Bony Pelvis, Pelvic Diaphragm, and Anal Region Flashcards
What forms the pelvic skeleton
2 hip bones anteriorly and laterally
saccrum and coccyx posteriorly
What makes up the hip bone
ilium
ischim
pubis
What is the largest foramen in the body and what forms it
obturator
pubic and ischial elements of hip bone
What nearly closes the obturator foramen
obturator membrane
Where do all 3 parts of the hip bone meet
acetabulum
what is the acetabulum
deep fossa for head of femur
What are the joints of the pelvis (3)`
Lumbosacral
sacroiliac
pubic symphysis
What do the iliolumbar ligaments unite
vertebra L5 to iliac crest and sacrum
What do the the iliolumbar ligaments do
limit axial rotation of L5 on the sacrum
help stabilize the lumbasacral joint
What is the what type of joint are the sacroiliac joints and what is their role
synovial
responsible for transmitting the weight of the hipbones
What holds together the sacral and illiac bones
anterior sacrolilac ligaments
interosseous sacrolilac ligaments
posterior sacrolilac ligaments
what are the acessory ligaments of sacroiliac articulation
sacrotuberous and sacrospinous ligaments
What does the sacrotuberous ligament do
anchor the sacrum and coccyx to the ischial tuberosity
What does the sacrospinous ligament do
anchor the sacrum and coccyx to the ischial spine
what conversion is caused by the location of the sacrotuberous and sacrospinous ligaments
makes greatter and lesser sciatic notches into greatter and lesser sciatic foramina
What does the pubic symphysis have at its articulation
interpubic disc of fibrocartlialge
what is the difference of the pubic symphysis between males and females
females have a broader fibrocartilage disc
What connects the pubic bones at the pubic symphysis
superior and inferior arcuate pubic ligaments
connect pubic bones
What is located at the sacrococcygeal symphysis
THIN interveterbral disc
Sacrococcygeal ligaments which reinforce it
How is the pelvis oriented in anatomical position
Anterior superior illiac spines and pubic tubercles in the same vertical plane
What are the features of the articulated pelvis (5)
pelvic brim greater pelvis lesser pelvis pelvic inlet pelvic outlet
What is the role of the pelvic brim
divides pelvis into greater and lesser pelves
What makes up the pelvic brim (4)
promontory (vertebrae) and alae (wings) of the sacrum
Arcuate line of the ilium
pectineal line of the pubis
pubic crest
What is the greater pelvis also known as
false pelvis
What is superior and inferior to the pelvic brim
superior: greater (false) pelvis
Inferior: lesser (true) pelvis
What does the greater pelvis form
inferior part of the abdominal cavity
What bounds the greater pelvis (ant, lat, post)
Anteriorly: abdominal wall
Laterally: iliac fossae
Posteriorly: L5 and S1 vertebrae
Which section of the pelvis contains the pelvic viscera
lesser pelvis
What bounds the lesser pelvis (ant, lat, post)
Anteriorly: pubis
Laterally: ilium and ischium
Posteriorly: sacrum and coccyx
What foramina are contained within the lesser pelvis
obturator
greater sciatic
lesser sciatic
What is another name for the pelvic inlet
superior pelvic aperture
What bounds the pelvic inlet opening
pelvic brim
When would the pelvic inlet be measured
for obstetric reasons during pelvic examination
What is another name for the pelvic outlet
inferior pelvic aperture
what forms the opening of the pelvic outlet (5)
pubic symphysis ischiopubic rami ischial tuberosities sacrotuberous ligaments coccyx
What 3 pieces of the pelvis are different from male to female
sacrum
ischial tuberosities
pubic arch
What is the difference in the sacrum from male to female
Female sacrum broader and less curved
What is the difference in the ischial tuberosities from male to female
Female ischial tuberosities everted
What is the difference in the pubic arch from male to female
Female pubic arch angle is greater
What is the overall effect of the pelvic skelton changes from male to female
female pelvis wider (larger aperatures)
female pelvis shallower
What muscles make up the pelvic wall
Obterator internus
piriformis
Which muscles make up the pelvic diagphragm
Levator Ani: pubococcygeus, puborectalis, iliococcygeus
Coccygeus
What muscles make up levator ani
ALL PAIRED
pubococcygeus
puborectalis
iliococcygeus
Where does the obturator internus muscle orignate travel and insert
Originates: obturator membrane
internal margin of obturator foramen
tendon passes through lesser sciatic foramen
Inserts:Greater trochanter of the femur
What innervates the obterator internus muscle
nerve to obturator internus and superior gemellus (L5 S1,2)
What is the role of obterator internus
lateral rotator of the thigh
What is the tendious arch (of levator ani)
thickening of the parietal fascia of obturator internus between the ischial spine and superior pubic ramus
What does the tendinous arch give origin to
iliococcygeus part of pelvic diaphragm
Where does the piriformis originate travel and insert
Originate: anterior surface of sacrum
leaves pelvic cavity through greater sciatic foramen
Insert: greater trochanter
What innervates piriformis
nerve to piriformis (S1,2)
What is the role of piriformis
lateral rotator of thigh
What forms a muscular bed for the sacral plexus
piriformis
What closses the pelvic outlet and forms the floor of the pelvic cavity
Pelvic diahragm
what shape is the pelvic diaphragm
funnel shaped
What do the urethra and vagina pass through in the pelvic diaphragm
fascial gap called urogenital haitus
What is the origin and insertion of pubococcygeus
runs posteriorly from the pubis and inserts onto the coccyx
