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Anatomy 3 > The Perineum > Flashcards

The Perineum Flashcards

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1
Q

Define the boundaries of the perineal region; how does the surgical differ from the anatomical perineum; boundaries? size?

A

A diamond-shaped area bounded by the pubic symphysis, ischial tuberosities and coccyx.

surgical:
posterior- anterior border of anus
lateral- medial thigh creases
anterior- root of scrotum/posterior commissure of vagina

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2
Q

How is the perineum subdivided?

A

A line between the ischial tuberosities divides the region into an anterior urogenital triangle (horizontal to the floor) and a posterior anal triangle (more vertical)

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3
Q

What structure forms the floor of the pelvis (pelvic diaphragm)?

A

The levator ani.

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4
Q

Where are the ischioanal (rectal) fossae located?

A

On either side of the rectum/anal canal below the levator ani.

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5
Q

Where does the anal canal begin?

A

On the inferior aspect of the levator ani (floor of the pelvic cavity).

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6
Q

What is the dentate/pectinate line?

A

A line drawn that connects the inferior aspect of the anal valves.

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7
Q

What is the white/ anocutaneous line?

A

A line inferior to the dentate/pectinate line where the epithelium changes from mucous to stratified squamous.

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8
Q

What is an anal valve?

A

A flap of mucosa bridging two anal columns and spanning an anal sinus in the wall of the anal canal.

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9
Q

What is an anal column?

A

Longitudinal column-like protrusions of epithelium between the anal vavles.

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10
Q

What is the clinical implication of this valvular arrangement?

A

The small cusp-like flaps of mucosa have anal glands emptying into them. Accumulation of fecal material in these cusps can lead to infected glands and abcess situations.

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11
Q

What are the 2 sphincters of the anal canal?

A

Internal and external anal sphincters.

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12
Q

Which of these two sphincters is under voluntary control?

A

The external is skeletal (voluntary) muscle, the internal is smooth (involuntary) muscle.

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13
Q

What are the 3 components of this external sphincter?

A

The subcutaneous, superficial; and deep portions.

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14
Q

To which two structures is the superficial portion of this sphincter connected?

A

Anteriorly to the perineal body and posteriorly to the coccyx via the anococcygeal ligament.

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15
Q

How does the puborectalis function in assisting the action of the anal sphincter for bowel control?

A

It pulls the lower rectum forward, “kinking” it to add a biomechanical sphincter-like feature for continence.

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16
Q

Why is the anocutaneous (white) line important?

A

It is a major watershed area (shift in supply) for numerous anatomical features/supply.

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17
Q

List the various “changes” in or around this line.

A

Arterial: above = superior rectal from inf. mesenteric a., middle rectal from int. pudendal a.; below = inf. rectal from int. pudendal a.;

Venous: above = to primarily portal system; below = to completely caval system;

Lymphatic: above = to deep (para- aortic) nodes; below = supf. inguinal nodes;

Sensory: above = visceral afferents (diffuse pain); below = somatic (sharp, well localized pain) & temperature;

Motor: above = ANS from pelvic splanchnics to smooth m.; below = somatomotor from pudendal nn. to skeletal m.

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18
Q

What fills the ischioanal fossa?

A

fat

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19
Q

What forms the roof of the ischioanal fossa?

A

The underside of the levator ani muscle.

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20
Q

What forms the lateral wall of the ischioanal fossa?

A

The medial aspect of the obturator internus muscle, lined with obturator fascia.

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21
Q

What forms the medial wall of the ischioanal fossa?

A

The underside of the levator ani muscle.

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22
Q

What is the relationship of the anterior recess of the ishioanal fossa to the UG diaphragm
(deep transverse perineal m.)?

A

It is a cavity immediately above the UG diaphragm (deep transverse perineal m.) continuous with the posteriorly located ischioanal fossa.

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23
Q

What structures are found in a sheath along the lateral wall of the ischioanal fossa?

A

The internal pudenal artery and vein and the pudendal nerve. They are in the pudendal canal (alcock’s canal)

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24
Q

What is the function of these vessels?

A

They supply the perineal region and external genitalia.

