Organization of the Pelvis and Perineum Flashcards
What space is located below the pelvic brim and is where the fetus can get caught between bony landmarks?
true pelvis
The (…) is situated above the pelvic brim, and bounded on either side by the ilium, while in the front it is incomplete
greater pelvis (false pelvis; pelvis major)
The (…) is situated below and behind the pelvic brim, and is divided into an inlet and outlet part
lesser pelvis (true pelvis; pelvis minor)
What is the anterior boundary of the pelvic inlet?
symphysis pubis (pubic symphysis)
What is the posterior boundary of the pelvic inlet?
- promontory of sacrum
- ala of sacrum
What is the lateral boundary of the pelvic inlet?
iliopectineal (arcuate) lines
What are the boundaries of the pelvic inlet?
- anteriorly: pubic symphysis
- posteriorly: promontory of sacrum; ala of sacrum
- laterally: iliopectineal (arcuate) line
What is the anterior boundary of the pelvic outlet?
symphysis pubis (pubic symphysis)
What is the posterior boundary of the pelvic outlet?
coccyx
What is the anterolateral boundary of the pelvic outlet?
- ischiopubic ramus
- ischial tuberosities
What is the posterolateral boundary of the pelvic outlet?
sacrotuberous ligament
What are the boundaries of the pelvic outlet?
- anteriorly: pubic symphysis
- posteriorly: coccyx
- anterolaterally: ischiopubic ramus; ischial tuberosities
- posterolaterally: sacrotuberous ligament
When looking from above, are you viewing the pelvic inlet or outlet?
pelvic inlet
When looking from below, such as in childbirth, are you viewing the pelvic inlet or outlet?
pelvic outlet
The pelvic inlet (superior pelvic aperture) is bounded by the (…)
linea terminalis of the pelvis
What forms the linea terminalis?
- pubic symphysis anteriorly
- posterior border of pubic crest
- pecten pubis (continuation of pubic ramus)
- arcuate line of ilium
- anterior board of ala of sacrum
- sacral promontory
What is important in females and childbirth (labor and delivery)?
the true pelvis
The (…) is in a steep oblique plane, which pushes the axis of the pelvis to be curved
pelvic inlet
What connects the vertebral column to the femurs?
the pelvic girdle
What does this describe:
- transfers weight from axial skeleton to lower appendicular skeleton
- withstand compression
- house and protect pelvic viscera
pelvic girdle
What are the 3 bones of the pelvic girdle?
- right hip bone
- left hip bone
- sacrum
The right and left hip bones are comprised of 3 separate bones, the (…), that fuse during puberty
- ischium
- ilium
- pubis
The hip bones are connected via the (…)
pubic symphysis
The hip bones and sacrum are connected via the (…), which is the posterior connection to the axial/appendicular skeleton
sacro-iliac joints
The sacrum is formed by the fusion of (…) sacral vertebrae
5
What forms the superior, posterior, and anterior part of the acetabulum?
- superior: body of ilium
- posterior: body of ischium
- anterior: superior pubic ramus
What type of joint is the hip joint and what is that area called?
- ball and socket joint
- called the acetabulum (not fossa)
The pubic arch is formed by (…)
the ischiopubic rami and the pubic symphysis
What is the distance between ischial tuberosities called?
subpubic angle
What is the general difference in the bony pelvis between males and females?
males: thick and heavy
females: thin and light
What is the difference in the pelvic inlet between males and females?
males: heart-shaped
females: oval
What is the difference in the pelvic outlet between males and females?
males: small
females: large
What is the difference in the pubic arch and subpubic angle between males and females?
males: narrow (<70°)
females: wide (>80°)
What is the difference in the greater pelvis (pelvis major) between males and females?
males: deep
females: shallow
What is the difference in the lesser pelvis (pelvis minor) between males and females?
males: narrow and deep
females: wide and shallow
What is the difference in the obturator foramen between males and females?
males: round
females: oval
What is the difference in the acetabulum between males and females?
males: large
females: small
What divides the true and false pelvis?
pelvic inlet
What is the greater (false) pelvis bounded by?
