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Endo Exam 2 > Pelvis and Perineum (Anatomy) > Flashcards

Pelvis and Perineum (Anatomy) Flashcards

1
Q

Pelvis and pelvic cavity overview

A

A. The pelvis is the inferior part of the trunk, continuous with the abdomen.

B. The pelvic cavity is the inferior portion of the abdominopelvic cavity, enclosed by the pelvic girdle. The pelvic cavity houses the reproductive organs, portions of the urinary system, as well as the inferior portion of the GI tract.

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2
Q

Perineum overview

A

C. The perineum is a diamond-shaped space located inferior to the pelvis, bounded by the coccyx and pubis and thighs laterally. It is divided into urogenital and anal triangles. The perineum contains the anal canal, external genitalia, and distal portion of urinary system.

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3
Q

Pelvic Girdle, structure and function

A

A. Basin-shaped bony structure supporting and protecting inferior abdominopelvic cavity.

B. Function

a. Support pelvic and lower abdominal viscera.
b. Attach the lower limbs to the vertebral column.
c. Bear the weight of upper body and transfer this weight to the lower limbs.
d. Muscle and fascial attachment.

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4
Q

Osseous Components of Pelvis

A

Os Coxa: Pubis, ischium, Ilium

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5
Q

Pubis parts

A
  1. Body
  2. Superior ramus
  3. Inferior ramus
  4. Crest
  5. Tubercle
  6. Pectineal line
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6
Q

Ischium parts

A
  1. Body
  2. Ramus (ischiopubic ramus)
  3. Lesser sciatic notch
  4. Spine
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7
Q

Ilium parts

A
  1. Ala
  2. Body
  3. Anterior superior iliac spine (ASIS)
  4. Anterior inferior iliac spine (AIIS)
  5. Posterior superior iliac spine (PSIS)
  6. Posterior inferior iliac spine (PIIS)
  7. Greater sciatic notch
  8. Arcuate line
  9. Auricular surface (for articulation with sacrum)
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8
Q

Orientation in anatomical position

A

a. ASIS and the pubic symphysis lie in the same coronal plane.
b. The pelvis tips forward 50-60o from the horizontal.
c. Sacral promontory directly superior to perineal body.

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9
Q

False (greater) Pelvis

A
  1. Superior to pelvic inlet

2. Contains abdominal organs (ileum, sigmoid colon)

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10
Q

True (lesser) Pelvis

A
  1. Inferior to pelvic inlet
  2. Contains: rectum, bladder, reproductive organs
  3. Separated from perineum by pelvic outlet (enclosed by pelvic diaphragm).
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11
Q

Pelvic inlet (pelvic brim)

A
  1. Bounded by:
    a. Pubic crest
    b. Pectineal line
    c. Arcuate line
    d. Promontory and ala of sacrum
    e. a+b+c = “terminal line”
  2. Separates true and false pelves
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12
Q

Pelvic outlet

A
  1. Bounded by:
    a. Pubic symphysis
    b. Ischiopubic ramus
    c. Ischial tuberosity
    d. Sacrotuberous ligament
    e. Coccyx
  2. Separates true pelvis from perineum
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13
Q

CLINICAL CORRELATION: Pelvic fractures

A
  1. Pelvic fractures are typically multiple and often result from traumatic compression.
  2. Weak areas of pelvic girdle include: pubic rami, area around acetabulum, region of sacroiliac joint, and alae of ilium.
  3. May cause damage to urinary bladder (and deeper structures).
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14
Q

Sexual dimorphism of the pelvic girdle

A

female: thin and light, shallow greater pelvis, wide, wide and shallow cylindrical lesser pelvis, oval and rounded wide inlet, comparatively large outlet, wide pubic arch and subpubic angle.
male: thick and heavy bones, deep greater pelvis, narrowo and deep tapered lesser pelvis, heart shaped narrow pelvic inlet, comparatively small outlet, narrow (

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15
Q

Classification of pelves

A
  1. Heart-shaped pelvic inlet.
  2. Most common male pelvis; 30% of female pelves.
  3. May present problems for vaginal delivery.
    b. Gynecoid
  4. Oval-shaped pelvic inlet.
  5. Most common female pelvis (47%).
    c. Anthropoid
  6. Exaggerated anterior/posterior inlet.
  7. 2nd most common male pelvis; 20% of female pelves.
    d. Platypelloid
  8. Exaggerated transverse inlet diameter.
  9. Least common in both sexes.
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16
Q

