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Anatomy 2
Exam 3: Anal & Urogenital Triangles of the Perineum
| Question | Answer |
|---|---|
| General Considerations of the Perineum | diamond-shaped area between the thighs, pubis to the coccyx, bounded by both bony and ligamentous structures |
| The Perineum is bounded anteriorly, antrolaterally, posteriorly, posterolaterally, by what structures? | 1) Anteriorly: Pubis 2) Anterolateral: Ischiopubic rami and Ischial tuberosities 3) Posteriorly: Coccyx and caudal part of sacrum 4) Posterolaterally: Sacrotuberous ligaments, from Sacrum to Ischial tuberosities |
| Superiorly, the perineum is separated from | the pelvic cavity by the pelvic diaphragm (Levator Ani muscle) |
| the diamond-shaped perineum can be divided into two triangles | 1. Anal Triangle 2. Urogenital Triangle |
| Bounderies of Anal Triangle. Ant., Sup., Lat. walls, Inf. | 1)Posterolateral: sacrotuberous ligaments 2) Ant: an imaginary line passing through the ischial tuberosities 3) Sup: inferior aspect of pelvic diaphragm 4) Lat. walls: obturator internus muscle 5) Inf.: skin and superficial fascia of perineum |
| The spaces within the bony and muscular limits of the anal triangle are the ___________ | Ischioanal Fossae (Ischiorectal Fossae) |
| The right and left ischioanal fossae communicate with one another _______ | posterior to the anus |
| Anteriorly, the right and left ischioanal fossae become ________ | separated from one another |
| The lateral portions of the ischioanal fossae, anterior to the anus, extend between the ________ and ________. | Levator ani, Deep Perineal Pouch |
| These create the anterior recess of the ischioanal fossae. | Levator ani, Deep Perineal Pouch |
| Levator ani and Depp perineal pouch make up the _______. Extends into the UG triangle. | Anterior recess |
| Formerly the UG diaphram | Deep Perineal Pouch |
| Ischioanal fossae is filled with | Adipose body (mass of fat & CT) |
| voluntary skeletal muscle surrounding the anal canal and extending from the lower surface of the levator ani to the inferior limit of the anal canal. | External Anal Sphincter |
| layers of External Anal Sphincter | a) subcutaneous fibers b) superficial fibers c) deep fibers |
| originates from the anococcygeal raphe | superficial fibers |
| a narrow tendinous band which extends from coccyx to posterior margin of anus | anococcygeal raphe |
| main part, originates from the anococcygeal raphe, splits to enclose the anal canal, then inserts into the perineal body/central tendon of the perineum | Superficial fibers of External Anal Sphincter. "Origin": Anococcygeal raphe "Insertion": perneal body/central tendon of perineum |
| completely encircle the anal canal, fibers blend with puborectalis superiorly. Most important component of the external anal sphincter. | deep fibers of External Anal Sphincter |
| Vessels of the Anal Triangle derived from | internal pudendal artery and vein |
| branch and tributary of the internal iliac artery and vein | internal pudendal artery and vein |
| The vessels of the Anal Triangle leave the pelvis by passing through | 1) through Greater sciatic foramen 2) then, dorsally cross ischial spine 3) and pass through lesser sciatic foramen 4) to lie high on lateral wall of Anal Triangle, within the pudendal canal |
| Is a fascial formed by the splitting of the obturator fascia. The nerves and vessels of the anal and UG regions traverse this. | pudendal (Alcock's) canal |
| Internal Pudendal Artery passes through the anal region (in the pudendal canal), it gives off important branches. | 1. Inferior rectal artery 2. Perineal artery |
| arises almost immediately after the internal pudendal artery enters the anal region of the canal | inferior rectal artery |
| inferior rectal artery passes through what and supplies what | through the ischioanal fossa ÂÂ> to external anal sphincter, anal canal, and skin about anal orifice |
| arises from internal pudendal near the posterior edge of the perineal membrane. | perineal artery |
| perineal artery give rise to two important artery | Tranverse Perineal a., Posterior Scrotal (Male) / Posterior Labial (Female) |
| After giving off important branches, Internal pudendal artery continues into ___________ | 1) In Anterior recess of the UG Triangle, 2) Enters Deep Perineal space, 3) Ends by dividing into deep & dorsal arteries of Clitoris/Penis |
| Nerves Of The Anal Triangle derived from 3 sources | pudendal nerve, perineal branch of S4, perineal branches of the posterior femoral cutaneous n |
| major branches of pudendal nerve within the anal triangle are | 1) inferior rectal nerve 2) perineal nerve 3) dorsal nerve of clitoris/penis |
