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Pelvis/Perineum
LECOM Yr 1
139
Anatomy
Graduate
09/07/2011

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Cards

Term
what is the superior boundary to the pelvic cavity?
Definition
the pelvic inlet
Term
what is the inferior boundary to the pelvic cavity?
Definition
pelvic outlet

closed by the muscular pelvic diaphragm
Term
which structures pass through the pelvic diaphragm?
Definition
rectum and urogenital structures
Term
where is the false pelvis located?
Definition
part of abdomen
Related to upper part of pelvic bones and lower lumbar vertebrae
Term
where is the true pelvis located?
Definition
Related to inferior parts of pelvic bones, sacrum and coccyx
Has an inlet and an outlet
Term
where is the pelvic peritoneum?
Definition
Pelvic cavity is lined by peritoneum, which is continuous with the abdominal peritoneum.
Peritoneum is “draped” over the pelvic organs.
Blood vessels and nerves can be thought of as retroperitoneal, as can the pelvic organs.
Term
which bones form the pelvis?
Definition
Right and left pelvic (hip) bones
Each is formed by three bones during development which fuse between 16 and 18 years of age.

Sacrum
Formed by 5 fused sacral vertebrae.

Coccyx
Formed by 4 fused coccygeal vertebrae
Term
where is the sacrospinous ligament located?
Definition
Extends from the ischial spine to the sacrum and coccyx
Term
where is the sacrotuberous ligament located?
Definition
Extends from a broad attachment to the sacrum to the ischial tuberosity
Term
what passes through the greater sciatic foramen?
Definition
Piriformis muscle
Superior gluteal nerve and vessels (above piriformis)
Inferior gluteal nerve and vessels (below piriformis)
Sciatic nerve
Posterior femoral cutaneous nerve
Pudendal nerve
Internal pudendal artery and vein
Term
describe the lumbosacral joint
Definition
Two zygapophyseal joints
Intervertebral disc between L5 and S1 vertebrae

Because the sacrum is angled posteriorly, the intervertebral disc between L5 and S1 vertebrae is thicker anteriorly than it is posteriorly.
This is the most common site of lumbar disc herniation
Term
describe the sacro-iliac joint
Definition
Transmit force to lower limbs

Synovial joints that fibrose and may ossify with age
Term
what type of cartilage is found in the pubic symphysis?
Definition
fibrocartilage
Term
compare the general structure of the male and female pelvis
Definition
Male – thick and heavy
Female – thin and light
Term
compare the greater pelvis in males and females
Definition
Male – deep
Female – shallow
Term
compare the lesser (true) pelvis in males and females
Definition
Male – narrow and deep
Female – wide and shallow
Term
compare the pubic arch in males and females
Definition
Male – narrow
Female - wide
Term
what is the female pelvis adapted for?
Definition
Female pelvis adapted for childbirth

Pelvic inlet is circular

Angle between two arms of pubic arch is greater in female pelvis (80-85°) than in male pelvis (50-60°)

Ischial spine in female do not project as far medially as in male pelvis
Term
which type of pelvic variation in females is most common?
Definition
gynecoid pelvis
Term
what is the ostetrical conjugate?
Definition
The narrowest fixed distance through which the baby’s head must pass in a vaginal delivery
Term
how would one perform an obstetric measurement?
Definition
Through the vagina, palpate the sacral promontory with middle finger.

Use the other hand to mark the level of the inferior margin of the pubic symphysis.

This is a measure of the diagonal conjugate (≈13cm).

Distance from tip of index finger to point marked is an estimate of the obstetric conjugate and it should be ≈11.5cm or greater to predict a successful vaginal delivery.
Term
what composes the anterior wall of the true pelvis?
Definition
Bodies and rami of pubic bone and pubic symphysis
Term
what composes the lateral walls of the true pelvis?
Definition
Hip bones covered by obturator internus M
Term
what composes the posterior wall of the true pelvis?
Definition
Sacrum and coccyx, adjacent parts of ilia and sacroiliac joints
Covered by piriformis posterolaterally
Term
what composes the floor of the true pelvis?
Definition
Muscles of pelvic diaphragm
Levator ani m and coccygeus m
Term
what is the origin and insertion of the obterator internus muscle?
Definition
Origin
Deep surface of obturator membrane and adjacent bone
Tendon exits lesser sciatic foramen
Insertion
Medial surface greater trochanter of femur
Term
what nerves innervate the obturator internus?
Definition
L5, S1
Term
what is the action of the obturator internus muscle?
Definition
Laterally rotates extended hip joint
Abducts flexed hip
Term
what is the origin and insertion of the piriformis muscle?
Definition
Origin
Anterior surface of sacrum between sacral foramina

