Download Anatomy Exam 2 Review Lecture 8-Thyroid and Adrenal Glands

Anatomy Exam 2 Review
Lecture 8-Thyroid and Adrenal Glands
 Thyroid Gland
o Located at the anterior side of the neck.
o Butterfly shaped organ, with two lobes connected by a bridge called the
isthmus.
o This gland lies anterior to the trachea, specifically the isthmus is anterior to
tracheal rings 2, 3, and 4.
o The lobes normally extend down to the level of the 6th ring.
o Muscles Covering the Thyroid:
 Infra-hyoid muscles cover the lobes of the thyroid, specifically the
sterno-thyroid and sterno-hyoid muscles.
 Sternocleidomastoid overlaps the strap muscles.
o Development of the Thyroid
 Thyroid gland develops as a pouch at the base of the tongue. The
remnant of this tongue is the foramen cecum.
 During development the thyroid gland descends into the neck and
moves around and pulls with it a layer of fascia.
 Problems with this migration can result in a Thyroglossal duct, which
connects the tongue to the thyroid.
 If migration doesn’t occur properly, thyroid tissues can be
deposited at various locations on its track. Most common is a
pyramidal lobe.
 The embryologic origin of parafollicular and C cells are neural crest
cells.
o Clinical Findings/Examination
 An enlarged thyroid can be visualized or palpated when a pt swallows,
which causes the thyroid to move superiorly then inferiorly.
 A pyramidal lobe will lie to one side of trachea and is a third lobe that
arises from the upper part of the isthmus and may ascend as far up as
the hyoid bone.
o Pretracheal fascia covers the thyroid gland and it also has a very thin capsule
that surrounds the thyroid gland.
 Parathyroid gland sits inside the pretracheal fascia.
o Vessels and Nerves
 Arterial Supply
 Superior thyroid artery from external carotid artery
 Inferior thyroid artery from thyrocervical trunk of the
subclavian
 Thyroidea ima from brachiocephalic artery or the arch of the
artery, present in 30% of population. Always the most inferior
of the blood vessels and can be hidden behind the sternum. If
this artery is cut during surgery, it can retract behind the
sternum and lead to internal bleeding.
Venous supply
 Superior thyroid veins end in the internal jugular
 Middle thyroid veins end in the internal jugular
 Inferior thyroid veins end in the brachiocephalic vein.
 Lymphatics accompany the arteries, because the arteries are more
consistent than veins.
 Nerves (always follow arteries) from the middle and inferior cervical
ganglia of the sympathetic trunk.
Nerves Related to the thyroid gland:
 External laryngeal nerve (supplies the cricothyroid muscle) runs with
the superior thyroid artery.
 Losing the function of the cricothyroid muscle will prevent the
pt from changing the tone of their voice.
 Recurrent laryngeal nerve runs posterior to the inferior thyroid
artery.
 Recurrent laryngeal supplies all muscle of the larynx, cutting it
will result in a loss of speech can cause the vocal folds to close
resulting in suffocation.
Posterior Relationship
 Parathyroid glands are imbedded in the posterior side of the thyroid
gland.
 Removal of the parathyroid glands can result in hypoparathyroidism. This manifests as paresthesias in the fingers,
toes and lips; muscle aches and leg cramps; twitching of
muscle, especially around the mouth; and fatigue.
 Esophagus, pharynx, and trachea lie posterior. Large tumors of the
thyroid can cause dysphagia.
Surgical Importance of Thyroid
 During tracheotomy, the isthmus must be excised in addition to
possible removal of 1 or 2 of the tracheal rings.
Control of Thyroid Hormones
 Hypothalamus produces thyroid-regulating hormone, which
stimulates the anterior pituitary gland to produce thyroid-stimulating
hormone, which stimulates the thyroid.
 In blood test, if TSH levels are higher than normal then the thyroid
gland is not functioning properly. If the levels are lower than normal,
then the thyroid feedback loop is functioning properly maybe even
hyperactive.
 Hypothyroidism:
 Weight gain
 Bradycardia
 Sleepiness
 Depression
 Non-pitting edema, myxedema (pre-tibial)
 Hyperthyroidism
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o
o
o
o
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 Weight loss
 Tachycardia
 Hyperactive
 Irritable
 Protruding eyeballs (exophthalmos)
 Hyperreflexia, tremors
Suprarenal Glands
o Two glands that are retroperitoneal and sit on top of each gland.
o Developmental arise from two distinct origins.
o Vessels and Nerves
 Arterial Supply
 Superior suprarenal artery, from inferior phrenic artery
 Middle suprarenal artery from the aorta
 Inferior suprarenal artery from the renal a.
 Suprarenal veins
 On the right side opens into the IVC
 On the left opens into the renal vein
 Lymphatics end in the lumbar glands
 Nerves from the celiac and renal plexus (sympathetic) and the phrenic
and vagus nerves (parasympathetic).
 Sympathetic fibers supply the medulla.
o Hormones
 Hypothalamus secretes CRH, which stimulates ACTH from the
pituitary, which stimulates the adrenal cortex.
 Cortex is divided into three layers:
o Zona glomerulosa secretes aldosterone hormone
 Controlled by the ECF concentrations of
angiotensin II and potassium
o Zona fasciculata secretes cortisol and small amounts of
adrenal androgens and estrogens.
o Zona reticularis secretes adrenal androgens and small
amounts of estrogens.
 Disturbances of Adrenal Cortex hormones
o Excess:
 Cushing syndrome-excess of cortisol, results in
behavior changes and obesity of the upper trunk
(buffalo back)
 Related to adenomas of the anterior
pituitary or large doses of corticosteroids.
 Hyperaldosteronism-excess of aldosterone,
results in high blood volume and HTN.
 Virilization syndrome-excess of androgens,
results in masculinization of a female (beard,
clitorispenis, hairy). In adult males it’s hard to
diagnose.


In young men, causes advancement of
puberty.
Can measure 17-ketosteroids in the urine.

o Insufficiency
 Primary acute adrenocortical insufficiencyadrenal crisis (comes from loss of suprarenal
glands).
 Primary chronic adrenocortical insufficiencyAddison disease (most commonly from infection,
in particular TB)
 Results from failure of adrenal cortex,
caused by atrophy.
 Lack of glucocorticoids results in inability
to regulate blood glucose levels.
 Lack of mineralocorticoid causes water
loss.
 Secondary adrenocortical insufficiency
Sympathetic CNS directly stimulates the adrenal medulla, which
secretes epinephrine.
 Excess of the adrenal medulla:
o Pheochromocytoma causes irritability, pallor,
palpitations, tachycardia, HTN and BP spikes, severe
headache, sweating and weight loss.
 Insufficiency:
o Congenital absence of the adrenal medulla is rare,
results in catecholamine insufficiency because of
sympathetic production of catecholamines.
Lecture 9-Kidneys, Ureters and Bladder
 Kidneys
o Retroperitoneal organs, two of them located on each side.
o They are placed in a paravertebral gutter and covered with a lot of fat.
o Hilum provides blood supply to the kidney, contains an artery, vein and urine
collecting duct.
o Fibrous capsule surrounding kidneys gives them a shiny appearance.
o Perinephric fat (perirenal fat) protects the kidneys.
o Renal fascia surrounds the perinephric fat, separates the kidney from the
suprarenal glands.
o Nephro-ptosis (floating kidney)-means that the kidneys drop in place. With
excess weight loss the perinephric fat can be lost, which allows the kidneys to
drop.
 Can cause the renal artery, renal vein and ureter to kink.
 Renal artery and vein are very sensitive to changes, results in
systemic effects like HTN and can cause urine to collect in the kidney,
called hydronephrosis.

