Pelvis and Perineum
1/14/2009 10:03:00 AM
January 14, 2008
Plate Number 354
 Male Pelvis-Anterior view of a boney male pelvis
o Differences between male and female
 Subpubic arch has a larger angle in female.
Approximatly 90 degrees in male
 Wider opening in the female
 Male pelvis tend to have heavier bones, bigger
projections (due to mass and muscles)
o Sacrum is part of the axial skeleton, belong to vertebral
column.
o Hip Bone belongs. to the appendicular skeleton, belong to
lower limb
 Form iliosacral joint with the sacrum.
Boney projection into the pelvic cavity is the spine of the
ischium
Large aperture is the obturator foramen. Presense of
obturator foramen thought to be to help reduce the weight of
the pelvis
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Female pelvis-Anterior view of a boney female pelvis
o Sub-pubic angle is MUCH greater.
o Ala of the ilium is more flared, are wider
o There is a sharp ridge that follows the entire pelvic inlet. It is
sharp bordered all the way around from the pubic symphysis
around to the sacrum on both sides. Called the pelvic brim or
inlet.
o Sharp ridge on the upper end of the S1 vertebra is the sacral
promontory
o There is bone that lies superior and inferior to the pelvic brim.
It divides the pelvic cavity from the abdominal cavity.
 Superior to the pelvic brim is called the false pelvis. It
has ABDOMINAL organs. False pelvis lies between the
iliac crest and the iliac brim between the two iliac
fossae.
 Inferior to the pelvic brim is the true pelvis and the
pelvic cavity
Pregnant uterus and a full urinary bladder will
expand above the pelvic brim
 Pediatric anatomy is different. Just keep that in mind.
 Inferior view of the boney pelvis
o Ischial spines are prominent
o Ischial tuberosity is a large prominence. Its subcutaneous so
you don’t sit on muscles.
Plate 486
 Acetabulum is cup that articulates with the head of the femur.
 The three bones meet in the acetabulum, fusion not until late teen
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years.
o Most superior portion is the Ilium
o Inferoposterior is the ischium
 Ischial spine protrudes infero-medially
 the ischial tuberosity is inferior to the ischial spine
o Inferoanteriorly is the pubis
Plate 353, 352
 Two notches
o The greater Sciatic Notch
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 Sacrospinous ligament
The lesser Sciatic Notch
 Sacrotuberous ligament
The notches are converted to foramen by soft tissue
ligaments from the sacrum
Most of the structures that are leaving the pelvic cavity and
going to the lower limb and the perineum exit through the
greater and lesser sciatic foramina
The lesser foramen is more lateral than the greater foramen.
The lesser foramen gives access to the perineum and the
greater foramen give s an exit from the pelvix.
Plate Plate 354
 Dimensions (more clinically relevant to females)
o Pelvic inlet is wide open, there is no diaphragm
o Pelvic outlet is from the lower aspect of the pubic symphysis
to the coccyx. There is a floor, it is called the pelvic
diaphragm. The pelvic diaphragm is a funnel shaped
muscular wall.
o Conjugate diameter is the that of the pelvic inlet. It should
be approximately 11 cm in a female (important for delivery)
 Diagonal conjugate is from lower aspect of the pubic
symphysis to the sacral promontory (can be measure
during vaginal exam and should be approx. 13.5 cm)
 During pregnancy, this is the only dimension that will
not change. Enzymes will loosen the sacrococcygeal
joint and the pubic symphysis. Conjugate and diagonal
conjugate will NOT change, no matter how much the
joints are loosened.
Plate 358-Male Pelvic Diaphragm
 Piriformis m is not part of the diaphragm (posteror to diaphragm,
part of posterior wall) It leaves through the greater sciatic foramen.
 Obturator interus is not part of diaphragm (lateral to diaphragm,
part of lateral wall.) It leaves through the lesser sciatic foramen
 Foramen in diaphram for vessels and anus and urethra.
Plate 359 and 356 Male and female pelvic diaphragm.
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Main difference is a vagina
Ischial spine is a prominent land mark in the pelvic exam.
Pelvic diaphragm defines border between the pelvis and the
perineum.
o False Pelvis-iliac crestpelvic brim
o True Pelvis-Pelvic brimpelvic diaphragm
o Perineum- Pelvic diaphragm and below
Side note: ASIS and pubic tubercle are on the same coronal plane. Pelvis is
on a 55 degree tilt.
