Perineum

Question 1

Perineum

Answer 1

Shallow compartment bounded by pelvic outlet 
1. Pelvic diaphragm fascia separates it from pelvic cavity
2. Surface diamond-shaped
  A. Mons pubis - anterior
  B. Medial thighs - lateral
  C. Gluteal folds - posterior
3. Bony boundaries
  A. Pubic symphysis
  B. Ischiopubic rami
  C. Ischial tuberosities
  D. Sacrotuberous lig
  E. Sacrum
  F. Coccyx
4. Anal canal
5. Urogenital triangle
6. Perineal body

Question 2

Anal triangle

Answer 2

1. Anal canal
2. Anus
3. Surrounded by ischio-anal fat

Question 3

Urogenital triangle

Answer 3

1. Closed by perineal membrane between ischiopubic rami
2. Urethra
3. Vagina
4. Membrane provide attachment for erectile bodies

Question 4

Perineal body

Answer 4

Central tendon of perineum
1. Irregular mass of collagenous and elastic muscles
2. Skeletal and smooth muscles posterior vaginal vestibule/bulb of penis and anterior angus
3. Muscle convergence
A. Bulbospongiosus
B. External anal sphincter
C. Superficial and deep transverse perineal
D. External urethral sphincter
E. Levator ani
F. Muscular coats of rectum
4. Blends w/ posterior border of perineal membrane anteriorly and rectovesical or rectovaginal septum superiorly

Question 5

Perineal fascia

Answer 5

1. Superficial fatty layer of subcutaneous
2. Deep membranous layer of subcutaneous
3. Deep perineal fascia (investing or Gallaudet)

Question 6

Superficial fatty layer of subcutaneous peritoneal fascia

Answer 6

1. Both sexes continuous posteriorly w/ ischio-anal fat pad
2. Females: continuous to labia majora and mons pubis
   A. Continuous w/ Camper’s fascia in abdominal cavity
3. Males: diminished in urogenital triangle
   A. Replaced by Darto’s in penis and scrotum

Question 7

Deep membranous layer of subcutaneous peritoneal fascia

Answer 7

1. Doesn’t extend into anal triangle
2. Attaches posterior margin perineal membrane and perineal body posteriorly and fascia lata laterally
3. Females: continuous w/ abdominal deep membranous fascia
4. Males: colles fascia couninuous w/ Dartos in scrotum and penis and scarpa’s in abdomen

Question 8

Deep perineal fascia

Answer 8

Investing or Gallaudet
1. Invests
  A. Ischiocavernosus
  B. Bulbospongiosus
  C. Superficial transverse perineal
2. Attaches
  A. Ischiopubic rami laterally
  B. Suspensatory lig of penis/clitoris anteriorly
3. Continuous w/ deep fascia in abdomen

Question 9

Superficial perineal pouch

Answer 9

1. Potential space between perineal fascia and membrane
2. Males
   A. Root of penis
   B. Ischiocavernosus m.
   C. Bulbospongiosus m.
   D. Bulbous part spongy urethra
   E. Superficial transverse perineal m.
   F. Deep perineal branch of internal pudendal vessels and nerves
3. Female
   A. Clitoris
   B. Ischiocavernosus m.
   C. Bulbs of vestibule
   D. Bulbospongiosus m.
   E. Greater vestibular glands
   F. Superficial transverse perineal m.
   G. Deep perineal branch of internal pudendal vessels and nerves

Question 10

Deep perineal pouch

Answer 10

1. Boundaries
  A. Perineal membrane - inf
  B. Inf fascia pelvic diaphragm - sup
  C. Obturator fascia - lat
2. Both sexes
  A. Part of urethra
  B. Inf part external erethral sphincter m.
  C. Ant extension of ischio-anal fat pads
3. Males 
  A. Intermediate urethra 
  B. Deep transverse perineal m.
  C. Bulbourethral glands
  D. Dorsal neurovascular structures of penis
4. Females
  A. Prox urethra
  B. Mass of smooth muscle
  C. Dorsal neuorvasculature of clitoris

Question 11

Anal triangle

Answer 11

1. Ischio-anal (ischiorectal) fossae
2. Pudendal canal (Alcock canal) and neurovascular bundle
3. Anal canal

Question 12

Ischio-anal (ischiorectal) fossae

Answer 12

Part of anal triangle

1. Fascia-lined, wedge-shaped spaces on sides of anal canal between skin and pelvic diaphragm
2. 2 communicate by posterior natal space over anococcygeal lig
3. Fat-filled: support anal canal but allow movement