Passes through greater sciatic foramen

Insertion
Medial side of superior border of greater trochanter of femur
Term
what nerves innervate the piriformis muscle?
Definition
(L5) S1 and S2
Term
what are the actions of the piriformis muscle?
Definition
Laterally rotates extended hip joint
Abducts flexed hip
Term
what is the origin and insertion of the coccygeus muscle?
Definition
Origin
ischial spine and pelvic surface of sacrospinous ligament

Insertion
Lateral margin of coccyx and related sacrum
Term
what nerves innervate the coccygeus muscle?
Definition
branches from anterior rami of S3 and S4
Term
what are the actions of the coccygeus muscle?
Definition
Contributes to floor of pelvis, helps support pelvic viscera, pulls coccyx forward after defecation
Term
what is the origin and insertion of the levator ani muscle?
Definition
Origin
Posterior aspect of pubic bone, tendinous arch (thickening of obturator internus fascia), ischial spine via the tendinous arch

Insertion
Anteriorly to superior surface of perineal body, posteriorly meets partner of other side and attaches along the anococcygeal ligament
Term
what nerves innervate the levator ani muscle?
Definition
Direct branch of S4 and inferior rectal branch of pudendal (S2- S4)
Term
what is the action of the levator ani muscle?
Definition
Major part of pelvic floor, supports pelvic viscera, pulls coccyx forward after defecation
Term
where is an area of potential weakness in women who have given birth?
Definition
urogenital hiatus
Term
where is the urogenital hiatus?
Definition
In the anterior portion of the pelvic floor, there is a gap between the medial borders of the levator ani muscles on each side, the urogenital hiatus
Term
what passes through the urogenital hiatus in males and females?
Definition
In the male, this gap allows passage of the urethra.

In the female, it allows passage of the urethra and vagina.

This gap is filled, in part, by the perineal membrane and associated muscles.
These muscles serve as sphincters and help support the urogenital organs
Term
the urethra is embedded in which wall of the vagina?
Definition
anterior wall
Term
describe characteristics of the rectum
Definition
Transition from sigmoid colon to rectum is at the S3 vertebral level.

While the sigmoid colon is suspended in the abdominal cavity by a mesocolon, the rectum lies retroperitoneally.

Rectum is continuous with the anal canal, which penetrates the pelvic floor to enter the perineum to end as the anus
Term
transition from the sigmoid colon to the rectum is at what vertebral level?
Definition
S3
Term
the anorectal junction is pulled forward by the puborectalis portion of which muscle to form the perineal flexure?
Definition
the levator ani
Term
does the upper part of the anal canal have mucosa?
Definition
yes, like the rectum
Term
what is the anal canal noteworthy for having?
Definition
is noteworthy for longitudinally-oriented anal columns that are joined inferiorly by crescent shaped folds called anal valves
Term
anal valves in the anal canal lie at which line?
Definition
Anal valves lie at the level of the pectinate or dentate line which marks the site of the proctodeal membrane. This is where embryonic endoderm and ectoderm meet
Term
describe sensory afferents above and below the pectinate line
Definition
Above the pectinate line, sensory afferents are visceral, below, they are somatic.
Term
the hymen and floor of urethra arise from which membrane?
Definition
the urogenital membrane
Term
the middle portion of the anal canal is characterized by what type of epithelium?
Definition
characterized by stratified squamous, non-keratinized epithelium
Term
what is the name for the middle region of the anal canal? where does it end?
Definition
the anal pectin

ends inferiorly at the anocutaneous line or the white line of Hilton where there is a transition from stratified squamous non-keratinized epithelium to skin
Term
what are the 3 major arteries which supply the rectum and anal canal?
Definition
Superior rectal, the terminal branch of the inferior mesenteric.

Middle rectal, a branch of the the anterior division of the internal iliac artery.

