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Anatomy Unit 4 > Perineum > Flashcards

Perineum Flashcards

1
Q

What is the function of the perineum?

A

Diamond-shaped region inferior to pelvic diaphragm that supports male + female external genitalia, as well as accommodates terminal pathways for the urinary and GI tracts

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2
Q

What are the boundaries of the perineum?

A

Anterior: Pubic symphysis
Posterior: Tip of coccyx
Lateral: Ischial tuberosities, ischiopubic rami, sacrotuberous ligaments
Superior: Pelvic diaphragm

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3
Q

What are the two triangular divisions of the perineum and what line demarcates the two triangles?

A
  1. Urogenital triangle - anterior, containing UG diaphragm, external genitalia, and terminal part of urinary tract
  2. Anal triangle - posterior, containing anal canal, ischioanal fat pad, and ischioanal fossa

Line: Between the two ischial tuberosities, bisecting the perineal body

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4
Q

What generally defines the deep pouch / compartment of the UG diaphragm?

A

It is comprised of a muscular diaphragm called the UG diaphragm attached laterally to ischiopubic rami and bridges across entire UG triangle.

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5
Q

What is the deep transverse perineal muscle and what lies inferior to it?

A

Muscle of UG diaphragm traversing entire UG triangle from ischiopubic rami. It has fibers which contribute to the urethra in males and females.

Inferior: Perineal membrane, a fibrous aponeurotic sheet also called the inferior perineal fascia. Maintains integrity of UG diaphragm

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6
Q

What anchors the UG-diaphragm posteriorly, and what is the continuation of this anchor?

A

Perineal body - anchored to anal canal. Anal canal is suspended posteriorly by the anococcygeal ligament.

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7
Q

What are the boundaries of the deep pouch of the UG diaphragm?

A

Anterior: body of pubic, just lateral to pubic symphysis
Lateral: IPR up to ischial tuberosities
Posterior: A transverse line through the ischial tuberosities + center attachment called perineal body
Superiorly: Investing fascia from levator ani + obturator internus
Inferiorly: Perineal membrane

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8
Q

What muscles are the contents of the deep pouch for men?

A 
Deep transverse perineal muscle
Membranous urethrae
Bulbourethral glands
Dorsal nerve of penis
Internal pudendal artery
Dorsal and deep arteries of the penis
Internal pudendal veins
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9
Q

What muscles are the contents of the deep pouch for women?

A 
Deep transverse perineal muscle
Compressor urethrae + sphincter urethrovaginalis
Membranous urethrae
Dorsal nerve of clitoris
Internal pudendal artery
Dorsal and deep arteries of the clitoris
Internal pudendal veins
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10
Q

What is the superior perineal fascia?

A

Discontinuous fascial covering over top of the deep pouch, going atop the deep transverse perineal muscle, etc. It is not continuous and not really important

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11
Q

What two fascial layers define the superficial pouch of the UG triangle?

A

Space between deep perineal fascia (Gallaudet’s) and membranous layer of superficial perineal fascia (Colle’s)

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12
Q

What is Colle’s fascia continuous with? What will in combine to form?

A

Scarpa’s fascia on the abdomen (membranous), as well as Dartos layer of superficial perineal fascia (makes outer covering of scrotum

Combines with Dartos layer to form superficial penile fascia

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13
Q

What is Gallaudet’s fascia continuous with?

A

Deep penile fascia (Buck’s fascia in males) which covers the corpus cavernosum and corpus spongiosum in males, as well as the external abdominal oblique fascia superiorly

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14
Q

What is the deep perineal fascia attached to and what does it invest?

A

(Gallaudet’s) It is firmly attached to the posterior border of the perineal membrane and laterally to the ichiopubic rami. It invests the erectile tissue muscles in both males and females

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15
Q

What are the erectile tissue muscles and what do they surround?