- anterior: abdominal wall
- posterior: L5/S1 vertebrae
- lateral: ala of ilium
What is the lesser (true) pelvis bounded by?
pelvic surfaces of the hip bones, sacrum, and coccyx
The (…) is found superior to the pelvic inlet; the (…) is found between pelvic inlet and outlet
- greater (false) pelvis
- lesser (true) pelvis
What does the lesser pelvis house?
pelvic viscera
What is the inferior extent of the lesser pelvis?
pelvic diaphragm
What are the primary joints of the pelvis?
- sacroiliac joint
- pubic symphysis
- lumbosacral joint
- sacrococcygeal joint
What are the three ligaments of the sacroiliac joint?
- anterior sacroiliac ligament
- interosseous sacroiliac ligament
- posterior sacroiliac ligament
What ligament is formed on the anterior capsule of the sacroiliac joint by the articulation between the auricle surfaces of the ilium and sacrum and is considered a synovial joint?
anterior sacroiliac ligament
What is formed of the posterior portion of the sacroiliac joint by the articulation of the tuberosities of the ilium and sacrum and is considered a syndesmosis joint?
posterior sacroiliac ligament
What ligament is responsible for transfer of weight of the upper body to the ilium and then the femurs during standing?
interosseus sacroiliac ligament
What does symphysis mean?
not a lot of movement, pretty fixed
What are the pelvic ligaments that stabilize the pelvic joints?
- pubic ligaments
- sacrococcygeal ligaments
- sacroiliac ligaments (anterior, posterior, interosseus)
- sacrotuberous ligament
- sacrospinous ligament
What ligament(s) resists the inferior sacrum being rotated superiorly?
the sacrotuberous and sacrospinous ligaments
What provides an exit from the pelvic cavity?
- greater sciatic foramen
- lesser sciatic foramen
- obturator canal
What ligament attaches the sacrum to the ischial tuberosity?
sacrotuberous ligament
What ligament attaches the sacrum to the ischial spine?
sacrospinous ligament
The sacrotuberous ligament is a strong ligament that forms the (…); the sacrospinous ligament is a strong ligament that forms the (…)
- lesser sciatic foramen
- greater sciatic foramen
What ligament provides so support to the pelvis?
inguinal ligament
Which ligament is longer, the sacrotuberous or sacrospinous ligament?
the sacrotuberous ligament
What forms the anterior, posterior, lateral, superior, and inferior walls of the pelvic cavity?
- anterior: pubic rami, pubic symphysis
- posterior: sacrum, coccyx, piriformis m
- lateral: obturator internus m
- superior(roof): open to ‘abdominal cavity’
- inferior(floor): pelvic diaphragm (levator ani + coccygeus m)
The obturator hole is blocked by the (…) except for a small hole, the (…)
- obturator internus m
- obturator canal
What are the muscles of the pelvic diaphragm?
- levator ani
- coccygeus m
What muscles are included in the levator ani group?
- iliococcygeus m
- pubococcygeus m
- puborectalis m
What are the attachments for the levator ani muscles?
- anterior: pubis
- anterolateral: tendinous arch
- posterior: ischial spine, anococcygeal body, perineal body, walls of pelvic organs
What are the actions of the pelvic diaphragm muscles?
- support pelvic viscera
- raise and lower pelvic floor, aids in defecation and urination
What are the muscles, from anterior to posterior that run through pelvic diaphragm?
- puborectalis m
- pubococcygeus m
- iliococcygeus m
- obturator fascia
- piriformis m
- coccygeus m
- obturator internus m
- tendinous arch
What muscles attach to the greater trochanter of the femur?
- obturator internus
- piriformis
What innervates the obturator internus?
nerve to obturator internus
What innervates the piriformis m?
anterior rami of S1-S2
What innervates the levator ani muscles?
- anterior rami of S3-S4
- perineal nerve
What innervates the coccygeus muscle?
anterior rami of S4-S5
What muscles rotate extended thigh laterally and abducts flexed thigh at hip?