o 3 Parts of Kidneys
 Cortex-outer portion and renal columns, contains renal corpuscles
 Medulla-Inner portion, 8-12 renal pyramids which contains loops of
henle and collecting tubules.
 Renal papilla is the apex of the pyramid which fits into the
minor calyx.
 Major Calyces 2-3 empty into the renal pelvis.
o Renal pelvis
 Funnel shaped, upper end of ureter
 Most posterior in the hilum.
o Vascular and Nerve Supply:
 Renal artery comes from the aorta.
 Right a. is longer and lies posterior to IVC, veins are anterior to
keep the least amount of pressure on them.
 Gives off inferior suprarenal artery
 Most anterior vessel in the renal hilum is the renal vein,
followed by renal artery and then ureter.
 Left renal artery gives off the inferior phrenic.
 Renal vein drains to IVC.
 Lymphatics drain to para-aortic nodes.
 Nerve supply:
 Sympathetics from the celiac and renal ganglia
 Parasympathetics from vagus nerve.
o Renal Arterial Segments
 5 segments based on branches of the renal artery.
 Anterior divisionsuperior (apical), anterior superior, anterior
inferior and inferior segments.
 Posterior divisionposterior segment.
 Surgically important in case a segment of the kidney has to be
removed.
o Posterior Relationships
 Ribs 11 and 12 lie posterior. Rib 12 can be removed during surgery to
access kidney, but must be careful to prevent formation of a
pneumothorax if lung pleura is punctured.
 Ileohypogastric and ileoinguinal nerves also lie posterior, can cause
numbness of the anterior pelvic region if cut during surgery.
o Renal Transplantation
 Transplanted kidney is placed in the pelvis, because the kidney has no
fat or fascia and it would be too difficult to replace all of that to place
the kidney in its anatomical location.
 Connected to inguinal arteries.
Ureter
o Fibro-muscular tube (25 cm or 10 in) from renal pelvis to bladder.
o Runs on anterior surface of psoas muscle.
o Blood supply: renal artery, aorta, gonadal artery and iliac artery.

o 3 narrow points:
 Pelvic-ureteric junction
 Crossing of pelvic brim
 Entrance to urinary bladder, oblique with a slit like opening.
o Pathway:
 Enters the pelvis over the bifurcation of the common iliac artery.
 Left: runs posterior to the sigmoid colon.
 Right: may run next to the appendix (appendicitis can be
misdiagnosed as renal colic, or renal colic can be misdiagnosed as
appendicitis)
 At level of ischial spine, turns anteriorly
 Male: ductus deferens crosses the ureter (water goes under the
bridge)
 Female:
 Runs in base of broad ligament
 Crossed by the uterine artery (water goes under the bridge)
 Close to lateral cervical ligament
 Ureter crosses lateral fornix
 Following a hysterectomy the ureter can be lacerated, creating
a fistula between vagina.
 Another complication can be ligation of both ureters, which
results in urine collection.
Urinary Bladder
o Pyramidal shape.
o Superior surface is covered with peritoneum, full bladder peels the
peritoneum off the posterior rectus sheath.
o Apex points anterior above symphysis pubis.
 Median umbilical ligament from apex to the umbilicus.
 Fibrous remnant of the urachus, which connected to the yolk
sac. If this is still patent, when the bladder is full then urine
can come out of the belly button.
o Base is posterior, anterior to rectum in males. In females anterior to cervix
and anterior vaginal wall.
o Trigone is a triangular area at the base of the bladder.
 It is fixed with fibrous tissue to pelvic fascia.
 The two ureteric opening connected at top of trigone by the interurteric ridge.
 The ureteric openings are slit like, and oblique.
 Internal urethral sphincter:
 Male-circular muscle fibers at the internal uretral opening
o This sphincter prevents retrograde ejaculation.
 Female-longitudinal muscle fibers NO internal sphincter
o Posterior Relationship of Bladder in Male
 Seminal vesicles
 Ductus deferens and ampulla
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 Ejaculatory ducts
 Prostate
o Nerve Supply
 Parasympathetics:
 S2-S4, pelvic splanchnic nerves.
 Inhibitory to the internal sphincter.
 Sympathetic
 T11-L2creates superior hypogastric plexus.
 Responsible for constriction of the internal sphincter
 Sensation
 Distension and pain
 Via both sympathetic and parasympathetic nerves.
 Control of Micturition (peeing)
 Parasympathicpee
 Sympatheticno pee
Female Urethra
o ~2 inches
o Embedded in anterior wall of vagina
o Opens in the vestibule between the clitoris and vaginal opening
o In urogenital diaphragm the external urethral sphincter is supplied by the
pudendalnerve.
Male Urethra
o ~8 inches
o Pre-prostatic part is at the neck of the bladder
o Prostatic part crosses through the prostate gland
 Openings: ejaculatory ducts, prostatic ducts, prostatic utricle.
o Membranous: 1-2 cm, passing through the external urethral sphincter.
 Narrowest part of the urethra.
o Spongy (penile)
 Runs on the ventral surface of the penis through the corpus
spongiosum
 About 15 cm long
 The ducts from the urethral gland open here.
 Bulbourethral glands-located in the urogenital diaphragm and open in
the spongy urethra.
 May be subdivided into two parts, the bulbous and pendulous urethra.
 External urethral meatus is a narrow vertical slit-like openingspiral
stream of urine.
o Congenital Anomalies
 Hypospadius-external urethral opening is abnormally located on the
underside of the penis, even in the scrotum or sometimes the
perineum.
 Epispadius-opening is located on the upper side of penis.
 Stricture/stenosis-narrowing of the external urethral meatus.