Question 13

Pudendal canal (Alcock canal)

Answer 13

Part of anal triangle
1. Horizontal passageway w/in obturator fascia
2. Enter at lesser sciatic notch
A. Internal pudendal a. And v.
B. Pudendal n.
C. N. To obturator internus
3. Internal pudendal vessels and pudendal n. Serve most of perineum
A. Micturation
B. Defecation
C. Erection
D. Ejaculation
E. Parturition
4. Internal pudendal a. And n. -> inf rectal a. And n.
A. Passes medially -> external sphincter and peri-anal skin
B. Inf. Rectum

Question 14

Pudendal n.

Answer 14

S2-S4
1. Major n. Of perineum
2. Exits sacral foramina, under greater sciatic foramen
3. Enters perineum via lesser sciatic foramen
4. Branches
A. Inferior rectal n. - external sphincter and anal canal inf pectinate line
1. Communicates w/ perineal br. Of post cutaneous n. In thigh
B. Perineal n.
C. Dorsal n. Of penis/clitoris

Question 15

Perineal n.

Answer 15

1. Superficial n. -> post scrotal/labial (cutaneous) br.

2. Deep n. -> muscles of deep and superficial perineal pouches, skin of vestibule, mucosa innermost vagina

Question 16

Dorsal n. Of penis/clitoris

Answer 16

Primary sensory n. Of penis/clitoris

1. Skin
2. Prepuce
3. Glans penis/clitoris, external urethral sphincter

Question 17

Anal canal

Answer 17

Terminal portion of GI tract from superior pelvic diaphragm -> anus

1. Puborectalis m. Sling = boundary from rectum
2. Surrounded by internal and external sphincters
3. Internal anal sphincter
4. External anal sphincter
5. Anal columns
6. Anorectal junction
7. Pectinate line

Question 18

Internal anal sphincter

Answer 18

Part of anal canal
1. Involuntary
2. Sup 2/3 anal canal
3. Thickening circular muscle layer
    A. Tonic contraction stim
       1. Sympathetic superior rectal
       2. Sympathetic hypogastric 
    B. Inhibited
       1. Parasympathetic pelvic splanchnic n.
       2. Distension rectal ampulla
       3. Requires voluntary contraction of sphincter to inhibit defecation

Question 19

External anal sphincter

Answer 19

Part of anal canal
1. Voluntary
2. Inf 1/3 anal canal
3. Attached
  A. Perineal body - ant
  B. Coccyx - post
4. Subcutaneous, superficial, deep parts - zones instead of bellies
5. Mostly S4 innervation via inf rectal n.

Question 20

Anal columns

Answer 20

Part of anal canal
1. Sup 1/2 mucous layer - longitudinal columns
A. Terminal branches sup rectal a. And v.

Question 21

Anorectal junction

Answer 21

Part of anal canal
1. Where rectum joins anal canal
A. Anal columns end and join anal valves
B. Recesses -> mucus when compressed by feces

Question 22

Pectinate line

Answer 22

Inf limit anal canal, separate visceral and somatic portions
1. Sup and inf differ
  A. Histology
  B. Arterial supply
  C. Innervation
  D. Venous and lymphatic drainage
2. Sup to pectinate line
  A. Supply from IMA
    1. Superior rectal a.
  B. Drain portal venous system 
  C. Lymph -> internal iliac nodes
  D. Hypogastric plexus
    1. Sympathetic- tone sphincter
    2. Parasympathetic- relax sphincter
    3. Visceral afferent travel w/ S2-S4
3. Inf to pectinate line
  A. Supply from internal iliac a. 
  B. Drain caval venous system via inf rectal v.
  C. Lymph -> sup inguinal nodes
  D. Inf rectal n.
    1. Sensory: pain, touch, temp
    2. Somatic: sphincters

Question 23

Superficial perineal muscles

Answer 23

1. Innervation by deep branch perineal n
2. Superficial transverse perineal m.
3. Ischiocavernosus m.
4. Bulbospongiosus m.

Question 24

Superficial transverse perineal

Answer 24

1. Prox: internal surface ischiopubic rami and ischial tuberosity
2. Distal: post border perineal body
3. Fxn: supports and fixes perineal body -> support abdominopelvic viscera and resist inc pressure
4. Innervation: deep branch perineal n.