| nerve that passes through the ischioanal fossa in to external anal sphincter, skin around anal orifice, and clinical anal canal (area below pectinate line). | inferior rectal nerve |
| perineal nerve has the following branches | a) posterior labial/scrotal nerve (labium majora (female) & scrotum (male)) b) deep branches (muscles & other structures of the UG region) |
| nerve that enters the upper surface of the deep perineal space | dorsal nerve of clitoris/penis |
| Nerve to skin of posterior part of anal triangle. Contribute to motor innervation of the external anal sphincter. | perineal branch of S4 |
| Nerve to lateral most aspect of the anal & UG regions and upper medial aspect of the thighs. | perineal branches of the posterior femoral cutaneous n. |
| The UG trangle bounded anteriorly, laterally, and posteriorly by | bounded anteriorly by the pubis, laterally by ischiopubic rami, and posteriorly by an imaginary line passing through the ischial tuberosities |
| The UG triangle occupies what part of the perineum? | The Anterior Portion |
| Formerly the "inferior fascia of UG diaphragm" | Perineal membrane |
| is a sheet of tough, deep fascia extending between the two ischiopubic rami, from the pubis anteriorly to ischial tuberosities posteriorly. | Perineal membrane |
| Anteriorly, the perineal membrane does not extend all the way to the symphysis pubis. There is a slight gap between the ________and ________ | transverse perineal ligament, inferior (arcuate) pubic ligament. |
| anterior thickening of the perineal membrane | transverse perineal ligament |
| The deep dorsal vein of the clitoris/penis enters the pelvis through this gap (bewteen tranverse perineal ligament & inferior (arcuate) pubic ligament; In the male the sheet is _______; In the female the sheet is _______ | a. In the male, the sheet is continuous. b. In the female, the sheet is split almost into two portions by the vagina and urethra. |
| a space located above the perineal membrane | deep perineal space/pouch |
| The deep perineal space is filled with skeletal muscle and is open superiorly, it is not enclosed superiorly, but actually opens into the __________. | anterior recesses of the ischioanal fossae |
| The muscles of the deep perineal space | External Urethral Sphincter, Deep transverse perineal muscles, Bulbourethral (Cowper's) gland. |
| muscle surrounding the membranous urethra | external urethral sphincter (sphincter urethrae) |
| present in the female, subdivisions of external urethral sphincter | compressor urethrae & urethrovaginalis |
| making up the posterior portion of the deep perineal space | deep transverse perineal muscles |
| Embedded within the external urethral sphincter and/or deep transverse perineal muscles of the male | bulbourethral (Cowper's) glands |
| The penis is formed by the union of three masses of erectile tissue arising in the UG triangle | corpus spongiosum, corpora cavernosa, |
| What part of corpus spongiosum receives the urethra? | Its most posterior part, the bulb |
| lying in the midline, adherent to the perineal membrane | corpus spongiosum |
| forming the crura of the penis. These bodies arise from the ischiopubic rami and adjacent perineal membrane. | corpora cavernosa |
| corpora cavernosa forms what part of the penis? | crura |
| corpora cavernosa forms the crura of the penis. These bodies arise from _________. . | ischiopubic rami & adjacent perineal membrane |
| In addition to its attachment via the bulb and the crura, the penis is also supported by | suspensory ligament, fundiform ligament |
| derived from the deep fascia of the lower abdomen; arises just inferior to die lower end of the linea alba and inserts onto the deep fascia of the penis. | suspensory ligament |
| derived from the deep layer of the superficial fascia (Scarpa's fascia) of the abdomen; it passes lateral to the suspensory ligament and inserts into the dorsum and sides of the superficial fascia of the penis | fundiform ligament |
| The erectile bodies have skeletal muscles associated with them. They are _________ | bulbospongiosus muscle, ischiocavernosus muscles |
| action of bulbospongiosus muscle | remove urine and ejaculate from the urethra of the bulb; in addition, it also impedes venous return from the bulb, thus assisting in erection of the penis |
| Origin & Insertion & Anterior fibers of bulbospongiosus muscle | *Origin: perineal body and perineal membrane. *Insertion: Most fibers insert on a midline raphe on ventral surface of corpus spongiosum. *The most anteriorly placed fibers: swing anteriorly and laterally to encircle the penis. |
| perineal body is also known as | central tendon of the perineum |