The Perineum
In the anatomical position, it is a small region commonly referred to as the
crotch.
If you abduct the thighs to the Lithotomy postion (lying on his back, thighs
abducted.
In the male there are two diverticuli of the perineum (penis and scrotum)
Plate 380
 Male and Female--Boney Landmarks to make a diamond shaped
region that defines the perineum
o Pubic symphysis
o Two Ischial tuberosities
o Coccyx
 Subdivisions of the diamond by drawing a line between the ischial
tuberosities
o Anal triangle
o Urogenital triangle
Plate 382-Penis (focus on anal triangle), Plate 379-Female perineum
 Anus is in the anal triangle.
 To the sides of the anus is a lot of fat in the ischioanal fossae
o Fat helps close the anal canal
 Perineal body has lots of connective tissue and is on a plane almost
between the two ischial bodies
o External anal sphincter runs between the perinal body and the
coccyx in a circular pattern around the anus.
 Episiotomy is an incision in the posterior vaginal wall to prevent
tearing of the vagina through the perineal body.
Plate 413-Nerves of the female perineum, Plate 404-vessels of the female
perineum, Plate 411-Male nerves and vessels of the perineum
 There is a neurovascular bundle in the wall of the ischioanal fossae,
the pudendal nerve and the internal pudendal artery and vein
o The inferior rectal nerve is a branch of the pudendal nerve. It
provides motor to the external anal sphincter and sensory to
the skin over lying the anal triangle
o The inferior rectal artery is from the internal pudendal artery.
o The Internal Pudendal artery is a branch of the internal iliac
artery and leaves through the greater sciatic foramen and
enters through the lesser sciatic foramen.
o The pudendal nerve (S2-4) exits through the greater sciatic
foramen and enters the perineum through the lesser sciatic
foramen
Pudendal gives off inferior rectal nn and then bifurcates
to form the perineal n and the dorsal n to the
penis/clitoris
o Pass through greater and lesser sciatic foramen
 Pudendal nerve
 Internal pudendal artery
 Internal pudendal vein
Plate 392-Coronal section through the plane of the anus.
 Notice the ischioanal fossae
o There is a base (skin)
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o Medial wall (levator ani m.)
o Lateral wall (obturator internus m.)
o Apex of the “pyramid” is where levator ani m. takes origin
from the fascia of the obturator internus m.
o The fascia of the lateral wall splits to form a neurovascular
bundle
 Pudendal n. and internal pudendal a. and v.
 Inferior rectal nerve branches from this and travels
through the fat.
Plate 356
 Levator ani take origin from the fascia of obturator internus. The
thickened portion of the fascia is called the tendonous arch.
 Some fibers of Levator ani m. take origin from the pubis, but the
lateral most take origin from the obturator internus m.
Plate 393-Rectum and Anal Canal
 Last 4 cm is the anal canal
o Upper anal canal has the longitunidal anal columns. The
superior rectal a and v lay in the submucosa of the anal
columns.
 Lower ends of adjacent anal columns are called valves
and contain sinuses. The sinuses catch mucus and
push the mucus out during defacation to help prevent
tearing of the anal canal.
o Pectinate Line is the divider between endodermal origin and
ectodermal origin. It is the lower portion of the anal canal.
The white line of Hilton become Keratinized, have hair and
glands. Below the white line it is skin.
 The pectinate line divides where the nerves and blood
supply change. Below the pectinate line is the somatic
nervous system and caval venous return. Above the line
is enteric nervous system and portal venous return.
Clinical Correlation!
Hemorrhoids
 Two types: Internal and External
 Internal
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o Associated with the superior rectal veins and the veins in the
anal columns. If there is portal vein back up, one of the
places they make back up is the superior rectal vein.
o There is no pain with internal hemorrhoids
o They are SUBMUCOSAL
o Treated only when prolapsed by placing a rubber band around
the hemorrhoid
External Hemorrhoids
o Just deep to the skin around the anus—subcutaneous
o There is pain with external hemorrhoids.