Phimosis-excessive narrowing of the foreskin, where it cannot be
retracted over the glans penis.
 Can lead to back pressure on bladder.
 Surgically corrected
Lecture 10-Development of the Urinary System
 Urogenital Ridge
o Longitudinal elevation of each side of the aorta that will develop into the
urogenital system.
o Nephrogenic cordurinary system
o Gonadal ridgegenital system
 Nephrogenic Cord
o 1. Pronephros-first kidneys
 Bilateral
 Appears early in the 4th week in the neck region.
 Pronephric ducts run caudally and open into the cloaca.
 The pronephroi degenerate by the end of 1st trimester, but the
pronephric ducts persist and are used by the next set of kidneys.
o 2. Mesonephros
 Appears late in the 4th week, caudal to the pronephroi.
 Function as interim kidneys for approximately 4 weeks, until the
permanent kidneys develop.
 Consist of glomeruli and tubules.
 The mesonephric tubules open into bilateral mesonephric ducts,
originally the pronephric ducts.
 The mesonephric ducts open into the cloaca
 Also degenerates by the end of the 1st trimester.
o 3. Metanephros
 Metanephroi-primorida of permanent kidneys.
 Begin to develop in the 5th week, become functional about week 9.
 Urine formation continues through fetal life.
 Permanent Kidneys develop from two sources:
 Ureteric bud is adiverticulum from the mesonephric duct near
its entrance into the cloaca.
 The metanephrogenic blastema is derived from the caudal part
of the nephrogenic cord. As the ureteric bud elongates, it
penetrates the blastema.
 A blastema is a mass of cells capable of growth and
regeneration.
o Mesonephric duct remains during development and becomes:
 In males the collecting ducts for the testicles.
 In females these become the round ligament.
 Development of the Collecting system
o The stalk of the ureteric bud becomes the ureter.
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o The cranial part of the bud undergoes repetitive branching, forming branches
which differentiate into the collecting tubules of the metanephros.
 1st four generations of tubules enlarge and become confluent to form
the major calices
 2nd four generations coalesce to form the minor calices.
o The end of each arched collecting tubule induces clusters of mesenchymal
cells in the metanephrogneic blastema to form small metanephric vesicles.
o These vesicles elongate and become metanephric tubules.
 Proximal ends of these tubules are invaginated by glomeruli.
 The tubules differentiate into proximal and distal convoluted tubules
and the nephron loop (Henle loop)
 Each distal tubule contacts an arched collecting tubule and the tubules
become confluent.
Fetal Kidneys
o At full term, nephron formation is complete.
o Fetal kidnesy are subdivided into lobes.
o The lobulation usually disappears at the end of the first year of infancy as the
nephrons increase and grow.
Migration of the Kidney
o Initially the primordial permanent kidneys lie close to each other in the
pelvis.
o As the abdomen and pelvis grow, the kidneys gradually relocate to the
abdomen and move farther apart. They attain their adult position by the 9th
week.
o Initially the hilum of each kidney face ventrally; kidneys rotate medially
almost 90 degrees. By the 9th week the hila are directed anteriomedially.
Changes in blood supply to Kidneys
o Kidneys receive blood supply from common iliac arteries, distal end of the
aorta or higher on the aorta.
o Normally the caudal branches of the renal vessels undergo involution and
disappear.
o Accessory renal arteries may persist in 25% of adults.
 Must be careful when removing kidney to stop any bleeding from
accessory kidneys.
Congenital Anomalies of Kidneys
o Renal agenesis-unilateral or bilateral (incompatible with life)
o Malrotated Kidney-hilum stays posterior
o Horseshoe Kidney-prevented from migrating by a vessel, typically the SMA.
Not defective functioning kidney, that is abnormally located.
o Supernumerary kidney-additional kidneys
o Ectopic Ureter-opens in an abnormal area, usually occurs in addition to
normal ureter.
o Duplications of ureter and/or renal pelvis.
o Ectopic Kidneys-most are located in the pelvis, also called pelvic kidneys
o Cystic Kidney Disease
Autosomal recessive polycystic kidney disease, diagnosed at birth or
by ultrasound.
 Results in renal insufficiency, and death of infant usually
occurs shortly after birth.
 Multicystic dysplastic kidney disease
Development of Urinary Bladder
o Urogenital sinus is divided into:
 Vesicle part that forms most of the urinary bladder and is continuous
with the allantois (precursor to urachus).
 Pelvic part that becomes the urethra in the neck of the bladder.
 Prostatic part of the urethra in males, and the entire urethra in
females
 Phallic part that grows toward the genital tubercle (primordium of
penis or clitoris).
o Initially the bladder is continuous with the allantois, which constricts and
becomes a thick fibrous cord called the urachus (median umbilical ligament).
o In males the orifices of the mesonephric ducts move together and enter the
prostatic part of the urethra as the caudal ends of these ducts develop into
the ejaculatory ducts.
o In females the distal ends of the mesonephric ducts degenerate
Urachal Anomalies
o In infants a remnant of the urachal lumen may persist in the inferior part of
the urachus. These can give rise to urachal cysts.
o The patent inferior end of the urachus may dilate to form a urachal sinus that
opens into the bladder. The superior end may dilate to form a urachal sinus
that opens at the umbilicus.
o Very rarely is the entire urachus patent which would allow urine to escape
from umbilical orifice.
Congenital Anomalies of the Urinary Bladder
o Congenital megacystitis
 Pathologically large urinary bladder may result from a congenital
disorder of the ureteric bud, which may be associated with dilation of
the renal pelvis. The large bladder may result from posterior urethral
valves.
 Many infants die from this disorder.
o Exstrophy of the bladder
 Deficiency of the anterior abd wall, caused by incomplete median
closure of the inferior part of the wall.
 Defect involves both the abd wall and the anterior wall of the urinary
bladder.
Development of the Urethra
o Epithelium of most of the male urethra and the entire female urethra and the
entire female urethra is derived from the endoderm of the urogenital sinus.
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o In males, the distal part of the urethra in the glans of the penis is derived
from a solid cord of ectodermal cells that grows inward from the tip of the
glans and joins the rest of the spongy urethra.
Development of the Suprarenal Glands
o Cortex develops from mesenchyme
o Medulla develops from neural crest cells from a sympathetic ganglion.
o During the 6th week, the cortex begins as an aggregation of mesenchymal
cells on each side of the embryo.
Congenital Adrenal Hyperplasia and Adrenogenital syndrome
o Excessive androgen production during the fetal period, due to abnormal
increase in the cells of the suprarenal cortex.
o In females this usually causes masculinization of the external genitalia.
o Male children have normal external genitalia.
o Later in childhood in both sexes, androgen excess leads to rapid growth and
accelerated skeletal maturation.
Lecture 12-Pelvis and Perineum
 Definitions
o Pelvis-may denote a variety of structures including the pelvic region, bony
pelvic girdle and the anatomical pelvis
 The pelvis refers to a region
 Anatomical Pelvis-space or compartment surrounded by the bony
pelvic girdle.
o Muscle and Ligament-though not usually explicitly stated the bowl-shaped
pelvis is completed by muscle and ligament.
 Subdivisions of Pelvis
o Greater Pelvis
 Also referred to as the false pelvis, generally considered part of the
abdomen.
 Provides protection to inferior abdominal viscera and supports gravid
uterus after 1st trimester.
o Lesser pelvis
 Referred to as the true pelvis
 Has an inlet and an outlet.
 Inlet-completely ringed by bone
 Outlet-formed by bone and ligament.
 Pelvic Girdle
o Basin-shaped ring of bones that connects the vertebral column to the femurs.
o Pelvic girdle is formed by 3 bones
 Right and left hip bones/coxal bones/os coxae/pelvic bones
 Sacrum
o Orientation
 In the anatomical position the front edge of pubic symphysis and
anterior superior iliac spines are in the same vertical plane.
 Inlet is tilted anteriorly