Inferior rectal, a branch of the internal pudendal artery, which is a branch of the anterior division of the internal iliac artery
Term
if an individual had cancer in the upper rectum, through which artery would it metastasize?
Definition
superior mesenteric
Term
if an individual had cancer in the middle rectum, through which artery would it metastasize?
Definition
internal iliac
Term
the superior rectal vein drains into the portal system via which vein?
Definition
the inferior mesenteric vein
Term
the middle and inferior rectal veins drain into which system?
Definition
the caval system
Term
what are hemorrhoids?
Definition
Varicosities of the internal or external rectal plexuses.
Internal are called piles.
Can prolapse and become strangulated.
External are covered by skin.
Term
where does the urinary bladder lie? describe its shape
Definition
lies most anteriorly in the pelvis

Shaped like a 3-sided pyramid.
Apex is directed toward the top of the pubic symphysis.
The median umbilical ligament, a remnant of the embryologic urachus, continues from it superiorly up to the umbilicus.
Base, which is shaped like an inverted triangle, is directed posteroinferiorly.
Ureters enter bladder at upper corners of the base.
Urethra drain inferiorly from the lower corner of the base
Term
the urinary bladder is separated from the pubic bones by which space?
Definition
the retropubic space
Term
describe the relationship of the fundus of the urinary bladder in males and females
Definition
Fundus is posterior wall.

In male, fundus related to rectum.

In female, related to vagina
Term
pain afferents for the superior bladder, that part covered by the peritoneum, travel with sympathetics at what vertebral levels?
Definition
T11-L2 (L3)
Term
describe the sympathetic innervation of the bladder
Definition
Sympathetic fibers from inferior thoracic and upper lumbar levels via hypogastric plexuses and nerves.

Cause contraction of internal sphincter during ejaculation in the male to prevent reflux of semen in the male.

Pain afferents for the superior bladder, that part covered by peritoneum, travel with sympathetics to T11-L2 or L3
Term
pain afferents from the inferior bladder travel with the __________.
Definition
parasympathetics
Term
describe the parasympathetic innervation of the bladder
Definition
Parasympathetics in pelvic splanchnics enter inferior hypogastric plexus.

Motor to detrusor muscle.

Inhibit internal sphincter.

Afferents signaling stretch travel with parasympathetics and cause reflexive contraction of the detrusor muscle and relaxation of the internal urethral sphincter.

Pain afferents from inferior bladder travel with parasympathetics
Term
describe the detrusor reflex
Definition
Afferents signaling stretch travel with parasympathetics (S2-S4).
Efferents cause detrusor contraction and relaxation of the internal urethral sphincter.
Regulated by the pontine micturation center
Descending pathways from the medial frontal micturation centers activate the detrusor reflex
Term
the external urethral sphincter is controlled by what?
Definition
motor neurons in Onuf’s nucleus (S3, S4) in sacral cord
Term
at what point do the ureters enter the pelvic cavity?
Definition
Enter the pelvic cavity by crossing the pelvic brim at the bifurcations of the common iliac arteries
Term
where in males and females do the ureters pass?
Definition
In the male, the ureter passes beneath the ductus deferens on its way to end in the ejaculatory duct.

In the female, the ureter passes beneath the uterine artery
Term
compare and contrast the urethra in males and females
Definition
In females, the urethra is about 4cm long.
Opens anterior to the vaginal opening in the vestibule.
Skene’s glands are paired mucous glands which drain via ducts into the lateral margins of the urethral opening.

Male urethra is 20cm long and has 2 bends along its course.
Divided into 4 parts: preprostatic, prostatic, membranous and spongy
Term
describe the 4 parts of the male urethra
Definition
Urethra in the bladder neck, preprostatic urethra (1-1.5cm in length)

Prostatic urethra (4cm long)
Receives the ejaculatory ducts.
Most distensible part of urethra

Membranous urethra (<1cm in length)
Passes through external urethral sphincter (voluntary)
Least distensible.

Spongy urethra
Within corpus spongiosum of penis
Term
what nerves innervate the testis?
Definition
T10-T11 spinal segments
Term
lymphatics from the testis drain where?
Definition
to lateral aortic and preaortic nodes
Term
the left testicular vein drains where?
Definition
into the left renal vein
Term
the right testicular vein drains where?
Definition
the inferior vena cava
Term
what is the epididymis?
Definition
Long, coiled duct on posterolateral aspect of testis.