- obturator internus
- piriformis m (also stabilizes hip joint)
What supports pelvic viscera and raises pelvic floor?
levator ani
What supports pelvic viscera and draws coccyx forward?
coccygeus
What muscle is more important and bigger than the obturator internus?
piriformis
All pelvic viscera are subperitoneal except for the (…) which are intraperitoneal
- uterine tubes
The (…) is not firmly bound to the suprapubic crest, allowing the (…) to expand between the peritoneum and anterior abdominal wall as it fills
- peritoneum
- bladder
The (…) is connective tissue that occupies the space between the membranous peritoneum and the muscular pelvic walls and floor not occupied by the pelvic organs
pelvic fascia
What is the continuation of the comparatively thin endo-abdominal fascia that lies between the muscular abdominal walls and the peritoneum superiorly?
pelvic fascia
What is a membranous layer of variable thickness that lines the internal (deep or pelvic) aspect of the muscles forming the walls and floors of the pelvis?
parietal pelvic fascia
What covers the pelvic surfaces of the obturator internus, piriformis, coccygeus, levator ani, and part of the urethral sphincter?
parietal pelvic fascia
The parietal pelvic fascia is continuous superiorly with the (1) and (2)
- transversalis fascia
- iliopsoas fascia
What includes membranous fascia that directly ensheathes the pelvic organs, forming the adventitial layer of each?
visceral pelvic fascia
What is the journey/name changes of scarpa’s fascia and external oblique fascia in the female pelvis?
- Scarpa’s fascia → Colle’s fascia
- External oblique fascia → deep perineal fascia
What is an area where a lot of things come together and attach in the male and female pelvis?
perineal body
What is the journey/name changes of Scarpa’s fascia and external oblique fascia in the male pelvis?
- Scarpa’s fascia → superficial fascia of the penis → Dartos fascia (scrotal area) → Colle’s fascia (behind scrotum)
- Deep fascia of external oblique → deep perineal fascia → bucks fascia (in penis)
What pelvic organs are included in the urinary tract? What are the differences in male/female urethras?
- ureters
- urinary bladder
- urethra
female urethra
male urethra: preprostatic, prostatic, membranous, spongy (penile)
What pelvic organs are included in the GI tract?
rectum
What pelvic organs are included in the female internal genital organs?
- vagina
- uterine/fallopian tubes
- uterus
- ovaries
What pelvic organs are included in the male internal genital organs?
- testes
- epididymis
- ductus (vas) deferens
- seminal glands (vesicles)
- ejaculatory duct
- prostate
- bulbo-urethral glands
The sacral spinal nerves/sacral plexus: sciatic (L4-S3), pudendal (S2-S4), superior gluteal (L4-S1), inferior gluteal (L5-S2), provide what?
motor and sensory for posterior thigh, most of the lower leg and foot, part of the pelvis
The coccygeal spinal nerves/coccygeal plexus is a small network from (…)
S4 and S5 and Co1
The obturator nerve passes through the pelvic, but supplies what?
medial thigh
What are the 4 routes of the pelvic autonomic nerves?
- sacral sympathetic trunks
- hypogastric plexuses
- pelvic splanchnic nerves
- peri-arterial plexuses
What provides innervation to the smooth muscle and glands of the pelvis?
pelvic autonomic nerves
The pelvic structures are innervated mainly by what?
- sacral (S1-S4, L4, L5)
- coccygeal spinal nerves and the pelvic part of autonomic nervous system
The anterior rami of S2 and S3 nerves emerge between the digitations of which muscles?
- piriformis m
- coccygeus m
Most of the sacral plexus is involved in innervation of the gluteal muscles and muscles of the lower limb, some small twigs innervate the (…)
the pelvic musculature (nerve to obturator internus muscle and nerves to the pelvic diaphragm_ and the perineum, which is supplied by the pudendal nerve (S2-S4)
What convey pain, touch, and temperature from the skin, skeletal muscles, and joints via nerves from these plexuses to the same relative spinal cord levels?
somatic afferent fibers (GVA)
What is the largest nerve in the body?
sciatic nerve
The anterior rami of Co goes right into what?
the anus
The sacral plexus runs from (…); the coccygeal plexus runs from (…)
- L4- S4
- S4-Co
The sacral plexus is (1) and consists of what nerves?
somatic
- sciatic nerve (L4-S3)
- pudendal nerve (S2-S4)
- superior gluteal n
- inferior gluteal n
- nerve to quadratus femoris
- nerve to obturator internus
What supplies the coccygeus m and a portion of the levator ani?
coccygeal plexus (S4-Co1)
The coccygeal plexus is (1) and includes what nerves?
somatic
- anococcygeal n
What provides cutaneous innervation to the small area between tip of coccyx and anus?
anococcygeal n
The lumbar plexus is (1) and includes what nerves?
somatic
- ilioinguinal n (L1)
- genitofemoral n (L1/L2)
What plexuses innervate the pelvis?