 Ischiopubic arch is nearly horizontal
 Anterior surface of the sacrum is directed forward and downward.
o Gender Differences
 Male and female pelvic girdles differ in several aspects.
 These differences arise for two main reasons
 Men-heavier build and larger muscles; thicker and heavier
pelvis
 Female-adaptation of female lesser pelvis to childbirth.
 Male:
 Pubic arch is more narrow.
 Female:
 Pubic arch is wider.
o Pelvic Diameters
 The size of lesser pelvis is of particular importance in obstetrics
 Lesser pelvis diameters (conjugates) may be noted radiographically
or manually during pelvic exam.
 Conjugates
 The obstetric (true) conjugate is the narrowest fixed distance
through which a baby’s head must pass.
o Represented by distance from the sacral promontory to
the closest point of the pubic symphysis
 Diagonal conjugate is measured during a manual exam, and
used to estimate the obstetric conjugate.
Pelvic Cavity
o Funnel-shaped cavity that is inferoposterior part of the abdominopelvic
cavity.
o Can be defined as the area between the pelvic inlet and the pelvic outlet
(lesser pelvis)
o Contents:
 Reproductive: most of the internal genitalia
 Digestive: lower end
 Urinary: lower end
o Boundaries
 Anteroinferior Wall
 Formed by the bodies and rami of pubic bones and the pubic
symphysis
 In the anatomical position, this wall is more of a weightbearing floor than a wall which bears the weight of the urinary
bladder.
 Lateral Walls
 Formed by multiple structures:
 Right and left hip bones-includes obturator internusmuscles
covering the obturator foramen
 Sacrospinous and sacrotuberous ligaments
 Piriformis muscles
Posterior wall/roof
 In the anatomical position the sacrum and the coccyx from the
bony wall and roof.
 In addition there are partial contributions from piriformis
muscle, and the sacrospinous and sacrotuberous ligaments
 Floor
 Covers the pelvic outlet
 Formed by the bowl-shaped pelvic diaphragm which is marked
by two openings
 The pelvic diaphragm lies within the lesser pelvis, separating
pelvic cavity from perineum.
 Two main muscles:
o Levator ani (not easily distinguishable
 Iliococcygeus
 Pubococcygeus
 Puborectalis
o Coccygeus
 Pelvic Diaphragm Function
o The muscles of the diaphragm function in two general
scenarios:
 They are tonically contracted most of the time,
supporting the pelvic viscera. Must relax for
urination and defecation to occur.
 Actively contract during certain activities such as
forced expiration, coughing and sneezing.
o Puborectalis
 Forms a U-shaped sling, which is key in
maintaining continence, passes posterior to
anorectal junction.
Pelvic Neurovasculature
o The major neurovascular structures of the pelvis lie extraperitoneally against
the posteriolateral walls
o Generally veins lie between arteries (more internal) and nerves (more
external)
o Pelvic Arteries
 Rich arterial supply which frequently anastomose.
 Major arteries are the internal iliacs, paired
 Females:
 Paired iliac arteries
 Paired ovarian arteries
 Unpaired median sacral and superior rectal arteries
 Males:
 Paired internal iliac arteries
 Testicular arteries DO NOT enter lesser pelvis
 Unpaired median sacral and superior rectal arteries
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
Internal Iliac: at approximately the superior border of the greater
sciatic foramen, the internal iliac artery divides into two trunks:
 Anterior trunk supplies mainly viscera
 Posterior trunk supplies posterior pelvic wall and gluteal
region
o Pelvic Veins
 Pelvic plexus of veins consists of various venous plexuses within the
lesser pelvis.
 These unite and are mainly drained by tributaries of the internal iliac
arteries.
 Some of the plexuses drain into the hepatic portal system via the
superior rectal vein
 Portocaval shunt during hepatic portal system blockage
o Pelvic Nerves
 Pelvic innervation derives from three main sources
 Somatic Innervation
o Sacral spinal nerves (sacral plexus)
 The bilateral sacral plexuses are formed by the
anterior rami of S1-S4 and the lumbosacral trunk
(L4, L5)
 Nerves emerging from this plexus innervate two
main areas including lower limb (sciatic nerve,
nerves to gluteal region) and the pelvis and
perineum (pudendal nerve and its branches)
o Coccygeal spinal nerves (coccygeal plexus)
 Small network of nerves formed by the anterior
rami of S4, S5 and the coccygeal nerve.
 Two main nerves emerge:
 Nerve to levator ani and coccygeus
 Anococcygeal nerves-supply small part of
skin between coccyx and anus.
 Pelvic part of autonomic nervous system
o Autonomic nerves supply the pelvic cavity via four main
routes:
o Sacral sympathetic trunks
 Provide sympathetic innervation to the lower
limbs, some distribution to perineum.
o Periarterial (prevertebral) plexuses
 Conveys sympathetic vasomotor fibers to most
of the arteries entering the pelvic cavity,
represents a minor route for sympathetic fibers.
o Hypogastric plexuses
 The superior hypogastric plexus enters the
pelvic cavity as bilateral hypogastric nerves.

Most important route by which sympathetic
fibers are conveyed to pelvic viscera.
 Mixed autonomic nerves
o Pelvic splanchnic nerves
 Carry parasympathetic fibers and form the
inferior hypogastric plexuses
o General Function
 Sympathetic Fibers
 Vasomotion, as elsewhere in the body
 Inhibition of peristaltic contraction of
rectum
 Ejaculation in male
 Parasympathetic Fibers
 Contraction of rectum and bladder
 Engorgement of erectile tissues
Visceral Afferents
o All fibers carrying reflex information travel with
parasympathetic fibers
o Pain fibers travel with both sympathetic and
parasympathetic fibers
o The course of visceral pain afferents differs based on
their relationship to the pelvic pain line
 Pelvic pain line is the inferior limit of the
peritoneum, exception is alimentary canal where
pain line is in the middle of sigmoid colon.
 Structures in contact with the peritoneum are
above the pain line and fibers travel with
sympathetics.
 Structures in deep to the peritoneum are below
the pain line and fibers travel with
parasympathetics.



Perineum
o Perineum is the region of the body between the thighs
o In a restricted sense the perineum is a small area between the vulva or
scrotum and the anus, this definition is used clinically.
o Anatomically the perineum has both depth and superficial boundaries.
o Superficial Boundaries
 With legs abducted (lithotomy position) the superficial boundaries of
the perineum are the scrotum/mons pubis anteriorly, the medial
thighs laterally and the superior end of the intergluteal cleft
posteriorly
o Bony Boundaries
 The previour boundaries can also be related to osseofibrous
structures
 Pubic symphysis, anteriorly
 Ischiopubic rami, anterolaterally
 Ischial tuberosities, laterally
 Sacrotuberous ligaments, posteriorly
 Coccyx, posteriorly
o Depth
 Superior border is the inferior fascia of the pelvic diaphragm
 Inferior border is the skin.
o Triangles of the Perineum
 Arbitrary line drawn between the ischial tuberosities divides the
diamond-shaped perineum into two triangles.
 Anterior urogenital triangle-faces down and forward.
 Posterior anal triangle-faces downward and backward.
 Main contents of the anal triangle are the anal canal and its
orifice, the anus.
 Surrounded by ischioanal fat.
 The anal triangle, when compared to the UG triangle, is open
and has no perineal membrane
 Ischioanal fossae
o Because the levator ani muscles essentially form a bowl,
wedge-shaped spaces are created on either side of the
anal canal called ischioanal fossae.
o Filled with fat and loose connective tissue and permits
movement of pelvic diaphragm and expansion of anal
canal during defecation.
 External Anal Sphincter
o Large, voluntary sphincter forms a borad band on either
side of the inferior two-thirds of the anal canal.
o The sphincter is attached to the perineal body and the
anococcygeal ligament
o Supplied by the inferior rectal nerve (mainly S4)
 Pudendal Canal
o Nearly horizontal passageway within the obturator
fascia
o Main contents are the internal pudendal artery and
vein, and the pudendal nerve.
o Prior to entering the canal, the internal pudendal artery
and the pudendal nerve give rise to the inferior rectal
artery and nerve.
Lecture 13-Female External Genitalia and Breast
 Urogenital Triangle
o The urogenital triangle represents the anterior half of the perineum, contains
the roots of the external genitalia and the openings of the UG system.
o Borders
Like the anal triangle, the roof of the UG triangle is the pelvic
diaphragm, however the perineal membrane is present forms a
support platform for muscles surrounding the external genitalia.
 The perineal membrane is a thin sheet of tough fascia that
stretches between the two sides of the pubic arch and covers
the anterior part of the pelvic outlet.
 Perforated by the urethra (both sexes) and the vagina.
o Faschiae and Pouches of the triangle
 The contents of the perineum are organized by a series of pouches
and fascial layers. Much of the fascia is continuous with similar fascia
of the anterior abdominal wall.
 Perineal Fascia
 Consists of two parts: superficial perineal fascia and deep
perineal fascia:
o Superficial perineal fascia further consists of two layers:
superficial fatty layer and deep membranous layer
(Colles fascia).
 Deep Membranous Layer does not extend into
the anal triangle; it is attached to the posterior
margin of the perineal membrane.
 Laterally the deep membranous layer is
continuous with the fascia lata (of the thigh).
 In males it is also continuous with the dartos
fascia of the penis and scrotum. On each side of,
and anterior to scrotum, it is continuous with
Scarpa fascia
 In femals the deep embrnaous layer passes
superior to the labia major and becomes
continuous with Scarpa fascia
o Deep Perineal Fascia invests the muscles of the
perineum (Gallaudet fascia).
 Attached laterally to the ischiopubic rami and
anteriorly it is continuous with deep fascia of the
external oblique and rectus abdominis.
 Superficial Perineal Pouch
 A potential space between the deep membranous layer of
superficial perineal fascia and the perineal membrane.
 The principle structures of this pouch are the erectile tissues
(penis and clitoris) and their associated skeletal muscle.
 Clinically significant because groin injuries such as straddle
injuries can result in passage of urine and blood into the
superficial perineal pouch and further extravasation.
 Deep Perineal Pouch



