface. The two openings are separated by a slight elevation, the =veru
montanum=.
_The Urethra_ (Fig. 111, _h_).--The urethra is the common urinogenital
duct which is formed by the union of the neck of the bladder (_f_) and
the vasa deferentia (_c_) dorsad of the cranial border of the pubis. It
extends thence to the end of the penis. It is divided into three
portions.
1. The =prostate= portion is the commencement of the urethra; it is
surrounded by the prostate gland (_g_).
2. The =membranous= portion (_h_) extends from the prostate portion to a
point between the crura of the penis. This portion is surrounded by the
thick compressor urethræ muscle, so that its wall appears much thicker
than it really is.
3. The =spongy= portion (pars cavernosa) extends along the ventral side
of the penis to its end in the groove between the corpora cavernosa
penis. At its beginning is an enlargement formed by the bulbocavernosus
muscle. This is known as the =bulbus urethræ=. The walls of the spongy
portion are thick and vascular and form the =corpus cavernosum urethræ=
or =corpus spongiosum=. At its end the corpus cavernosum urethræ is
greatly enlarged and forms the glans penis (_m_).
GLANDS OF THE URETHRA.--1. The =prostate= (Fig. 111, _g_) is a bilobed
gland lying on the dorsal wall of the urethra and surrounding the ends
of the vasa deferentia (_c_). It opens into the urethra at its beginning
by numerous small ducts visible to the naked eye on the inner surface of
the urethra.
2. The =bulbourethral= or =Cowper’s glands= (Fig. 111, _i_).--There are
two bulbourethral or Cowper’s glands, one on either side of the bulbus
of the urethra between the ischiocavernosus and bulbocavernosus muscles.
Each has a covering of muscle-fibres derived from the neighboring
bulbocavernosus (Fig. 113, _l_). Each is said to open by a single duct
into the urethra at the root of the penis.
[Illustration: FIG. 111.--MALE GENITAL ORGANS.
_a_, bladder; _b_, _b′_, ureters; _c_, vasa deferentia; _d_, spermatic
cord; _e_, spermatic artery and vein; _f_, neck of bladder; _g_,
prostate gland; _h_, urethra; _i_, bulbourethral (or Cowper’s) gland;
_j_, corpus cavernosum penis, cut from ischium; _k_, ischiocavernosus
muscle (cut); _l_, penis; _m_, glans penis; _n_, testis.]
_The penis_ (Fig. 111, _l_; Fig. 113, 6) is a cylindrical organ with the
apex directed backward. It is covered by integument which projects at
its free end in the form of a fold, the =prepuce= (Fig. 113), which
ensheaths the glans (Fig. 113, 7) of the penis. Beneath the integument
is a layer of strong fibrous subcutaneous fascia continuous with that of
the surrounding parts. On the dorsum of the penis a thin band of fibrous
tissue, the =ligamentum suspensorium penis=, is continued from the
middle line beneath the pelvic symphysis. This band divides distally,
and its halves ensheath the glans and thus form a support of the penis.
The penis is formed by three bodies, the two =corpora cavernosa penis=
and the single =corpus cavernosum urethræ= (corpus spongiosum).
The =corpora cavernosa penis= (Fig. 111, _j_). Each is a cylindrical
sheath of dense fibrous tissue within which are trabeculæ separating
blood-sinuses. Each corpus cavernosum is attached by the one pointed end
to the caudal border of the ramus of the ischium near the symphysis.
From their attachments the corpora cavernosa approach one another,
forming the =crura= of the penis. They become closely united by their
medial surfaces and pass thus to the free end of the penis where their
somewhat pointed distal ends are imbedded in the glans (_m_). A groove
is left between the corpora cavernosa on the dorsum of the penis, and
there is a second groove on the ventral side. In the latter groove lies
the urethra.
The =corpus cavernosum urethræ= is the spongy portion of the urethra
which lies in the groove on the ventral surface of the penis, between
the corpora cavernosa penis. It becomes greatly enlarged at the distal
end of the penis, forming the =glans= (_m_). A small bone (=os penis=)
is imbedded in the distal end of the penis.
B. FEMALE GENITAL ORGANS (Fig. 112).--The urinal organs of the female
are like those of the male. The neck (_k_) of the bladder is, however,
much longer, extending almost to the border of the ischiatic ramus. The
urethra is consequently short.