Affected persons
o Pregnant people
o Liver disease
o Chronic constipation
Fissures
 Tear in the lining of the epithelium of the anal canal
 Can lead to an abscess
 If the fissure does not heal and the abscess remains in
communication with the anal canal, this is called a fistula
January 15, 2009
Plate 399
 Internal and External venous plexuses have elaborate
communications which are portal caval anastomoses
Plate 398-Arteries of the Anus
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Superior and Inferior rectal arteries and an inconsistent middle
rectal artery.
Dermatomes of the perineum
 S3 is dominant
 Some from S4 and minor from S5
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Urogenital Triangle-Anterior to the inter-ischial tuberosity line.
 There is continuation of the Scarpa’s Fascia from the anterior
abdominal wall. Is called Colle’s Fascia. Its still the membranous
fascia. Colle’s fascia extends onto the shaft of the penis/clitoris as
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well as the scrotum/labia.
Camper’s fascia loses its fat as it continues below the anterior
abdominal wall. It changes to muscular tissue in the scrotum called
the Darto’s muscle. They insert into the dermis of the scrotal skin.
Darto’s muscle is temperature sensitive. Warm—Relaxed, Cold—
Contracted. There are NO Darto’s muscles in the labia. It does
have fat, which is the same fat layer of the camper’s fascia from the
anterior abdominal wall. There is no fat on the shaft of the clitoris.
The combination of the Darto’s muscle and the Colle’s fascia are
together called the Darto’s Tunic. The skin is NOT part of the
Darto’s Tunic.
If damage to the bulb of the penis with damage to the urethra,
urine can extravasate into the scrotum, penis and even anterior
abdominal wall.
Perineal membrane meets the perineal body and the inferior pubic
arch.
o Potential space between the perineal membrane and Colle’s
Fascia is called the superficial perineal pouch/space.
Superior Fascial of the UG diaphragm travels superior to the
perineal membrane and creates the deep perineal pouch/ space.
Plate 381-Male UG Triangle
 Ischiocavernosis muscles are paired muscles that diverge inferiorly.
o Attached to the bone of the ischial tubersosity, not attached
to the perineal body.
 Bulbospogiosus muscle is medial to the ischiocavernosis mm.
o Does attach to the perineal body.
 Muscles stop as the shaft of the penis extends out from the body
wall.
 Superficial transverse perineal mm are paired mm that converge on
the perineal body.
Plate 382-Erectile
 Bulb of the penis is unpaired. When the bulb loses its attachment
and extend beyond the body wall it becomes the corpus
spongiosum. It travels on the ventral surface of the penis.
 Crura of the penis are laterally paired. When they extend into the
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shaft, the become the corpus cavernosum.
What do the muscles do that coat the bulb? (bulbospongiosum)
o During arousal and ejaculation. Makes the penis turgid.
o Squeezing the last bits of urine out.
What do the muscles that coat the crura (ischiocavernosum)
o Maintain turgidity of the penis during arousal and ejaculation.
o NOT used for urinary function
There is a dense connective tissue septum between the corpus
cavernosum
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Corpus spongiosum expands distally to become the glans of the
penis.
Every new born male has a foreskin (prepuce) which is a double fold of skin
over the glans of the penis.
 Removal is called that circumcision.
 Balonitis is inflammation of the glans of the penis
 Posthitis is inflammation of the foreskin of the penis.
 Some situations where the foreskin is tightly adhered to the glans.
This is called Phimosis
 Paraphimosis is when it retracts, but does not re-cover the glans.
Priapism is an erection that will not disapate. Priapism is NOT related to
sexual stimulation. Blood does not escape from the penis. The blood is
stagnant and runs the risk of causing necrosis of the penis.
Plate 381-Cross Section through the penis.
 Just Deep to the skin is the Darto’s Tunic. In the darto’s tunic is a
mid line vein called the superficial dorsal vein. Very irregular
course.
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There is a thick layer of Deep fascia called buck’s fascia. It is very
thick and tough. Deep to Buck’s Fascia there is a series of nerves
and vessels
o Deep Dorsal vein is mid line and runs sort of between where
the two corpus cavernosa come together.
o The deep dorsal vein is flanked on either side by the Right
and Left Dorsal Vein.
o Lateral to the two dorsal arteries are the dorsal nerves.
 In the core of the corpus caversona is the deep artery of the penis.