Bounded inferiorly by the perineal membrane, superiorly by
the fascia of the pelvic diaphragm, and laterally by obturator
fascia of obturator internus.
 The deep perineal pouch includes the fat-filled anterior
recesses of the ischioanal fossa.
 Contents include part of the urethra and associated part of the
external urethral sphincter; neurovascular structures for
external genitalia; various muscles; and fat.
Female Urogenital Triangle
o Female UG triangle includes the external genitalia and perineal muscles.
o External Genitalia
 Female external genitalia comprise several structures:
 Mons pubis
o Rounded, fatty eminence anterior to the pubic
symphysis.
o Under influence of estrogen it enlarges at puberty and
becomes covered with coarse hair
 Labia majora
o Two prominent longitudinal folds of skin running from
the mons pubis to the perineal body.
o Covered with hair and consist primarily of loose
subcutaneous tissue
o Provides some protection to the clitoris and urethral
and vaginal openings
 Labia minora
o Rounded, hairless folds of fat-free skin
o They surround and close over the vestibule of the
vagina
o Anteriorly, each labium contributes to the formation of
the prepuce of the clitoris
 Clitoris
o Corresponds to the penis in the male, erectile organ
located where the labia minora meet anteriorly.
 Unlike penis it is not related to the urethra.
o Clitoral epithileum has high cutaneous sensitivity,
which is important in the sexual response
o Attaches to the inferior pubic rami and the perineal
membrane by its two crura
o Additional named parts: root, body and glans
 Bulbs of vestibule
o Paired masses of elongated erectile tissue, ~3cm long.
o They lie along the sides of the vaginal orifice,
immediately inferior to the perineal membrane, in the
superficial perineal pouch.
 Greater and lesser vestibular glands
o The round greater vestibular (Bartholin) glands lie on
either side of the vaginal orifice, posterior to the bulbs
of the vestibule.
 Located in the superficial perineal pouch
 These glands secrete mucus into the vestibule
during sexual arousal
o Perineal Muscles
 A series of UG triangle perineal muscles are found in both sexes in two
general locations: deep perineal pouch and superficial perineal pouch
 Muscles in Superficial Perineal Pouch
 Both males and females have the same three muscles, all
innervated by muscular branch of the perineal nerve (branch
of pudendal):
 Superficial transverse perineal muscle
o Functions to help fix the perineal body and the pelvic
diaphragm
o Supports abdominopelvic viscera and resists increased
intraabdominal pressure.
 Bulbospongiosus
o In females, attaches to the perineal body posteriorly and
the crus of the clitoris.
o Functions to constrict the vaginal orifice, compresses
the greater vestibular gland and assists in erection of
clitoris.
 Ischiocavernosus
o In females, the ischiocavernosus covers the crura of the
clitoris.
o This muscle maintains erection of the clitoris by
compression of outflow veins and by pushing blood
from root into body.
 Muscles in Deep Perineal Pouch
 Muscle content differs between males and females.
 Common muscles: compressor urethrae and external urethral
sphincter
 In females only: band of smooth muscle and sphincter
urethrovaginalis
 In males only: deep transverse perineal (in lieu of smooth
muscle)
 Know differences between males and females
o Innervation of External Genitalia
 From the lumbar plexus the anterior labial nerves supply the anterior
aspect of the external genitalia: mons pubis and anterior labia.
 The anterior labial nerves derive from the ilioinguinal nerve
and the genital branch of the genitofemoral nerve
 From the sacral plexus:


The perineal branch of the posterior cutaneous nerve of the
thigh, innervates the external genitalia laterally.
 The pudendal nerve supplies the external genitalia centrally.
o Posterior labial nerves supply the labia
o Dorsal nerve of the clitoris supplies deep perineal
muscles and sensation to the clitoris
o Deep branch of perineal nerve serves the superficial
perineal muscles
o Innervation of the Vulva
 The bulb of the vestibule and the erectile bodies of the clitoris receive
parasympathetic innervation via cavernous nerves from the
uterovaginal nerve plexus.
 Parasympathetic stimulation produces increased vaginal
secretion and engorgement of the clitoris and bulbs of the
vestibule
 Sympathetic stimulation is primarily vasomotor.
o Blood Supply of External Genitalia
 Blood supply is from branches of the internal and external pudendal
arteries.
 Internal supplies most of the skin, external genitalia and perineal
muscles
o Lymphatics
 Three main routes of drainage:
 Vulva (most parts) drains to superficial inguinal nodes
 Glans clitoris and labia minora to the deep inguinal or internal iliac
nodes
 Urethra to internal iliac or sacral nodes
Breast
o Defined as the pectoral surface of the thorax.
o Specialized accessory glands of the skin.
 Females-secondary sexual feature and milk production
 Males-rudimentary and functionless
o General Anatomy
 Breasts consist of glandular and supporting fibrous tissue embedded
within a fatty matrix, together with blood vessels, lymphatic and
nerves.
 Located in subcutaneous tissue.
 Surface Anatomy
 At the greatest prominence of the breast is the nipple,
surrounded by a circular pigmented area of skin called the
areola.
 Gross Anatomy
 The bed of the breast is formed by deep fascia covering pec
major, serratus anterior and external oblique.

o
o
o
o
The retromammary space (females only) is superficial to the
deep fascia and allows breast movement.
 A small part of the breast may extend toward the axilla, called
an axillary tail.
 Mammary Glands
 One lobule and its terminal duct make up the basic secretory
unit of the female breast.
 A lobe consists of numerous lobules and each mammary gland
consists of 15-20 lobes.
 Each lobe has its own lactiferous duct, thus 15-20 ducts
converge and open independently on the nipple.
o Near its orifice each duct is slightly expanded to form a
lactiferous sinus
 Mammary gland is attached in two ways
o Firmly attached to the dermis of overlying skin by
ligaments called suspensory ligaments of Cooper.
o Loose attachment to deep fascia of muscle
Blood Supply
 Arterial supply is from three sources
 Medial mammary branches
 Lateral mammary branches
 Branches of anterior intercostals
 Venous drainage is mainly to the axillary vein, some drainage to
internal thoracic vein.
Innervation
 Nerve supply from three sources
 Lateral mammary branches
 Medial mammary branches
 Supraclavicular nerves
 These convey sensory and sympathetic fibers
Lymphatics
 Lymphatic drainage in the breast follows one major route to the
axillary nodes.
 The remaining lymph drains to parasternal and abdominal nodes.
 Clinically significant because of metastatic dissemination via
lymphatic routes from breast.
 5 yr survival rate in breast cancer, pts correlate most strongly
with the number of nodes involved at various levels.
Male Breast
 Male breast contains no unique elements.
 Glands are underdeveloped, usually only small ducts that do not
extend beyond areola.
 Fat content is not different from that of subcutaneous tissue
elsewhere.
 Approx 1.5% of breast cancer cases occur in males

