Lecture 5: Pelvis and Perineum

Flashcards about Pelvis and Perineum Lecture Notes

Cavity that lies below and behind the abdominal cavity, communicating with the lower limbs, surrounded by the pelvic girdle from the pelvic brim to the pelvic diaphragm.

Pelvic cavity

What is the pelvic diaphragm?

Muscular "hammock" forming the inferior extent of the pelvic cavity.

• related to continence and prolapsed uterus

What is the perineum?

What is it the attachment site for?

Area between the legs and the shallow compartment below the pelvic diaphragm.

• place of attachment for genitalia

What are the main functions of the pelvis?

Transmit body weight to the lower limbs and support and protect pelvic viscera.

What forms the Os Coxae (hip bone)?

Fusion of ilium, ischium, and pubis.

“Wing"-lateral surface of ilium is known as the

Ala of the Os Coxae

1. What is the Greater Sciatic Notch?

2. What is the lesser Sciatic Notch?

1. Between PIIS and ischial spine; enclosed by sacrospinous ligament to form Gr. Sciatic foramen containing piriformis + neurovascular structures.

2. Between ischial spine and ischial tuberosity; enclosed by sacrotuberous and sacrospinous ligaments to form lesser sciatic foramen. Transmits tendon of obturator internus.

What is the Pubic Tubercle?

Raised eminence on lateral end of pubic crest; attachment of inguinal ligament.

What is the attachment site of the inguinal ligament in the pelvis?

Pubic Tubercle

_______ and ______ form the true pelvic brim

• arcuate line

• pectineal line

What is the function of the ligaments of the pelvis?

Stabilize the pelvis and form spaces for the passage of vessels, nerves, and muscles.

What do the Sacrotuberous and Sacrospinous ligaments do?

Transform the greater and lesser sciatic notches into the greater and lesser sciatic foramina.

The obturator foramen is closed by the obturator membrane except for a small obturator canal allowing for passage of which nerve?

Obturator nerve.

Compare the False Pelvis to the True Pelvis

• The false pelvis is superior to the pelvic brim aka pelvic inlet

• True pelvis is the basin inferior to the pelvic brim holding pelvic organs

  • has inlet and outlet where are bony dimensions the baby’s head must pass through

which organs are in the true pelvis basin?

• bladder

• terminus of GI

• reproductive apparatus

How can you differentiate a male vs female pelvis on a skeleton?

Male

• Pelvic inlet is heart shaped (red)

• Pubic arch and Subpubic angle is less than 80 degrees (green)

• greater sciatic notch is narrow (blue)

Female

• pelvic inlet is wide oval (red)

• Pubic arch and subpubic angle is greater than 90 degrees (green)

• greater sciatic notch is wide (blue)

Which two structures form the pelvis?

Pelvic diaphragm - Muscles and fascia that line the floor of the pelvis.

Perineal membrane (urogenital diaphragm) - gives passage to urethra in females

What are the muscles of the pelvic diaphragm?

• these two are the most important for incontenece

• coccygeus

• levator ani muscles

What is the action of the Coccygeus muscle?

Draws pelvic diaphragm upwards; pulls coccyx forward; helps maintain fecal continence.

What is the innervation of the Coccygeus muscle?

Pudendal nerve.

What are the three muscles that make up the Levator ani? Name their action and innervation

• Puborectalis - draws rectum upward and forward to aid anal sphincter; innervated by Pudendal nerve

• Pubococcygeus - elevation of pelvic floor; inn: Pudendal

• Illiococcygeus - supports pelvic viscera; innervated by sacral n

Which muscles in the pelvis are supplied by the inferior gluteal artery?

Muscles of Levator ani = puborectalis, pubococcygeus, and Illiococcygeus

Describe the viscera of the pelvis?

Holds both the Bladder and rectum in both sexes; uterus and part of the vagina in females; prostate and seminal vesicles in males.

Portions of these organs bulge into the abd cavity and covered by reflections of the peritoneum

• reflections (green) are where the membrane changes direction

What are the peritoneal reflections/pouches responsible for?

Permit expansion and collect debris

Describe the pouches found in males and females

Male

• Rectovesical pouch

Female

• Vesicouterine pouch

• Rectouterine pouch

What are the ureters?

Muscular tubes connecting the kidney to the urinary bladder.

They conduct urine from the kidney to the urinary bladder

_______ crosses over the iliac vessles and pelvic brim

Ureters

Hollow distensible organ located posterior to the pubic bone (pubic symphysis)

urinary bladder

Where does the bladder sit in males vs females

Males - upon prostate

Females - rests on the anterior wall of the vagina posteriorly

The walls of the bladder are composed of the ______ and are continuous with the ______ which guards the urethra

• detrusor muscle

• internal urethral sphincter

What is the trigone of the bladder?

Triangle-shaped area between urethra and 2 ureter openings.

What supplies blood to the Is Urinary Bladder?