- sacral plexus
- coccygeal plexus
- lumbar plexus
What provides sensation via the femoral branch to the superior medial thigh, anterior scrotum and mons pubis?
genitofemoral nerve
The genital branch of the genitofemoral nerve provides what type of innervation?
motor
What nerve is not considered a pelvic nerve?
obturator nerve (L2-L4)
What runs through the obturator canal in the obturator membrane with the obturator artery and vein?
obturator n
What provides cutaneous innervation to the medial thigh and motor to the adductor muscles of the thigh?
obturator n
What passes through the greater sciatic foramen?
- pudendal n. and internal pudendal a. and v.
- piriformis m
- superior and inferior gluteal n., a., and v.
- sciatic n.
- posterior femoral cutaneous n
- nerve to obturator internus and quadratus femoris
What passes through the lesser sciatic foramen?
- pudendal n. and internal pudendal a. and v.
- tendon of obturator internus
The pudendal n (1) the greater sciatic foramen, hooks around the sacrospinous ligament, (2) the lesser sciatic foramen, passes into the (3) and runs forward to the perineal pouches
- exits
- enters
- pudendal canal
What is the proximal attachment of the piriformis m?
- sacrum
- greater sciatic notch
- sacrotuberous ligament
What is the primary function of the sacral sympathetic trunks?
to provide postsynaptic fibers to the sacral plexus for sympathetic innervation of the lower limb
What is the end of the sympathetic chain called?
the ganglion impar
The sacral trunk is a continuation of the lumbar sympathetic trunks and descend on the pelvic surface of the sacrum just medial to the pelvic sacral foramina and commonly converge to form the small median (1) anterior to the coccyx
ganglion impar
What includes networks of sympathetic and visceral afferent nerve fibers?
hypogastric plexuses
The main part of the superior hypogastric plexus lies just inferior to (…). This plexus is the inferior prolongation of the (…)
- the bifurcation of the aorta and descends into the pelvis
- intermesenteric plexus
What does the inferior hypogastric plexus travel along?
the sacral spine
Visceral afferent fibers hop on the (…) with (…)
- hypogastric plexuses
- pelvic splanchnic nerves
Visceral afferent fibers travel with (…)
parasympathetics
What surrounds and supplies the superior rectal, ovarian, and internal iliac aa. and is a mixed plexus?
periarterial plexus
What provides postsynaptic, sympathetic, vasomotor fibers to each of the arteries and its branches?
periarterial plexus
What do GVA fibers of the pelvis travel with?
autonomic nerve fibers
GVA fibers of the pelvis carry (…)
reflexive fibers
GVA sensation fibers of the pelvis travel with what?
parasympathetic fibers
GVA fibers conducting pain will travel with (1) or (2) depending on their orientation to the (3)
- sympathetic (or)
- parasympathetic nerves
- pelvic pain line
The (…) corresponds with the inferior extend of the peritoneum EXCEPT the (…) for the sigmoid colon occurs (…)
- pelvic pain line
- pain line
- midway along its length
Superior to the pain line includes structures that what?
do contact the peritoneum and proximal sigmoid colon
Superior to the pain line, pain travels with (…)
Inferior to the pain line, pain travels with (…)
- sympathetic fibers (thoracic and lumbar splanchnics)
- parasympathetic fibers (pelvic splanchnics)
Inferior to the pain line includes structures that what?
don’t contact the peritoneum and distal colon/rectum
What provides somatic innervation the the pelvis?
