Perineum - Urogenital and Anogenital Triangles Flashcards
Describe pelvis in general - specifics about triangles
Pelvic diaphragm = U shape, makes 2 triangles (pelvic diaphragm = levator ani - puborectalis, coccygeus), seals pelvic floor
Perinuem = outside pelvic diaphragm
Name the 2 triangles of perinuem
Front - anterior = urogenital triangle
Back - posterior = anal (anogenital) triangle
Describe pelvic floor
Delineates pelvic and perineal region
Muscular component has tonic role
*puborectalis
Describe perineal membrane
Seals urogenital triangle
Tough ct, membrane sealing urogenital triangle so weight of ext genitalia not added to muscle - need to support pelvic organs
What is perineal body
Levator ani and perineal membrane anchored
Fibrotic structure —> connects muscles
Describe perineum
Diamond shaped space inferior to pelvic floor
Pelvic diaphragm - levator ani and coccygeus muscles
Funnel shaped, with anal aperture at inferior apex
Ischial tube = where you sit on bike
Delineated by bony features and lines
Name all margins of perineum
Anterior = inferior aspect of pubic symphysis
Posterior = tip of coccyx
Lateral = ischial tuberosity= ischiopubic rami, sacrotuberous ligament
Ceiling = pelvic diaphragm
Floor = skin
What is perineum divided by
An imaginary line between ischial tuberotisties
Where are triangles of perineum
Urogenital = anterior
Anal= posterior
Give a very general explanation of the 2 triangles and what the boundaries are
Urogenital = sex specific structures and urinary system, join at pubic symphysis, ischial pubic rami
Ischial tube = imaginary line
Anal triangle = apex is Coccyx, sacrotuberous lig laterally
Describe urogenital triangle
Oriented in horizontal plane
Pelvis tilted forwards, asis and pubic symohysis in same plane
Basically sitting on it
What is urogenital triangle defined by
Laterally = Ischiopubic rami
Posteriorly = Horizontal line between ischial tuberosity, Superficial transverse perineal muscle: to perineal body
Antyeriorly = Pubic symphysis
Roof= is the pelvic diaphragm
Describe urogenital hiatus
U shaped opening in levator ani
Closed by perineal membrane - thick fibrous sheet
For urinary and genital systems
Pelvic diaphragm open at central line
Describe where deep perineal pouch is
Between levator ani and perineal membrane
Describe role of urogenital triangle
Provide support to ext genitalia and support of pelvic viscera
Compare urogenital to anal triangle
Anal trinagle = facing more posterior - back
Describe perineal membrane of urogenital triangle - gen
Triangular, fibrous sheet,
Between ischiopubic rami, pubic symphysis, ischial tuberosities
Describe perineal membrane of urogenital triangle - specifics
Posterior edge free - floats, except at perineal body
Attach point for erectile tissue and their muscles
Contains urethral openings and vaginal opening in afab
Describe perineal body of urogenital triangle
Central tensions structure of perineum
Between urogenital and anal triangles
What attaches at perineal body of urogenital triangle
Muscles of pelvic floor - levator ani and perinuem attach (bulbospongiosus, transverse perineal muscles)
Compare afab vs amab urogenital triangle
Amab = diff
Urethra opening anchored in perineal membrane directly
Afab = urethral opening and vaginal openings contained in membrane
Describe episiotomy
Enlarge vaginal opening - episiotomy, now done to avoid perineal body, - helps maintain dynamic integrity
Describe deep perineal pouch
Between perineal membrane and pelvic diaphragm
Contains thin muscular sheet = sphincters for urethra, thin deep layer, smooth muscle, Sphincters to close orifices
Name a muscle that is important for urogenital trinagle
Superficial transverse perineal muscle
Core, tone, to membrane, provide more tension, ischial tuberosity to perineal body
Describe anal triangle
Oriented postero inferior
Not flat, more dome shaped
What is anal triangle defined by
Laterally = sacrotuberous ligament
Anteriorly = horizontal line between ischial tuberosity
Posteriolry = coccyx
Roof= pelvic diaphragm
Describe anal aperture
Funnel shaped levator ani’s central opening
What is external anal sphincter
Surrounds anal canal, after passing through levator ani
Describe what anal aperture and external anal sphincter do
Divide anal triangle in 2 lateral spaces = ischioanal fossa
What are ischioanal fossae
Paired wedge shaped spaces on either side of anal canal, filled with adipose tissue
Tilted anteriorly
What are ischioanal fossa defined by
Superiorly = pelvic diaphragm
Laterally = ischium and sacrotuberous ligament
Ifneiorly = skin of anal region
What is role of ischioanal fossae
Allows for movement of pelvic diaphragm - puborectalis needs to relax so needs soft tissue here so can expanded
Allows movement of pelvic diaphragm
Expansion fo anal canal during defecation
Possess of internal pudendal vessels, pudendal nerve and associated brnaches
What is found near ischioanal fossa
N/v = in pudendal canal
Away from levator ani (since would stretch vessels) and close to bone = embedded in fascia of obturator muscle
Describe anterior recesses
Ischioanal fossa of anal trinagle projects anteriorly in urogenital triangle
Forms 2 anterior reccesses on each side = anterior recess of ischioanal fossae
Space between dome shaped levator ani and perineal body, continuous with ischioanal fossa and forms recess
What are anterior reccesses defined by
Superomedial wall = levator ani
Lateral wall = obtruator internus
Floor = deep perineal pouch, and perineal membrane, not skin, solid floor
Describe what passses through anterior reccesses
Where levator ani enlarges when need
Vessels continue in space to where they need to go
Describe blood supply of perineum
Internal pudendal artery
Describe entire pathway of internal pudendal artery
From anterior trunk of internal illiac artery —> leaves pelvic cavity through greater sciatic for amen inferior to piriformis —> Passes lateral to ischial spine —> Reaches perineum through lesser sciatic for amen —> Enters pudendal canal (alcocks) formed by obturator internus muscles fascia
What does internal pudendal artery supply
Erectile tissue, perineum, inferior rectum
What branches does internal pudendal artery give
Inferior rectal artery
Perineal arteries = erectile tissues and muscles, skin, scrotum, labia and bulb glands
Describe innervation perineum
Pudendal nerve - s2-3-4 = motor and sensory
Describe pathway of perineum n/v generally
Vessels use for amen to leave and then loop back and travel to perineum - pudendal canal
Why is it called pudendal nerve and not internal pudendal nerve
Arteries = called internal pudendal
Nerve = just pudendal since no external
What is pudendal block
Episiotomy or procedure
Palpate spine and inject and numb nerve
Since pudendal nerve goes around ischial spine
Describe pathway of pudendal nerve
Leaves pelvic cavity through greater sciatic formaen inferior to piriformis —> Passes around sacrospinous ligament, loops over ischial spine —> Through lesser sciatic foreman to reach perineum —> Enters perineum through pudendal canal - alcocks with internal pudendal arteries
What does pudendal nerve inervate
Somatic innervation of perineum and associated structures
Name branches off pudendal nerve
Inferior rectal
Perineal nerve
Dorsal nerve of penis/clitoris
Describe inferior rectal nerve
Sensory = anal region
Motor = external anal sphincter
Describe perineal nerve
Sensory = perinuem
Motor= muscle of ext genitalia
Describe dorsal nerve of penis/clitoris
In anterior recess sensory to penis/clitoris
Describe path of pudendal vessels and nerve
Greater sciatic, piriformis = leaves pelvic and loops back in outside pelvic diaphragm = leaves Cavoty and bypasses levator ani insertion and now in perinuem