Plate 411-Nerves of the male Perineum
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Three branches of the pudenal nerve
o Inferior rectal nerve-Mixed Nerve
o Perineal nerve-Mixed Nerve
o Dorsal nerve of the penis-Pure Sensory
Plate 405-Vessels of the UG triangle
 Internal Pudenal Artery gives of the inferior rectal then perineal
artery
 The internal pudenal distal to the bifurcation of the perineal artery
continues into the deep pouch and then bifurcates into its terminal
branches
o Dorsal artery of the penis
o Deep artery of the penis
Plate 383-Perineal spaces
 By removing everything we expose the perineal membrane
 Removing the perineal membrane exposes the deep perineal pouch.
o Notice the cowper’s glands (bulbourethral glands). They add
add preejaculate to the ejaculate. It is alkaline and
neutralizes any acidity in the urethra and the vagina. The
duct of the bulbourethral gland pierces the perineal
membrane. The duct will enter the urethra in the bulb of the
penis.
o Two muscles.
 Posterior fibers of the UG triangle is the deep transverse
perineal m. Is separated from the superficial transverse
perineal m by the perineal membrane
External urethra sphincter m. is skeletal muscle that
circumnavigates the urethra and can compress to stop
flow through urethra.
o The portion of the urethra that travels through the deep
pouch is called the membranous part of the urethra.
o The prostate gland sits right on this muscle is and just
superior to this muscle. The urethra when it enters the
urethra is the prostatic urethra (we have three parts of the
urethra: penile, membranous, prostatic)
All skeletal mm in the UG triangle are innervated by the perineal
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nerve (branch of the pudenal)
Plate 358
 There is a gap in the levator ani called the urogenital diaphragm.
 Therefore there are TWO diaphragms that close the pelvic outlet.
 The UG diapram has three parts. Superior Fascia of the UG
diaphragm, the perineal membrane, and the Deep perineal pouch.
Plate 377-Female genitalia
 Thicker subcutaneous fat deposition on the anterior aspect—called
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the Mons Pubis.
The two skin folds radiating from the mons pubis is the labia
majora. Diverge at from a commissure and come back together in
a posterior comissure (only before first vaginal delivery)
The vulva is all the external genitalia including the mons pubis.
Labia minora is a skin fold. They meet posteriorly. Anteriorly the
meet and form a hood/prepuce over the clitoris.
Clitoris has ONE function: Sexual arousal.
Area within the labia minora is the vestibule.
o The glans clitoris is the vestibule
o The urethral orifice is the vestibule
o The vaginal orifice is in the vestibule
o The paired openings of the greater vestibular glands
Labia minor DO NOT have fat. They do have erectile tissue that
engorge during sexual arousal.
An Episiotomy is a posterior cut from the vaginal orifice through the
perineal body to aid in delivery. Two methods:
o Medial—Healing takes longer, less risk of bleeding
o Mediolateral—higher risk of bleeding
o BOTH START AT THE SAME SPOT
 Vaginal Orifice is typically irregular. The tags of irregular tissue are
remnants of the hymen. In some cases it can be an imperforate
hymen, it is usually perforated through normal gym class activities.
The vaginal orifice changes with age and activity (tampons, sexual
activity, exercise)
Plate 395
 Ischiocavernosus mm and bulbospongiosum mm are the same idea.
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Superficial transverse perineal mm.
There are TWO bulbospongiosum mm in females to maintain the
patency of the vaginal orifice. They overlay the bulbs of the
vestibule (erectile tissue. The bulbs of the vestibule come together
anteriorly and STOP. They DO NOT extend into the shaft of the
clitoris.
The ischiocaverosus mm overlay the crura of the clitoris.
The shaft of the clitoris only has TWO erectile bodies (the crura)
There is a glans clitoris
Plate 379
 The greater vestibular gland is below the bulbospongiosum mm
(also called bartholin’s gland) is a mucus secreting gland to
lubricate the vestibule and keep it moist.
 Ischiocavernosis maintains erection of the clitoris.
o There is no bulb contribution to the clitoris.
 Bulbospongiosum engorge and compresse the vaginal walls to help
stimulate the penis. They increase the pleasure of the male and
female. Compression of bulbospongiosa help push secretions from
the greater vestibular gland.
Plate 413—Nerves of the perineum
 Same branching pattern as in male. Pudenal gives of internal
rectal, perineal and dorsal clitoral nerves.
Plate 404—Vessels of the female perineum
 Same as male. Get on it.