Pubic symphysis

A
  1. Articulation between opposing pubic bones.
  2. Symphysis joint – bones united by fibrocartilaginous disc (interpubic disc).
  3. Supporting ligaments
  4. Superior pubic ligament
  5. Inferior public ligament (arcuate ligament)
  6. Interpubic disc is thicker in females than males.
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17
Q

definition of a symphysis

A

2 bones united by fibrocartilage

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18
Q

Sacroiliac joint - articulation, movements, and ligaments

A

a. Articulation between sacrum and ilium.
b. Anterior portion of joint is synovial between auricular surface of sacrum and ilium.
c. Posterior portion of joint is a syndesmosis between the tuberosities of sacrum and ilium.
d. Allows limited gliding and rotary movements; movement is limited due to irregular surfaces of bony surfaces and strong supporting ligaments.
e. Supporting ligaments:
1. Anterior sacroiliac ligament
2. Posterior sacroiliac ligament
3. Interosseous sacroiliac ligament (syndesmosis portion of joint)
a. These are thick, strong ligaments that span from tuberosity of the ilium to tuberosity of the sacrum.
b. Main structures involved in transmitting the weight of the axial skeleton to the pelvis and ultimately to the lower limb.
4. Sacrotuberous ligament
a. Extends from sacrum, coccyx, and ilium to ischial tuberosity.
b. Limits posterosuperior rotation of sacrum and coccyx.
5. Sacrospinous ligament – from sacrum to ischial spine.
6. The sacrospinous and sacrotuberous ligaments transform the sciatic notches into greater and lesser sciatic foramina.

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19
Q

what is a syndesmosis?

A

2 bones are connected by ligaments (very strong, thick, usually)

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20
Q

Which ligaments form the syndesmosis part of the sacroiliac joint?

A

the interosseous ligaments

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21
Q

Lumbosacral joints

A

a. Articulation between LV5/SV1
b. Typical features of intervertebral joint
c. Fibrocartilaginous intervertebral disc
d. Synovial zygapophysial joints
e. The iliolumbar ligament supports this joint and also supports the sacroiliac joint.

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22
Q

Sacrococcygeal joint

A

a. Articulation between sacrum and coccyx.
b. Symphysis joint
c. Supporting ligaments
1. Anterior sacrococcygeal ligament
2. Posterior sacrococcygeal ligament

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23
Q

CLINICAL CORRELATION: Pelvimetry

A
  1. Used in obstetrics to assess the dimensions of the pelvis for management of labor.
  2. Diameters of the pelvic inlet
    a. True (obstetric) conjugate – sacral promontory to mid-level of pubic symphysis; narrowest fixed distance which infant’s head must pass during vaginal delivery.
    b. Diagonal conjugate – sacral promontory to inferior margin of symphysis
    c. Oblique –sacroiliac articulation to iliopectineal eminence.
    d. Transverse – greatest width of the pelvic inlet; arcuate line to arcuate line.
  3. Diameters of the pelvic outlet
    a. Transverse diameter – from ishial tuberosity to ischial tuberosity.
    b. Anteroposterior diameter – from pubic symphysis to coccyx.
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24
Q

CLINICAL CORRELATION: Pregnancy and Pelvic Articulations

A
  1. The sacroiliac and pubic symphysis joints are sensitive to pregnancy-related hormones; primarily relaxin which is produced by the placenta.
  2. Relaxation of these joints can increase the diameters of the pelvis by 10-15%.
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25
Q

Most important structure in forming the floor of the pelvis?

A

the pelvic diaphragm

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26
Q

Pelvic Wall Muscles: Obturator internus

A

a. Origin: Inner surface of obturator foramen
b. Insertion: Greater trochanter of the femur
c. Nerve Supply: n. to obturator internus (L5,S1,S2)
d. Action: Lateral rotation of the thigh
e. Tendon of muscle exits the lesser pelvis via the lesser sciatic foramen.
f. Muscle is covered by a thick obturator fascia. A medial thickening of this fascia forms attachment site for levator ani musculature (tendinous arch of levator ani).

