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Gross II Exam 4 > Perineum > Flashcards

Perineum Flashcards

1
Q

What is the perineum?

A

the part of the trunk below the pelvic diaphragm

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2
Q

What is the shape of the perineum?

A

a diamond-shaped space which has the same boundaries as the pelvic outlet

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3
Q

What divides the perineum into two triangles?

A

a transverse line connecting the two ischial tuberosities

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4
Q

What are the triangles of the perineum?

A
  • urogenital triangle (anterior)

- anal triangle (posterior)

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5
Q

What is the position of the triangles in anatomical position?

A

the urogenital triangle lies in the horizontal plane while the anal triangle is tilted upward

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6
Q

What are the boundaries of the urogenital triangle?

A
  • anterior: pubic symphysis
  • anterolateral: ishiopubic rami
  • posterior: transverse line through ischial tuberosities
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7
Q

What are the layers of the urogenital triangle?

A
  1. skin
  2. superficial perineal pouch
    - superficial perineal fascia
    - deep perineal fascia
    - contents
  3. perineal membrane
  4. deep perineal pouch
  5. inferior fascia of the pelvic diaphragm
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8
Q

What is the superficial perineal fascia?

A
  • includes fatty layer (superficial) and membranous layer (deep)
  • membranous layer is also known as Colle’s Fascia
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9
Q

What is Colle’s fascia continuous with?

A
  • dartos muscle of the scrotum

- Scarpa’s fascia

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10
Q

Describe the deep fascia.

A
  • it intimately invests the muscles of the superficial perineal pouch
  • is fused anteriorly with the suspensory ligament of the penis/clitoris
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11
Q

Where is the superficial perineal pouch?

A

lies between the superficial perineal fascia and the perineal membrane

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12
Q

What does the superficial perineal pouch contain?

A
  1. perineal body
  2. superficial transverse perineal membrane
  3. ischiocavernosus muscle
  4. crura of the penis/clitoris
  5. blubospongiosus muscle
  6. bulb of the penis/vestibule
  7. greater vestibular gland (females)
  8. branches of the internal pudendal artery
  9. branches of the pudendal nerve
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13
Q

What kind of tissue are the crus and bulb composed of?

A

cavernous erectile tissue

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14
Q

What is the perineal body?

A
  • a fibromuscular mass which is located in the center of the perineum between the anal canal and bulb of the penis/vagina
  • it is an important point of muscle attachment
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15
Q

Which muscles attach to the perineal body?

A
  1. superficial transverse perineal
  2. deep transverse perineal
  3. bulbospongiosus
  4. levator ani
  5. sphincter ani externus
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16
Q

Which muscle does not attach to the perineal body?

A

ishiocavernosus

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17
Q

What is an episiotomy?

A
  • an incision is made from the posterior vaginal wall to the perineal body
  • done to prevent uncontrolled tearing of the perineal body and its muscles during parturition
  • two ways: median, mediolateral
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18
Q

What is the origin, insertion, nerve supply, and function of the superficial transverse perineal muscle?

A
  • O: ishcial tuberosity
  • I: perineal body
  • N: perineal branch of pudendal nerve
  • F: stabilizes the perineal body
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19
Q

What is the origin, insertion, nerve supply, and function of the ischiocavernosus muscle?

A
  • O: medial surface of ischial tuberosity and ischiopubic ramus
  • I: crus of the penis or clitoris
  • N: perineal branch of pudendal nerve
  • F: impedes venous return, by compressing the crus of the penis or clitoris, thereby maintaining erection
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20
Q

What is the origin, insertion, nerve supply, and function of the bulbospongiosus muscle in the male?

A
  • O: perineal body, median raphe of the bulb of the penis
  • I: corpus spongiosum, deep fascia on dorsum of penis
  • N: perineal branch of pudendal nerve
  • F: impedes venous return by compressing the bulb of the penis, thereby maintaining erection; it also constricts the corpus spongiosum to empty the urethra at the end of micturition and during ejaculation
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21
Q

What is the origin, insertion, nerve supply, and function of the bulbospongiosus muscle in the female?

A
  • O: perineal body, fibers surrounding the bulb of the vestibule and vagina
  • I: pubic arch and corpus cavernosum of clitoris
  • N: perineal branch of pudendal nerve
  • F: constricts the vaginal orifice and maintains erection of clitoris
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22
Q

What are the greater vestibular glands?

A
  • two ovoid glands which are located in the superficial perineal pouch, posterior to the bulb of the vestibule
  • their ducts open into the vestibule along the posterolateral margin of the vaginal orifice
  • homologous to the bulbourethral gland of the male
  • secretes mucus which lubricates the vagina during sexual intercourse
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23
Q

Describe the mechanism of erection.

A
  1. Parasympathetic activation (S2, S3, S4) causes dilation of the small, coiled arteries within the corpora cavernosa known as helicine arteries.
  2. The flow of blood into the cavernous spaces compresses venous plexuses at the periphery of the corpora, impeding venous return.
  3. The bulbospongiosus and ishiocavernosus muscles contract to maintain erection.
24
Q

Where is the deep perineal pouch?

A

lies between the perineal membrane and the inferior fascia of the pelvic diaphragm

25
Q

What does the deep perineal pouch contain?

A
  1. deep transverse perineal muscle
  2. external urethral sphincter
  3. intermediate part of urethra
  4. bulourethral gland (males)
  5. branches of the internal pudendal artery
  6. pudendal nerve
26
Q

What is the origin, insertion, nerve supply, and function of the deep transverse perineal muscle?

