[Anatomy] Pelvis

Front 1

pelvic girdle

Back 1

▪ formed by fusion of ilium, pubis, ischium
▪ articulates with sacrum and forma
▪ transfers weight from upper body to lower extremities, serves as bottom of abdominopelvic cavity, protects lower abodimonopelvic organs

Front 2

ilium

Back 2

- superiormost of the hip bones, and is comprised of a body and a wing
- forms the superior part of the acetabulum

Front 3

parts of ilium

Back 3

ala, body, iliac crest, anterior iliac spine

Front 4

ala

Back 4

the wing of the ilium as it sweeps laterally

Front 5

body of the ilium

Back 5

the "handle" of the fan, or the solid part of the bone

Front 6

iliac crest

Back 6

superior rim of the ala

Front 7

anterior superior ilia spine

Back 7

most anterior part of iliac crest; palpable and prominent landmark

Front 8

McBurney's point

Back 8

1/3 of the way from ASIS to umbilicus; appendix location and site of surgery

Front 9

parts of the ischium

Back 9

body, ramus, ischial tuberosity, ischial spine

Front 10

body of ischium

Back 10

helps to form acetabulum

Front 11

ischium ramus

Back 11

extends inferiorly and then curves anteriorly, serving as inferior border of obturator foramen

Front 12

ischial tuberosity

Back 12

protrusion inferiorly and posteriorly from the body of the ischium

Front 13

ischial spine

Back 13

protrusion from posterior body of ischium, origin of sacrospinous ligament, an important clinical landmark

Front 14

pubis

Back 14

third bone of pelvis, has body and two rami which are both fused with ischium

Front 15

superior pubic ramus

Back 15

forms anterior part of acetabulum

Front 16

inferior pubic ramus

Back 16

fuses with ischium to form inferior boundary of obturator space

Front 17

body of pubis

Back 17

attaches in midline to opposite pubic bone to complete circle of pelvic girdle

Front 18

retropubic space

Back 18

cave of Retzius; area posterior to pubic arch; lies posterior to pubis and anterior to bladder

Front 19

ischiopubic rami (pubic arch)

Back 19

formed as two arches come together in midline anteriorly, varies significantly between sexes

Front 20

acetabulum

Back 20

cup like socket that articulates with head of the femur, where hip replacements are done, superior rim much heavier as it is weight bearing, inferior rim is incomplete; formed by body of ischium and superior pubic ramus (form anterior part), superior part formed by ilium

Front 21

obturator foramen

Back 21

large foramen inferior to acetabulum, closed by membrane in life, becoming important in some types of surgical procedures for urinary incontinence

Front 22

obturator membrane

Back 22

covers obturator foramen with exception of small opening at superior aspect called the obturator canal

Front 23

obturator canal

Back 23

opening in obturator membrane by which obturator vessels and nerve leave the pelvis to enter the medial compartment of the thigh

Front 24

greater sciatic notch

Back 24

large concavity on posterior ischium and ilium above ischial spine

Front 25

lesser sciatic notch

Back 25

smaller concavity between ischial spine and ischial tuberosity

Front 26

sacrum

Back 26

fusion of five sacral vertebrae, articulates with pelvic girdle

Front 27

sacral promontory

Back 27

smooth ventral surface of sacrum, forms posterior part of pelvic cavity

Front 28

coccyx

Back 28

3-4 rudimentary vertebrae attached at bottom of sacrum, end of vertebral column, may be fused, “tailbone”

Front 29

sacrotuberous ligament

Back 29

posterior strong bracing ligament attaching sacral vertebrae (sacrum) to the ischial tuberosity, medial border of both greater and lesser sciatic foramen

Front 30

sacrospinous ligament

Back 30

smaller ligament attaching coccyx and sacrum to ischial spine, divides greater sciatic foramen from lesser sciatic foramen

Front 31

sacroiliac joints

Back 31

strong weight bearing joints, supporting upper body as attaches to sacrum to pelvic girdle

Front 32

pubic symphysis

Back 32

cartilaginous joint from the joining of the two pubic bones in the midline, wider in women than men