A

Ischiocavernosus - corpus cavernosum

Bulbospongiosus - corpus spongiosum

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16
Q

What structures are contained by the deep perineal fascia in the male?

A

Corpora cavernosa (crus of penis), corpus spongiosum (bulb of penis), erectile muscles, superficial transverse perineal muscles, deep perineal nerves (motor), perineal arteries

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17
Q

What structures are contained by the deep perineal fascia in the female?

A

Crus of clitoris, bulb of vestibule, erectile muscles, superficial transverse perineal muscles, deep perineal nerves (motor), perineal arteries, greater vestibular gland

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18
Q

What is the attachment of the superficial perineal fascia, and what is the membranous portion continuous with?

A

Attached to posterior margin of perineal membrane and ischiopubic rami. It is continuous with the superficial penile / clitoral fascia, and the membranous layer is continuous with Colle’s fascia and Scarpa’s fascia of the anterior abdominal wall

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19
Q

What is the Dartos muscle?

A

The muscular layer of the superficial perineal fascia made of smooth muscle fibers, attaching to skin of scrotum and penis.

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20
Q

What is the suspensory ligament of the penis?

A

Ligament which is continuous with Buck’s (Deep penile fascia) to attach to pubic symphysis

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21
Q

What are the two layers over the scrotum?

A

It is a double sac separated by a fascial septum. Outer layer: Thin skin. Inner layer: Superficial perineal fascia containing smooth muscle fibers of Dartos muscle

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22
Q

What is the sensory innervation of the scrotum provided by?

A
  1. Anterior scrotal nerve (branch of ilioinguinal nerve)
  2. Posterior scrotal nerve (branch of pudendal)
  3. Genital branch of genitofemoral nerve
  4. Perineal branch of posterior femoral cutaneous nerve
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23
Q

What gives blood to the scrotum (3 vessels)?

A

Posterior scrotal artery - branch of internal pudendal
Anterior scrotal artery - branch of external pudendal
Testicular artery - small

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24
Q

What are the corpora cavernosum? What is their attachment?

A

Paired erectile tissues forming the crus of the penis, attaching proximal to UG diaphragm and ischiopubic rami. They fuse distally and form 2/3 of the penile body, and terminate with blunt ends capped by the glands of the penis

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25
Q

What invests the crus of the penis in UG triangle?

A

Buck’s fascia and Gallaudet’s fascia, with the ischiocavernosus muscle between them. This forms the root of the penis

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26
Q

What is the body of the penis and what invests it?

A

The portion of the penis outside the pubic symphysis, invested by deep penile fascia (combination of Gallaudet’s and Buck’s fascia)

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27
Q

What are the functions of the ischiocavernosus and bulbospongiosus muscles and where are they found?

A

They contract to push penis or clitoris forward during sexual arousal, and are only found in the perineum (not body of penis, only in root)

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28
Q

What is the corpus spongiosum and what does it contain? What are at its proximal and distal ends?

A

A single midline cylinder of erectile tissue which contains the penile urethra.
Proximal: Attached to perineal membrane and is called penile bulb
Distal: Terminates as glans, which also caps the blunt ends of corpus cavernosum

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29
Q

What invests the glans?

A

Trick question: the corpus spongiosum is invested by deep penile fascia only up to the glans.

30
Q

What is the penile bulb and what is defined by it?

A

The beginning of the corpus sponiosum. It receives glandular secretions from the bulbourethral / Cowper’s glands and defines the transition from membranous urethra to penile urethra.

31
Q

What is the tunica albuginea?

A

The thick fibrous outer capsule of the erectile tissues which is not a fascia (corpora cavernosum and spongiosum)

32
Q

What is the narrowest part of the urethra?

A

The external urethral meatus - the smallest part to get the catheter through

33
Q

What is the navicular fossa?

A

An expanse just deep to the urethral meatus which is to interrupt the linear flow of urine to produce a concentrated stream upon urination

34
Q

What is the path of the pudendal nerve and what is it accompanied by?