Gynecomastia can occur which results in excessive proliferation of the
male mammary glands due to ductal proliferation.
 Generally secondary to increased estrogen levels.
Lecture 14-Male External Genitalia
 Background
o Male external genitalia consists of scrotum and penis (includes distal
urethra)
 Location
o The male external genitalia are considered part of the urogenital triangle.
 Scrotum
o Cutaneous fibromuscular sac for the testes and associated structures.
o Consists of two layers
 Heavily pigmented skin
 Dartos fascia-contains smooth dartos muscle, which plays a role in
thermal regulation of testes.
o Septum of Scrotum
 Internally divides the scrotum into two compartments.
o The scrotum is located posteroinferior to the penis and inferior to the pubic
symphysis
o Blood Supply
 Derives from two sources:
 Anterior scrotal arteries from external pudendal artery
 Posterior scrotal arteries from internal pudendal artery
 Scrotal veins accompany the arteries and drain primarily to the
external pudendal veins.
o Innervation
 Cutaneous innervation of the scrotum derives from two sources:
 Anterior scrotal nerves, which are branches of the ilioinguinal nerve
and genital branch of the genitofemoral nerve.
 Posterior scrotal nerves are branches of the superficial perineal
branches of pudendal nerve
o Sympathetic Innervation
 Scrotal nerves carry sympathetic fibers that function in
thermoregulation of the testes.
 In the cold, dartos muscle is contracted which causes scrotal skin to
wrinkle and tighten. This decreases surface area for heat loss.
 In the heat, dartos muscle is relaxed which results in scrotal skin to be
flaccid and losse. Increases surface area for heat loss.
 Testes
o Background
 The testes are male gonads and produce sperm, and testosterone.
 Suspended within the scrotum by the spermatic cords
 Left testis generally hangs more inferiorly than the right.
o Microanatomy
The seminiferous tubules are the main constituents of the testes and
the structures within which sperm are produced.
 Visible to the naked eye as extremely fine threads, the tubules
are essentially microscopic structures.
 The tunica albuginea provides the testes with a tough, fibrous outer
surface.
 Has a fibrous septa that extends inward, partitioning testes
into lobules.
 Each lobule contains ~800 seminiferous tubules.
 Epididymides are elongated, comma-shaped structures on the
posterior aspect of the testes.
 These are the site of sperm maturation
 Each epididymis is a single coiled duct about 6m long
consisting of head, body and tail.
o Coverings and Spermatic Cord
 Development
 During development, peritoneum, muscle and fascia of the
abdominal wall form an evagination (processus vaginalis),
which leads to the inguinal canal.
 As the testes move through the canal, they bring with them all
the layers of the abd wall, which sheaths them.
 The spermatic cord also becomes ensheathed
 Tunica Vaginalis-only covers the testes, not the spermatic cord!
 Double-layered, closed-off peritoneal sac surrounding the
testes. It represents the peritoneum, or the innermost layer of
processus vaginalis.
 The visceral layer of tunica vaginalis covers the testes and
epididymides
 The parietal layer of tunica vaginalis lines the internal
spermatic fascia.
 Remaining layers-common to both testes and spermatic cord
 The cremasteric fascia contains loops of cremaster muscle,
which pulls in testes usually in response to cold.
 Layers from inside-out: internal spermatic fascia
(continuation of transversalis fascia)  cremasteric fascia 
external spermatic fascia (continuation of external oblique).
Spermatic Cord
o The spermatic cord contains structures running to and from the testis and
suspends the testis in the scrotum.
o Cord begins at deep inguinal ring, passes through the inguinal canal and ends
in the scrotum
o Vessels:
 The ductus (vas) deferens is a muscular tube conveying sperm from
the epididymis to ejaculatory duct.




Testicular artery (a branch of aorta) supplies the testis and
epididymis.
 The pampiniform plexus is a network of veins that converge to
form right and left testicular veins.
Lymphatic vessels drain the testis

o Nerves
 Two sources of innervation carried by the spermatic cord, supplying
both testis and cord.
 Genital branch of the genitofemoral nerve supplies the cremaster
muscle.
 Testicular plexus of nerves carries sympathetics, parasympathetics
and visceral afferents.
Penis
o Structure
 The penis is the male organ of copulation, also conveys the urethra
creating a common pathway for urine and semen.
 Anatomical position is erect.
 The Corpora
 Consists of three bodies of erectile tissue:
o Two corpora cavernosa located dorsally
 Begin as left and right crura which are firmly
attached to the ischiopubic rami.
 Anteriorly the crura converge and are fused with
each other in the medial plane.
o One corpus spongiosum located ventrally and contains
the spongy urethra.
 Begins as a dilated posterior end, the bulb of the
penis.
 Lies between the curar and is firmly attached to
the inferior aspect of the perineal membrane
 The three erectile bodies are further described in terms of a
root and a body of the penis.
o Root-attached part of the penis
o Body-free pendulous part of the penis
 Fasciae of the Penis
 Each erectile body has an outer fibrous covering, the tunica
albuginea.
 The deep fascia of the penis (Buck fascia) forms a strong
membranous covering for the entire penis. This binds all the
corpora together.
o Continuation of the deep perineal fascia.
 The superficial fascia (Dartos fascia) of the penis is just deep to
the skin.
o Continuation of Scarpa fascia of the abdomen. It is also
continuous with the deep membranous layer of
superficial perineal fascia (Colles)
Ligaments
 The body of the penis is supported by two ligaments:
 Suspensory ligament of the penis is a condensation of deep
fascia arising from the anterior surface of the pubic symphysis
 Fundiform ligament arises from the lowest parts of the linea
alba and forms a sling around the penis.
 Distal Urethra
 The urethra is a tube that conveys urine from the internal
urethral orifice of the bladder to the external urethral orifice,
which is at the end of the penis in males.
 Parts (four parts):
o Intramural
o Prostatic
o Intermediate (membranous)
 Begins at apex of the prostate, traverses deep
perineal pouch where it is surrounded by the
external urethral sphincter
 Finally penetrates the perineal membrane
o Spongy
 Begins at the bulb of the penis, and ends at the
external urethral orifice.
 Spongy urethra is expanded in two area:
 Intrabulbar fossa (bulb of penis)
 Navicular fossa (glans penis)
o Perineal Muscles
 Superficial perineal muscles (located in the superficial perineal
pouch) assist in maintaining erection of the penis and voiding urine
and semen from the urethra.
 As a result, these muscles tend to be more developed in males than
females.
 Superficial Transverse Perineal muscles
 Support the pelvic viscera
 Contraction of the superficial transverse perineal muscle
(along with the other superficial perineal muscles and the deep
transverse perineal muscle) helps form a firm base for penile
erection
 Bulbospongiosus
 Acts as a constrictor compressing the bulb of the penis and
corpus spongiosum.
 Helps urethra empty residual urine and semen and assists in
erection.


Provides pressure on root of penis forces blood into penis and
prevents venous drainage of blood.
 Ischiocavernosus
 Like Bulbospongiosus, acts as a contstrictor on the crura.
 Forces blood from crura into the corpora cavernosa
 They restrict venous drainage
o Vasculature of Penis
 Arterial Supply
 Two main arteries, both branches of internal pudendal artery:
 Dorsal arteries of penis supplies skin, fibrous tissue and corpus
spongiosum
 Deep arteries of penis supplies corpora cavernosa.
 Venous Drainage
 Blood from cavernous spaces drained by a venous plexus that
joins the deep dorsal vein of the penis. Drains into prostatic
venous plexus.
 Blood from skin and subcutaneous tissue drains into the
superficial dorsal veins, drain to external pudendal vein.
o Innervation
 Sensory and sympathetic innervation to the penis is provided by the
dorsal nerve of the penis (terminal branch of pudendal nerve)
 Sympathetic stimulation constricts blood vessels following
erection.
 Cavernous nerves carry parasympathetic fibers which cause dilation
of penile arteries
o Lymphatics
 Lymph from all parts of perineum drains to superficial inguinal nodes.
 Lymph from the testes drains along testicular veins to lumbar nodes.
 Lymph from glans penis drains to deep and superficial inguinal nodes.
Lecture 15-Female Pelvic Viscera
 Female Internal Genital Organs
o These consist of the ovaries, the uterus, the uterine tubes and the vagina.
o Function to produce sex hormones and gametes.
o In addition, the female repro system must be able to protect and support a
developing embryo.
 Ovaries
o The ovaries, uterus and uterine tubes are all supported in the pelvic cavity
within a common mesentery called the broad ligament.
 The broad ligament is a double-layer of peritoneum that extends from
the sides of the uterus to the floor and lateral walls of the pelvis.
 Assists in keeping the ovaries, uterus and uterine tubes in position.
 Parts of Broad Ligament:
 Mesometrium is the largest part and supports the uterus.




