1 - Pelvic Vasculature & Perineum Flashcards
Internal Iliac Artery
Anatomical definition
Location
Branches
- Anatomical Definition
- Branch of common iliac;
- Location
- Enters true pelvis to supply pelvic viscera, walls, perineum, and gluteal region
- Branches
- Posterior Division
- Anterior Division
Internal Iliac Artery
Posterior Division:
Iliolumbar Artery
Lateral Sacral Artery
Superior Gluteal Artery
- Iliolumbar Artery
- Sends branches to iliac foss and lower lumbar region
- Lateral Sacral Artery
- Descends anterior to sacrum; branches to anterior sacral foramina to supply radicular branches to anterior spinal artery
-
Superior Gluteal Artery
- Large artery
- Passes posteriorly between lumbosacral trunk (ant. rami of L4,L5) and anterior ramus of S1
- Exits pelvis via greater sciatic foramen (superior to piriformis muscle) to supply gluteal muscles
Internal Iliac Artery
Anterior Division (variable branching)
Obturatory Artery - Surgical Complication?
Umbilical Artery
- Obturartor Artery
- Passes with obturator nerve on later wall of pelvis, then through obturatory foramen
- Clinical: 25% of obturator arteries originate from Inferior Epigastric Artery; beware of this variation when repairing inguinal hernia; may also arise directly from external iliac artery
- Umbilical Artery
- Patent, proximal part gives off 2-3 superior vesical arteries (upper urinary bladder supply)
- Obliterated distal part forms medial umbilical ligament that courses toward umbilicus; represents obliterated fetal umbilical artery
Internal Iliac Artery
Anterior Division (variable branching)
Inferior Vesical Artery
Vaginal Artery
- Inferior Vesical Artery
- Supplies base of urinary bladder, prostrate, and seminal vesicles
- Found ONLY in MALES
- Equivalent to vaginal artery in females
- Vaginal Artery
- Passes to sides of vagina
- Found only in femalesEquivalent to inferior vesical artery in males
Internal Iliac Artery
Anterior Division (variable branching)
Middle Rectal Artery
Uterine Artery (Clinical)
- Middle Rectal Artery
- May arise from Inferior Vesical Artery in males
- Often absent, especially in females
- Uterine Artery
- Crosses superior to ureter (lateral to cervix) to enter broad ligament of uterus
- May be damaged during hysterectomy; ligate and sever the artery, NOT the ureter
- “Water under the bridge”
- May have a vaginal branched (not confused with vaginal artery)
Internal Iliac Artery
Anterior Division:
Inferior Gluteal Artery
Internal Pudendal Artery
- Inferior Gluteal Artery
- Passes posteriorly between anterior rami of S1 and S2 (or S2 and S3)
- Passes between piriformis muscle / coccygeus muscles
- Passes through greater sciatic foramen
- Can arise from posterior branch
- Internal Pudendal Artery
- Main blood supply to structures of perineum
- Passes between piriformis and coccygeus, leaves via greater sciatic forman
- Passes through lesser sciatic formane to enter perineum
- Does NOT pass through the diaphragm; would be potential site of weakness
Perineum-Anal Triangle
Perineum
Boundaries
- Perineum
- Region inferior to pelvic diaphragm
- Diamond shaped
- Boundaries:
- Anterior to Posterior: Pubic Symphysis to Tip of Coccyx
- Lateral: Pubic arches, ischial rami, ischial tuberosities, sacrotuberous ligament
Perineum-Anal Triangle
Urogenital Triangle
- Anterior triangle
- Contains urogenital structures: Root of Penis/Vulva, Urogental Diaphragm
Perineum-Anal Triangle
Anal triangle
- Posterior triangle
- Contrains: Anal canal, adjacent external anal sphincter in midline; surrounded by fat filled wesge shaped space–the ischioanal fossa
- Borders:
- Posterior - Tip of Coccyx
- Lateral - Sacrotuberous Ligament
- Anterior - Imaginary Transverse Line through Ischial Tuberosities
Contents of Anal Triangle
Ischioanal Fossa
Borders, Contents
- Borders (wedge shaped)
- Base - Located superficially at skin surrounding anus
- Lateral - Obturator Internus Muscle
- Medial - Levator Ani
- Contents
- Much fat, allowing distension of anal canal while cutting turds
- Pudendal Nerve / Internal Pudendal Artery and Vein
-
Pudendal Canal (Alcock’s Canal)
- Pudendal Neurovascular Bundle
- Within Obturator Internus Fascia
Contents of Anal Triangle
Pudendal Nerve
Origin
Innervation Type/Locations
Passage
Branches
- Origin
- Formed from Anterior Rami of S2-S4 of Sacral Plexus
- Type
- Somatic Nerve (voluntary) not autonomic
- Locations
- Somatic Innervation to most of perineum
- Passage
- Passes out of main pelvic cavity via inferior part of greater sciatic foramen to enter gluteal regions; descends posterior to ischial spine and passes through lesser sciatic foramen to enter pudendal canal
- Branches
- Inferior Rectal Nerve - Ext. Anal Sphincter/Lower half anal canal
- Perineal Nerve
- Dorsal N. of Penis / Clitoris
Contents of Anal Triangle
Branches of Pudendal Nerve:
Inferior Rectal Nerve
Perineal Nerve
Dorsal N. of the Penis/Clitoris
- Inferior Rectal Nerve
- Innervates External Anal Sphincter and suppl sensory fibers to mucous membrane of lower half of anal canal
- Perineal Nerve
- Motor branches to muscles in superficial and deep perineal pouches and cutaneous branches to posterior scrotum and labia
- Dorsal N. of the Penis/Clitoris
- Sensory to respective organ
What is the innervation for the External Anal Sphincter/supplies sensory fibers to mucous membrane of lower half of anal canal?