What is the origin and insertion / path of puborectalis
passes posteriorly from the pubis and fuses with its companion of the
other side behind the anorectal junction,
forms a U-shaped rectal sling
What is the thinnest part of levator ani
iliococcygeous
what is the origin and insertion of iliococcygeous
originates: from the tendinous arch and ischial spine
inserts: onto the coccyx
What innervates the levator ani muscles
nerve to levator ani and coccygeus (S3,4)
What are the roles of the levator ani
support pelvic viscera
raise the pelvic floor
assist in compression of abdominal and and pelvic contents during vomiting urnination etc
What are the specific and important roles of the puborectalis
holds anorectal junction anteriorly
supports most of fecal mass
(this relieves external anal sphinter from fecal pressure)
What is the origin and insetion of the coccygeus
origin: ischial spine
Insert: sacrum and coccyx
What innervates the coccygeus
nerve to levator ani and coccygeus
S3,4
What is the role of the coccygeus
pulls coccyx anteriorly (thus raising pelvic floor)
What is the perineum bounded by (4)
pubic symphysis
ishciopubic rami
sarcotuberous ligament
coccx
What is the perineum divided into (2) and wher would the line be that divides them
anal triangle
urogenital triangle
line between ischial tuberosities
What is the best way to view the perineum
lithotomy position (supine hips and knees flexed)
What bounds the anal triangle
Posteriorly: coccyx (apex of triangle)
posterolaterally: sacrotuberous ligment
overlying: gluteus maximus
What main things are contained in the anal fossa (4)
anus
external anal sphincter
anal canal
Ischioanal fossae
What is the name for the opening for the anal canal and where is it located
anus
centrally in anal triangle
What surrounds the anus
subcutaneous part of external anal sphincter
Is the external anal sphincter voluntary or involuntary
voluntary
What portion of the anal canal does the external anal sphincter surround
inferior 2/3rds
How is the external anal sphincter divided
into
subcutaneous
superficial
and deep parts
What innervates the external anal sphincter
inferior rectal branches of the pudendal nerve (S2-S4)
What is the anal canal
distal 2 inches of the gi tract
Where does the anal canal begin
at the level of the U-shaped sling formed by the puborectalis
which direction is the anal canal and how is it oriented with respect to the rectum
directed posteroinferiorly
longitudinal axis right angle to rectum
Where is the internal anal sphincter
Superior part of the canal
Is the internal anal sphincter involuntary or voluntary
involuntary
What is the relation of the internal to external anal sphincter
internal deep to external
external overlaps internal
What are the anal columns and where are they
longitudinal ridges of MUCOSA in the superior part of the anal canal
What joins the lower end of the anal columns
anal valves
What is located at the inferior limit of the anal valves
pectinate line
What does the pectinate line indicate
junction of endodermal hindgut and ectodermal proctodeum
And as such (due to dual embro origin)
Approx site of seperation for vascular lymphatic and neural supply of the anal canal
What supplies the blood superior to the pectinate line
superior rectal vessels of inferior mesenteric
What supplies the lymphatics superior to the pectinate line
lymphatic tributaries of internal iliac nodes
What is the innervation superior to the pectinate line
autonomic innervation (GVA and GVE)
What supplies the blood inferior to the pectinate line
inferior rectal (hemorrhoidal) vessels of internal illiac
What supplies the lymphatics inferior to the pectinate line
lymphatic tributaries of superficial inguinal nodes
What is the innervation inferior to the pectinate line
somatic innervation (GSA and GSE) from pudendal nerve
What do the middle rectal arteries and veins anastomose with and where do they come from
Middle: from internal illiac
Anastomose with
Inferior rectal: internal pudendal
Superior rectal: Inferior messenteric
What is the the superior part of the anal canal sensitive to and why
stretching
differences in innervation
What is the the inferior part of the anal canal sensitive to and why
pain
touch
and temperature
differences in innervation
Where is the ischioanal fossa
wedge shaped spaces on either side of anal canal
what forms the base of the ischioanal fossa
skin of the anal region
What forms the vertical lateral wall of the ischioanal fossa
obturator internus and ischial tuberosity
What forms the superomedial wall of the ischioanal fossa
levator ani and anal canal
What restricts the ischioanal fossa anteriorly
deep fascia of the urogenital triangle
What is found extensively in the ischioanal fossa and what is its purpose
fat
supports anal canal but is readily displaced to allow feces to pass
What bounds the ischioanal fossa
lateral: obturator internus and ischial tuberosity
Superomedial: levator ani and anal canal
Anterior: deep fascia of the urogenital triangle
Base: skin of the anal region
What nerves and vessels will the ischioanal fossa contain
internal pudendal vessels and pudendal nerve
Where do the nerves and vessels in the ischioanal fossa run
on the lateral wall in a fibrous sheath (pudendal canal)
What do the Pudendal nerves and vessels run in and what is it derived from
Pudendal canal (sheath/ alcocks canal)
derived from fascia of obturator internus
What do the internal pudendal vessels and nerves give off in the ischioanal fossa and what do they supply
inferior rectal vessels and nerves cross the fossa and supply external anal sphincter inferior part of anal canal perianal skin