| Origin and insertion of ischiocavernosus muscles | Origin: from the ischiopubic rami and surrounding the free surfaces of the cavernous bodies. Insertion: into the respective cavernous bodies just prior to their union anteriorly. |
| What is the function of Ischiocavernosus muscles | These muscles impede venous return from the crura, thereby assisting in erection of the penis. |
| a third pair of muscles present on the inferior surface of the perineal membrane running inferior to the posterior edge of the perineal membrane | superficial transverse perineal muscles |
| Origin and Insertion and Action of superficial transverse perineal muscles | Origin: from the ischial tuberosities, Insert: into Perineal body, Action: support the perineal body |
| Characteristics of the clitoris | 1) homologous with the male penis 2) approx. 1 inch in length & is bent downward & backward upon itself. 3) It is buried in skin (the prepuce) & attached to pubic symphysis by suspensory lig. of the clitoris. |
| The clitoris is formed by the union of three masses of erectile tissue arising from the UG triangle | vestibular bulbs, corpora cavernosa |
| homologous with the bulb of the corpus spongiosum in the male | vestibular bulbs |
| Anteriorly, the Vestibular bulbs are united by small thread-like extensions called | the pars intermedia |
| union of small thread-like extensions called the pars intermedia | commissure |
| contributes to the ventral portion of the body of the clitoris | commissure |
| Deep to the dorsal ends of the vestibular bulbs | greater vestibular (Bartholin’s) glands |
| homologous with the male bulbourethral glands | greater vestibular (Bartholin’s) glands |
| The ducts of greater vestibular glands open into ______ on each side of the vagina, specifically, in the groove between the hymen and the labia minora. The glands provide lubrication during coitus | vestibule |
| the area between the labia minora | vestibule |
| Form the crura of the clitoris. Anteriorly, they converge (with the commissure contribution of the vestibular bulbs) to form the body of the clitoris | Corpora Cavernosa |
| Corpora cavernosa forms what part of the clitoris | Crura |
| Structures associated with the clitoris | prepuce & suspensory ligament |
| sometimes termed the "hood of the clitoris". This structure is formed by the lateral folds of the labia minora meeting over the glans of the clitoris. | prepuce |
| originates from the deep fascia of the lower abdomen; it arises just inferior to the lower end of the linea alba and inserts into fascia of the clitoris. | suspensory ligament |
| The muscular elements associated with the erectile tissue of the female | bulbospongiosus muscle, ischiocavernosus muscles |
| arise from the perineal body, divided into right and left portions by the pudendal cleft. Each portion covers the vestibular bulb of the respective side and inserts anteriorly into the dorsum of the body of the clitoris and perineal membrane. | bulbospongiosus muscle |
| Opening/Cleft/Fissure between labia majora | Pudendal Cleft |
| Origin and insertion and function of bulbospongiosus muscle | O: Perineal body I: anteriorly into the dorsum of the body of the clitoris and perineal membrane A: impede venous return from the erectile tissue, thus assisting in erection of the clitoris. |
| ischiocavernosus muscles Origin and insertion | Origin: from the ischiopubic rami. Insetion: They cover the respective corpora cavernosa and insert into the pubic arch and crura of the clitoris. |
| Origin and insertion and function of Ischiocavernosus muscles | O: Ischioppubic rami I: pubic arch and crura of clitoris A: impede venous return from the erectile tissue, thus assisting in erection of the clitoris. |
| bulbospongiosus and the ischiocavernosus muscles act to | impede venous return from the erectile tissue, thus assisting in erection of the clitoris. |
| are a third pair of muscles on the inf. surface of the perineal membrane, located along the posterior edge of the perineal membrane. They arise from ischial tuberosities, insert into the perineal body of the perineum & act to support the perineal body. | superficial transverse perineal muscles |
| Origin and insertion and action of superficial transverse perineal muscles | O: Ischial tuberosities I: Perineal body of the perineum A: to Support the perineal body |
| also called "perineum of the obstetrician". This structure is larger & more prominent in the female. Receives the attach. of musc. compts: external anal sphincter, superficial transverse perineal, bulbospongiosus, & deep transverse perineal muscles. | Perineal body/Central tendon |
