Download Clinical anatomy of the human female pelvic overview Objectives

Clinical anatomy of the human female pelvic overview
Objectives
To get the student intoduced into the most important clinical significance to the anatomy of the female
genital system. I this way understanding of later on clinical lectures which are associated with morbid
anatomy or pus formation become more easier and obvious.
The skeleton and the ligaments
As far as both male and female anatomy the skeleton of the pelvis is similar.
1. To large innominate bones are joined anteriorly by fibrous joint called the pubic symphysis. On
the other hand both innominate bones are joined to a large 4 fused sacral vertebrae called the
sacrum by two synovial joints. This joint is the target of wide range of rheumatic disorders like
rheumatoid arthritis and ankylosing spondylitis.
2. Each innominate bones is actually fusion of three bones those are the ilium, ischium and pubis.
Their fusion leaves a large foramen called the obturator formaen. This foramen has a defect in
the anterior part called the obturator canal through which the obturator artery, vein as well as
nerve exit the true pelvic cavity to supply the obturator groups of muscles which have internal
rotation as well as internal abduction of the thigh.
3. The first sacral vertebra has a projection which is called sacral promontory. While the sacrum
itself has four pairs of foramen to allow exit of sacral branches of spinal cord as far as S1 to S4.
4. The sub pubic angle in female pelvis should divergent and more than 90 degree. Those bony
landmarks are used to assess the adequacy of females pelvis with regard to vaginal delivery
through what is called clinical pelvimetry
5- each innominate bone has a sine shaped projection called Ischial spine which is situated
between greater and lesser notches. Those notches are converted into two foramen the greater
sciatic and lesser sciatic foramen by the sacrospinal ligament and the sacrotuberous ligaments.
The Ischial spine in female pelvis is usually small and everted.
6- Nerve and vessels which has to exit the true pelvic cavity into the perineum has to hook
around the ischial spine and enter the perineum through the lesser sciatic notch. Mainly the
pudendal vessels and nerve.
The cardial ligament of the pelvis
1- The cardinal ligament of the pelvis is a unique ligament which has a fan shaped appearance
and extends from the pelvic side wall and inserted directly into the lower part of the uterus
exactly at the same level of internal os which herald the beginning of the cervical canal.
2- The internal oss is the main structure which keeps the product of gestation from expulsion
before the onset of labor.
3- Damage to this ligament may lead to recurrent second trimester abortions or preterm
labor.
4- On the other hand this ligament is the only structure which holds the uterine body in its
position. Damage to this ligament may lead to descent of the uterine body into the vaginal
and eventually become protruded outside the vulva which a condition is called procedentia.
5- The main cause of damage to this ligament is the application of obstetrical forceps before
full cervical dilatation. Otherwise precipitate labor which is defined as labor with first
second and third stage is less than 2 hours may cause its damage. Maternal strong push
desire before full cervical dilatation rarely may cause its damage.
6- The most important clinical significance of those two fan shaped connective tissue is that
they are the main direct spread of carcinoma of the cervix. In staging of this gynecological
carcinoma spread of malignant cells over it is used to classify the staging of cervical
carcinoma. Pelvic examination indicator of spread is feeling a hard mass either in one side
or both. Once the tumor spread over them the condition becomes incompatible with any
surgical interference while before their spread radical hysterectomy may bring about 5 year
survival up to 90%. The other aspect of this spread is involvement of the ureter as it lies on
its course leading to intractable uretrovaginal fistula which has no surgical interference
possible with it. This fistula affects significantly the life quality of the woman and all the
treatments available like diversion of ureters into the bowel is done on palliative basis
rather than curative to alleviate the woman sufferings.
The muscular system of the pelvis
The levator ani or pelvic floor muscle is the main muscle of the pelvis in female. They are fan
shaped extension from the pelvic side wall to meet in the mid line. In the anterior part a defect
is present to allow the passage of urethra, vagina as well as the rectum. This defect is called the
urogenital hiatus. Each half of this large muscle is composed of 3 pairs of the followings
1- Puborectalis muscle
2- Pubococcygeous muscle
3- Iliococcygeous muscle
In addition to those 3 pairs further 2 pairs of
1- Coccygeous muscle
2- Piriformis muscle
Have further action full separation of the pelvic cavity from the perineal cavity. In addition to that the 2
sphincter muscles sphincter ani and sphincter urethrae are blended with the fiber of this muscle.
1- The levator ani is composed of striated voluntary muscle fibers and only special exercises
may elicit its action, this muscle is the main base for all the pelvis viscera to rest on it firmly.