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27
Q

Pelvic Wall muscles: Piriformis

A

a. Posterolateral wall and roof of pelvis
b. Origin: Sacrum
c. Insertion: Greater trochanter of the femur
d. Nerve Supply: n. to piriformis (S1,S2)
e. Action: Lateral rotation and abduction of the thigh
f. Exits the lesser pelvis via the greater sciatic foramen.

28
Q

Pelvic floor muscle: pelvic diaphragm

A

a. Hammock-shaped set of muscles which partially close the pelvis inferiorly.
b. Separates lesser pelvis from perineum.
c. The main action of the pelvic diaphragm is to support the pelvic viscera and resist increases in abdominal pressure (for example, during coughing, sneezing, etc).
d. When the pelvic diaphragm contracts, it elevates.
e. The pelvic diaphragm is incomplete centrally to allow for passage of viscera from pelvis to perineum; rectum and urethra and in the female, the vagina (urogenital/levator hiatus).
f. A second diaphragm, the urogenital diaphragm provides support for midline structures: urethra, vagina (female), and prostate (male).
g. Composed of levator ani and coccygeus muscles

29
Q

Levator Ani muscle: Puborectalis m.

A
  1. Origin – pubis
  2. Insertion – opposite puborectalis m. posterior to the rectum
  3. Innervation – S3, S4
  4. Forms the lateral boundaries of the urogenital hiatus.
  5. Muscle fibers pass posterior to the rectum and merge with fibers from the opposite side, forming the puborectal sling around the rectum. The puborectalis is tonically contracted to maintain the anorectal junction; an important mechanism in maintaining fecal continence.
  6. Midline slips of muscle from puborectalis form supporting muscles:
    a. Puboprostaticus (male)
    b. Pubovaginalis (female)
30
Q

Levator Ani muscle: Pubococcygeus m.

A
  1. Origin – pubis, tendinous arch of levator ani
  2. Insertion – coccyx and anococcygeal body (referred to clinically as the levator plate).
  3. Innervation – S3, S4
31
Q

Levator Ani muscle: Iliococcygeus m.

A
  1. Origin – tendinous arch of levator ani, ischial spine
  2. Insertion – anococcygeal body
  3. Innervation – S3, S4
32
Q

Coccygeus m.

A

a. Origin – ischial spine
b. Insertion –coccyx and sacrum
c. Innervation – S4, S5 ventral rami

33
Q

2 muscles that compose the pelvic diaphrabm

A

leavtor ani and coccygeus

34
Q

Pelvic Peritoneum

A
  1. Continuation of abdominal peritoneum into pelvis.
  2. Does not reach pelvic floor; draped over upper portions of pelvic viscera.
  3. Peritoneal coverings of viscera
    a. The urinary bladder is peritonealized only on its superior surface; the urethra is subperitoneal (inferior to the peritoneum).
    b. Female reproductive organs
  4. Uterus, uterine tubes are peritonealized. The broad ligament is a thick, double layer of peritoneum extending from uterus to lateral pelvic walls.
  5. The ovaries are suspended to the broad ligamented, but not actually invested with peritoneum.
  6. The cervix and vagina are subperitoneal.
    c. All male reproductive organs are subperitoneal.
    d. Rectum: superior third is peritonealized anteriorly and laterally, middle third is peritonealized anterioly, inferior third is subperitoneal.
35
Q

Peritoneal folds and fossae (male)

A
  1. Supravesical fossa – between anterior body wall and bladder.
  2. Paravesicle fossa – on either side of bladder
  3. Rectovesical pouch – between bladder and rectum.
  4. Pararectal fossa – on either side of lateral rectal wall; bounded laterally by sacrogenital folds (formed by thick ligaments underlying peritoneum; pass from base of bladder to sacrum).
36
Q

Peritoneal folds and fossae (female)

A
  1. Supravesical fossa
  2. Paravesicle fossa
  3. Vesicouterine pouch – between bladder and uterus.
  4. Rectouterine pouch (pouch of Douglas) – between uterus/vagina and rectum.
  5. Pararectal fossa – on either side of lateral rectal wall; bounded laterally by uterosacral (rectouterine folds) (homologue of sacrogenital fold).
37
Q