Front 33

obturator internus

Back 33

lies on inner surface of pelvic bones, exits posteriorly through lesser sciatic foramen and attaches to femur (trochanteric fossa)

innervation: branches of sacral plexus
action: laterally rotate & stabilize hip joint

Front 34

piliformis

Back 34

lines inner pelvis posteriorly, exits through greater sciatic foramen
laterally rotates and stabilizes hip joint
inn. by sacral plexus

Front 35

pelvic diaphragm

Back 35

funnel shaped floor of pelvis, comprised of levator ani and coccygeus

Front 36

levator ani

Back 36

complex muscle comprised of three main muscles, function in support of pelvis structures but also assists in some of the functions of the pelvic organs

Front 37

coccygeus

Back 37

posterior part of pelvic diaphragm, extends from inferior sacrum and coccyx to ischial spine

Front 38

obturator arteries and veins

Back 38

arises from internal iliac vessels and runs across surface of obturator internus, exits obturator canal to supply pelvic muscles and head of femur

Front 39

internal pudendal arteries and veins

Back 39

arise from internal iliac, exits through greater foramen and enters perineum by lesser foramen, primary artery to perineum

Front 40

superior gluteal arteries and veins

Back 40

arise from internal iliac, exits through greater sciatic foramen, superior to piriformis muscle, distributed to buttock

Front 41

inferior gluteal arteries and veins

Back 41

arise from internal iliac, pass through greater sciatic foramen, inferior to piriformis muscle and superior to the coccygeus muscle, and distributed to buttock

Front 42

sacral plexus (parts)

Back 42

muscular branches of sacral plexus, sciatic nerve, pudendal nerve, superior gluteal nerve, inferior gluteal nerve, obturator nerve

Front 43

sciatic nerve

Back 43

(L4-S3), largest nerve in body, leaves body by greater sciatic foramen inferior to piriformis muscle into buttock then turns caudal to supply hamstring muscles and all of leg and foot; Very important clinically as care has to be taken so as not to give intramuscular injections into the nerve as it passes through buttock, can cause lifelong pain or paralysis of leg and foot

Front 44

pudendal nerve

Back 44

(S2-S4); main nerve of perineum and primary
sensory nerve of external genitalia, very susceptible to damage with childbirth with significant pelvic symptoms

Front 45

superior gluteal nerve

Back 45

(L4-S1); exits pelvis through greater sciatic foramen, superior to piriformis, and supplies muscles of buttocks (gluteus medius, minimus, tensor fascia lata)

Front 46

inferior gluteal nerve

Back 46

(L5-S2); exits through greater sciatic foramen, inferior to piriformis, and supplies muscles of buttocks (gluteus maximus)

Front 47

muscular branches of sacral plexus

Back 47

small branches to muscles of pelvis (e.g., obturator internus, piriformis, levator ani)

Front 48

damage to pelvic floor & prolapse/incontinence

Back 48

see page 4 of pelvis I

Front 49

rectum

Back 49

o Primarily retroperitoneal
o Terminal portion of the large intestine (a hindgut derivative)
o Continuous proximally with sigmoid colon
o Continuous distally with anal canal (located in the perineum)
o Lacks teniae coli, haustra, and omental appendices
o Not a straight tube (it has lateral flexures)

Front 50

anorectal flexure

Back 50

o where rectum and anal canal meet at an abrupt angle, created and maintained by a portion of the levator ani

Front 51

rectal ampulla

Back 51

lies superior to the flexure; it expands to store fecal material

Front 52

defecation

Back 52

the levator ani relaxes, permitting the anorectal flexure to straighten and fecal material to move inferiorly from the ampulla into the anal canal

Front 53

rectal exam

Back 53

• In females, the anterior wall of the rectum is related to the vagina
• In males, the anterior wall of the rectum is related to the prostate (posterior lobe) and seminal vesicles

