This lecture discusses the male and female pelvis and perineum.
We remind ourselves that the abdominal pelvic cavities are continuous,
and that the pelvic organs are supported inferiorly by the pelvic diaphragm.
This is an image we've seen before.
This is an inferior view of the pelvic diaphragm.
And we see a gap anteriorly called
the urogenital hiatus for passage of the urinary and reproductive systems.
And posteriorly, the anal aperture for passage of the digestive system.
The artist has now added the urogenital diaphragm.
We see that the urogenital diaphragm has probably three functions.
It serves as an attachment for the external genitalia.
It houses the sphincter urethrae muscle,
and it reinforces the pelvic diaphragm.
Together, the urogenital diaphragm and the pelvic diaphragm form the pelvic floor.
This is the midsagittal section through the female pelvis.
The levator ani and the urogenital diaphragm are identified.
We can see then that the pelvic floor supports GI,
urinary, and reproductive organs.
By definition, structures which are superior to the pelvic floor are in the pelvis,
and structures which are inferior to the pelvic floor are in the perineum.
As we can see in this midsagittal section of the male pelvis,
the pelvic floors serves the same important functions.
The artist is drawn a midsagittal section through
the female pelvis as well as drawing structures of the lateral pelvic wall.
So this has been done in order to emphasize the position of the peritoneum.
We see the peritoneum covers the superior surface of the pelvic organs.
And there is an important space between the rectum and
the uterus called the recto-uterine pouch of Douglas,
where the peritoneal cavity and the vagina lie very close to each other.
There is a gap in the peritoneal cavity at the opening of
the fimbria where it surrounds the ovary.
This is a chloral view showing the vagina and the cervix and the parts of the uterus.
We see the uterine tube also commonly called the fallopian tube.
And we see the fimbria,
where the uterine tube opens to surround the ovary.
Normally the uterus lies on top of the bladder.
This position is called anteverted and anteflexed.
However, the uterus may lie in different positions.
During childbirth, it is important to understand the size of the pelvic cavity.
Pelvic inlet is a plane that runs from the superior border of
the pubic symphysis to the sacral promontory.
And the pelvic outlet is a plane that runs from
the inferior border of the pubic symphysis to the coccyx.
The size of the pelvic inlet can be estimated by vaginal exam,
measuring the diagonal conjugate which runs from
the inferior border of the pubic symphysis to the sacral promontory.
The space between the ischial spines is the narrowest part of the pelvis.
We return to pelvic and peritoneal structures in the male.
This is a diagram which emphasizes the urinary and reproductive systems in the male.
We see the testis where the sperm travels into the epididymis and travels up
the vas deferens to join with the seminal vesicles to form the ejaculatory duct.
During ejaculation, semen enters the prostatic urethra.
The male urethra is divided into three parts.
The first part is the prostatic urethra which runs through the prostate.
The prostate rests on the urogenital diaphragm.
That portion of the urethra are passing through
urogenital diaphragm is called the membranous urethra.
The membranous urethra then becomes the penile urethra.
The external genitalia in both the male and
the female are attached to the urogenital diaphragm.
This image shows the erectile tissue of the female.
And this image shows the erectile tissue in the male.
This is an inferior view of the perineum in the female showing erectile tissue.
In the midline, we see the glans of the clitoris and the crus of the clitoris
bilaterally attaching to the tissue of pubic rami.
And we see the vestibular bulbs of
erectile tissue surrounding the vestibular or opening of the vagina.
The urethral orifice is between the glans of the clitoris and the vagina.
This image shows the erectile tissue in the male.
The crus of the penis extends onto the shaft bilaterally as the corpus cavernosum.
The bulb of the penis is a mid-line structure
which extends onto the shaft of the penis as of corpus spongiosum.
The corpus spongiosum terminates as the glans of the penis.
The urethra enters the bulb of the penis and
passes through the corpus spongiosum to the urethral orifice.
The erectile tissue of the crus and bulb are surrounded by muscle.
In the female, muscles surround the crus of the clitoris and the vestibular bulbs.
The central perineal tendon is a fibrous structure that
lies between the vaginal orifice and the anal canal.
The external anal sphincter,
the muscles of the perineum,
the ural-genital diaphragm and the pelvic diaphragm,
all attached to the central perineal tendon.
So this structure is very important in maintaining integrity of the pelvic floor.
This structure is also present in the male.
Recall that the pudental nerve arises from the S2-S4 sacral spinal segments.
And that it passes around the sacrospinous ligament to enter the perineum,
where it supplies both motor and sensory innervation.
The pudendal nerve has anterior and posterior branches.
The anterior branch supplies sensation to
the external genitalia and innervation of the urethral sphincter.
The posterior branch supply's sensation to
the perineal region and innervation of the external anal sphincter.
The artist has shown in green,
the autonomic nerves that supply the pelvis and the perineum.
These nerves do not follow their pudendal nerve,
but they reach to your general diaphragm by
passing with the urethra and the vagina in the female,
and with the urethra in the male to reach the erectile tissue.
This image emphasizes a close relationship between the autonomic nerves and
the prostate gland as nerves pass around
the prostate to follow the urethra to the erectile tissue.
This close relationship puts these nerves at risk during prostate surgery.
This image shows how contrast can be used to study the male reproductive tract.
In this individual, contrast was injected bilaterally in the vas deferens.
We can follow the vast proximately,
we can see the contrast has filled the seminal vesicles and the ejaculatory duct.
This kind of study would be done for male infertility.
This study shows how contrast can be used to study the female reproductive tract.
In this individual, dye was injected in
the cervical loss and it's filled the uterus and the uterine tubes.
And we see dye spilled into the peritoneal cavity on each side.
This kind of study would be done for infertility.
And this study is called the hysterosalpingogram.
I hope you've appreciated the similarities and
differences between the male and female reproductive systems.