Efferent ductules form head of epididymis.

True epididymis is a single coiled duct made up of the body and the tail along the posterolateral aspect of the testis.

Storage site for sperm and place where they acquire motility
Term
what is the ductus (vas) deferens?
Definition
Long tubular structure with a thick, smooth muscle wall.

Extends from the tail of the epididymis to the ejaculatory duct.

Enclosed within the spermatic cord distal to the superficial inguinal ring.

After it passes through the deep inguinal ring, turns medially around the inferior epigastric vessels and passes over the ureter on its way to join the duct of the seminal vesicle to form the ejaculatory duct.

Between the ureter and ejasculatory duct, the ductus deferens expands to form the ampulla of the ductus deferens
Term
where is the seminal vescile located?
Definition
Develops as an outgrowth of the ductus deferens.

Lies between the bladder and the rectum.

Lies lateral to the ductus deferens.

Its duct joins the ductus deferens to form the ejaculatory duct
Term
describe the prostate and its features
Definition
In young male, about the size of a walnut, the prostate is a midline gland that surrounds the urethra within the pelvic cavity.

Lies inferior to the bladder and anterior to the rectum.

Inferolateral aspects of the prostate are cradled by the levator ani muscles.

Fibrous capsule contains a plexus of veins and nerves (cavernous nerves), which innervate the erectile tissue of the penis
Term
urologists often refer to the seminal colliculus in the prostatic urethra as what?
Definition
verumontanum
Term
what occurs during benign prostatic hypertrophy (BPH)?
Definition
hypertrophy blocks urethra

Affects men in their 50s and older

symptoms are nocturia and dysuria
Term
where is prostate carcinoma mostly found?
Definition
70% involve peripheral zone

“Gold standard” treatment – radical prostectomy.

Nerve sparing radical prostectomy done to preserve erectile function
Term
true or false: all the organs in the female pelvis are retroperitoneal essentially
Definition
true
Term
what is the lowest point in the recto-abdominal cavity?
Definition
the pouch of douglas
Term
where did the ovaries develop and where do they lie?
Definition
Like the testes, the ovaries develop high in the abdominal cavity and descend into the pelvis before birth, bringing their blood supply and nerves with them.

Lie adjacent to the to the lateral pelvic wall, just below the pelvic brim.

Suspended by a mesentery (mesovarium) from the posterior aspect of the broad ligament of the uterus.

Suspensory ligament of the ovary contains the nerves and blood vessels of the ovary.
Term
the _____ _____ of the ovary contains the nerves and blood vessels of the ovary.
Definition
suspensory ligament

The ovary is suspended by a mesentery (mesovarium) from the posterior aspect of the broad ligament of the uterus
Term
what is the broad ligament?
Definition
The broad ligament is a sheet-like fold of peritoneum that extends from the lateral pelvic wall to the uterus.

Within this fold of peritoneum is the uterine (fallopian) tube.

The portion of the broad ligament between the origin of the mesovarium and the uterine tube is called the mesosalpinx.
Term
describe the uterus
Definition
Thick-walled, muscular organ which lies posterior to the bladder and anterior to the rectum.

Superior, rounded end, above the uterine tubes, is called the fundus.

The body is flattened anteroposteriorly and is continuous inferiorly with the cervix, which opens into the vagina.
Term
the lumen of the uterine tube connects what 2 regions?
Definition
connects the peritoneal cavity to the lumen of the uterus
Term
what encloses the uterine tube?
Definition
Enclosed in the upper margin of the mesosalpinx, a portion of the broad ligament
Term
describe the uterine tube
Definition
Expanded end is the infundibulum, which has finger-like projections called fimbriae.

Fimbriae sweep up ovulated eggs that are released into the peritoneal cavity.

More medial is the ampulla.