A
  • O: medial surface of ischial ramus
  • I: perineal body and median raphe (males) or walls of the vagina (females)
  • N: perineal branch of the pudendal nerve
  • F: stabilizes the perineal body and supports the prostate gland or vagina
27
Q

What does the external urethral sphincter muscle consist of in the male?

A
  • Inferior part: true anatomical sphincter which encircles the urethra below the prostate (membranous urethra)
  • Superior part: trough-like portion which extends up to the neck of the bladder, investing anterior part of prostatic urethra within the isthmus of the prostate
28
Q

What does the external urethral sphincter muscle consist of in the female?

A
  • Sphincter urethrovaginalis: inferior part which encircles both the urethra and vagina
  • Compressor urethrae: originates from ischiopubic ramus on each side and forms a band anterior to the urethra; forms a sling
  • Superior part: trough-like portion which extends to the neck of the bladder
29
Q

What may happen to the external urethral sphincter muscle during parturition?

A

it may be damaged, which may result in urinary incontinence

30
Q

What is the nerve supply and function of the external urethral sphincter muscle in both sexes?

A
  • N: perineal branch of pudendal nerve

- F: compresses urethra at the end of micturition

31
Q

What are the bulbourethral glands?

A
  • two glands which lie posterolateral to the intermediate part of the urethra (membranous urethra) in the male
  • their ducts pass downward through the perineal membrane into the bulb of the penis to empty into the spongy urethra
  • secrete a mucus-like substance, and are homologous to the greater vestibular glands in the female
32
Q

What are the boundaries of the anal triangle?

A
  • anterior: transverse line through the ischial tuberosities
  • posterolateral: sacrotuberous ligaments
  • posterior: tip of the coccyx
33
Q

Is the anal triangle different between the sexes?

34
Q

What does the anal triangle contain?

A
  • anal canal
  • external anal sphincter
  • ischioanal fossa
35
Q

What is the ischioanal fossa?

A
  • a space which lies on either side of the anal canal
  • it extends between the skin of the anal region below and the inferior surface of the pelvic diaphragm above
  • lateral wall is formed by the obturator fascia
36
Q

What does the ischioanal fossa contain?

A
  • fat: allows for distension of the anal canal and supports the anal canal, preventing rectal prolapse
  • pudendal canal (and contents)
  • inferior rectal nerve and vessels
  • perineal branch of posterior cutaneous nerve of thigh
37
Q

What are the anterior recesses of the ischioanal fossa?

A
  • extend anteriorly into the urogenital triangle

- allow infection to spread forward into the urogenital triangle

38
Q

What is the anococcygeal ligament?

A

connects external anal sphincter to coccyx

39
Q

What is the pudendal canal?

A
  • lies on the lateral wall of the ischioanal fossa

- formed by the obturator fascia

40
Q

What does the pudendal canal transmit?

A
  • internal pudendal vessels

- pudendal nerve

41
Q

What is the blood supply to the perineum?

A

primarily from the internal pudendal artery

42
Q

What is the course of the internal pudendal artery?

A
  • arises from the internal iliac artery, exits the pelvis through the greater sciatic foramen between piriformis and coccygeus, and enters the perineum through the lesser sciatic foramen
  • travels within the pudendal canal and is accompanied by the pudendal nerve during its course
43
Q

What are the branches of the internal pudendal artery?

A
  1. inferior rectal artery
  2. perineal artery
  3. posterior scrotal (labial) artery
  4. artery of the bulb
  5. urethral artery
  6. deep artery of the penis or clitoris
  7. dorsal artery of the penis or clitoris
44
Q

What does the inferior rectal artery supply?

A

the muscles and skin around the anal canal

45
Q

What doe the perineal artery supply?

A

the perineal body and adjacent muscles

46
Q

What does the posterior scrotal or labial artery supply?

A
  • posterior aspect of scrotum

- labia majora

47
Q

What does the artery of the bulb supply?

A

bulb of the penis or vestibule

48
Q

What does the urethral artery supply?

A

membranous urethra

49
Q

What is the external pudendal artery and what does it supply?

A
  • small branch of the femoral artery

- supplies the male and female external genitalia

50
Q

What is the innervation of the perineum?

A

pudendal nerve (S2, S3, S4)

51
Q

What is the course of the pudendal nerve?

A
  • exits the pelvis through the greater sciatic foramen below the piriformis
  • enters the perineum through the lesser sciatic foramen, and travels with the internal pudendal artery within the pudendal canal
52
Q

What are the branches of the pudendal nerve?

A
  • inferior rectal nerve
  • perineal nerve
  • dorsal nerve of the penis or clitoris
53
Q

What does the inferior rectal nerve supply?

A

the external anal sphincter muscle and the skin around the anus

54
Q

What are the branches of the perineal nerve and what do they supply?

A
  • deep branch: all the muscles of the perineum

- superficial branch (posterior scrotal or posterior labial nerve): sensory to the scrotum or labia majora

55
Q

What does the dorsal nerve of the penis or clitoris supply?

A

skin, prepuce, and glans of the penis or clitoris

56
Q

What may happen in long-distance bicycle riders, triathletes, etc.?

A

they sometimes develop perineal pain due to chronic compression of the pudendal nerve

Gross II Exam 4 (22 decks)

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