The genital organs consist of the =ovaries= (_c_) (the organs which
produce the eggs), the =oviducts= or =uterine tubes= (_e_) (=Fallopian
tubes=), which receive the eggs from the ovaries; a bifid =uterus= (_f_
and _i_) in which the ova undergo their development, and a =vagina=
(_m_) which leads from the uterus to its junction with the neck of the
bladder.
The neck of the bladder (_k_) unites with the vagina to form the
=urogenital sinus= (_n_) which is very short, leads to the external
opening, and is comparable to the male urethra. Ventrad of the external
orifice of the urogenital sinus is the =clitoris=, a rudimentary
structure homologous with the penis of the male.
_The Ovaries_ (_c_).--The ovaries lie in the abdominal cavity in the
same longitudinal line with the kidneys and a short distance caudad of
them. Each is an ovoid body about one centimeter long and one-third to
one-half as broad. On its surface are numerous whitish projecting
vesicles, the larger of which show clear centres. They are the =Graafian
follicles= (best seen in section), which contain the eggs. There may be
present one or more elevations of the size of the largest Graafian
follicles, but of a bright red or brown color. They are the =corpora
lutea= (sing. corpus luteum),--Graafian follicles from which the eggs
have been discharged.
The ovary is held in position by the =broad ligament= of the uterus, a
fold of the peritoneum, which passes here from the uterine tube to the
adjacent body wall. The ovary lies in a sort of a pocket formed by the
broad ligament. In the natural position the pocket opens ventrolaterad.
The ovary is further held in position by the ligament of the ovary
(=ligamentum ovarii=), a short thick cord which passes from the ventral
face of the ovary at its uterine end to the adjacent ventral surface of
the uterus.
_The Uterine Tubes_ (_e_).--The uterine (or Fallopian) tubes or oviducts
are the tubes which convey the ova from the ovary (_c_) to the uterus
(_f_). Each begins with an expanded trumpet-shaped opening, the =ostium
tubæ abdominale= (_d_). Its walls are thin, and the mucosa of its inner
surface is thrown up into undulating, radiating ridges.
The ostium (_d_) lies on the lateral side of the ovary (_c_) at its
cranial end, and the trumpet partly clasps the ovary. From the ostium
the tube (_e_) turns craniad, then mediad, and then caudad, so as to
describe a curve about the cranial end of the ovary. It then extends
caudad on the mediodorsal aspect of the ovary to its junction with the
uterine cornu (_f_). It is sinuous throughout its course, and the first
two-thirds (the =vestibulum=) is of considerably greater diameter than
the last third. Throughout the last two-thirds of its course it lies in
the free border of the broad ligament. Its mucosa is thrown into
irregular folds, mostly longitudinal, and is lined by ciliated
epithelium. From the foregoing description it is seen that the ova must
pass through the body cavity in order to reach the ostium tubæ.
[Illustration: FIG. 112.--FEMALE UROGENITAL ORGANS, OBLIQUELY VENTRAL
VIEW.
_a_, kidney; _b_, ureter; _c_, ovary; _d_, ostium tubæ abdominale;
_e_, uterine (Fallopian) tube; _f_, cornua of the uterus; _g_, cranial
edge of broad ligament; _h_, round ligament of the uterus; _i_, body
of the uterus; _j_, bladder; _k_, neck of the bladder; _l_, position
of cervix uteri; _m_, vagina; _n_, urogenital sinus or vestibule, with
M. urethralis; _o_, corpus cavernosum clitoridis, with M.
ischiocavernosus (cut); _p_, fibres of M. constrictor vestibuli. 1,
aorta; 2, internal spermatic arteries; 3, uterine arteries; 4,
external iliac arteries; 5, hypogastric arteries; 6, umbilical artery;
7, inferior hemorrhoidal artery; 8, branches of N. pudendus.]
_The Uterus_ (_f_, _i_).--The =uterus= consists of a median portion or
=body= (_i_) which is unpaired, and of two =horns= or =cornua= (_f_)
which extend from the body to the uterine tubes. The body (_i_) of the
uterus is a tube about four centimeters long which lies in the abdominal
cavity, ventrad of the rectum and between it and the bladder. Its caudal
end is at the level of the cranial border of the pubis. The cranial end
of its cavity is divided by a median dorsoventral partition into lateral
halves, while the cavity of its caudal portion is unpaired. The mucosa
is thrown up into large longitudinal folds. At its caudal end the uterus
projects into the vagina (_m_), so that when the vagina is opened the
end of the uterus is seen projecting into it as a prominent papilla. The
portion of the uterus thus enclosed by the vagina is the =cervix uteri=
or =neck= of the uterus. Its free end is directed ventrocaudad, and a
prominent ridge is continued from its caudodorsal side along the
mid-dorsal wall of the vagina. The uterine cavity communicates with the
vaginal cavity by a V-shaped opening, the =os uteri=, which looks
ventrocaudad and has its apex directed cranioventrad. Each horn (_f_) of
the uterus passes craniolaterad in a nearly straight course from the
body (_i_) to the uterine tube (_e_). It narrows rapidly and becomes
continuous with the tube. The mucosa is thrown into longitudinal folds.