Inferior Rectal Nerve (branch of Pudendal)
Contents of the Anal Triangle
Internal Pudendal Artery
Branches
- Internal Pudendal Artery
- Branch of internal iliac artery
- Courses w/pudendal nerve
- Branches
- Inferior Rectral Artery
- Courses w/Inferior Rectal Nerve through ischioanal fossa to supply lower half of anal canal
- Branches to penis/clitoris
- Inferior Rectral Artery
Perineum-Urogenital Triangle
Location of Urogenital Triangle / Boundaries
- Location:
- Anterior part of perineum
- Lies below part of pelvic diaphragm which has acentral urogenital gap; allows for passage of urethra in males/females, and vagina in females
- Boundaries:
- Posterior: Imaginary line between ischial tuberosities
- Lateral: Inferior Rami of Pubis and Ramus of Ischium
Perineum-Urogenital Triangle
Urogenital Diaphragm
Location?
Function?
Layers?
Major structures which pass through?
- Location
- Inferior to pelvic diaphragm
- Attached to inferior rami of pubis and rami of ischium
- Function
- Prevent herniation (prolapse) or bladder, prostate, and uterus
- Layers
- Superficial Fascia, Muscle, Inferior Fascia
- Major Structures
- Urethra (both sexes)
- Vagina
Perineum-Urogenital Triangle
Layers of Urogenital Diaphragm
Superior Fascial Layer
Deep Perineal Pouch*
Inferior Faschial Layer (Perineal Membrane)
*own card
- Superior Fascial Layer
- Deep Perineal Pouch
- Males - Striated Muscles / Bulbourthral Glands
- Branches of Pudendal N, Int. Pudendal Vessels
- Inferior Faschial Layer (Perineal Membrane)
- Thick fascial layer
- Superior/Inferior layers fuse ant / post to form an enclosed fascial space
Perineum-Urogenital Triangle
Deep Perineal Pouch Muscular Contents:
Deep Transverse Perineal Muscle
External Urethral Sphincter
- Deep Transverse Perineal Muscle
- Action: Stabolize perineal body; reinforce pelvic diaphragm
- Innervation: Pudendal Nerve
- External Urethral Sphincter
- Surrounds urethra in urogenital diaphragm
- Action: Voluntary sphincter of urethra; controls flow of urine
- Innervation: Somatic innervation by Perineal Branch of Pudendal Nerve
Perineum-Urogenital Triangle
Deep Perineal Pouch Male Non-Muscular Contents:
Membranous Urethra (clinical)
Bulbourethral Glands
What A, V, N branches?
- Membranous Urethra
- Thinnest, shortest, narrowest, least dilatable part of urethra
- Clinical: Subject to tear during insertion of catheter
- Bulbourethral Glands
- Posterior to membranous urethrea
- Ducts pass through inferior fascia layer or urogenital diaphragn and open into spongy (penile) urethra in bulb of penis
- Secretes lubricant during sexual arousal
- Internal Pudendal Artery, Vein, Nerve branches
Perineum-Urogenital Triangle
Deep Perineal Pouch Female Non-Muscular Contents:
3x structures that pass through urogenital diaphragm?
- Urethra
- Vagina
- Internal Pudendal neurovascular bundle
Superficial Perineal Pouch
Definition?
Contents:
Roots
Muscles
Glands (gender dependent)
- Superficial Perineal Pouch
- Space in the urogenital triangle between inferior fascial layer of the urogenital diaphragm and the superficial perineal fascia
- Contents
- Dick/Vagina Roots
- Muscles
- Superficial Transverse Perineal Muscle
- A: Fix position of perineal body, support floor of pelvis
- Bulbospongiosus
- A: Covers bulb of penis/bulb of vestibule
- Ischiocavernosus Muscles
- A: Covers crura pf penis/clitoris
- Superficial Transverse Perineal Muscle
- Female - Greater Vestibular Glands
Superficial Perineal Fascia (Colle’s Fascia)
Continuation of?