A

From ventral rami of S2-4 of sacral plexus. Exits into gluteal region via greater sciatic foramen, enter perineum through lesser sciatic foramen, anterior to sacrotuberous ligament and posterior to sacrospinous ligament and tip of ischial spine. Enters perineum in ischioanal fossa of the anal triangle.

Accompanied by internal pudendal artery

35
Q

What is the inferior rectal nerve?

A

The first 2-3 midline branches of pudendal nerve to ischioanal fossa to provide sensory to anal canal

36
Q

Where does the pudendal nerve run after giving off inferior rectal branches?

A

In the pudendal canal, invested by obturator internus fascia laterally until reaching posterior border of UG diaphragm

37
Q

What are the branches of the pudendal nerve at the posterior boundary of the UG diaphragm?

A

Perineal nerve and dorsal nerve of penis / clitoris

38
Q

What are the branches of the perineal nerve and where do they run?

A

Deep perineal nerve - runs in deep compartment

Superficial perineal nerve - runs in superficial compartment

39
Q

What does the deep perineal nerve do?

A

Motor to erectile tissue muscles, superficial and deep transverse perineal muscles, and external urethra sphincter.

40
Q

What does the superficial perineal nerve do or become?

A

Terminates as posterior scrotal or posterior labial branch and provides sensory to these regions

41
Q

What is the course of the dorsal nerve of the penis or clitoris?

A

After branching from pudendal, enters deep pouch on superior surface of UG diaphragm, runs along ischiopubic rami border almost to anterior border of UG diaphragm. Exits UG-diaphragm by piercing perineal membrane and running along crus of corpus cavernosum to dorsal body of penis or clit, run superioly between Buck’s fascia and tunic albuginea of corpus cavernosum

42
Q

What is the function of the dorsal nerve of penis / clitoris

A

Provides sensory to body and glans of penis

43
Q

What is the autonomic input to erectile tissues?

A

PANS: pelvic splanchnics - S2-4
SANS: sacral splanchnics - inferior hypoglastric plexus from sacral splanchnics.

These converge together to form cavernous nerves, and pierce pelvic and UG diaphragms to innervate erectile tissues in male and female

44
Q

What is the internal pudendal artery? What does it give off before accompanying?

A

A branch of the internal iliac artery located in the pelvis.

Before accompanying the pudendal nerve in the pudendal canal, it gives off the inferior rectal artery

45
Q

What artery supplies the superficial compartment? Where is it given off?

A

Perineal branch, given off but internal pudental artery after it passes through the pudental canal at the free border of the UG diaphragm

46
Q

What are the two arteries of the deep compartment of the penis / clitoris and where do they run?

A

Branches of internal pudental artery after it pierces the deep compartment of the UG diaphragm:

  1. Deep artery of penis / clitoris - supplies corpus cavernosum
  2. Dorsal artery of penis / clitoris - Above corpus cavernosum, between vein and nerve, within the deep fascia
47
Q

What supplies the skin of the penis and surrounding the clitoris?

A

External pudendal artery, a branch of femoral artery

48
Q

What vein drains the deep compartment? Where does it drain into in males and females?

A

Dorsal vein of penis / clitoris drains deep compartment
Male: Prostatic plexus
Female: Inferior vesical plexus

49
Q

What is the mons pubis?

A

Rounded fatty elevation located anterior to pubic symphysis, covered with course pubic hair beginning at puberty. The labia are posterior

50
Q

What is the labia majora? What is the slit between the labia majora called? Where do they meet anteriorly?

A

Two symmetrical folds of skin providing projection of vaginal and urethral orifices. Lined with subcutaneous fat. Slit is called pudendal cleft which opens into vestibule of vagina.

They meet anteriorly to form the anterior labial commisure

51
Q

What is the female external genitalia called?

A

Vulva or pudendum

52
Q

What is the labia minora and how does it differ from the labia majora?