Question 25

Ischiocavernosus m.

Answer 25

1. Prox: internal surface ischiopubic rami and ischial tuberosity 2. Distal: inf and medial crus and perineal membrane 3. Fxn: maintains erection - contracts around veins or erectile organs 4. Innervation: deep branch perineal n.

Question 26

Bulbospongiosus m.

Answer 26

1. Males A. Prox: median raphe on ventral surface bulb of penis and perineal body B. Distal: perineal membrane 1. Surrounds bulb of penis C. Fxn: 1. Support and fixes perineal body 2. Compress bulb of penis -> expel urine/semen 3. Assists erection - compresses outflow and pushes blood from bulb into penis 2. Females A. Prox: perineal body 1. Encloses bulb and greater vestibule glands B. Distal: pubic arch and corpora cavernosa fascia of clitoris C. Fxn: 1. Supports and fixes perineal body 2. “Sphincter” of vagina 3. Assists in erection of clitoris 4. Compresses greater vestibule glands

Question 27

Male urogenital triangle: external genitalia

Answer 27

1. Distal male urethra 2. Scrotum 3. Penis

Question 28

Distal male urethra

Answer 28

1. Intramural: extends thru neck of bladder, surrounded by internal urethral sphincter 2. Prostatic: descends thru prostate, bound by rhabdosphincter A. Urethral crest w/ seminal colliculus B. Flanked by prostatic sinuses C. Ejaculatory ducts open into colliculus (union of urinary and reproductive tracts) 3. Intermediate (membranous): begins apex of prostate and passes thru deep perineal pouch A. Surrounded by external urethral sphincter B. Penetrates perineal membranous and ends as it enters bulb of penis 4. Spongy: thru corpus spongiosum and ends at external urethral orifice A. Narrow except bulb of penis and glans (navicular fossa) B. Bulbo-urethral glands and urethral glands open into it

Question 29

Scrotum

Answer 29

Cutaneous fibromuscular sac that houses testes and assoc. structures 1. Midline scrotal raphe: continuous w/ penile raphe (ventral surface of penis) and perineal raphe 2. Septum of scrotum: continuous dartos fascia, separate scrotum -> 2 compartments 3. Arterial supply: anterior scrotal a. And post scrotal a. 4. Innervation: ilio-inguinal and perineal br. Of pudendal br. Of pudendal n.

Question 30

Penis

Answer 30

1. 3 cavernous bodies erectile tissue: paired corpora cavernosa (dorsally) and single corpus spongiosum that houses spongy urethra (ventrally) A. All have fibrous covering = tunica albuginea 2. Root A. Crura B. Bulb C. Ischiocavernosus m. D. Bulbospongiosus m. E. In superficial perineal pouch between membrane and deep perineal fascia 3. Body A. Skin B. CT C. Blood and lymph vessels D. Fascia E. Corpora cavernosa F. Corpus spongiosum w/ spongy urethra -> surface of glans G. Skin + fascia = prepuce at neck of glans H. Suspensory lig: deep fascia anchors erectile bodies to pubic symphysis 1. Spilts and surrounds penis and unites -> blends w/ dartos fascia -> scrotal septum

Question 31

Female urogenital triangle

Answer 31

1. External genitalia A. Mons pubis B. Labia majora C. Labia Minorca D. Clitoris (root and body) 1. 2 crura 2. 2 corpora cavernosa 3. Glans E. Vestibule of vagina: space surrounded by labia minora 1. Paraurethral gland: open on medial aspect labia minora 2. Vaginal orifice and hymen 3. Bulbs of vestibule: erectile 4. Greater vestibular glands (Bartholin glands): secrete mucus into vestibule during arousal 5. Lesser vestibular glands: moisten labia and vestibule

Question 32

Ilio-inguinal n. (L1)

Answer 32

1. Skin at root penis 2. Ant scrotum 3. Labia majora

Question 33

Cavernous nerves

Answer 33

Parasympathetic | 1. Helicine arteries erectile tissue

Question 34

Peritoneal lymphatic drainage

Answer 34

``` 1. Superficial inguinal nodes -> lumbar aortic nodes A. Lower abdominal wall B. Buttocks C. Penis D. Scrotum E. Labia majora F. Inf vagina G. Anal canal 2. Deep inguinal nodes and external iliac nodes A. Glans penis/clitoris B. Labia minora ```