Plate 379
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The crus of the clitoris is much easier to fine that the bulbe of the
vestibule.
 Observe the crura converge to form the shaft of the clitoris.
 Deep transverse perineal mm are the same. The differnce in deep
pouch mm are caused by the vagina (damn vaginas). The
sphincter urethrae has a compressor vaginae portion.
Plate 366
 Two bulbs of the vestibule flank the urethra flanked by the
bulbospongiosus mm.
 Two crura flanked by the ischiocavernosus mm.
Lesser vestibular glands (paraurethral glands) lay only the urethra between
the urethra and the vagina as it approaches the external urethral orifice.
They are the homolog of the prostate. They produce a female ejaculate.
There is a dense network of on the anterior vaginal wall (the “G Spot”—G
stands for Grafenberg)
Plate 360
 Just getting oriented.
January 16, 2009
True Pelvis—The region between the pelvic diaphragm and the pelvic brim
Plate 362-Pelvic Contents--Female
 Most anterior is the bladder right behind the pubic symphysis.
Extending superiorly from that is the urachus in the median
umbilical fold.
 Just posterior to the bladder is the uterus.
o Lateral to the uterus is the fallopian tubes suspended by the
broad ligament. Associated with the fallopian tubes are the
ovaries The round ligament of the uterus extends laterally
(bilaterally) to the pelvic wall toward the deep inguinal ring.
 Posterior to the bladder is the rectum
Plate 360
 Urinary Bladder sits right on the pubic symphysis
 From a sagital section, we can notice that the uterus is not so much
posterior, but supero-posterior. The location of the uterus in
relation to the bladder is cconstantly changing due to urinary
bladder distention.
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There are reflections of peritoneum in the true pelvis. As the
peritoneum descends down the anterior abdominal wall, it becomes
loose. This allows for the bladder to expand. The peritoneum coats
the superior aspect of the urinary bladder. At the posterior edge of
the urinary bladder, the peritoneum will encounter the uterus and
coat nearly the entire surface of the uterus. On the inferoposterior
aspect of the uterus where the uterus meets the vagina, the
peritoneum moves to the rectum.
o The lower third of the rectum does not contact peritoneum
o The middle third of the rectum has peritoneum on the
anterior surface
o The upper third of the rectum has peritoneum on the anterior
and R/L lateral.
The Reflections make 2 pouches of the greater sac in the female
pelvis
o Vesicouterine pouch between the urinary bladder and the
uterus. This pouch is most often empty.
o Rectouterine pouch between the Rectum and the Uterus
 Aka pouch of douglas/cul de sac
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This is the lowest point of the peritoneal cavity,
therefore if there is fluid in the peritoneal cavity, it will
accumulate in the rectouterine pouch when the pt is
standing.
The upper end of the vagina is right next to the
rectouterine pouch. (only a few mm separate the
peritoneum from the outside environment)
 Great access to the peritoneal cavity to remove
fluid (if necessary)
Many times there will be a loop of small intestine in the
rectouterine pouch.
Plate 366-Urinary Bladder—Female
 Thick muscular wall known as the detrusor muscle. It is smooth
muscle
 Lined by a mucus membrane that is loosely attached
 When the bladder is non distended, it will have rugae
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There is an area where the mucus membrane is bound tightly to the
detruser muscle in the area bouned by the three orifices. This is
called the trigone. There are NO RUGAE
o Two ureters
o Urethra
The ureters pass through the bladder wall very obliquely to cause
the urine to stay in the bladder. The muscle walls will compress the
ureters when the bladder is distended.
In the female, there is no true sphincter. There is an internal
urethra sphincter of sorts made by the portion of the detruser
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Detruser motor innervation is parasympathetic
o General contraction except in the area of the urethra orifice.
 The vesicle venous plexus surrounds the bladder
Plate 369—The uterus
 Domed portion of the uterus that extends superiorly to the entrance
of the fallopian tubes is the fundus. All the uterus is the body and
the fundus is part of the body.
 The portion of the uterus that narrows as it enters the vagina is the
cervix.
o There is a vaginal and a supravaginal portion of the cervix
Plate 371-Uterus and ovaries—standing with back to the rectum looking
toward the pubic symphysis
 The peritoneum drapes over the uterine tubes to form a double
layer of peritoneum called the broad ligament. There is a stalk of
the broad ligament that suspends the ovary.