_Ligaments of the Uterus._--=The Broad Ligament.=--The uterus is held in
place principally by the broad ligaments. These are two folds of the
peritoneum, each of which is attached to the whole length of one of the
cornua and the adjacent part of the uterine tube and to the
corresponding lateral surface of the body of the uterus. Each ligament
ends craniad in a concave free border. Its attached border forms a
curved line which begins laterad of the kidney and extends thence to the
lateral ligament of the bladder. From the lateral ligament of the
bladder the broad ligament extends caudad into the =rectovesical= pouch
of the peritoneum, which lies between the rectum and the bladder. It
holds the body of the uterus to the lateral wall of this pouch, and
together with the opposite ligament and the body of the uterus forms
thus a transverse partition, which divides the rectovesical pouch into
dorsal and ventral portions.
The =round ligament= (_h_) is a fibrous band which extends from a point
of the body wall, which corresponds exactly to the internal inguinal
ring of the male, to the cornu of the uterus about two centimeters from
the cranial end. It is attached to the broad ligament by an intervening
fold of peritoneum.
_The Vagina_ (_m_).--The =vagina= extends from the os uteri (at _l_)
dorsad of the symphysis of the pelvis to a point a short distance
craniad of the caudal border of the ischiatic symphysis. At this point
it joins the neck of the bladder (_k_) to form the =vestibulum= or
=urogenital sinus= (_n_), which is homologous with the urethra of the
male.
_Urogenital Sinus_ (_n_).--The =urogenital sinus= extends from the
caudal end of the vagina (_m_) to the external opening, which is
situated ventrad of the anal opening. It is about a centimeter long and
nearly as wide, and is marked off from the vagina by a circular fold of
mucosa, while its inner surface presents longitudinal folds. On its
ventral wall at its cranial end is the opening of the neck of the
bladder, which is enclosed by a ring-like elevation of the mucosa, most
prominent at the sides. The external entrance to the urogenital sinus
forms the =vulva=.
_The Clitoris._--The =clitoris= is a minute organ homologous with the
penis and lying on the ventral floor of the urogenital sinus. Its distal
end lies at the entrance of the urogenital sinus on its ventral border.
In adult specimens the =prepuce= of the clitoris appears as a slight
elevation of the integument surrounding a central vascular structure
which appears red in the fresh organ. From the clitoris there are two
small =corpora cavernosa clitoridis= (_o_) passing craniad and then
diverging to be attached to the ischiatic rami. The ischiatic portion of
each is covered by a muscle (ischiocavernosus). The clitoris is said to
contain a bone.
=Mammary Glands.=--The mammary glands secrete the milk, and lie on the
ventral surface of the body beneath the integument. The separate glands
are closely gathered into two chief masses, one on each side the ventral
middle line. Each of these extends from about the region of the fourth
rib to the caudal end of the abdomen, ending over the pubic symphysis.
On each side the glands are gathered into five groups, each of which is
furnished with a =nipple=. The nipple is a projection of the integument,
having near its distal end numerous fine openings for the ducts of the
glands. The first two nipples are on the thorax, the other three on the
abdomen, the most caudal ones being about two or three centimeters in
front of the cranial edge of the pubis.
Rudimentary mammary glands and nipples are present in the male.
MUSCLES OF THE UROGENITAL ORGANS, RECTUM, AND ANUS (Figs. 113 and
114).--The muscles connected with the caudal openings of the alimentary
canal and of the urogenital organs are closely interrelated, a single
muscle sometimes acting on parts of both systems. For this reason all
these muscles are described together.
The region lying between the anus and the external opening of the
urogenital organs is known as the =perineum=. The perineum is formed
chiefly by muscles and fascia.