Nearest the uterus is the isthmus
Term
the ligament of ovary and the round ligament are remnants of what?
Definition
the gubernaculum

Ligament of the ovary
From the ovary to the uterus

Round ligament of the uterus
From the uterus to the labia majora
Passes through the inguinal ligament
Term
what is the broad ligament?
Definition
Sheet-like fold of peritoneum that extends from the lateral pelvic wall to the uterus.
Term
what are the 3 parts of the broad ligament?
Definition
Mesometrium
Largest part
Serves as mesentery for the uterus

Mesosalpinx
Uterine tube lies in anterosuperior free boader of the broad ligament within this small mesentery

Mesovarium
Small mesentery in the posterior aspect of the broad ligament
Term
which blood vessels anastomose around the uterine tube?
Definition
ovarian and uterine vessels
Term
what is a hysterosalpingogram?
Definition
At times the uterine tubes get block with mucus.

Blockage inhibits sperm from reaching and fertilizing ovum.

Hysterosalpingogram uses a water soluble radiopaque dye to visualize uterus and uterine tubes.

Dye should fill tubes and enter peritoneal cavities through the abdominal os
Term
true or false: infections in the vagina and uterus can spread into the peritoneal cavity and thereby cause peritonitis
Definition
true
Term
describe characteristics of the vagina
Definition
Fibromuscular tube which extends from the vestibule, between the labia minora to the uterus.

Within the vestibule, the ostium of the vagina is surrounded by a ring-like fold of membrane, the hymen.

During development, the hymen separates the vagina from the urogenital sinus.

Within the anterior wall of the vagina is the urethra.

Upper end of the vagina surrounds the cervix.

Posterior wall of vagina related to the rectum and separated superiorly by the rectouterine pouch, pouch of Douglas

No muscularis mucosa

Some smooth muscle found

Hymen marks difference between visceral and somatic blood supply/innervation change
Term
the posterior vaginal fornix has a close relationship with what structure?
Definition
the rectouterine pouch
Term
where does the lymphatic drainage of the ovaries go?
Definition
drain to lumbar nodes along the ovarian vessels
Term
where does the lymphatic drainage from the middle and upper vagina, cervix and ody of the uterus drain?
Definition
to nodes along the internal iliac arteries
Term
where does the lymphatic drainage from the superolateral uterus near the attachment of the round ligament drain?
Definition
drains to the superficial inguinal nodes
Term
where does the lymphatic drainage from the ostium of the vagina, below the hymen and the vulva, drain?
Definition
to the superficial inguinal nodes
Term
what is the importance of the pelvic fascia?
Definition
Continuation of extraperitoneal connective tissue of the abdomen.
Thickenings of the fascia form ligaments.
In the female, most important of these is the transverse cervical or cardinal ligament.
In the male, there is a condensation of fascia around the the anterior and lateral regions of the prostate.
Term
what is the most severe consequence of pelvic diaphragm weakness?
Definition
vaginal prolapse; more common is stress incontinence

Kegel exercises were devised to strengthen the pelvic floor muscles
Term
what happens during stress incontinence?
Definition
Some people believe that the female urethral sphincter is not as competent as that in the male. The idea for normal continence is that the architecture of the normal pelvic floor allows intra-abdominal pressure to exert a sphincter-like action at the neck of the bladder.

In stress incontinence, the neck of the bladder slips through the pelvic diaphragm, moving it below the effects of
intraabdominal pressure.

Childbirth weakens the pelvic diaphragm and thereby allows the neck of the bladder to slip inferior to the pelvic diaphragm
Term
pelvic structures are innervated by what nerves?
Definition
S2, S3, and S4 and coccygeal nerves

S2 and S3 anterior rami emerge between digitations of piriformis and coccygeus muscles.
L4 and L5 form the lumbosacral trunk that unites with sacral plexus.
Term
which nerve supplies the perineum?
Definition
the pudendal nerve (S2,S3,S4)
Term
the sympathetics are associated with ______ splanchnics
Definition
sacral
Term
the parasympathetics are associated with _____ splanchnics
Definition
pelvic
Term
describe the 2 divisions of the internal iliac artery
Definition
Artery of the pelvis.

Has 2 divisions:
Anterior division – mainly to viscera
Umbilical artery
Obturator artery
Inferior vesical artery (only in males)
Middle rectal artery
Vaginal artery (female equivalent of inferior vesical)
Uterine artery
Internal pudendal artery
Inferior gluteal artery
Posterior division – mainly body wall
Superior gluteal artery
Iliolumbar artery
Lateral sacral arteries
Term
where is the perineum located and describe its divisions
Definition
Anatomically defined as the entire outlet of the pelvis whereas clinically, the term is more restricted to the region between the scrotum and anus in the male or the vulva and the anus in the female .

