13. Pelvis Flashcards by iya gerzon

region of the trunk that lies below the abdomen

pelvis

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4 bones that make the pelvis

2 hip boes
sacrum
coccyx

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bony projection at the supero-lateral border of the body of the pubic bone

pubic tubercle

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surface landmarks of the pelvis

iliac crest
anterior superior iliac spine
pubic tubercle 
symphysis pubis 
posterior superior iliac crest

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pelvic brim boundaries

anterior - symphisis pubis
lateral- iliopectineal line
post- sacral promontory

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above the pelvic brim

are these structures

false pelvis
greater pelvis
pelvis major

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below the pelvic brim

are these structures

true pelvis
lesser pelvis
pelvis minor

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forms part of the abdominal cavity
bounded behind by lumbar vertebra
laterally by iliac fossa and iliacus muscle
in front by anterior abdominal wall

a. false pelvis
b. true pelvis

a. false pelvis

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great important for obstetrics (bony canal through which the baby passes during birth)

true pelvis

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pelvic inlet

borders

Ant- symphisis pubis
lat- ileopectineal line
post- sacral promontory

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pelvic outlet borders

Ant- pubic arch
lat- ischia tuberosities
Post - tip of coccyx

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contents of Male pelvic cavity

urinary bladder
ureter 
vas deferens
seminal vesicle
prostate gland
prostatic urethra
sigmoid colon
rectum

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female pelvic cavity

urinary bladder
ureter
ovary
uterine tube
uterus 
vagina
sigmoid colon
rectum

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ligaments of the pelvic cavity

sacrotuberous ligament - lateral

sacrospinous ligament - lateral

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ligaments of the pelvis divide the sciatic notches to

greater sciatic foramen

lesser sciatic foramen

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nerves in greater sciatic foramen

pudendal nerve 
nerve to obturator internus 
internal pudendal vessels
piriformis 
superior and inferior gluteal vessels and nerves 
sciatic nerve 
post. femoral cutaneous nerv e 
nerve to quadratus femoris

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lesser sciatic foramen

nerves

pudendal nerve
nerve to obturator internus
internal pudendal vessels
tendon of obturator internus

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is an opening (foramen) in the posterior human pelvis. It is formed by the sacrotuberous and sacrospinous ligaments. The piriformis muscle passes through the foramen and occupies most of its volume.

greater sciatic foramen

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is an opening (foramen) between the pelvis and the back of the thigh. The foramen is formed by the sacrotuberous ligament which runs between the sacrum and the ischial tuberosity and the sacrospinous ligament which runs between the sacrum and the ischial spine.

lesser sciatic foramen

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this nerve passes through both greater and lesser sciatic foramens

pudendal nerve

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tearing of the pelvic diaphragm during childbirth leads to paralysis of

levator ani

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closed except where it transmits the urethra and anal canal (vagina- females)

pelvic outlet

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urogental diaphragm is formed by

sphincter urethrae

deep transverse perineal m.

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pelvic diaphragm formed by

levator ani - puborectalis, pubococcygeus, iliococcygeus

coccygeus

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seals the opening of bony pelvis supports pelvic organs pierced by rectum, urethra, vagina

pelvic diaphragm

The pelvic viscera (bladder, rectum, pelvic genital organs and terminal part of the urethra) reside within the

pelvic cavity (or the true pelvis)

lateral walls of the pelvis include

obturator internus | piriformis

what muscle forms posterior wall of the pelvis

piriformis

pelvic floor is also known as the

pelvic diaphragm.

muscles that make up the inferior lining of the pelvic cavity

pelvic diaphragm

an anteriorly situated gap, which allows passage of the urethra (and the vagina in females).

urogenital hiatus

centrally positioned gap, which allows passage of the anal canal.

rectal hiatus

Between the urogenital hiatus and the anal canal lies a fibrous node known as the

perineal body

joins the pelvic floor to the perineum

perineal body

functions of pelvic floor muscles

Support of abdominopelvic viscera Resistance to increases in intra-pelvic/abdominal pressure Urinary and faecal continence.

levator ani m. innervated by

anterior ramus of S4 and branches of the pudendal nerve (roots S2, S3 and S4).

broad sheet of muscle. It is composed of three separate paired muscles; pubococcygeus, puborectalis and iliococcygeus.

levator ani

thickened fascia of the obturator internus muscle, known as the

tendinous arch

attachments of levator ani m

Anterior – pubic bodies of the pelvic bones. Laterally – thickened fascia of the obturator internus muscle, known as the tendinous arch. Posteriorly – ischial spines of the pevlic bones.

is a U-shaped sling, extending from the bodies of the pubic bones, past the urogenital hiatus, around the anal canal

puborectalis m.