Superior vesicle (bladder) arteries

Males: Inferior vesicle artery

Females - vaginal artereis

T/F: when the bladder is full, it ascends in the abd above the pubic symphesis

true

What do the male internal genital organs include?

Testes

epididymides

ductus deferens

ejaculatory ducts

seminal glands

prostate

bulbourethral glands.

Describe the ductus deferens

• continuation of the epididymis

• crosses over the ureter and ends by forming an ampulla (for sperm storage)

_____ and _____ in the male genitalia join to from the ejaculatory duct

• ductus deferens

• seminal vesicle

What does the prostate produce?

Largest male reproductive ACCESSORY organ

Milky fluid for activating and transporting sperm.

What does the seminal vesicle provide?

Fructose food for sperm in alkali fluid.

What is the function of the bulbourethral glands?

Lubricate urethra for passage of semen during ejaculation.

What is the ejaculatory duct?

Union of seminal vesicle and ductus deferens leading to the prostate gland and urethra

Clinical application: _____ is common in older men usually not malignant but it can cause difficulty with urination and patients tend to feel incontenence

enlarged prostate

Clinical application: _______ is described as a cancer common among men over 75 but it is not considered problematic because it spreads slowly

Prostate cancer

What are the three parts of the male urethra?

Anterior prostate (prostatic urethra) (1)

pelvic diaphragm (intermediate (membranous) urethra) (2)

bulb of the urethra (spongy urethra) (3)

1. Where do the prostatic ducts in males empty into? Why is that important?

2. T/F: the prostate is vascularized and has nervous tissue as well

1. Anterior prostate (prostatic urethra) (1) - important because it adds prostatic fluid to ejeculate and support sperm

2. True

List the male internal genital organs of the pelvic viscera

• ductus deferens

• seminal vesicle

• Ejaculatory duct

• Prostate

• Bulbourethral gland

List the female internal organs of the pelvic viscera

• vagina

• uterus

• uterine (fallopian) tubes

• Ovaries

What are the functions of the vagina?

Excretory flow during menstruation

birth canal

reproductive organ that receives the penis during intercourse.

“cup” around the cervix: analyzed during childbirth to judge cervical thinning is known as______

vaginal fornices

What is the structure of the uterus?

Contains 3 parts: fundus, body, and cervix.

What is the broad ligament?

Fold of peritoneum that suspends the uterus.

What is the ovarian ligament vs the suspensory ligament

Both are forms of the broad ligament

OL: Remnant of gubernaculum; attaches ovary to uterus.

SP: Lymphatics, nerves, and ovarian vessels that supply the ovary.

What are the ovaries? How are they suspended to the uterus?

Almond-sized; produce eggs and hormones.

By a short, mesentary fold of the broad ligament called the mesovarium.

What makes of the broad ligament on the uterus?

• mesovarium

• mesosalpinx

• mesometrium

What are the four parts of the uterine tubes?

Isthmus - entrance to the uterus

Ampulla - where fertilization occurs

Infundibulum - funnel shaped end leading away from the fimbriae

Fimbriae - finger like projections over the ovaries

______ conduct oocytes to the uterine cavity

They are invested by which part of the broad ligament?

1. Uterine tubs

2. Mesosalpinx

What is the Pelvic part of the GI that is continuous with the sigmoid colon?

Rectum

Which pelvic muscle is a “sling” around the anal canal and dictates defication and relaxation?

Puborectalis

What artery primarily supplies the pelvis and perineum?

Internal iliac artery.

What does the anterior division (of the pelvis) of the internal iliac artery supply?

Supplies most pelvic viscera, perineal structures (via pudendal), and some gluteal muscles (via inferior gluteal)

What does the posterior division of the internal iliac artery (of the pelvis) supply?

Supplies posterior abdominal wall, lower back, and gluteal region.

• all via superior gluteal

From the internal iliac and its branches (anterior and posterior division), where does the blood drain into that is surrounding the organs?

Where does it go to next?

Venous plexus (network around the organs)

Internal iliac vein OR portal system

What are the branches of the anterior division of the internal iliac artery?

Superior vesical (umbilical)

obturator

inferior vesical

uterine and vaginal (female)

middle rectal

internal pudendal

What are the branches of the posterior division of the internal iliac artery?

Iliolumbar, lateral sacral, superior gluteal, and inferior gluteal

_______ is the site for hemorrhoids - due to portal/system shunts

rectal veins

Where does the superior rectal drain into?

What about the middle and inferior rectal?

1. portal system

2. systemic venous vessels (internal iliac)

Where do the pelvic lymphatics receive drainage from?

Where do they drain into?

Receive from inguinal nodes

Drain into thoracic duct

What are the groups of lymphatic nodes in the pelvis?

Internal iliac nodes, common iliac nodes, lumbar nodes, external iliac nodes, and superficial inguinal nodes.

What is the difference between the somatic and autonomic nerves in the pelvis?

• Somatic is supplied by pudendal nerves and innervate superficial areas

• Autonomic carry sensations for reflex (urination, defecate)

Where do the branches of the somatic nerves innervate to?