2- In addition to that this muscle contributes significantly to the integrity of both sphincter
muscles especially the sphincter urethrae.
3- Weakening of this sphincter may follow pregnancy especially after delivery leading to stress
incontinence with leak of urine upon any maneuver which increases intra abdominal
pressure like cough straining at defection and other related condition.
4- For this purpose special exercise has been advocated like Kegel pelvic floor exercise which
aims to increase the number of muscle fibers supplied to this muscle.
5- On the other hand especially among women with grand multi parity damage to this muscle
may lead to herniation of the bladder into the anterior vaginal wall a condition called
cystocele.
6- Otherwise may lead to herniation of the rectum to posterior vaginal wall which lead to
rectocele. Both of the last conditions are treated usually by special surgery for correction of
those conditions.
7- Those subjects are further detailed in the lecture of genital tract prolapse.
The vascular supply to the pelvis
1. The vascular supply and drainage of the pelvis is one of the most interesting among others
in human body. It is so extensive and huge to the extent that ligation of the internal iliac
artery on bilateral basis has no effect on any organ as far as blood supply is concerned.
2. This is mediated by the vast anasthomosis of pelvic blood supply with other major vessels
whether before the pelvis, or at the level of pelvis or even beyond the level of pelvis
3. As an example the superior epigastric artery which comes from the aorta and internal
thoracic artery anasthomose with inferior epigastric artery which is the last branch of
external iliac artery. Another pathway is the anasthomosis between terminal branches of
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the lumbar artery with superior and inferior gluteal artery. A third pathway is anasthomosis
between the femoral artery branches with inferior epigastric artery.
4. The main blood supply to the pelvis internal iliac artery which gives branches as follows
Uterine artery
Vaginal artery
Superior and inferior vesical artery
Lateral sacral artery
Middle rectal artery
Obturator artery
Pudendal artery
Venous drainage of the pelvis
The venous drainage of the pelvis is also unique in the form that bladder wall, uterine wall as well as
rectum wall contains extensive venous pampiniform plexus which drains gradually to veins with names
similar to the counterpart artery and ultimately drains into the internal iliac artery and common iliac
artery and inferior vena cava.
Of more interesting branched of the internal iliac artery are the obturator artery and pudendal artery.
The obturator artery exits the pelvic cavity through the obturator canal while the pudendal artery leaves
the pelvic cavity to enter perineal cavity through hocking around the ischial spine. Its name changes to
the lateral perineal artery and after supplying the perineal body it terminates either in the corpus
spongiosm under the clitoris or corpora cavernous each one under the labia major fold.
Overview of the pelvic cavity and contained organs
1. The pelvic cavity as viewed from above shows the overall arrangement of pelvic organs.
Anteriorly the bladder is a cystic hollow organ which lined with transitional epithelium which
allows the bladder to distend several times its original volume.
2. The detrusor muscle of its wall is arranged in interlacing character which accepts both distension
as well as contraction in smooth way to expel the stored urine.
3. The urine reaches the bladder via bilateral ureter which has a unique arrangement with the
uterine vessels as water under bridge. Failure to appreciate this fact may lead to ligation of the
ureter in the course of obstetrical or gynecology surgery as cesarean section and hysterectomy.
4. The bladder is covered with peritoneal surface as it is taken from anterior pelvic wall to reach
the anterior surface of the uterus at the vesico uterine reflection.
5. The sphincter urethrae muscle is composed of internal smooth muscle fibers and outer striated
muscle fibers and blend with the levator ani.
6. Parasympathetic stimulation will result in opening the internal part of the sphincter and
contraction of the detrusor muscle. This reflex is at the level of s2, s3 and s4.
7. The uterine body is contained within a large fold of peritoneum which is called the broad
ligament.
8. The round ligament arises from the uterine body and after a long course covered with
peritoneal fold enters the inguinal canal to be inserted after exit into the labia majora base.
9. Next the ovarian ligament arises from the uterine wall and attached to the ovary.
10. On the to reflexion of the broad ligament the
11. Fallopian tubes appear from lateral fambrial part, ampullary part ischemic part to the uterine
cavity.
12. Posterior two ligaments called uterosacral ligament and arise from the level of internal os and
inserted into the sacrum.
13. This arrangement leaves a potential cavity behind the uterine wall called the pouch of Douglas.
14. The rectum is usually fixed to the sacrum by pelvic peritoneum and separated from the vaginal
wall by this sheet of fibrous tissue called recto vaginal septum.
15. The terminal part of rectum undergoes S shaped turn to form the rectal valve before ends into
the anal canal with sphincter ani is situated between them.