 The portion of the broad ligament that extends to the sides of the
body of the uterus is called the mesometrium
 The portion that is between the ovary and the uterine tube is the
mesosalpinx
 The portion that suspends the ovary is called the mesovarium
Plate 372
 Better illustration of the mesometrium, mesosalpinx and
mesovarium
 The mesovarium is at a right angle with the mesometrium and
mesosalpinx
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The germinal epithelium is on the exterior of the ovary. The
germinal epithelium is a mesothelium continuous with the
peritoneum.
When the egg is released from the surface of the ovary, it is
released into the peritoneal cavity. The fimbrae of the uterine tube
find it.
The peritoneal cavity is open to the environment through the
uterine tube.
Endometriosis is when the endometrium establishes itself outside of
the uterus.
Plate 371
 In the mesosalpinx you may find vestigial mesonephric ducts called
the opoophoron.
 The surface of the ovary will change as the woman ages. The older
woman will have a pitted appearance due to all the ovulations.
 There may be a vesicle associated with a fimbriae that is the
embryonic remnant that would have been the epididymus in the
male called the vesicular appendage
 The distal part of the uterine tube is called the infudibulum. Its
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fluted, trumpet shaped that has the finger like fimbriae associated
with it. Usually there is one fibriae that is attached to the ovary.
The ampulla of the uterine tube is the longest portion. This is
where the egg is usually fertilized
The isthmus is the narrowed portion before it enters the uterine
wall
The uterine portion of the uterine tube pierces the wall of the
uterus.
The uterine wall is thick, mostly due to the smooth muscular wall
called the myometrium
The cervix has two parts: supravaginal and vaginal. Most of the
tissue in the wall of the cervix is mostly fibrous. The lining of the
cervix is not sloughed like the endometrium of the body
Where the body opens into the cervix is the internal os.
Where the cervix a vagina open is the external os
Because the cervix juts into the vagina, there is a recess between
the vagina and cervix, called the vaginal fornix.
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Three functions of the vagina.
o Lower birth canal
o Female organ of copulation
o Duct for the passage of menses
 The epithelium transitions in the vaginal portion of the cervix
o Supra vaginal cervix and uterus-Columnar
o Vagina and vagnial cervix-non keratinized stratified squamous
The external os is smooth and round if there have been no vaginal births.
After a vaginal delivery it becomes “stellate” which means irregular shaped.
Plate 369
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The portion of the uterus that is fixed is the supravaginal cervix.
o Most of the uterus is highly mobile
 There are thickenings in the endopelvic fascia
o Transverse cervical ligaments come from the lateral walls
 Also called cardinal ligament
 The uterine artery is in the transverse cervical ligament.
o Pubocervical and sacrocervical ligaments are less important
 The other primary support is the pelvic floor.
Plate 361
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The cervix pierces the vagina at the anterior wall. The vagina is
10-12 cm
Drawing I don’t have
 The cervix pieces the anterior vaginal wall at a right angle (there
may be variation due to bladder distension, postpartum, post gravid
etc)
 The normal uterus is ANTIVERTED. That means is is at 90 degree
angle to the vagina at the external os
 The internal os has another angle. This angle is refered to as
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Ectopic
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ANTIFLEXED. The normal angle is ~170 degrees.
IF the angles increase, we called it retroflexed or retroverted.
If retroverted, the uterus may prolapse into the vagina.
pregnancy
Most common place for extrauterine pregnancy is the ampulla of
uterine tube.
Would occur if there is scar tissue in the ampulla
o STI or PID can cause this
Pelvis and Perineum
1/14/2009 10:03:00 AM
January 20, 2009
Plate 363-Superior view of the pelvic contents
 Major difference in midline is there is NOTHING between urinary
bladder and the rectum
 Simple anatomy
o Urinary bladder
o Rectum
Plate 361-Sagital Section
 Major difference is the prostate gland resting on the pelvic floor
between the pelvic floor and the urinary bladder
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Seminal Glands (vesicles) on posterior wall of bladder between
bladder and rectum
There is a well developed venous plexus with the bladder and
rectum. Deep dorsal vein of the penis joins the prostatic plexus
The peritoneum reflects on the rectum in the same fashion as the
females (divide the rectum in thirds)
There is only one true recess in the male true pelvix called the
recto-vesicle pouch. This is between the urinary bladder and the
rectum. Clinically not much significance except in imaging.