Its tonic contraction bends the canal anteriorly, creating the anorectal angle (90 degrees) at the anorectal junction (where the rectum meets the anus).

puborectalis m.

main fx of puborectals muscle is to

maintain faecal continence – during defecation this muscle relaxes.

These fibers are very important in preserving urinary continence, especially during abrupt increase of the intra-abdominal pressure i.e. during sneezing.

pubovaginalis or sphincter urethrae / vaginae)

Some fibers of the puborectalis muscle (pre-rectal fibers) form another U-shaped sling that flank the urethra in the male and the urethra and vagina in the female

pubovaginalis or sphincter urethrae / vaginae

main constituent of the levator ani.

Pubococcygeus

They arise from the body of the pubic bone and the anterior aspect of the tendinous arch. The fibres travel around the margin of the urogenital hiatus and run posteromedially, attaching at the coccyx and anococcygeal ligament.

Pubococcygeus

has thin muscle fibres, which start anteriorly at the ischial spines and posterior aspect of the tendinous arch. They attach posteriorly to the coccyx and the anococcygeal ligament.

Iliococcygeus

This part of the levator ani is the actual “levator” of the three: its action elevates the pelvic floor and the anorectal canal.

Iliococcygeus

Coccygeus | innervated by

anterior rami of S4 and S5

is the smaller, and most posterior pelvic floor component – as the levator ani muscles are situated anteriorly.

coccygeus (or ischiococcygeus)

this m. originates from the ischial spines and travels to the lateral aspect of the sacrum and coccyx, along the sacrospinous ligament.

coccygeus

During the second phase of childbirth, these structures are at high risk of damage.

levator ani muscles and/or the pudendal nerve Pubococcygeus and puborectalis are the most prone to injury due to them being situated most medially.

injury to the pelvic floor muscles during childbirth lead to

urinary stress incontinence and rectal incontinence

Prolapse of the vagina can also occur if there is damage to the ___ during childbirth

perineal body

If the medial fibres of the puborectalis are torn within the perineal body, then this can occur

rectal herniation

There are a number of risk factors which can increase the chances of prolapse

Age Number of vaginal deliveries Family history of pelvic floor dysfunction Weight Chronic coughing (e.g from a lung disorder)

levator ani | innervation

pelvic side - lower sacral n. | perineal side - inferior hemorrhoidal n.

cervix, isthmus, and body of the uterus protrude into the superior aspect of the vagina , bleeding and discharge into the vagina

uterine prolapse

bladder herniates into the upper part of the anterior wall of the vagina •urinary problems

cystocele

rectum herniates into the lower part of the posterior wall of vagina

rectocele

divides the perineum into the posterior anal triangle and anterior urogenital triangle.

theoretical line connecting the two ischial tuberosities of the pelvis

is an anatomical region in the pelvis. It is located between the thighs, and represents the most inferior part of the pelvic outlet.

perineum

separated from the pelvic cavity superiorly by the pelvic floor.