16. The ovary in both sides is suspended by a strong ligament called suspensory ligament of the
ovary in which the ovarian artery comes directly from the aorta and the vein drains directly into
the inferior vena cava.
17. The uterine cavity is lined with special tissue which responds to estrogen in the proliferative
phase of the cycle and become fully filled with adenoid glands in the luteal phase of the cycle.
18. The muscles in the uterine wall are smooth types with outer longitudinal layer and inner circular
layer and in between them a huge interlacing fibers cross each other in about 45 angles.
19. This arrangement is compatible with huge enlargement of the uterine cavity from slit like to the
full grown fetus beyond 37 weeks with its liquor and placenta.
20. The cervix is attached to the uterus at the level of internal os and usually remains closed until
onset of labor.
21. The cervix is a thick tubular structure with internal can lined with simple columnar epithelium
and outer surface covered with stratified squamous epithelium.
22. The cervix undergoes huge changed during labor in the form of consistency, position, shortening
and dilatation.
23. When it is 10 cm dilated is said t be fully dilated.
24. During pregnancy the uterus shows infrequent contractions which are called Braxton hicks
contraction. They are usually painless and don’t cause cervical dilatation.
25. The vaginal is attached to the uterus in such a way that cervix form anterior, lateral and
posterior vaginal fornix.
26. The axis of vagina and non pregnant uterus forms 90 degree angle.
27. The vaginal is lined with stratified squamous epithelium and strong yet thin smooth muscle
fibers.
28. The uterus has only sympathetic supply with 2 types of receptor alpha which promotes uterine
muscle contractions and beta receptors which induce relaxation of the uterine muscle.
29. While the urethra after emerging from the sphincter muscle is totally perineal structure 4 cm in
length,
30. The vaginal with upper 2/3 is pelvic organ and lower 1/3 is perineal bellow the levator ani.
31. The lymphatic vessels in the true pelvic cavity ultimately end in the lymph nodes along the
internal iliac vein to the common and at last to the aorta lymph nodes.
32. The scraping from vaginal cells usually stain red under the effect of estrogen only while it stains
blue after exposure to progesterone. Those correspond to the proliferative and secretory phase
of the menstrual cycle.
33. While scraping from the squamou columnar junction at the external os of the cervix is used to
screen for premalignant cells in carcinoma of the cervix.
The perineal cavity
The perineal cavity differs greatly in females than male. The most significant structure which has to be of
interest is the perineal body. The perineal body is a condensation of fiber tissue and muscular tissue
from the following structure.
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Sphincter urethrae
Sphincter anus
Levator ani
Deep transverse perineum muscles
Superficial transverse perineum muscles
This organ is the main organ which keeps the rectum separated from the vaginal. It is liable to be
damaged in extended episiotomy with 3d to 4d perineal tears. In this case the recto vaginal septum will
be torn and ultimately the rectum protrudes into the posterior vaginal wall a condition called rectocel. It
is associated with large mass coming from posterior vaginal wall and fecal incontinence. The prevention
of this condition is to evaluate carefully the extension of vaginal tear and suturing it in layers. The clinical
indication of this condition during examination is the loss of 2-3 cm between the fourchete of the vulva
and the anal opening.
The external genitalia
1. The mons veneris is a fatty tissue condensation over the pubic symphsis
2. The clitoris is a distensible projection lie in the upper part of the vulva. During sexual arousal it
becomes enlarged due to the presence of corpus spongiosum bellow it
3. Labia major in each side which harbors the Bartholin gland in each. Their openings are bellow
4. The labia minora are usually small fold of thin red skin below which a fatty tissue.
5. Vestibule is the space between the 2 labia minor
6. Bulbs of the vestibule paired of erectile tissue which lie medial aspect of labia minor and enlarge
by the underlying corpora cavernosa spongy tissue
7. Greater vestibular glands are pairs of glands posterior to the bulb of the vestibule which
secretes mucous around sexual arousal
8. Fourchete is the meeting point of each labia posterior to the vestibule
Laymphatic drainage of the vulva
1. It should be mentioned that lymphatic drainage of the vulva usually ends in the superficial and
deep lymphatic nodes of the femur.
2. The deep node is a single lymphatic node lays in the inner most compartment of the femoral
sheath followed by the femoral vein in the middle and femoral artery in the outer compartment.
The femoral nerve passes outside the femoral sheath.
3. This arrangement of lymphatic drainage should be considered in carcinoma of the vulva where
in addition to excision of the whole vulva, those lymph nodes should be removed as well
otherwise distant metastasis is inevitable.