Front 54

ureters

Back 54

o Primarily retroperitoneal
o Ureters descend into the pelvis near the bifurcation of the common iliac vessels into external and internal branches
o Course inferior/posterior to the uterine artery in the female and ductus deferens in the male (“water under the bridge”)
o Due to its close proximity to the uterine artery, the ureter is vulnerable to injury during a hysterectomy, when the uterine artery is ligated and severed to remove the uterus
o Ureters pass obliquely through posterosuperior bladder wall (its oblique passage forms a one-way valve, preventing reflux of urine into the ureters

Front 55

urinary bladder

Back 55

o Primarily retroperitoneal
o Related to the rectovesical pouch in the male and the vesicouterine pouch in the female
o The bladder receives urine from the ureters, stores it, then expels it through the urethra
o Highly distensible organ with smooth muscle walls (detrusor muscle)

Front 56

internal urethral sphincter

Back 56

o Smooth muscle sphincter at the neck of the bladder that surrounds the opening of the urethra
o Sympathetic innervation stimulates its contraction (preventing micturition)
o In males, it is continuous with smooth muscle of base of prostate

Front 57

effect of para/symp innervation on rectum

Back 57

o Parasympathetic innervation (pelvic splanchnic nerves) stimulates peristaltic contractions (defecation); Sympathetic innervation inhibits contractions

Front 58

parasympathetic innervation of urinary bladder

Back 58

(pelvic splanchnic nerves); stimulate contraction of detrusor muscle, allowing micturition to occur

Front 59

rugae of urinary bladder

Back 59

o Mucosal folds are prominent when the bladder is empty
o Folds disappear as the bladder distends

Front 60

trigone

Back 60

• Triangular portion of the posterior wall defined by the two ureteric orifices superiorly and the urethral orifice inferiorly
• Smooth (no rugae)
• Very sensitive to stretch (stimulates urge to void)

Front 61

position of bladder in males

Back 61

bladder rests upon the prostate gland

Front 62

position of bladder in babies and children

Back 62

until puberty, the bladder (even when empty) extends superior to the pubis, into the abdomen, where it is susceptible to injury

Front 63

distended bladder

Back 63

in adult, extends into the abdomen; When the bladder is full, a suprapubic incision can be made to access the bladder without traversing the peritoneum and entering the peritoneal cavity

Front 64

female pelvic organs

Back 64

broad ligament, ovaries, uterine tubes, uterus, vagina

Front 65

broad ligament

Back 65

o Double layer of peritoneum (mesentery) that extends from the sides of the uterus to the lateral walls and floor of the pelvis
o Helps hold the uterus in position
o The uterine tubes lie in the superior edge of the broad ligament
o The ovaries are attached to the posterolateral border of the broad ligament
o Also encloses the remnants of the gubernaculum (ovarian ligament, round ligament of uterus)

Front 66

suspensory ligament of the ovary

Back 66

o An extension of the broad ligament, encloses the ovarian arteries and veins, lymphatic vessels, and nerves

attaches ovary to lateral walls?

Front 67

ovarian ligament

Back 67

between ovary and uterus, remnant of gubernaculum, enclosed by broad ligament

Front 68

round ligament of uterus

Back 68

between uterus and labium majus, remnant of gubernaculum, enclosed by broad ligament

Front 69

ovaries

Back 69

o Female gonads originate on the posterior abdominal wall, attached to the gubernaculum
o Descend into the pelvis and become attached to the posterior aspect of the broad ligament (ovaries are intraperitoneal)
o The ovarian vessels, nerves, and lymphatics that accompanied the descent of the ovary are enclosed within the suspensory ligament of the ovary
o During ovulation, an oocyte is expelled from the ovary into the peritoneal cavity, towards the abdominal orifices of the uterine tubes

Front 70

uterine tubes

Back 70

o Intraperitoneal (enclosed in the superior edge of the broad ligament)
o Uterine tubes open into peritoneal cavity at their abdominal orifices which are surrounded by finger-like fimbriae
o Uterine tubes enter the superolateral walls of the uterus at their uterine orifices
o The uterine tubes are the most common site of an ectopic pregnancy

Front 71

peritoneal cavity (males vs. female)