perineum

shape of the perineum

diamond shaped

anatomical borders of the perineum

``` Anterior – pubic symphysis. Posterior – tip of the coccyx. Laterally – inferior pubic rami and inferior ischial rami, and the sacrotuberous ligament. Roof – pelvic floor. Base – skin and fascia. ```

The perineum can be subdivided by a theoretical line drawn transversely between the

ischial tuberosities

The perineum can be subdivided by a theoretical line drawn transversely between the ischial tuberosities. This split forms the

anterior urogenital triangle and the posterior anal triangle

surface borders of the perineum

Anterior – mons pubis in females, base of the penis in males. Laterally – medial surfaces of the thighs. Posterior – superior end of the intergluteal cleft

posterior half of the perineum. It is bounded by the coccyx, sacrotuberous ligaments, and a theoretical line between the ischial tuberosities.

anal triangle

main contents of the anal triangle are:

Anal aperture – the opening of the anus. External anal sphincter muscle – voluntary muscle responsible for opening and closing the anus. Ischioanal fossae (x2) – spaces located laterally to the anus.

this nerve supplies the whole perineum with somatic fibers

pudendal nerve

anal aperture is located centrally in the triangle with these structure on either side

ischioanal fossae

anterior half of the perineum.

urogenital triangle

boundaries of the urogenital triangle

pubic symphysis, ischiopubic rami, and a theorectical line between the two ischial tuberosities

Unlike the anal triangle, the urogenital triangle has an additional layer of strong deep fascia; the

perineal membrane

The layers of the urogenital triangle (deep to superficial):

1. deep perineal pouch 2. perineal membrane 3. superficial perineal pouch 4. perineal fascia 5. skin

potential space between the deep fascia of the pelvic floor (superiorly) and the perineal membrane (inferiorly).

deep perineal pouch

It contains part of the urethra, external urethral sphincter, and the vagina in the female. In males, it also contains the bulbourethral glands and the deep transverse perineal muscles.

deep perineal pouch

a layer of tough fascia, which is perforated by the urethra (and the vagina in the female). The role of the membrane is to provide attachment for the muscles of the external genitalia.

perineal membrane

a potential space between the perineal membrane (superiorly) and the superficial perineal fascia (inferiorly)

superficial perineal pouch

this layer contains erectile tissues that form the penis and clitoris, and three muscles – the ischiocavernosus, bulbospongiosus and superficial transverse perineal muscles.

superficial perineal pouch

The greater vestibular glands (Bartholin’s glands) are also located in the

superficial perineal pouch

superficial perineal pouch | bounded posteriorly to the

perineal body

this layer of urogenital triangle is a continuity of the abdominal fascia

perineal fascia

layers of the perineal fascia

``` Deep fascia: covers the superficial perineal muscles and protruding structures (e.g. penis & clitoris). Superficial fascia is composed of a further two layers of fascia: Superficial layer – continuous with Camper’s fascia of the anterior abdominal wall Deep layer (Colles’ fascia) – continuous with Scarpa’s fascia of the anterior abdominal wall ```

irregular fibromuscular mass. It is located at the junction of the urogenital and anal triangles – the central point of the perineum

perineal body

perineal body acts a s a point of attachment of

Levator ani (part of the pelvic floor). Bulbospongiosus muscle. Superficial and deep transverse perineal muscles. External anal sphincter muscle. External urethral sphincter muscle fibres. perineum

it acts as a tear resistant body between the vagina and the external anal sphincter, supporting the posterior part of the vaginal wall against prolapse. In the male, it lies between the bulb of penis and the anus.

perineal body

The major neurovascular supply to the perineum is from the

pudendal nerve (S2 to S4) and the internal pudendal artery.

The pudendal nerve (along with the internal pudendal artery and vein) travel along the inner surface of the ischial tuberosities, through a “canal” formed by a thickening of the obturator fascia

Alcock’s canal

Bartholin’s glands are not detected on physical examination. However, if the duct becomes blocked, then these glands can swell to form fluid-filled cysts. These cysts can become infected and inflamed, a condition known as

Bartholinitis

Bartholinitis | most common cause

Staphylococcus spp. and Escherichia coli.

incision is made in the perineal body from the midline of the hymenal ring through the connective tissue that unites the bulbocavernous muscle, the superficial transverse perineal muscles, and the perineal membrane (urogenital diaphragm).

midline episiotomy

the anatomic structures involved in this episiotomy include

vaginal epithelium, transverse perineal muscle, bulbocavernosus muscle, and perineal skin.

3 cylinders of erectile tissue of males are enclosed by

Buck’s fascia

penis contains

root - 3 erectile tissues (bulb of penis and r/l crura of penis ) •bulb forms corpus spongiosum •crura forms corpora cavernosa body - 3 cylinders enclosed by buck’s fascia

blood supply of the penis

deep arteries and dorsal arteries of the penis- internal pudendal

lymph drainage | penis

skin- superficial inguinal nodes | deep structures- internal iliac nodes

outpouching , contains testes, epididymis, lower ends of spermatic cord

scrotum

wall of the scrotum | superficial -> deep

``` skin superficial fascia with dartos muscle external spermatic fascia cremasteric muscle internal spermatic fascia tunica vaginalis ```

contents of the female urogenital triangle

* external genitalia of the urethra and vagina * clitoris * body * glans

this structure is situated at the apex of the vestibule

clitoris

boundaries of the ischioanal fossae

base - skin overlying anal triangle lateral - obturator internus m. and fasci a medial- levator ani

contents of ischioanal fossae

fats inferior rectal A/V inferior rectal N perineal branch of the femoral cutaneous n.

each common iliac artery ends at this structure

pelvic inlet | in front of sacroiliac joint

common iliac artery divides into

external iliac a. | internal iliac a.

at this structure the internal iliac divides into anterior and posterior division

greater sciatic foramen

anterior division of the internal iliac a.