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25
What is the pathway of the internal pudendal artery and pudendal nerve prior to its appearance in this fossa?
They left the pelvic cavity via the greater sciatic foramen, passes under the sacrospinous ligament and entered the perineum via the lesser sciatic foramen by passing over the top of the sacrotuberous ligament.
26
Be able to label a coronal section through the male and female pelvic/perineal regions.
This objective is done in more detail later.
27
What is Scarpa's fascia?
The deep aspect of the superficial fascia of the lower abdomen and pelvis.
28
What does Scarpa’s fascia form?
The membranous layer of superficial fascia (Scarpa’s fascia) can be subdivided into a number of continuous fascial layers in the perineum (Buck’s, Colle’s, etc.) that essentially define the outermost extent of the superficial perineral space/pouch.
29
What are the contents of the deep perineal space (pouch)?
Boundaries of the deep perineal space are: superior fascial layer of the deep transverse perineal m.; and the inferior fascial layer of the deep transverse perineal m. - the perineal membrane. Contents: the deep transverse perineal m., the sphincter urethra m., the membranous urethra and the bulbourethral glands (in the male). Also the dorsal nerves and arteries of the penis/clitoris. In the female it is the two muscles, the urethra and vagina.
30
What are the contents of superficial perineal space (pouch)?
The crura of the penis and clitoris + the ischiocavernosus muscle, the bulb of the penis in the male and vestibular bulbs in the female + the overlying bulbospongiosus muscle. In the female the greater vestibular glands are also found in the space. Also the superficial transverse perineal muscle and the perineal a,v,n.
31
How is the spread of extravasated urine contained?
The membranous layer of superficial fascia (Scarpa’s) fuses with the UG diaphragm posteriorly and with the fascia lata of the thigh laterally. It does not therefore spread posteriorly into the anal triangle or inferiorly into the thigh.
32
In which space (pouch) is this extravasated urine located?
The superficial perineal space/pouch.
33
What structure(s) form the what used to be called the urogenital (UG) diaphragm?
The deep transverse perineal muscle and the sphincter urethra.
34
Where is the UG diaphragm located in the male?`
At the inferior border of the prostate.
35
Which of the two structures of the UG diaphragm form its major component?
The deep transverse perineal muscle.
36
What structures pierce the UG diaphragm (deep transverse perineal m.) in the male?
The membranous urethra.
37
What structures are found along the posterior edge of the deep transverse perineal m.?
The superficial transverse perineal muscle.
38
The penis is composed of how many cylinders of erectile tissue? What are they wrapped in?
3.. wrapped in buck's fascia
39
What are the two paired dorsal ones called?
Corpora cavernosa (paired) corpus cavernosum (individually).
40
What is thick CT capsule of these two cylinders called?
The tunica albuginea. 2nd layer pierced of testis
41
What is the single, unpaired ventral cylinder called?
The corpus spongiosum.
42
Why doesn't the unpaired cylinder have a thick CT capsule?
It does not become as rigid during erection.
43
What is the implication of having the urethra traverse this unpaired cylinder?
The urethra must remain patent to allow ejaculation so it does not become as rigid.
44
What is the dilated distal end of the corpus spongiosum called?
The glans penis
45
What is the dilated proximal portion of the corpus spongiosum called?
The bulb of the penis.
46
What does the shaft of the penis consist of?
Three cylinders of erectile tissue.
47
What structures lie under the deep transverse perineal m. in the male?
The crus and bulb of the penis.
48
What muscle layers cover the bulb of the penis?
The bulbospongiosus.
49
What muscle layers cover the crura of the penis?
The ischiocavernosus.
50
What fascial layer overlies all these muscles?
The membranous layer of superficial (Colle’s) fascia.
51
Be able to label a diagram of the male perineal region in both the lithotomy and coronal views.
The diagrams on the bottom left of page 261 and bottom of page 264 are important and have been used on the exam before.
52
What is the outer serous lining on the testis?
The visceral tunica vaginalis.
53
Where did this serous lining come from?
The peritoneum.
54
Where is the parietal counterpart to this visceral serous membrane?
On the inside of the scrotal wall.
55
What separates one testis from the other?
A fibrous median septum.
56
What gives the scrotum its wrinkled appearance? Why?
The dartos muscle. The fibers of this muscle insert directly into the skin (no deep fascia covers it).
57
What is the function of the dartos muscle?
It elevates/lowers the testes to keep them at a constant 95 degree temperature, ideal for spermatogensis.
58
Be aware of the contents of the pudendal cleft in the female, in order from anterior to posterior.
Clitoris, urethral opening, vaginal opening.
59
What is the frenulum and where is it found?
The anterior union of the labia minora, just under the glans clitoris.
60
What is the fourchette and where is it found?
The posterior union of the labia minor just posterior to the vaginal opening.
61
What structures pierce the deep transverse perineal m. in the female?
The urethra and vagina.
62
What structure has separated the bulb of the penis into two smaller bulbs in the female?
The vagina
63
What structures lie under the deep transverse perineal m. in the female?
The crura of the clitoris and the vestibular bulbs.
64
What muscle layers cover the bulbs of the vestibule?
The bulbospongiosus.
65
What muscle layers cover the crura of the clitoris?
The ischiocavernosus.
66
What fascial layer overlies all these muscles?
The membranous layer of superficial (Colle’s) fascia.
67
Be able to label a diagram of the female perineal region in both the lithotomy and coronal views as well as a sagittal section through the pelvis that would include the internal reproductive organs.
These diagrams (page 262 and bottom of page 265) have been used on the exam before.
68
The perineum lies inferior to _____ and medial to _____
levator ani m. (roof of perineum, floor of pelvis) sacrotuberous ligament
69
Name the muscles that attach to the perineal body
1) levator ani 2) deep perineal mm. 3) bulbospongiousus mm. 4) external anal sphincter therefore tears of this may lead to prolapse
70
The _____ sends ____ into the testes that converge to form the _____.
tunica albuginea septa mediastiunum testis (which contains rete testis)
71
The round ligament of the uterus ends in the ______
fatty connective tissue of the labia majora
72
The labia minor divide into an upper fold called the __ that encloses the ___ and a lower fold called the ____. They unite posteriorly to form the
prepuce glans clitoris frenulum of the clitoris frenulum of the labia minor (fourchette) (ruptured first in child birth)
73
list the main arterial branches off the internal pudendal artery and what they supply (5)
1) inferior rectal arteries: rectum 2) dorsal arteries of the penis/clitoris: deep perineal pouch and skin of penis/clitoris 3) artery to the bulb of the penis/vestibule 4) deep arteries of the penis / clitoris: erectile tissue/ corpus cavernosum 5) perineal arteries: skin overlying superficial pouch, posterior scrotum, ischocavernosus m., bublospongiousis m.
74
What does the inferior rectal nerve supply? the perineal nerves? the dorsal nerve nerve of the penis/clitoris?
- inferior rectal: external anal sphincter & overlying skin - perineal: lots - dorsal: terminal branch, glans penis/clitoris.

Anatomy 3 (8 decks)

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