Back 71

o The peritoneal cavity is open in the female and closed in the male
• Pelvic inflammatory disease is much more common in females, as the vagina, uterus and uterine tubes provide a pathway into the peritoneal cavity

Front 72

uterus

Back 72

o Most of the uterus is intraperitoneal (due to broad ligament)
o Pear-shaped organ located between the bladder and rectum
o includes myometrium, endometrium, body, isthmus, cervix, supporting ligaments

Front 73

myometrium of uterus

Back 73

• Smooth muscle of uterus (distends greatly during pregnancy)

Front 74

endometrium of uterus

Back 74

• Internal lining, glandular mucosa, site of implantation, shed each month during menses

Front 75

body of uterus

Back 75

• Superior two thirds of the uterus
• Fundus (rounded superior portion of the body, located superior to the orifices of the uterine tubes)

Front 76

isthmus of uterus

Back 76

• Constriction marking the junction of the body and the cervix

Front 77

cervix of uterus

Back 77

• Cylindrical inferior one third of the uterus
• Central canal opens superiorly into the body of the uterus at the internal os
• Central canal opens inferiorly into the vagina at the external os (site of pap smears, small and round if the woman has never given birth vaginally, wide and slit-like if she has)

Front 78

supporting ligaments of uterus

Back 78

(e.g., cardinal ligaments)
• Located deep to the parietal peritoneum
• Connect the cervix to the pelvic walls
• Support the uterus, prevent it from descending
• However, the pelvic diaphragm is the primary supporter of the uterus
• During childbirth, these means of support can be damaged/weakened, allowing the uterus to descend through the vagina (prolapse of the uterus)

Front 79

vagina

Back 79

o Located between the urinary bladder and the rectum
o Continuous with the cervix at the external os
o Runs superiorly and posteriorly
o Anterior and posterior walls contact each other
o The cervix projects into the vagina at its superior end, creating recesses anteriorly, laterally, and posteriorly called vaginal fornices

Front 80

male pelvic organs

Back 80

testes, epididymis, ductus defernes, seminal vesicles, ejaculatory ducts, prostate

Front 81

testes

Back 81

o Male gonads originate on the posterior abdominal wall, attached to the gubernaculum
o Descend into inguinal region, pass through deep ring and the inguinal canal, and exit the superficial ring to enter the scrotum
o Each testis is covered by a tough fibrous coat, the tunica albuginea
o Internally, the testis contains seminiferous tubules (where the spermatozoa mature)

Front 82

path of spermatozoa

Back 82

seminiferous tubules > rete testis > efferent ductules > epididymis > ductus deferens > seminal vesicles > ejaculatory duct > prostatic urethra

Front 83

epididymis

Back 83

o Highly coiled tube located on the posterior surface of the testis
o Connects the testis to the ductus deferens

Front 84

ductus deferens

Back 84

o connected to testis via epididymis
o Thick walled muscular tube
o Ascends within the spermatic cord, through the superficial ring and inguinal canal, and into the abdomen via the deep inguinal ring (lateral to the inferior epigastric vessels)

o Crosses the ureter superiorly near the superior angle of the bladder (“water under the bridge”)
o When it reaches the posterior aspect of the bladder the ductus deferens enlarges to form an ampulla
o The ampulla of each ductus deferens joins the duct of the seminal vesicle

Front 85

seminal vesicles

Back 85

o Thin walled tubes that are coiled to form a mass that lies between the posterior wall of the bladder and the rectum
o When enlarged due to disease, the seminal vesicles can be palpated through the anterior wall of the rectum
o The seminal vesicles secrete a nutrient rich fluid that mixes with the spermatozoa
o Ducts of the seminal vesicles join the ampullae of the ductus deferens to form the ejaculatory ducts

Front 86

ejaculatory ducts

Back 86

o formed by ducts of seminal vesicales joining ampullae of ductus deferens
o Ejaculatory ducts enter the posterosuperior part of the prostate gland
o Open into the prostatic urethra

Front 87

prostate

Back 87

o Surrounds the prostatic urethra
o Secretes a thin fluid into the prostatic urethra via numerous ducts
o parts include base, apex, lobes