``` umbilical- superior vesical obturator inferior vesical (male)/ vaginal (female) middle rectal internal pudendal inferior gluteal uterine ```

posterior division of the internal iliac a.

iliolumbar lateral sacral superior gluteal

blood supply of the superior part of UB

superior vesical

blood supply of the pelvic muscles; medial compartment of the thigh

obturator a.

blood supply of the base of UB, rostate, seminal vesicle, ductus deferens, lower ureter

inferior vesical

blood supply of the rectum and anal canal

middle rectal

blood supply of the m. of the anal canall skin and muscles of the perineum

internal pudendal

blood supply of the uterus

uterine

branches of the internal pudendal artery

``` inferior rectal perineal superficial perineal deep artery of the penis/ clitoris dorsal artery of penis/ clitoris perineum, skin and m. of anal triangle and urogenital triangle and erectile bodies ```

leaves the main pelvic cavity through greater sciatic foramen and enters perineu through lesser sciatic foramen

pudendal nerve

branches of the pudendal nerve

inferior rectal - perianal skin, ext. anal sphincter, mucous membrane - lower anal canal dorsal nerve of the penis/ clitoris perineal - perineal m. / skin

this structure serves as a hallmark in doing pudendal block anesthesia through transvaginal approach

ischial spine

bony landmark in doing pudendal nerve block, perineal procedure

ischial tuberosity

motor fx of pudendal nerve

``` maintain voluntary urinary continence maintain voluntary fecal continence supports pelvic viscera maintain erection facilitates expulsion of urine from the penile urethra during micturition; sperm and seminal fluid during ejaculation ```

early genital systems in 2 sexes are similar and is referred to as indifferent stage and lasts until __ week of human development

7th week

gonadal sex is determined by

testis determining factor on the Y chromsome

directs testicular differentiation

TDF

induces masculine differentiation of mesonephric ducts and external genitalia

testosterone

___ week leydig/ interstitial cells secrete testosterone and androstenedione which induce masculine differentiation of mesonephric ducts and external genitalia

leydig/ interstitial cells

secretes mullerian inhibiting substance/ MIH or antimullerian hormone / AMH which inhibits development of paramesonephric ducts

sertoli cells

how ovaries develop

absence of Y chromosome ovaries develop mesonephric duct regress paramesonephric duct develop

dev of male genital ducts

fetal testes product testosterone (8th week) -> mesonephric duct -> epidymidis, vas deferens and ejaculatory duct develop

failure of the fusion of paramesonephric duct may give rise to

bicornuate uterus

paramesonephric duct gives rise to

uterine tubes uterus vagina

gametogenesis is controlled by this hormone

FSH from anterior pituitary gland

primary oocytes formed ___ month remain dormant until puberty

5th month

primary oocytes arrested in this stage of cell cycle

prophase of Meiosis I

primordial germ cells form gonad at week

week 4 q

after puberty, primary oocyte completes meiosis I forming

secondary oocyte and 1st polar body

secondary oocyte are arrested at this stage until fertilization occurs

metaphase Meiosis II

at fertilization, secondary oocyte completes meiosis II forming

mature oocyte and second polar body

at puberty, gonad diff into spermatogonia ->

primary spermatocytes (meiosis I) -> two secondary spermatocytes (Meiosis II) -> 4 spermatids

growth and differentiation of spermatogenesis occurs

puberty until old age

oogenesis | growth and differentiation

fetal life until birth

meiosis I | spermatogenesis

reductional and equal

oogenesis | meiosis I

reductional and unequal

meiosis II in spermatogenesis

always take place and completed

meiosis II in oogeness

not always completed

transformation | spermatogenesis

present

transformation | oogenesis

absent

gametes formed | spermatogenesis

4 sperm cells

gametes formed | oogenesis

1 egg

normal meiosis, disjunction | gametes with ___ chromosomes are produced

23 single chromsomes

in nondisjunction- abnormal gametes ___ chromosomes are produced

gametes ith 24 or 22 chromosomes

fetilization between normal gamete and abnormal gamete forms

47, trimomy | 45, monosomy

47, XXY | only in males

klinefelter syndrome

45, XO only in females

turner syndrome

s and sx of klinefelter

sterility, testicular atrophy gynecomastia

incidence of klinefelter’s syndrome

1 in 500

turner syndrome | s and sx

``` absence of ovaries short stature webbed neck skeletal deformities broad chest with widely spaced nipples ```