S2 Anatomy Exam 1: Pelvis & Perineum

Front 1

Obj.
1. Name the major subdivisions of the pelvis and their boundaries.

Back 1

1. Greater (false) pelvis
inferior: pelvic brim
lateral: iliac fossae & iliacus muscles
anterior: lower ant. abdominal wall
posterior: lumbar vertebra

2. Lesser (true) pelvis
superior: pelvic inlet/brim
inferior: pelvic outlet

Front 2

Obj.
2. Define pelvic inlet and identify boundaries

Back 2

pelvic brim
-divides greater & lesser pelvis
borders:
anterior- pubic crest (linea terminalis)
lateral- iliopectinal line
posterior- sacral alae & sacral promontory

Front 3

Obj.
2. Define pelvic outlet & identify boundaries

Back 3

diamond shaped
-pelvic cavity is space btwn inlet & outlet
borders:
anterior- pubic arch, pubic symphysis
lateral- ischiopubic rami, ischial tuberosities, & sacrotuberous ligament
posterior- coccyx

Front 4

Obj.
3. Name the boundaries and divisions of the perineum.

Back 4

boundaries:
superior: pelvic diaphragm
lateral: thighs
peripheral: pelvic outlet

divisions: (by imaginary line btwn ischial tuberosities)
-ant. urogenital triangle
-post. urogenital triangle

*contains external genitalia & external GI & urogenital system openings

Front 5

Obj.
4. Name the component parts of the bony pelvis.

Back 5

-pelvic girdle (2X (ilium, ischium, pubis, fused w/ acetabulum) articulate at pubic symphysis)
-sacrum (articulate w/ pelvic girdle at sacroiliac joint)
-coccyx

Front 6

Obj.
5. Identify the joints of the bony pelvis and briefly describe their various functions.

Back 6

-sacroiliac joints (btwn sacrum & iliac bones)
synovial plane joint

-pubic symphysis (btwn pubic bones)
fibrocartilage joint

-lumbosacral joint (bwtn lumbar vertebrae & sacrum L5 & S1)
zygapophysial joint

-sacrococcygeal joint (btwn last sacral & first coccygeal vertebrae)
cartilaginous joint

*hold together bones of pelvis

Front 7

Obj.
5. Identify the ligaments of the bony pelvis and briefly describe their various functions.

Back 7

-sacroiliac ligaments (btwn sacrum & ilium, anterior, posterior & interosseous)

-pubic ligaments (reinforce pubic symphysis inferiorly & superiorly)

-iliolumbar ligaments (L5 TP to iliac crest)
limit rotation of L5 on sacrum & prevent anterior glide

-lumbosacral ligaments (L5 TP to sacrum)

-sacrotuberous ligaments (sacrum to ischial tuberosity, forms lesser sciatic foramen)
prevent upward tilting of inferior aspect of sacrum & the pelvis from rotating anteriorly

-sacrospinous ligaments (sacrum & coccyx to ischial spine, form greater sciatic foramen)
prevent upward tilting of inferior aspect of sacrum & the pelvis from rotating anteriorly

Front 8

Obj.
6. Describe the normal anatomical positions of the bony pelvis and perineum.

Back 8

-ASIS & upper margin of pubic symphysis is same vertical plane
-coccyx & upper margin of pubic symphysis in same horiontal plane
-anal triangle in coronal (vertical) plane
-urogenital triangle is oriented horizontally

Front 9

Obj.
7. Differentiate the gross features of the male and female bony pelvis.

Back 9

male-
heart-shaped
thicker bones
more prominent bone markings
deeper pelvic cavity

female-
oval shaped
shorter inlet
shorter, wider, flatter sacrum
rounder, wider pubic arch
everted ischial spines

Front 10

Obj.
8. Identify the structures forming the pelvic walls.

Back 10

anterior: pubic bones, pubic rami, & symphysis pubis
posterior: sacrum/coccyx, piriformis, & pelvic fascia
lateral: hip bone, obturator membrane, obturator internus & fascia, sacrospinous & sacrotuberous ligaments
inferior: pelvic diaphram & (sup/inf) fascia

Front 11

Obj.
9. Name the pelvic muscles

Back 11

piriformis
obturator internus
levator ani
(Ischio-)coccygeus

Front 12

Obj.
9. Give the action and innervation of the piriformis muscle

Back 12

action- lateral rotator of hip joint, abducts thigh

innervation- nerve to piriformis
(from ant rami S1 & 2)

-from sacrum to greater trochanter (through greater sciatic foramen)

Front 13

Obj.
9. Give the action and innervation of the obturator internus muscle

Back 13

action- lateral rotator of thigh

innervation- nerve to obturator internus
(from ant rami L5 & S1 or 2)

Front 14

Obj.
9. Name the pelvic diaphragm muscles & their action

Back 14

muscles- levator ani & (ischio-)coccygeus muscles

action- supports pelvic viscera

*pelvic diaphram forms floor of pelvis, separates pelvic cavity from perineum

Front 15

Obj.
9. Name the levator ani muscles, their action, and innervation.

Back 15

muscles-
iliococcygeus (tendinous arch to raphe btwn anal canal & coccyx)
pubococcygeus (pubis to vagina/prostate, anorectal jxn to perineal body)
puborectalis (pubis to jxn of anus & rectum, part of external anal sphincter)

actions-
form muscular sling that supports & immobilizes pelvic viscera
resists increased intrapelvic pressure
sphincter action on anorectal junction

innervations-
nerve to levator ani (perineal branches of S4)
inferior rectal nerve
coccygeal plexus

Front 16

Obj.
9. Give the action and innervation of the (ischio-) coccygeus muscle

Back 16

action- assists levator ani muscles in supporting pelvic viscera

innervation- branches of S4 & 5

-traingular muscle arising from ischial spine, inserting into sacrum/coccyx
-covered inferiorly by sacrospinous ligament

Front 17

What 4 things makes up the linea terminalis?

Back 17

arcuate line
pecten pubis
pubic crest
pubic symphysis

Front 18

What 2 things make up the iliopectineal line?

Back 18

pectin pubis (pectineal line)
arcuate line

Front 19

What are the pelvic conjugates & why are they important?

Back 19

anatomical dimensions of the pelvic inlet

important because the infant must pass through true pelvis to be born vaginally

Front 20

What are the 3 AP diameters (pelvic conjugates)?
Which one is the narrowest fixed distance?

Back 20

1. True conjugate
2. Obstetric conjugate
3. Diagonal conjugate

-obstetric is the narrowest (btwn sacral promontory to post aspect of pubic bone, ~10 cm)

Front 21

Which AP diameter can be easily assessed by vaginal exam?

Back 21

diagonal conj (btwn sacral promontory & in margin of pubic symphysis)

* can be used to estimate obstestric conj, by - 1.5-2 cm

Front 22

Injury to the pelvic diaphragm can occur during a difficult childbirth, what would this lead to ?

Back 22

prolapse of internal pelvic organs (uterus, vagina, urinary bladder, and/or rectum)

Front 23

The levator ani muscles originate from the post. aspect of the body of pubis, tendious arch, & ischial spine. What is the tendinous arch?

Back 23

thickening of the pelvic fascia covering the obturator internus muscle

Front 24

What is the urogenital hiatus?

Back 24

Incomplete anterior portion of tendinous arch that allows for passage of urethra & vagina in females

Front 25

Which levator ani muscle is responsible for the anorectal flexure, playing a major role in maintaining fecal continence?

Back 25

Puborectalis muscle

(thicker, inferomedial part of levator ani muscle, U-shaped sling that passes post. to anorectal jxn)