Plate 366-Urinary Bladder
 Same a female
 Detrusor muscle, trigone, uretral orifices
 Only difference is at the urethral orifice the detrusor muscle travels
circularly to create a internal urethral sphincter. Relaxed at all
times except during sexual arousal. Prevents retrograde motion of
the semen.
 Urethra has three parts
o Prostatic-Most distendable
o Membranous-Narrowest part of the urethra, its the least
distendable
o Penile/Spongy
Plate 384
 Crossing superiorly to the ureters are the ducti deferense. As they
pass medially, they distend and become wider and is called the
ampulla of the vas deferens. They NEVER UNITE. They do unite
with a seminal gland on that same side. The ampulla and the duct

Benign



of the seminal gland meet and form the ejaculatory ducts and then
enter the prostate gland.
Seminal glands produce one of the components of semen. They DO
NOT store semen.
prostatic hypertrophy
Can grow into the bladder and can cause urine to stagnate causing
frequent urinary bladder infections
Can also grow into the prostatic urethra which can cause week
stream of urine, urgency
All depends on where it grows to.
 Suprapubic incision as to not cut into the peritoneal cavity.
Plate 384-Prostatic Urethra
 There is a ridge on the posterior wall called the urethra crest
 The most prominent hill is called the urethral colliculus
o Median diverticulum is the prostatic utricle. Is an embryonic
vestige of the upper vagina
o Flanking the prostatic utricle is the R and L ejaculatory ducts.
 There are paired prostatic sinuses on either side of the urethral
crest with many pin points that are the ducts of the prostate (there
are many, up to thirty)
 Semen is formed in the prostatic urethra
o Process is called emission. Smooth muscles contract to mix
all the components. Emission is the warning bell to pull out if
you are using withdrawl for birth control
o Formed from prostatic secretions, the seminal vesicle
secretions, sperm, some fluid from the testicle
 Very rich arterial blood supply
Male accessory glands

Seminal glands
o 60% of the semen
o Mucoid in nature
o Fuctose, citric acid, and other nutrients
o Prostaglandins cause reverse persistalsis of the uterine tube
to bring the sperm toward the egg. Allow sperm to reach egg
in 5 minutes
 Also make the vagina more conducive to sperm


o Fibrinogen to help retain the mucoid consistency to hold
semen in upper vagina.
Prostate gland
o 30% of semen
o alkaline, milky, thin,
o nutrients
o profibrinolysis-converted to fibrinolysin after a period of time
to help break apart the mucoid clot formed y the seminal
contribution
Testes and epididymus only contributes about 10%

Bulbourethral glands are are not mixed with the volume of semen
and are released ahead of time. Is the only gland that does not
produce and store, is only produced during sexual arousal.
How long can a sperm remain viable in the epididymus? Median of 40 days.
MALE SEX RESPONSE
 Erection
o Engorgement of erectile tissues (with helecine aa that relax to
allow blood to flow in.
o Contraction of perineal muscles



o Parasympathic in control
Emission
o Contraction of smooth muscle in ductus deferens, prostate
gland, seminal vesicles
o Contraction of internal urethral sphincter
o Release of secretions of testes, prostate gland, seminal
vesicles and bulbourethral glands
Ejaculation
o Rhythmic, spasmodic contraction of perineal muscles, levator
ani, external anal sphincter, gluteal muscles
o Propulsion of semen along penile urethra
o Initiated by secretions entering penile urethra
o Mostly under control of the somatic muscles.
o Probably initiated by emission
Detumescence/Resolution
o Return of erectile tissues to flaccid state
o Involves a refractory period (minutes to days depending on
age and overall health of the male)
o Sympathetic control causes helecine arteries to recoil and the
blood drains.
FEMALE SEX RESPONSE
 Arousal/Excitement
o Increased secretions; vestibular and vaginal
 Mostly serous. There are no glands in the vagina, it
kinda of like oozing from the vaginal wall. Mucous
comes from the cervix

o Erection of clitoris
Plateau (minutes to hours)
o General vascular engorgement (clitoris, labia, breast, lower
vagina)
o Erection of nipples
o “Sex flush”; reddish vascular flushing of skin over breasts,
chest
o Dilation of upper vagina
o Uterine “tenting”


Orgasm
o Rhythmic contractions of perineal muscles (~1 second
intervals)
o Number of and intensity of rhythmic contractions highly
variable
o Dilation of cervix
o Uterine contractions (due to release of oxytocin)
Theory is it will help move the sperm toward the uterine
tube
o Uterine “dipping”
 Drops deeper in to the pelvix so that the cervix will drop
into the semen that is deposited into the vagina.