Mesosalpinx is the superior free border and supports the
uterine tubes.
 Mesovarium is a small mesentery along the posterior aspect of
the broad ligament and supports the ovaries.
o The ovaries are small, lumpy, almond-shaped organs and are the female
gonads.
 The ovaries produce the female gamete and reproductive hormones.
 Repeated ovulation gives the ovaries their scarred and distorted
appearance.
 Not covered with peritoneum, and ovum must be released.
o Ligaments
 Two other ligaments in addition to the broad ligament are associated
with the ovaries.
 Ovarian ligament extends from the uterus to ovary.
 Suspensory ligament is a peritoneal fold that extends from ovary to
pelvic wall, contains vessels and nerves of ovary.
Uterine Tubes
o The uterine tubes/oviducts/fallopian tubes connect the ovaries to the uterus.
o Each tube is ~10cm long and ~0.7cm in diameter.
o They conduct the ovum to the uterus and are generally the site of
fertilization.
o In the ‘ideal’ disposition they extend laterally and arch superiorly and
anteriorly above the ovaries.
o Parts:
 Infundibulum-funnel shaped distal end that terminates with fimbriae
 Ampulla-widest and longest part, usually the site of fertilization
 Isthmus-part entering the uterus
 Uterine part-within the walls of the uterus
Uterus
o A thick-walled, pear-shaped, hollow muscular organ
o The site of development of the embryo and fetus.
o Anatomy
 Divided into two main regions:
 Body forms the upper 2/3rds, contains slit-like uterine cavity (~6cm
long)
 Cervix forms the lower third, it is cylindrical and ~2.5cm long.
 The body is demarcated from the cervix by the isthmus
Pelvic Fascia
o Connective tissue occupying the space between the peritoneum and the
muscular pelvic walls.
o It is a continuation of the endoabdominal (transversalis) fascia.
o Components
 Divided into two components:
 Membranous pelvic fascia
 Further subdivided into parietal and visceral parts.


Parietal pelvic fascia lines the muscles that make up the
muscular walls and floor of the pelvis.
 Visceral pelvic fascia directly ensheaths the pelvic organs.
 Where the organs penetrate the pelvic floor, the parietal and
visceral layer are continuous. At this point the parietal and
visceral layers are thickened to form the tendinous arch of
pelvic fascia.
 Endopelvic fascia
 The endopelvic fascia varies markedly in density and content,
and thus may be subdivided into two basic parts:
 Loose areolar tissue serves as ‘packing’ material and allows the
bladder and rectum to expand
 Other parts of the pelvic fascia are condensed to form a
hypogastric sheath.
o Hypogastric sheath is a thick band of condensed pelvic
fascia and forms a barrier between potential spaces.
o Serves as a conduit to essentially all nerves and vessels
passing from the lateral wall of the pelvis to the pelvic
viscera.
o Forms ligamentous extensions (pelvic ligaments)
Position of the Uterus
o Located posterior to the bladder and anterior to the rectum. Normally
positioned so that the cervix tilts forward relative to the axis of the vagina
(anteversion).
o The body of the uterus tilts forward relative to the cervix (anteflexion)
o Ligaments:
 The body of the uterus is principally supported by its anteverted and
anteflexed position and by the broad ligament.
 The cervix is additionally supported by two major pelvic ligaments:
 Cardinal (transverse cervical) ligaments (part of the
endopelvic fascia)
 Uterosacral ligaments (part of the tendinous arch of pelvic
fascia, thus part of membranous pelvic fascia)
o Variation in Position
 The uterus is possibly the most dynamic structure in the human body,
with several factors influencing the size, proportion and position of
the uterus.
 Rapid physiological changes involving the rectum and bladderchanges based on whether bladder and rectum are full.
 Age
 At birth the uterus has nearly adult proportions due to
influence of maternal hormones.
 Within weeks postpartum, the childhood ration of 1:1 (length
of body to length of cervix) is established until puberty when a
2:1 ratio is re-established.
 Following menopause the uterus reassumes a 1:1 ratio.
Pregnancy
 During pregnancy the uterus grows to occupy most of the
abdominopelvic cavity and press against most organs.
 The uterus becomes very thin-walled
 Multiparous non-gravid uterus may cause slight protrusion of
abdominal wall.
 Prolapse
 When intra-abdominal pressure is increased, the normally
anteverted and anteflexed uterus is pressed against the
bladder.
 A retroverted uterus is more likely to prolapse through the
vagina.
 Prolapse is also more likely in the presence of a disrupted
perineal body or other pelvic diaphragm weakness
o Pouches
 Peritoneum covers most of the superior and anterior parts of the
uterus.
 Anterior the peritoneum reflects off the uterus onto the bladder, while
posteriorly it reflects onto the rectum, creating pouches.
 The rectouterine pouch, in particular, is clinically important as an area
where fluid/infection can accumulate.
Vagina
o Location
 The vagina is a distensible, musculomembranous tube.
 It lies posterior to the urinary bladder and urethra and anterior to the
rectum, passing between the medial margins of levator ani.
 The vagina ascends posteriorly at a 90 degree angle to the axis of the
uterus
o Anatomy
 The vagina is usually collapsed.
 Near the orifice the lateral walls are in apposition.
 Superior to the orifice, the anterior and posterior walls touch.
 At its most superior end, the cervix of the uterus holds the vagina
open
o Muscle
 The vagina has layers of smooth muscle within its walls.
 Three main muscles act as sphincters and compress the vagina.
Neurovasculature of the Internal Genital Organs:
o Arterial Supply
 Blood supply to the female internal genital organs derives from three
main sources:
 Ovarian artery (branch of lumbar aorta)
 Supplies the ovaries and uterine tubes (along with ascending
branches of uterine arteries)



Uterine artery
 Supplies the uterus and part of the vagina (vaginal branch)
 Internal pudendal artery
 Supplies middle and inferior parts of the vagina
o Venous Drainage
 The uterus and vagina drains primarily into the uterovaginal plexus of
veins, which drains into the internal iliac veins.
 The uterine tubes and ovaries drain primarily into the ovarian plexus
of veins, which drains into the ovarian vein.
 All four organs may drain into either plexus.
o Lymphatics
 Lymph drains primarily to iliac and lumbar nodes, and then into the
lumbar lymphatic trunks and the cysterna chyli.
 Lymph gets to the iliac and lumbar nodes in vessels that mainly
parallels venous drainage
 Superior and anterior pelvic structures drain to external iliac nodes
and does not parallel venous drainage.
o Innervation
 Somatic
 Inferior vagina-only the inferior quarter of the vagina is
sensitive to touch and temperature.
 Somatic innervation is from the deep perineal nerve (branch of
pudendal)
 Autonomic
 Supplied by two nerve plexuses
o Ovarian plexus supplies ovaries and uterine tubes
o Uterovaginal plexus supplies the uterus and vagina.
 Sympathetic, parasympathetic and visceral afferent fibers pass
through these plexuses
 Parasympathetic activity results in vasodilation (engorgement
of erectile tissues) and glandular secretion.
o May inhibit uterine contractions
 Sympathetic activity results in vasoconstriction (remission
from erection) and may produce uterine contractions
 Visceral Afferents
o The ovaries and uterine tubes are intraperitoneal, thus
superior to the pelvic pain line.
o Pain fibers travel with sympathetic motor fibers tot
T11-L1
 Caudal Epidural Anesthesia
 This block is popular for participatory childbirth.
 The anesthetic agent is injected through the sacral hiatus
where it bathes S2-S4 nerve roots.
 Structures inferior to the pelvic pain line (birth canal, pelvic
floor, perineum) are anesthetized.