Clinical?
- Contuation of Scarpa’s Fascia of lower abdominal wall over penis (Superficial Penile Fascia)
- Continues into scrotum as dartos fascia
- Continues posterior into urogenital triangle as Superficial Perineal Fascia (Colle’s Fascia)
- Clinical: Common site of rupture of spongy urethra and extravastion of urine in the bulb of the penis; “Straddle Injury” or catheter insertion due to 90-deg bend
During a clinical rupture of Spongy Urethra from a straddle or catheter injury, where can the extravasated urine enter?
Where will it not enter?
- Urine can enter:
- Superficial Perineal Pouch
- Scrotum
- Around penis
- Anterior Abdominal Wall
- Urine will not enter:
- Ischioanal Foss (attachment to superficial perineal fascia to urogenital diaphragm)
- Thigh (attachment of superficial perineal fascia to ischiopubic rami)
- Thigh from anterior abdominal wall (attachment of Scarpa’s fascia)
What is the root of the penis fixed to?
What are it’s subdivisions?
Urogenital diaphragm
Crura (legs), Bulb
What are the major characteristics of the crura and bulb of penis
- Crura
- Paired, lateral erectile tissue
- Attached to inferior ramus of pubis and ramus of ischium
- Attached to urogenital diaphragm
- Bulb
- Single, central erectile tissue
- Attached to Perineal Membrane or urogenital diaphragm
- Contains proximal portion of spongy urethra
Bulbospongiosus Muscle
- Origin: Median Raphe, Perineal Body
- Intsertion: Fibers cover bulb of penis
- Actions: Aids in emptying urethra during micturition and ejaculation; contributes to erection by compressing blood engorged bulb of penis
Ischiocavernosus Muscle
Origin: Ischial Tuberosity
Insertion: Covers medial side and undersurface of crus of penis
Action: Aids in erection by compressing crus of penis
Is the body of the penis located in the superficial perineal pouch?
Corpus Cavernosa?
Corpus Spongiosum? What does this expand as distally? What distal part of a major structure does this contain?
No, the body is NOT located in superficial perineal pouch
- Corpora Cavernosa - Superior located cylinders (2x) of erectile tissue which are continuations of crura
-
Corpus Spongiosum - Inferior located cylinder, continuation of bulb
- Expands distally as glans penis
- Contains distal part of spongy urethra
What is the Navicular Fossa?
What does the urethra terminate at?
Navicular Fossa is dilated part of penile urethra in the glans penis
Urethra terminates at external urethral orifice
Fascial Layers of Penis:
Prepuce
Clinical?
Folded double layer of superficial fascia/skin that surrounds glans penis
Clinical: Removed during circumcision; if unremoved can become chronically infected and inflamed and obstruct urination
Fascial Layers of Penis:
Suspensory Ligament of Penis
Fundiform Ligament of Penis
Superficial Penile Fascia
Deep Penile Fascia
Tunica Albuginea
- Suspensory Ligament of Penis
- Arises from symphysis pubis, inserts into fascia surrounding penis
- Fundiform Ligament of Penis
- Descends from Linea Alba to attach to penile fascia
- Superficial Penile Fascia
- Continuous with Scarpa’s Fascia, Dartos Fascia of Scrotum, and Superficial Perineal Fascia of Superficial Perineal Pouch
- Deep Penile Fascia
- Located deep to superficial vein of penis
- Encloses deep dorsal arteries, veins of penis and corpora
- Tunica Albuginea
- Invests corpora cavernosa with thick dense fascia to hold corpora together; fuses in midline to form a septum
What is the major artery which supplies blood to the penis?
What supplies erectile tissues of crura and corpora cavernosa?
What supplies skin of penis and anastomoses with artery of bulb of penis at glans penis?
What drains blood from corpora?
What drains blood from skin into the superficial external pudendal vein?
Pudendal Artery
Deep Arteries of Penis
Dorsal Artery of Penis
Deep Dorsal vein of Penis
Superficial Dorsal Vein of Penis
What is the lymphatics drainage patter of the penis?
Skin?
Deep structures?
Skin drains to medial group of superficial inguinal nodes
Deep structurs drain to internal iliac nodes
What supplies sensory innervation to the penis?
What does it pass through?
Dorsal Nerve of Penis, a branch of the Pudendal Nerve
Passes through Deep Perineal Pouch
What nerve/nerve system completes the following:
Erection
Emission
Ejaculation
What stops your boner?