_a. Muscles common to the Male and Female._--=M. sphincter ani externus=
(Fig. 113, _i_; Fig. 114, _a_).--This muscle is confounded with the
levator scroti (Fig. 113, _j_) or the levator vulvæ (Fig. 114, _b_). The
two take origin in common from the integument on the dorsum of the root
of the tail dorsad of the fifth caudal vertebra. There the fibres from
the opposite sides are intermingled. The common muscle passes ventrad
about the tail as a flat band close to the integument. Dorsad of the
anus the inner fibres of the muscles of the opposite sides are united.
They then separate and surround the anus as a band five millimeters wide
situated beneath the integument. Ventrad of the anus the fibres are
again intermingled. Some fibres on each side then continue to the
scrotum as the levator scroti (Fig. 113, _j_) or to the vulva as the
levator vulvæ (Fig. 114, _b_). Fibres also pass onto the anal pouch and
unite with the sphincter ani internus, forming the =constrictors of the
anal pouch= (Strauss-Durckheim).
=M. sphincter ani internus= (Fig. 113, _h_; Fig. 114, _c_).--The
sphincter ani internus is a broad and thick band of striated
muscle-fibres which surrounds the rectum at the anus. Dorsad the band is
about two centimeters broad, while ventrad it is less than one. In the
ventral median line some of the fibres pass craniad to help in forming
the bulbocavernosus muscle. The muscle surrounds the anal sac.
(The muscle here described under this name is that described under the
same name in the cat by Strauss-Durckheim and Mivart; it corresponds,
however, to a part of the sphincter ani externus of the dog, as
described by Ellenberger and Baum.)
=M. levator ani= (or =pubiocaudalis=) (Fig. 162, 11).--This muscle lies
in the pelvic cavity. Each muscle forms a nearly vertical sheet, and
between the two are the rectum and the urethra.
_Origin_ from the symphysis of the pelvis.
_Insertion_ into the midventral line of the centra of the third, fourth,
and fifth caudal vertebræ, close to the muscle of the opposite side.
This muscle is frequently continuous with the iliocaudalis (Fig. 162,
11′).
_Action._--Bends the tail and compresses the rectum.
=M. ischiocavernosus= (Fig. 113, _m_; Fig. 114, _e_).--A small, flat,
spindle-shaped muscle which lies upon the crus of the penis or clitoris.
Each has
_Origin_ from the caudal border of the ramus of the ischium, about one
centimeter from the median line.
_Insertion_, in the male, into the whole outer surface of the crus
penis, or bulb of the corpus cavernosum penis. In the female the muscle
is smaller than in the male, and the insertion is into the ventral
surface of the urogenital sinus, at the base of the clitoris.
=M. transversus perinei= (Fig. 114, _i_).--A small bundle of fibres
which arises from the medial surface of the ischium, just dorsad of the
origin of the ischiocavernosus, and passes mediad to join the sphincter
ani internus (_c_).
=M. caudoanalis= (S.-D.) (Fig. 113, _f_; Fig. 114, _g_).--A slender,
flat bundle of fibres having origin on the middle line of the ventral
surface of the second and third caudal vertebræ. It passes caudoventrad,
lying between the levator ani and the caudorectal (Fig. 113, _e_; Fig.
114, _j_), and unites with the ventral portion of the sphincter ani
internus (Fig. 113, _h_).
_Action._--Draws the anus craniodorsad.
[Illustration: FIG. 113.--MUSCLES OF THE ANUS, UROGENITAL ORGANS, AND
TAIL IN THE MALE (SLIGHTLY SCHEMATIC).
One side of the pelvis has been removed, _a_, _a′_, M. extensor caudæ
lateralis; _b_, M. abductor caudæ externus; _c_, _c′_, M. flexor caudæ
longus; _d_, M. flexor caudæ brevis; _e_, M. caudorectalis; _f_, M.
caudoanalis; _g_, M. caudocavernosus; _h_, M. sphincter ani internus;
_i_, M. sphincter ani externus; _j_, M. levator scroti; _k_, M.
rectocavernosus; _l_, M. bulbocavernosus; _m_, M. ischiocavernosus
(cut); _n_, M. compressor urethræ membranaceæ. 1, tail; 2, rectum; 3,
bulbourethral or Cowper’s gland; 4, prostate gland; 5, symphysis
pubis; 6, penis; 7, glans penis; 8, testis; 9, spermatic cord.]
=M. caudorectalis= (Fig. 113, _e_; Fig. 114, _j_).