Therefore, chances of implantation increased after an
orgasm.
Resolution


The uterus is lifted up out of the depths of the pelvis.
Also causes cervix to be pulled out a little bit.
o Return to pre-excitement stage
o No refractory period
Plate 358, 356
 Dividing the levator ani into parts
o Pubococcygeus fibers have origin from the pubis
o Iliococcygeus fibers have origin from the tendonous arch
 Ischiococcygeus m from ischum to coccyx
 The pubococcygeus, iliococcygeus and ischiococcygeus form the
pelvic diaphragm


UG diaphram fills in the missing parts of the muscular diaphragm.
Medial most fibers of the pubococcygeus meet posteriorly behind
the anorectal juction to form the puborectalis, which is a subdivision
of pubococcygeus
o Puborectalis helps maintain the feces in the rectum and
relaxes during defectation.
 Nerve supply of S4.
Plate 392
 Levator ani of before can now be called iliococcygeus.
Plate 499-Somatic Nerve supply of the true pelvis
 Sympathetic chain comes all the way down to the coccyx
 Ventral rami leave through the apertures in the sacrum
 L4-L5 lumbosacral trunk adds to the sacral plexus once it crosses
the pelvic brim.
 The trunks are large (for the most part) but will not be as nice as
the brachial plexus.
 The gray rami comunicans add to the trunks.
 There are small branches off S2,S3, and S4 and are pelvic

splanchnic nerves (sympathetic)
o Some pierce pelvic floor and go to the perineum (mediate
erection).
o That’s the only example of these parasympathetics leaving
the pelvic cavity
o S2-3-4 keep the penis off the floor
There are 2 branches of the trunks, also called splanchics, but they
are sacral (sympathetic)
Plate 402-Blood supply
 Common iliac divides in the external and internal iliac aa. Internal
iliac a goes into the true pelvis. Don’t memorize a branching
pattern, because it wont work. Look at the target tissue to name
the arteries.
 Internal iliac divides into anterior and posterior division
 Posterior division
o Iliolumbar a goes up into the lumbar region along the lumbar
vertebral bodies.
o 1 or 2 or 3 lateral sacral aa. Some can even enter sacral

foramina and supply the cauda equina
o Superior glutal artery is the continuation of the internal iliac.
Leaves between lumbosacral trunk and the S1
Anterior Division
o Obturator a (is possible that it comes from the inferior
epigastric a off of the external iliac a.
o Umbilical a is patent for a distance and gives of superior
vesicle arteries. After it gives off those vessels it become
fibrous and continues as the medial umbilical fold.
o Uterine a. supplies the uterus
o Vaginal a. typically a branch of the uterine, but can be a
branch of the anterior division
o Inferior vesicle a from the anterior division
o Middle rectal a is inconstant
o Internal pudendal a through the greater sciatic foramen
Plate 402, 403 vessels
 The uterine a and the ureter cross at the cervico-vaginal junction.
Ureter passes inferior to the uterine artery.
o Identify the ureter in order to not ligate it during a
hysterectomy.
Plate 410-Autonomics
 Pelvic splancnic come off of S2, S3 and S4.
 There are a lot of autonomics on the ventral aorta. When the aorta
bifurcates, some travel will the common iliac, but a lot stay central
and form the superior hypogastric plexus (all sympathetic) and will
give rise to the right and left hypogastric nerves.

The R and L hypogastric will coalesce to form the inferior
hypogastric plexus posterior to the rectum along with the pelvic
spanchnic nerves (therefore the inferior hypogastric plexus is both
sympathetic and parasympathetic
Plate 408
Lymphatic drainage follows along the vessels in the pelvix
Perineal drainage will drain into the inguinal nodes, then into the pelvis
along with the vessel nodes
Big thing to remember are the testicles have different drainage than the
penis and the scrotum
1/14/2009 10:03:00 AM