Rhomboid-shaped region inferior to the pelvic diaphragm.

Divided into two triangles by a line joining the two ischial tuberosities.
Anterior triangle is the urogenital triangle.
Posterior triangle is the anal triangle.

These two triangles are not in the same plane.
In the anatomical position, the urogenital triangle is oriented horizontally and the anal triangle is oriented more posteriorly
Term
describe the orientation of the urogenital triangle
Definition
In anatomical position, oriented horizontally.

In this region, the pelvic diaphragm has a u-shaped opening, the urogenital hiatus, which allows the passage of the urethra in the male and the urethra and vagina in the female.

The perineal membrane spans the urogenital triangle
Term
describe the perineal membrane
Definition
Thick, fascial membrane attached to the bones of the pubic arch.

In anatomical position, it is oriented in a horizontal plane.

Has a free, posterior margin.

Superior to (deep to) the perineal membrane is a thin space, the deep perineal pouch or space.

Inferior to (superficial to) the perineal membrane is the superficial perineal pouch or space.

Inferiormost boundary of this space is Colles’ fascia.
Term
colle's fascia is tightly adherent posteriorly to the posterior edge of which membrane?
Definition
perineal membrane
Term
the membranous layer of the superficial perineal space is which fascia?
Definition
colle's fascia
Term
where is the perineal space located?
Definition
Lies between the perineal membrane and the membranous layer of superficial fascia
Term
describe what colle's fascia is continuous with and adherent to?
Definition
Continuous with Scarpa’s fascia of the abdominal wall, Dartos (superficial ) fascia of the scrotum and the penis.

Tightly adherent, laterally, to the pubic and ischial rami and, posteriorly, to the posterior edge of the perineal membrane
Term
what is found in the superficial perineal space in males and females?
Definition
Erectile tissues that form the penis in the male and clitoris in the female.

In the male, contains, the crura of the corpora cavernosa, corpus spongiosum and bulb of the penis.

In the female, it contains homologous structures and the greater vestibular glands (Bartholin glands).

Contains muscle associated with erectile tissues and the superficial transverse perineal muscle as well as the investing fascia of these muscles (Gallaudet’s fascia).

Branches of the internal pudendal vessels and pudendal nerve
Term
what are the 3 erectile masses of the penis?
Definition
Two corpora cavernosa, each surrounded by a dense, fibrous capsule, the tunica albuginea.

One corpus spongiosum
Term
where is the root of the penis attached?
Definition
to the pubic arch and the perineal membrane
Term
describe characteristics of the penis
Definition
Three erectile masses.
Two corpora cavernosa, each surrounded by a dense, fibrous capsule, the tunica albuginea.
One corpus spongiosum.

Root is attached to the pubic arch and the perineal membrane.

Ischiocavernosus muscles cover the crura.

Bulbospongiosus covers the bulb.

Body is the free part
Term
the skeletal muscle of the penis is innervated by which nerve?
Definition
the perineal nerve, a branch of the pudendal nerve (S2-S4)
Term
an erection involves which type of reflex?
Definition
a sacral spinal reflex
Term
describe the afferents and efferents for erection of the penis
Definition
Afferents.
Sensation from the penis are carried in the dorsal nerve of the penis, the terminal branch of the pudendal nerve (S2-S4).
Damage to the pudendal nerve can cause penile insensitivity, but has no effect on psychogenic erection.
Psychogenic involves descending pathways from the cortex.
Plays a big role in human sexual behavior.

Efferents.
Parasympathetics travel in pelvic splanchnics.
Enter inferior hypogastric plexus, prostatic plexus and the cavernous nerves.
Release acetylcholine and nitric oxide (NO).
Term
what happens during an erection?
Definition
Under the influence of acetylcholine and NO, helicine arteries relax, allow greater blood flow into penis.

Corpora cavernosa and corpora spongiosum become engorged with blood.

The ischiocavernosus muscles and bulbospongiosus muscle compress the veins and prevent venous return.