_Origin_ from the ventral surface of the sixth and seventh caudal
vertebræ. A small, at first unpaired band two or three millimeters wide
is formed, which passes cranioventrad, soon dividing into two lateral
halves. These spread out over the sides of the rectum, forming a broad
sheet of fibres which pass into the walls of the rectum, among the
transverse fibres of the latter. This muscle is covered by the
caudoanalis (Fig. 113, _f_), caudocavernosus (_g_) (or caudovaginalis,
Fig. 114, _h_), iliocaudalis, and levator ani.
_b. Muscles Peculiar to the Male_ (Fig. 113).--=M. levator scroti=
(_j_).--This is a band of fibres which passes ventrad in the median line
from the sphincter ani externus (_i_) onto the scrotum. Here it spreads
out beneath the skin, forming especially a well-marked bundle in the
median furrow between the two testes.
=M. rectocavernosus=, or =retractor penis= (_k_).--A small bundle of
fibres which arises in two parts from the ventral surface of the
sphincter ani internus (_h_). The two parts unite into a single bundle
which passes caudad on the middle line of the ventral surface of the
penis; it is inserted into the corpus cavernosum just proximad of the
glans. The muscle is covered only by integument, and overlies the
ischiocavernosus (_m_).
=M. caudocavernosus= (S.-D.) (_g_).--A slender bundle just craniad of
the caudoanalis (_f_).
_Origin_ on the median ventral line of the first two caudal vertebræ.
The muscle passes caudoventrad, lying between the levator ani and the
caudorectal (_e_). It divides into two bands, one of which is inserted
into the base of the corpus cavernosum, while the other extends farther
caudad and is inserted at the distal extremity of the corpus cavernosum.
_Action._--Flexes the penis (bends it backward).
=M. bulbocavernosus= (=accelerator urinæ=) (_l_).--The two muscles cover
the ventral surface of the penis.
_Origin_ of each from a median raphe, which passes from the bulbous
portion of the urethra toward the anus. The fibres pass toward the
distal end of the penis and have their
_Insertion_ into the distal half of the lateral surface of the corpus
cavernosum penis.
=M. compressor urethræ membranaceæ= (_n_).--A thick layer of striated
muscle-fibres which surrounds the urethra between Cowper’s gland (3) and
the prostate (4). The fibres have a circular course, and the cranial
ones are attached to the crura of the penis. The other fibres have no
fixed attachment.
_c. Muscles Peculiar to the Female_ (Fig. 114).--=M. levator vulvæ=
(Strauss-Durckheim), or =constrictor cunni= (_b_).--This is homologous
with the levator scroti of the male. It consists of a band of fibres
which pass ventrad from the external sphincter ani (_a_) and surround
the vulva (3), lying immediately beneath the integument.
=M. constrictor vestibuli=, or =rectovaginalis= (Strauss-Durckheim)
(_d_).
[Illustration: FIG. 114.--MUSCLES OF THE ANUS AND UROGENITAL ORGANS IN
THE FEMALE.
_a_, M. sphincter ani externus; _b_, M. levator vulvæ; _c_, M.
sphincter ani internus; _d_, M. constrictor vestibuli; _e_, M.
ischiocavernosus (cut); _f_, M. urethralis; _g_, M. caudoanalis; _h_,
M. caudovaginalis; _i_, M. transversus perinei; _j_, M. caudorectalis.
1, the tail; 2, anus; 3, vulva; 4, rectum; 5, vagina; 6, neck of the
bladder.]
_Origin_ from the sides of the sphincter ani internus (_c_). The muscle
forms a distinct bundle two or three millimeters wide, which passes
ventrocaudad and is _inserted_ into the ventral surface of the
urogenital sinus, caudad of the insertion of the ischiocavernosus (_e_).
=M. caudovaginalis= (Strauss-Durckheim) (_h_).--A slender band just
craniad of the caudoanalis (_g_), and corresponding to the
caudocavernosus of the male.
_Origin_ from the median line of the ventral surface of the first two
caudal vertebræ. The muscle passes caudoventrad, lying between the
levator ani and the caudorectal (_j_), and is _inserted_ into the
ventral side of the urogenital sinus, at the base of the clitoris.
=M. urethralis= (_f_).--This consists of fibres surrounding the cranial
part of the urogenital sinus and the caudal parts of the vagina and neck
of the bladder.
_Origin_ partly on the caudal part of the symphysis of the ischium,
partly from the ventral surface of the urogenital sinus, where the
fibres are attached to the corpora cavernosa clitoridis. The fibres pass
dorsad over the surface of the sinus, and over the surface of the union
of the vagina and neck of the bladder, to be inserted into the sides of
the vagina and the dorsal surface of the urogenital sinus.