| The central tendon/perineal body receives the attachment of what muscular components | external anal sphincter, bulbospongiosus, superficial transverse perineal, and deep transverse perineal muscles |
| What two fascial layers of the UG Triangle are present inferiorly | Deep Perineal Fascia, Superficial perineal fascia (two layers: Superficial layer & Deep layer) |
| covers the superficial transverse perineal, bulbospongiosus, and ischiocavernosus muscles | Deep perineal fascia |
| Extent of Perineal Fascia laterally, posteriorly, anteriorly | L: from one ischiopubic ramus to other P: attached to post. edge of the perineal membrane A: continued as a sleeve-like extension onto the clitoris/penis, where it becomes the deep fascia of clitoris/penis (Buck's). Above it is fused to pubic bones. |
| Superficial perineal fascia has what two layers? | 1) Superficial layer [fatty-layer continuation - superficial fascia of abdomen Camper's layer] 2) Deep layer (Collesâ) [membranous continuation - deep layer of abdomen Scarpa's layer] |
| this fatty layer is the perineal continuation of the superficial layer of the superficial fascia of the abdomen | Camper's layer |
| Anteromedially, the superficial layer of the superficial perineal fascia continues into | Female : the labia majora Male: the superficial layer of the superficial perineal fascia is continuous with the dartos of the scrotum (dartos with no fat.) |
| 1) What membranous layer is the perineal continuation of the deep layer of the superficial fascia of the abdomen? 2) What is the name for the superficial fascia of the abdomen? | Deep Layer (Colle's), Scarpa's layer |
| Anteromedially, the deep layer of the superficial perineal fascia joins what in the female & male | Female: joins the superficial layer into the labia majora. Male: joins the superficial layer to become continuous with the dartos of the scrotum |
| Evaginations of this deep layer extend over the clitoris/penis as | superficial fascia of clitoris/penis |
| What creates the superficial perineal space | presence of the deep perineal fascia |
| The superficial perineal space is bounded by | 1) superiorly: by the perineal membrane 2) inferiorly and posteriorly: deep perineal fascia 3) laterally: ischiopubic rami 4) anteriorly: by attachment of deep perineal fascia to pubic bones |
| The superficial perineal space contains | crura of penis/clitoris, bulb of penis, vestibular bulbs, ischiocavernosus and bulbospongiosus muscles, superficial transverse perineal muscles, erectile bodies, vessels and nerves of just mentioned muscles, and greater vestibular glands. |
| internal pudendal a. gives rise to | 1) transverse perineal a. 2) posterior labial/scrotal a. |
| Name two artery of the UG triangle | Perineal branch of internal pudendal, internal pudendal artery |
| after giving off the perineal branch, continues into the anterior recess of the ischioanal fossa, above the deep perineal space. After passing forward for a distance, it passes into the deep perineal space. | internal pudendal artery |
| internal pudendal artery passes into the deep perineal space. While in this space it gives off what branches | 1) artery to the bulb —> to bulb of corpus spongiosum, vestibular bulbs; and bulbourethral glands & greater vestibular glands 2) urethral artery —> to urethra 3) arteries to muscles of deep perineal space |
| terminal branches of the internal pudendal artery are | Deep & Dorsal arteries of the clitoris/penis |
| artery supplies corpora cavernosa | 1) deep artery of the clitoris/penis |
| pierces the perineal membrane and continues forward to reach the dorsal surface of the penis/clitoris. It is found deep to the deep fascia of the penis/clitoris. | dorsal artery of the clitoris/penis |
| Venous of the UG triangle corresponds closely to the arteries with the exception of | deep dorsal vein of penis/clitoris |
| deep dorsal vein of penis/clitoris once in the pelvis, it drains into | vesical plexus (female) or prostatic plexus (male). |
| Nerves of the UG triangle | Pudendal nerve (S2-S4) gives branches to the UG area: A) perineal nerve 1. posterior labial/scrotal nerves scrotum 2. deep branches B) dorsal nerve of clitoris/penis |
| run in superficial perineal space to labia majora/ scrotum | posterior labial/scrotal nerves |
| supplies corpora cavernosa (accompanies dorsal artery of clitoris/penis) and to skin of clitoris/penis | dorsal nerve of clitoris/penis |
| Name homologues of men and female | Greater vestibular glands (Bartholin’s) = Bulbourethral glands (Cowper’s), Vestibular bulbs = Bulb of corpus spongiosum, Clitoris = Penis, Labia majora = Scrotum, Urethral & paraurethral glands (Skene’s) = Prostate gland |
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legend3series