What regions of the body do the somatic nerves of the sacrum innervate?

Branches from somatic nerves (lumbar and sacral plexus (L4-S4), and coccygeal plexus (S4-5).

They innervate the lower limb, perineum, and gluteal region

Important branch of the sacral plexus and is the primary nerve to the perineum.

Pudendal nerve

What is the role of the pudendal nerve on the body?

1. provides motor innervatoin to external anal sphincters and levator ani

2. Cutaneous innervation to scrotum, vulva, and perianal skin

3. sensory innervation to glans penis and clitoris

What are the types of autonomic innervation in the pelvis?

Sympathetic - provide sympathetic fibers for the pelvis/lower limb via sacral plexus

parasympathetic - nerves originate in the sacral cord and join with the hypogastric nerves to form the inferior hypogastric plexus

Which nerve of the anterior division supplies skin and muscles of the perineum?

Pudendal nerve

What are the Pelvic splanchnic nerves?

Originate in sacral cord (S2-4) and join with the hypogastric nerves forming the inferior hypogastric plexus.

PNS innervation to descending, sigmoid colon + pelvis (hindgut)

Which nerve plexus regulates erection, urination, and defection?

Inferior hypogratric plexus (part of PNS)

What ganglia provides sympathetic input to the bladder?

Sacral ganglia.

Sensation from the pelvis are carried by _____ to different regions of the cord depending on the relation to the peritoneum

afferent

Explain the pain sensation from the pelvis

• sensations above the pain line follow sympathetic nerves. They terminate T10-T12 and refer to anterior thigh up to suprapubic region

• Sensations below the pain line pass through the pelvic plexi (PNS fibers) and terminate at S2-S4. Refer to buttocks and posterior thigh

• Sensations from the skin are carried by pudendal n

What is the perineum?

Shallow space below the pelvic diaphragm; diamond-shaped.

• subdivided into the anal triangle and urogenital triangle

  • Levator ani is the muscle covering the triangles

What are the boundaries of the perineum?

Pubic symphysis, ischial tuberosities, and coccyx.

What are the contents of the anal triangle?

• Levator ani muscle

• ischioanal fat pad

• perineal body

• pudendal canal (space the pudendal n goes through)

• anal canal and anus

which triangle subdivision of the perineum surrounds the anus?

anal triangle

Convergence of muscles including posterior margin of the UG diaphragm, transverse perineal muscles, pelvic diaphragm, and external anal sphincter.

Perineal body

What is the role of the perineal body?

supports the abd viscera

Applied clinical: tearing during childbirth can lead to urinary incontinence and prolapse of the pelvic viscera here

perineal body

What is the pudendal nerve?

Main nerve of the perineum, formed from 3 branches from S2-4.

What muscles do the pudendal nerve pass between?

• piriformis and coccygeus to enter the obturator canal with internal pudendal vesseles

Describe the Pudendal nerve branching and course

In the Pudendal canal, the pudendal nerve branches into the inferior rectal nerve and artery - supplies the external sphincter and perianal skin

As it continues through the canal it bifurcates into the perineal nerve and the dorsal nerve of the penis/clitoris

• perineal nerve supplies scrotum and labia

• DNP/C supplies glans penis with the shaft and the clitoris

What nerve supplies the scrotum and labia?

The perineal nerve

Which nerve supplies glans penis with the shaft and the clitoris?

The dorsal nerve of the penis/clitoris

What is the Anal Canal?

Terminal part of GI, extends from pelvic diaphragm to anus.

Consists of the internal and external anal sphincters

What artery supplies the internal sphincter

Sympathetic -hypogastric plexus (and superior rectal a) - promote contraction

PNS- pelvic splanchnic - inhibits contraction

What nerve supplies the external sphincter

Pudendal-inferior rectal nerve

Describe sensation of the anus

• the pectinate line separates the sensitive and insensitive areas; above the line is visceral sensation, while below is somatic sensation.

  • insensitive to pain is elicited by stretching

  • sensitive areas detect pain, touch, and temp

What is the Innervation for the anus below the pectinate line?

Above?

Pudendal nerve

Inferior hypogastric plexus

Applied Clincal: explain hemorrhoids

• Internal hemorrhoids are painless because they are above the pectinate line

• external hemorrhoids are below the pectinate line and are very sensitive to pain and usually require treatment

What is the Urogenital Triangle?

Anterior portion of the perineum.

function: attachment site for genitalia in both genders

Pierced by the urethra in both genders and the vagina in females, it provides a stable base for attachment of external genitalia and associated muscles

Perineal membrane

What are the two spaces that the Perineal membrane divides the UT into?

Deep perineal space or pouch (superior) and superficial perineal space or pouch (inferior).

Give the layers of the fascia layers of the perineum from deep to superficial

1. Pelvic diaphragm muscles

2. Deep pouch (perineal space)

3. Perineal membrane

4. superficial pouch

5. superficial faccia

6. Skin of perineum