Front 88

base and apex of prostate

Back 88

base:
• Located superiorly
• Surrounds the neck of the bladder
• Internal urethral sphincter of the bladder is continuous with the smooth muscle of the prostate
apex: located inferiorly

Front 89

vaginal fornices

Back 89

o The cervix projects into the vagina at its superior end, creating recesses anteriorly, laterally, and posteriorly called vaginal fornices

Front 90

posterior fornix

Back 90

deepest of the vaginal fornices and is related to the rectouterine pouch, the rectum and anal canal posteriorly
• An incision can be made through the posterior fornix to examine the peritoneal cavity endoscopically
- plate 360

Front 91

lobes of prostate

Back 91

anterior (ant to prostatic urethra), two lateral lobes (either side of PU), middle lobe (btwn PU and ejaculatory ducts), posterior lobe (posterior to PU and inferior to ejaculatory ducts)

Front 92

median (middle) lobe of prostate (clinical)

Back 92

commonly involved in benign hypertrophy of the prostate. When the median lobe is enlarged, it stretches the internal urethral sphincter (causing urine leakage), puts pressure on the trigone (creating intense desire to void, especially at night-nocturia), and can obstruct/narrow the prostatic urethra

Front 93

posterior lobe of prostate (clinical)

Back 93

most common site of prostatic carcinoma; Posterior lobe is palpable through the anterior wall of the rectum

Front 94

pelvic arteries

Back 94

superior rectal artery, gonadal (ovarian/testicular), common iliac, internal iliac artery (superior gluteal, inferior gluteal, internal pudendal), umbilical, obturator, middle rectal, female only: uterine, vaginal, male only: inferior vesical

Front 95

superior rectal artery

Back 95

o Terminal branch of the inferior mesenteric artery
o A major source of blood to the rectum

Front 96

gonadal arteries (ovarian or testicular)

Back 96

o Branches of the abdominal aorta
o Testicular arteries travel within the spermatic cords inferiorly
o Ovarian arteries travel within the suspensory ligaments of the ovaries
o In addition to supplying the gonads, the ovarian arteries also supply the uterus

Front 97

common iliac arteries

Back 97

divide into the external and internal iliac arteries

Front 98

internal iliac artery

Back 98

o Primary blood supply to the pelvis, perineum and gluteal region
o Branching pattern varies greatly

o Major Branches (paired, left and right): superior and inferior gluteal, internal pudendal

Front 99

superior gluteal artery

Back 99

branch of internal iliac; Exits greater sciatic foramen superior to piriformis to supply gluteal region

Front 100

inferior gluteal artery

Back 100

branch of internal iliac; exits greater sciatic foramen inferior to piriformis to enter the gluteal region

Front 101

internal pudendal artery

Back 101

branch of internal iliac
• Exits greater sciatic foramen inferior to the piriformis to enter the gluteal region
• It then travels with the pudendal nerve to the perineum
• Eventually gives rise to inferior rectal artery which supplies the anal canal

Front 102

umbilical artery

Back 102

• Courses along the lateral wall of the pelvis
• Gives off the superior vesical artery (or arteries) supplying the superior aspect of the bladder (and ductus deferens in the male)
• Obliterated portion continues on the internal surface of the anterior abdominal wall as the medial umbilical ligaments

Front 103

obturator artery

Back 103

• Courses along the lateral wall of the pelvis with the obturator vein and nerve
• Exits the pelvis via the obturator canal to enter the thigh

Front 104

middle rectal artery

Back 104

branch of internal iliac; Anastomoses with the superior and inferior rectal arteries

Front 105

uterine artery

Back 105

• Passes anterior to the ureter (“water under the bridge”)
• Enters the broad ligament to reach the uterus (where the body and cervix meet)
• Anastomoses with the ovarian and vaginal arteries
• During a hysterectomy, one must ligate both the uterine and ovarian arteries (and upper vaginal branches if necessary) to control bleeding