Tunica albuginea of the penis helps maintain turgidity.
Term
sympathetics from which spinal segments causes peristalsis to move semen to the prostatic urethra via the ejaculatory ducts during ejaculation?
Definition
L1-L2

Sympathetics (L1-L2) close internal urethral sphincter of the bladder.

Contraction of urethral smooth muscle is parasympathetic (S2-S4).

Contraction of bulbospongiosum muscle is somatic reflex (pudendal nerve, S2-S4).
Term
contraction of urethral smooth muscle during ejaculation is sympathetic or parasympathetic?
Definition
parasympathetic (S2-S4)
Term
describe the scrotum and its innervation
Definition
Cutaneous sac with 2 layers

Heavily pigmented thin skin

Dartos fascia
Fat-free fascial layer containing smooth muscle
When cold, dartos muscle contracts, reduces scrotal surface area and helps cremasteric muscle keep testes against the body

Innervation

Anterior scrotal nerve
Branches of Ilioinguinal and genitofemoral nerves

Posterior scrotal nerves from pudendal nerve
Term
the labia majora are innervated by which nerves?
Definition
Labia majora are innervated by the anterior labial nerves from ilioinguinal and the posterior labial nerves from the superficial perineal.
Term
where is the deep perineal pouch located and what does it contain?
Definition
Immediately superior to the perineal membrane.

Contains skeletal muscle, blood vessels and nerves.

In the male, in addition to muscles, blood vessels and nerves, the deep pouch or space contains the bulbourethral glands or Cowper’s glands.
Term
describe the muscles of the deep pouch of the perineum and their functions
Definition
Sheet of skeletal muscle functions as a sphincter for the urethra in the male and for the urethra and vagina in the female.

External urethral sphincter in male and female.

Two additional muscles in female.
Sphincter urethrovaginalis.
Compressor urethrae.

In males and females, deep transverse perineal muscles parallel the free margin of the perineal membrane and help stabilize the perineal body
Term
where does the anal triangle face and what are its boundaries?
Definition
In anatomical position, faces postero-inferiorly.

Laterally, bordered by the medial margins of the sacrotuberous ligaments.

Anteriorly, bounded by the line between the ischial tuberosities, which marks the free posterior border of the perineal membrane.

Posteriorly, it is bounded by the coccyx
Term
where is the ischioanal fossa?
Definition
Lie on either side of anal canal.

Large fascia-lined, wedge shaped spaces between the skin and the inferior fascia of the pelvic diaphragm.

Communicate with each other via the deep postanal space superior to the anococcygeal ligament
Term
what happens if there is an abcess in the ischioanal fossa?
Definition
Can be very painful.

Inflammation in anal canal can lead to a fistula between the anal canal and the ischioanal fossa.

Can spread to the anterior recess and posteriorly through the deep postanal space to the opposite side.
Term
what is the major blood supply to the perineum?
Definition
Internal pudendal artery

Branch of the anterior division of the internal iliac artery
Leaves the pelvic cavity via the greater sciatic foramen
Loops around the ischial spine lateral to the pudendal nerve
Enters the perineum through the lesser sciatic foramen
Enters the pudendal (Alcock’s) canal
Within anal triangle gives off Inferior rectal arteries
Within urogenital triangle gives off
Arteries to bulb of penis or vestibule
Deep dorsal artery of penis or clitoris
Dorsal artery of the penis or clitoris
Term
does the pudendal nerve contain autonomics involved in erection and ejaculations?
Definition
no
Term
describe the major innervation of the perineum
Definition
Major somatic nerve is the pudendal nerve (S2-S4)
Exits the pelvic cavity via the greater sciatic foramen
Loops around the ischial spine to enter the lesser sciatic foramen
Enters the pudendal (Alcock’s) canal in the anal triangle
Gives off the inferior rectal nerve or nerves in the anal triangle
Continues as perineal nerve to supply urogenital triangle
Ends as dorsal nerve of the penis or clitoris
Term
what is bicycle seat neuropathy?
Definition
One of the more common injuries reported by cyclists.
Complain of numbness.
Some complain of impotence.
Believed to be caused by compression of the pudendal nerve in Alcock’s canal.
Bicycle seat design is a factor.
Wider seats that support ischial tuberosities seem to reduce incidence.
Term
what region would a physician use to locate the position of the pudendal nerve during a pudendal nerve block during childbirth?
Definition
the ischial spine
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