Structures superior to the line (body of uterus) is not
anesthetized allowing mother to be aware of uterine
contractions.
Lecture 16-Male Pelvic Viscera
 Male internal genitalia have three functions:
o Sperm production
o Sperm transport
o Production of secretions to facilitate the sperm’s job.
 Male Internal Organs
o Testes and epididymides (sperm production)
o Ductus deferentes
o Ejaculatory ducts
o Seminal glands
o Prostate gland
o Bulbourethral glands
 Ducts
o Ductus Deferens
 The continuation of the duct of the epididymis.
 The ductus deferens starts where the epididymis straightens out and
turns superiorly.
 Terminates by joining the duct of the seminal gland to form the
ejaculatory duct.
 Course
 Ductus Deferens ascends in the spermatic cord, and is a tough,
cord-like muscular tube, which is easily palpable on the
cadaver.
 It passes through the inguinal canal and enters the abdomen at
the superficial inguinal ring.
 Then bends medially crossing the external iliac vessels to enter
the pelvis.
 The ductus deferens descends medially on the pelvic wall, deep
to the peritoneum
 Crosses the ureter posterior to the bladder and continues
inferomedially along the base of the bladder.
 Nearly reaches the midline of the bladder, anterior to the
rectum, before merging with the seminal gland.
 Vasculature
 The ductus deferens is supplied by the artery to the ductus
deferens, which usually arises from the superior vesicle
arteries
o The artery to the ductus anastomoses with the
testicular artery.
 Veins drain into the testicular vein.
The common method of sterilizing males is deferentectomy
(vasectomy), which is cutting the ductus deferens and ligation
through an incision in the scrotum.
 Ejaculation is still possible, but sperm should not be present.
Accessory Glands
o Seminal Glands
 The seminal glands develop as blind-ended outgrowths from the
ductus deferentes.
 Each gland is essentially at 10-15cm tube whose coiled length is ~5
cm
 The seminal glands produce ~60% of semen.
 Location
 Lie sub-peritoneally in between the rectum and the bladder
and superior to the prostate.
 The may be palpated, or massed for secretion release during a
rectal exam.
 Vasculature
 Seminal glands derive arterial supply from two sources:
inferior vesicle arteries and middle rectal arteries.
 Venous drainage occurs by same named veins.
o Ejaculatory Ducts
 Slender tubes that arise by the union of the ducts of the seminal
glands with the ductus deferentes.
 The ducts pass anteroinferiorly through the posterior part of the
prostate.
 The ducts terminate in the prostatic urethra
o Prostate
 Firm, walnut-sized gland that is the largest accessory gland of the
male reproductive system.
 Lies immediately inferior to the bladder, posterior to the pubic
symphysis and anterior to the rectum.
 Surrounds the prostatic urethra
 Function:
 Prostate produces secretions which make up about 30% of
semen
 Prostatic fluid plays an active role in sperm motility
 Encapsulation
 Fibrous capsule of the prostate is dense and neurovascular,
incorporating the venous and nerve plexuses.
 The capsule is further surrounded by the visceral layer of
pelvic fascia, forming a prostatic sheath, which is continuous
with the puboprostatic ligaments anteriorly
 Vasculature
 Arterial supply is principally from the inferior vesical arteries
(from the internal pudendal artery)




The prostatic venous plexus, in the fibrous capsule of the
prostate, drains into the internal iliac veins.
 Clinical
 Enlargement of the prostate is a common cause of urethral
obstruction. Leads to dysuria, nocturia and urgency.
 Enlargement and/or presence of tumors can be ascertained by
digital rectal exam.
 In transurethral resection of prostate, part or the entire
prostate can be removed.
o Bulbourethral Glands
 Two pea-sized bulbourethral (Cowper) glands lie near the bulb of the
penis and the urethra, they are embedded within the external urethral
sphincter.
 The glands produce a secretion, which serves as a lubricant and
neutralizes uric acids.
 The ducts of the glands pass through the perineal membrane and
open into the spongy urethra.
o Innervation of all Accessory Glands
 Ductus deferens, seminal glands, ejaculatory ducts and prostate are all
richly innervated by sympathetic fibers.
 Internal genital organs are also supplied by the parasympathetic
fibers, though function is unclear.
 Many fibers pass on to penis to cause engorgement of erectile
tissues.
 Sympathetic Function
 During orgasm, the sympathetic system stimulates rapid,
peristaltic contraction and secretion of the various ducts and
glands.
 Promotes secretion and ejaculation of semen.
 Sympathetic system stimulates contraction of the internal
urethral sphincter, preventing retrograde ejaculation.
 Finally, sympathetics cause vasoconstriction resulting in
remission of erection
 Fiber Course
 Sympathetic fibers originate in T12-L2 cord segments
o Traverse the paravertebral ganglia to become
components of lumbar splanchnic nerves and then
hypogastric and pelvic plexuses
 Parasympathetic fibers originate in S2-S4 cord segments
o Traverse pelvic splanchnic nerves and also join
hypogastric/pelvic plexuses
Anal Canal
o About 2.5-5cm long, represents terminal part of digestive tract.
o Begins at anorectal junction (flexure), where the U-shaped sling of
puborectalis muscle is located.
o Anal canal ends at the anus
o Internal Features:
 Anal Columns:
 The superior half of the anal canal has longitudinal ridges
called anal columns, that contain terminal branches of the
superior rectal vessels.
 Inferior ends of the columns join to form anal valves.
 The valves create anal sinuses, which exude mucus when
compressed by feces and aids in evacuation.
 Pectinate Line
 The inferior comb-shaped limit of the anal valves forms the
pectinate line.
 This represents an embryonic junction.
o Areas superior derived from embryonic hindgut
o Areas inferior derive from surface ectoderm
o Sphincters
 Full length of anal canal is surrounded by muscular sphincters
 Regulated by two sphincters:
 Internal anal sphincter
o Consists of involuntary muscle and surrounds the upper
2/3rds of anal canal.
o Tonically contracted most of the time, relaxes in
response to distension of the rectal ampula.
 External anal sphincter
o Consists of voluntary muscle and surrounds most or all
of the anal canal.
o Attached anteriorly to the perineal body and posteriorly
to the anococcygeal ligament.
o Blends superiorly with puborectalis muscle
 Both must relax for defecation to occur
o Innervation, Blood supply and lymphatics
 Arterial Supply
 Arterial blood supply derived from two general sources:
 Above pectinate line-superior rectal artery from IMA
 Blow pectinate line
o Middle rectal artery from anterior trunk of internal iliac
o Inferior rectal artery from internal pudendal artery
 Venous Drainage
 Above pectinate line, blood drains to superior rectal vein and
into portal circulation.
 Below pectinate line, blood drains to the invferior rectal veins
and into the caval venous system.
 Lymphatic Drainage
 Above pectinate line drainage to internal iliac nodes
 Below pectinate, drainage to the superficial inguinal nodes

Innervation
 Above pectinate, the anal canal receives autonomic
innervation.
o Sympathetic fibers maintains internal sphincter tone.
o Parasympathetic fibers inhibit internal sphincter and
promote peristalsis
o Only sensitive to stretching
 Inferior to Pectinate
o Nerve supply of the anal canal inferior to the pectinate
line is somatic, from the inferior rectal nerves.
o This part is sensitive to pain, touch and temperature.
o Efferent fibers stimulate contraction of the external
sphincter