A

Paired hairless folds of skin with little subcutaneous fat that flanks the vestibule of the vagina.

Unlike the labia majora, they join anteriorly and posteriorly to make the anterior and posterior frenulum.

53
Q

What forms the clitoris and what muscle covers it? What fascia covers it?

A

Paired corpus cavernosum form cruses which attach to the perineal membrane and ischiopubic rami.

Invested by deep clitoral fascia. The cruses are covered by deep perineal faschia and are covered by ischiocavernosus muscles.

54
Q

What is the prepuce?

A

The wrap of skin analogous to the foreskin which covers the body and glans of the clitoris.

55
Q

What is the vestibular bulb and how does it differ from the male analog?

A

Male equivalent of corpora spongiosum, it is a ctually split in two and located lateral to vagina / urethra orifice at base of labia minor. It is firmly attached to perineal membrane and invested by a thin layer of deep clitoral fascia.

56
Q

What muscle is associated with the vestibular bulb and what fascia invests it?

A

Bulbosponiosus muscle, invested by deep perineal fascia

57
Q

What are the greater vestibular glands and where are they located?

A

Glands located within the base of the labia minora, posterior to vestibular bulbs and just lateral to vaginal opening. They have ducts which provide lubrication to the vaginal opening upon sexual stimulation, opening lateral to vaginal opening.

58
Q

Where does the dorsal nerve of the clitoris run?

A

Enters deep compartment and travels along ischiopubic ramus. Pierces perineal membrane and travels on the superior surface of the crus of the clitoris, before reflecting on dorsal surface of body and terminating in glans of clitoris

59
Q

What are the borders of the anal triangle?

A

Line between ischial tuberosities anteriorly, laterally by the sacrotuberous ligaments

60
Q

What is the ischioanal fat pat?

A

Fibrous / elastic fat mass that maintains shape or region surrounding the anal canal + anterior recess, lateral to birth canal in female. Sits in ischioanal fossa

61
Q

What is the roof of the ischioanal fossa?

A

Levator ani / diaphragm

62
Q

What are the walls of the ischioanal fossa?

A

Coccyx, sacrotuberous ligament, obturator internus muscle, and ischiopubic rami

63
Q

What are the boundaries of the anterior recess?

A

Medially: Levator ani / pelvic diaphragm
Laterally: Obturator internus muscle / fascia + ischiopubic rami
Inferiorly: UG diaphragm
Anteriorly: Body of pubis

64
Q

What are the contents of the ischioanal fossa?

A
  1. Pudendal canal
  2. Inferior rectal artery, nerve, and veins
  3. Ischioanal fat pat
65
Q

What is the pudendal canal?

A

Between the surface of the obturator internus muscle and its fascia, accommodates internal pudendal artery + vein and pudendal nerve

66
Q

Where is a pudendal nerve block given?

A

At the pudendal canal for childbirth or surgical procedures involving structures within the perineum

67
Q

What is an episiotomy? What do you want to avoid?

A

Procedure during birthing sometimes done to enlarge birth canal to accommodate delivery of baby.

Avoid damaging pubococcygeus muscle during incision by cutting median posteriorly, or medial / laterally on posterior wall towards ischiopubic rami

68
Q

Where is the most dangerous spot in the male anatomy for catheterization?

A

The 80-90 degree superior bend in the bulb of the penis in the membranous portion (deep perineal pouch)

69
Q

Where will the urine remain contained if the fascia surrounding the membranous urethra remains intact?

A

Deep perineal pouch

70
Q

What is the worst-case scenario for urine accumulation following bad catheter?

A

Worse than containment in deep-space of superficial compartment (deep perineal fascia / Buck’s fascia is not torn), you can have a tear of Buck’s fascia allowing drainage into superficial space of superficial compartment, which will have urine all around Colle’s superficial fascia + Dartos layer accumulating into scrotum, body of penis, and anterior abdominal wall

Anatomy Unit 4 (10 decks)

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