-
Erection
- Parasympathetics
- Pudendal Nerve
-
Emission
- Sympathetics
-
Ejaculation
- Pudendal Nerve
-
Cessation of Erection
- Sympathetics
- Pudendal Nerve ceases
How do parasympathetics regulate an erection?
How does the Pudendal Nerve regulate an erection?
How do sympathetics regulation emission?
How does the Pudendal Nerve regulate ejaculation?
Cause relaxation of smooth muscle of deep arteries of penis, and artery to bulb; blood flows into erectile tissues; veins become compressed
The Pudendal N. innervates bulbospongiosus and eschiocavernosus which compress venous return
Sympathetics cause contraction of smooth muscle of urethra to expel semen; closes internal urethral sphincter to prevent reflux of semen into bladder
The Pudendal nerve causes rhythmic contraction of bulbospongiosus to compress spongy urethra to aid in expulsion of semen
How do sympathetics and the pudendal nerve cause cessation of an erection?
Sympathetics cause constriction of smooth muscles of arteries (opposite of parasympathetics at start) causes end of boner :(
Pudendal Nerve stimulation ceases which results in relacation of bulbospongiosus and ischiocavernosus; allows venous blood flow
What is the entire complex of female external genitalia known as?
What are the major parts of the Clitoris?
Where does the urethra not enter?
Vulva
- Crura of Clitoris
- Laterally located erectile tissues
- Attached to inferior ramus of pubis/ischium
- Becomes body of clitoris anterior
- Bulbs of Vestibule
- Comparable to bulb of penis, but split into two halves by orifice of vagina and urethra
- Terminates as glans of clitoris
- Urethra does not enter body of clitoris or bulb of vestibule
What are the bulbospongiosus muscles attached to?
What is their role/action?
What are the Ischiocavernosus muscles attached to?
What is their role/action?
2x Bulbospongiosus Muscles are attached to perineal body
Cover vestibule and extend around vagina to body of clitoris; diminishes vaginal opening
2x Ischiocavernosus Muscles are attached to ischial tuberosity
Cover under surface of crus clitoris, aids in erection of clitoris by compressing blood engorged erectile tissue of crura
What is the blood supply to the following structures?
Bulb of Vestibule
Crura/Corpus Cavernosum
Glans Clitoris
- Arteries of the Bulb of Vestibule
- Deep Arteries of Clitoris
- Dorsal Arteries of the Clitoris
What are the Greater Vestibular Glands? (Bartholin’s Glands)
Clinical?
What are the paraurethral glands? (Skene’s Glands)
Homologues to bulbourethral glands of male (cowper’s)
Located in superficial perineal pouch, open to lateral vaginal orifice
Secrete lubricating mucus
Clinical: Commonly blocked/infected, can form cysts
- - -
Homologues to prostrate gland; open on either side of urethral orifice
What is the Mons Pubis?
Labia Majora?
Labia Minora?
Differences between these two?
Vestibule of Vagina
Mons Pubis - Mass anterior to pubic symphysis, formed by pad of fat and covering of hair
Labia Majora - Two folds of skin, filled with fat/covered with hair; correspond to scrotum, meet to form A/P labial commissure
Labia Minora - Two folds of skin, no fat/hair, between labia majora/urethral orifices, unite P to form fourchette, A splits to cover clitoris as pepuce of clitoris
Vestibule of Vagina - Area between labia minora, contains urethral orifice and vagina orifice, covered in virgins by hymen
What is the Sensory Innervation of Clitoris?
Provided by Dorsal Nerve of Clitoris (branch of Pudendal Nerve)
What is a episiotomy?
Overstretching of the vaginal opening during childbirth can lead to t_earing of perinal body_
Results: Weakness of pelvic diaphragm, collapse of rectum and bladder against vaginal wall or prolaps of uterus through vaginal orifice
What is a Mediolateral Episiotomy?
Surgical cutting of vagina and posterior wall of vulva, lateral to perineal body to enlarge vaginal orifice
Prevents tearing of perineal body with prolapse of pelvic organs
What is a Median Episiotomy?
Midline incision of posterior wall of vagina, fourchette, and perineal body
Easily repaired vs jagged tear from overstretching in childbirth
Less common than mediolateral episiotomy since clinician at risk in cutting the external anal sphincter
What is a Pudendal Nerve Block?
used to anesthetize perineum prior to episiotomy
Clinician locates the ischial spine by transvaginal palpation
Needle is passed through vaginal wall toward the ischial spine and through sacrospinous ligament
What structures are attached to perineal body? (6)
- External Anal Sphincter
- Superior/Inferior Layers of Urogenital Diaphragm
- Superficial Transverse Perineal Muscle
- Deep transverse Perineal Muscle
- Superficial Perineal Fascia
- Bulbospongiosus Muscle
What structures attached to Anococcygeal Ligament?
Pubococcygeus
Iliococcygeus