What provides visceral innervation to the pelvis?
somatic innervation
- sacral plexus
- coccygeal plexus
- lumbar plexus
visceral innervation
- sympathetic nerves (lumbar and sacral splanchnic)
- parasympathetic nerves (pelvic splanchnic)
- visceral afferent fibers
Sympathetic efferent fibers generally mediate the following functions in the pelvis?
- vasoconstrict and/or maintain vasomotor tone
- increase secretion of skin’s sweat/sebaceous glands
- contract male internal urethral and internal anal sphincters in both genders
- move sperm along male reproductive tract through smooth muscle contraction and stimulate secretion from seminal vesicles and prostate
- stimulate secretion from greater vestibular (Bartholin’s) glands in females and bulbourethral (Cowper’s) glands in males, along with minor lubricating glands in both genders
The parasympathetic efferent fibers of the pelvis generally mediate the following functions?
- vasodilate
- contract bladder’s detrusor smooth muscle
- stimulate engorgement of the erectile tissues in both sexes
- modulate enteric nervous system’s control of the distal bowel
- inhibit contraction of both the male internal urethral sphincter for urination and the internal anal sphincter for defecation in both genders
What is found inferior to the inferior pelvic aperture (pelvic outlet) and is separated from pelvic cavity by pelvic diaphragm?
perineum
What are the boundaries of the perineum?
- anteriorly: pubic symphysis
- anterolaterally: inferior pubic and ischial rami
- laterally: ischial tuberosities
- posterolaterally: sacrotuberous ligaments
- posteriorly: inferiormost sacrum and coccyx
- roof: all muscles in pelvic diaphragm
What is a fibromuscular mass that gives support to the pelvic viscera and is the central tendon of the pelvis?
the perineal body
A transverse line joining the anterior ends of the ischial tuberosities divides the perineum into what triangles?
- anal triangle
- urogenital triangle
What is the dividing body in the urogenital triangle?
perineal body
What does the anal triangle contain?
the anal canal and the anus
The (…) around the wall of the anal canal are large fascia-lined, wedge-shaped spaces between the skin of the anal region and the pelvic diaphragm
ischio-anal fossa
What is the ischio-anal fossa bounded by?
- laterally: ischium and inferior portion of obturator internus m
- medially: external anal sphincter
- roof: levator ani
- posteriorly: sacrotuberous ligament
- anteriorly: bodies of pubic bones
What are the levels of the anal triangle from superior to deep?
- pelvic diaphragm (roof)
- fatty layer of superficial perineal fascia (fat in ischioanal fossa)
- skin
Which triangle is not as concerning for damage?
anal triangle - not many important structures are located here
What is contained in the urogenital triangle?
- root of scrotum and penis in males
- vulva in females
What is contained in the deep pouch of the urogenital triangle?
- bulbourethral glands (M)
- sphincter urethrovaginalis muscles (F)
- compressor urethrae muscles
- external urethral sphincter muscle
- deep transverse perineal muscles
What is contained in the superficial pouch of the urogenital triangle?
- greater vestibular glands (F)
- ischiocavernosus muscles → corpus cavernosus
- bulbospongiosus muscles → corpus spongiosum (M) and bulb of vestibule (F)
- superficial transverse perineal muscles
From superficial to deep, what are the layers of the urogenital triangle?
skin → Camper’s fascia → Scarpa’s fascia → Colle’s fascia → superficial pouch → deep perineal fascia → deep pouch → pelvic diaphragm → parietal pelvic fascia
The perineal membrane is a continuation of the (1)
- deep perineal fascia
What muscles help maintain erection of the clitoris or penis?
- ischiocavernosus
- bulbospongiosus
What supports abdominopelvic viscera and resists increased abdominal pressure?
superficial and deep transverse perineal muscles
What produces secretions for the vagina?
greater vestibular gland
What surrounds the bulbs of vestibule in females?
bulbospongiosus m
What overlies the corpus spongiosum in males?
bulbospongiosus m
The root/bulb of the penis is associated with what?
the ischiocavernosus and bulbospongiosus mm
The bulbourethral glands (Cowper’s) in the deep pouch in males are homologous to what?