Front 106

vaginal artery

Back 106

Supplies vagina, inferior bladder (via inferior vesical branch), and urethra

Front 107

inferior vesical artery

Back 107

o (direct branch of internal iliac in male only)
o Supplies inferior bladder, urethra, seminal vesicles, prostate

Front 108

pelvic veins

Back 108

o Venous pattern is similar to arterial pattern (share same names)
o In addition, there are numerous venous plexuses around the pelvic organs (e.g., prostatic, uterine, vaginal, rectal, and vesical plexuses)

Front 109

Portal-caval anastomosis related to the rectum and anal canal (hemorrhoids)

Back 109

o Proximal drainage into the superior rectal vein > IMV (portal system)
o Distal drainage into the inferior rectal vein > internal pudendal vein(caval system)

Front 110

Pelvic Lymphatics

Back 110

o Most of the lymph from structures within the pelvic cavity drains to internal iliac nodes
o Drainage pattern: internal iliac nodes -> common iliac nodes -> lumbar nodes (along the aorta)-> chyle cistern -> thoracic duct
o Exception: lymph from the ovaries and testes follows the ovarian and testicular vessels, and drains directly into lumbar lymph nodes

Front 111

pelvic nerves

Back 111

obturator nerve, sacral plexus (lumbosacral trunk, ventral rami S1-S4), parasympathetics, sympathetics

Front 112

obturator nerve

Back 112

o Branch of the lumbar plexus (ventral rami L2-L4)
o Located medial to psoas major
o Courses along the lateral wall of the pelvis, with obturator vessels along surface of obt internus muscle
o Exits the pelvis through the obturator canal (in the obturator membrane) to reach the thigh

Front 113

sacral plexus

Back 113

ventral rami L4-S4, includes lumbosacral trunk (L4-L5), ventral rami S1-S4
o can be compressed by pelvic tumors or the fetal head during childbirth

Front 114

lumbosacral trunk

Back 114

- L4-L5; part of sacral plexus
• Located medial to psoas major
• Descends from the abdomen to join the sacral ventral rami

Front 115

ventral rami S1-S4

Back 115

part of sacral plexus;
- emerge from the anterior sacral foramina and travel through the piriformis muscle
• Inflammation of the piriformis muscle can compress the sacral ventral rami

Front 116

parasympathetic innervation of pelvic organs

Back 116

• Preganglionic cell bodies: S2-S4 spinal cord (lateral horn)
• Preganglionic fibers: pelvic splanchnic nerves
• Postganglionic cell bodies and fibers: walls of organs

Front 117

sympathetic of pelvic organs (not rectum, ovary, testes)

Back 117

• Preganglionic cell bodies: lateral horn of the thoracolumbar spinal cord
• Preganglionic fibers travel from ventral root > spinal nerve> white ramus communicans > sympathetic trunk > lumbar and sacral splanchnic nerves
• Postganglionic cell bodies: superior or inferior hypogastric ganglia (primarily the inferior hypogastric)
• Postganglionic fibers: follow arterial branches to target organ

Front 118

ovary / testes sympathetic innervation

Back 118

• Preganglionic fibers: thoracic splanchnic nn.
• Postganglionic cell bodies: superior mesenteric ganglion
• Postganglionic fibers: follow gonadal vessels to target organ

Front 119

visceral pain of pelvic organs

Back 119

• Follow the sympathetic and parasympathetic pathways back to the spinal cord

Front 120

vasectomy

Back 120

performed by making an incision in superior aspect of scrotum to expose and ligate ductus deferns

Front 121

aberrant obturator artery

Back 121

• In approximately 20% of the population, there is an aberrant obturator artery arising from the inferior epigastric artery
o Courses over the superior pubic ramus to exit via the obturator canal
o An aberrant obturator artery can be accidentally damaged during hernia repairs

Front 122

semen

Back 122

Spermatozoa + secretions of seminal vesicles, prostate, and bulbourethral glands

Front 123

hysterectomy

Back 123

one must ligate both the uterine and ovarian arteries (and upper vaginal branches if necessary) to control bleeding; must be careful of ureter