Bartholin’s glands in females
What are the actions of the transverse perineal mm?
supports/fixes perineal body
What innervated the transverse perineal mm?
the deep branch of the perineal n
What part of the urogenital triangle will you find the transverse perineal mm?
both superficial and deep
What are the actions of the bulbospongiosus m?
- fix/support perineal body and pelvic floor
- assist in ejaculation in males, erection in females
What are the actions of the ischiocavernosus m?
maintains erection by compressing outflow veins
What parts of the urogenital triangle can you find the bulbospongiosus and ischiocavernosus muscles?
the superficial pouch
What are the bulbospongiosus and ischiocavernosus muscles innervated by?
deep branch of the perineal nerve
What are the actions of the external anal sphincter?
- fix/support perineal body and pelvic floor
- resists defecation
What are the actions of the external urethral sphincter?
- compress urethra/urinary continence
What triangle can you find the external anal sphincter?
anal
Where in the urogenital triangle can you find the external urethral sphincter?
deep pouch
What innervated the perineum?
the pudendal nerve
What levels is associated with the pudendal nerve?
S2-S4
What are the named branches to the perineum (innervation)?
pudendal n
- inferior rectal n
- superficial and deep perineal nn
- dorsal n to penis/clitoris
What branches off of the perineal nerve before it enters the perineal canal?
the inferior rectal nerve
What provides both motor and sensory innervation; and provides a lot of innervation to skeletal muscles?
pudendal nerve
What provides a major sensation for the perineum?
pudendal nerve
The superficial perineal n provides more (…) to the perineum
sensation innervation
The deep perineal nerve provides more (…) to the perineum
motor innervation
The pudendal canal and nerve is running through the (…)
ischioanal fossa
What provides sensory innervation to the perineum?
- pudendal n (main nerve)
- ilioinguinal n
- anococcygeal n
The aorta bifurcates at about the L4 vertebral level into the (…) (right and left branches), which then bifurcates into the (…) and the (…) at about the L5-S1 intervertebral level. The (…) passes inferiorly to the thigh, where it becomes the (…) after passing deep to the inguinal ligament
- common iliac artery
- internal iliac artery
- external iliac artery
- external iliac artery
- femoral artery
What are the two branches that the internal iliac artery divides into?
- posterior trunk
- anterior trunk
What are the branches that come off the posterior trunk of the internal iliac artery? (from posterior to inferior)
- iliolumbar artery
- lateral sacral arteries
- superior gluteal artery
What are the branches that come off the anterior trunk of the internal iliac artery? (in order that they branch)
- umbilical artery
- obturator artery
- superior vesicle artery
- inferior vesical(M)/vaginal(F) artery
- internal pudendal artery
- middle rectal artery
- inferior gluteal artery
- uterine artery (ductus deferens in males)
What does the obturator artery travel with?
the obturator n
What are the branches of the internal pudendal artery?
- inferior rectal arteries
- perineal artery
- posterior scrotal/posterior labia artery
- dorsal artery of penis/clitoris
- deep artery of penis/clitoris
- artery of bulb of penis/vestibule
- urethral artery
How many rectal arteries are there and what do they branch from?
3 different rectal arteries branching from 3 different arteries
- superior rectal a: IMA
- middle rectal a: anterior trunk of internal iliac a
- inferior rectal a: internal pudendal a
What is the main artery to the perineum that includes muscles of the anal canal and perineum, skin and urogenital triangle, and erectile bodies?
internal pudendal artery
The veins of the pelvis and perineum course with arteries and have same names; they drain largely back into the (…), common iliac vein, inferior vena cava, and then to the heart
internal iliac vein
Important portosystemic anastomoses occur between the (1), (2), and (3) and what do they drain into?
- superior rectal v → inferior mesenteric v
- middle rectal v → internal iliac v
- inferior rectal v → internal pudendal v
Much of the lymphatic drainage of the pelvis parallels the venous drainage and drains into lymph nodes along the (…)
internal iliac vessels
Lymphatic drainage from the ovaries and the adjacent uterine tubes and upper uterus, and from the testes and scrotal structures flows directly back to the (…)
aortic (lumbar) nodes of the mid-abdomen.
Gonadal lymphatics drain lymph from the gonads where?
directly to aortic (lumbar) nodes