Pelvic Fascia: Membranous

A

a. Parietal layer
1. Covers internal surface of pelvic wall and floor (forms obturator internus, piriformis, pelvic diaphragm fasciae).
2. Obturator internus fascia is thickened along its horizontal midline to form the tendindous arch of levator ani.
b. Visceral layer
1. Covers pelvic viscera.
2. Where pelvic organs pass through pelvic diaphragm, membranous fascia is thickened and forms the tendindous arch of pelvic fascia.
a. Anterior part = puboprostatic (males) or pubovesical ligament (females).
b. Posterior part = sacrogenital (uterosacral) ligaments.

38
Q

Pelvic Fascia: Endopelvic

A

a. Loose fascia filling space between parietal and visceral membranous fascias.
b. Specializations:
1. Lateral ligament of bladder
2. Cardinal ligament (transverse cervical ligament) – conveys uterine vessels

39
Q

E. CLINICAL CORRELATION – During vaginal deliveries…

A

the muscles and fasciaes of the pelvic floor can be torn and damaged. This can lead to urinary and fecal incontinence in some women.

40
Q

Internal Iliac aa.origination

A

Originates from common iliac artery at LV5/SV1 level; anterior to sacroiliac joint.

41
Q

Internal iliac artery Posterior division

A
  1. Iliolumbar a. – courses superolaterally along the pelvic wall to the iliac fossa dividing into an iliac branch, supplying the iliacus m, and a lumbar branch, supplying psoas major and quadratus lumborum mm. and also sending a spinal branch through intervertebral space LV5/SV1.
  2. Lateral sacral a. – usually paired; course medially to provide sacral spinal branches to cauda equina.
  3. Superior gluteal a. – exits the pelvis via the greater sciatic foramen.
42
Q

Internal Iliac Artery Anterior Division

A
  1. Umbilical a. – courses along lateral pelvic wall and then ascends anterior body wall as the medial umbilical ligament.
    a. Superior vesicle a. – branch(s) of umbilical a.
    b. Artery to ductus deferens – branch of umbilical a.
  2. Obturator a. – courses along lateral pelvic wall to exit obturator canal.
  3. Uterine a. – to cervix, uterus. CLINICAL CORRELATION – the ureter passes beneath the uterine artery (“water passes under the bridge”). The ureter can inadvertently be damaged during hysterectomies.
  4. Vaginal a. – supplies vagina and cervix.
  5. Inferior vesicle a. – in males, provides branches to bladder and reproductive organs; in females, often replaced by vaginal a.
  6. Middle rectal a. – courses medially to rectum.
  7. Internal pudendal a. – exits pelvis via greater sciatic foramen, then passes around the ischial spine to reenter the perineum via the lesser sciatic foramen.
  8. Inferior gluteal a. – exits pelvis via greater sciatic foramen.
43
Q

Arterial Anastomoses- CLINICAL CORRELATION

A

Anastomotic connections exist amongst pelvic arteries providing important collateral circulation in cases of blockage or severing of the internal iliac a.

44
Q

Arterial Anastomoses of the Pelvis

A

b. Lumbar aa and deep circumflex iliac a.
1. Lower lumbar arteries from abdominal aorta.
2. Deep circumflex a is a branch of the external iliac a.
3. Anastomosis with iliolumbar a.

c. Ovarian a.
1. Arises from abdominal aorta below renal arteries.
2. Travels through the suspensory ligament of the ovary.
3. Anastomosis with uterine a.

The male homolog to that is:

d. Testicular a.
1. Arises from abdominal aorta below renal arteries.
2. Descends along posterior body wall to the deep inguinal ring, courses within spermatic cord.
3. Anastomosis with artery of ductus deferens.

e. Superior rectal a.
1. Arises from inferior mesentery a.
2. Provides branches to rectum, anastomoses with middle and inferior rectal aa.

f. Deep femoral aa.
1. Medial circumflex femoral branches participate in cruciate anastomosis
2. Anastomosis with inferior gluteal a.

g. Median sacral a.
1. Arises from abdominal aorta just prior to its bifurcation.
2. Anastomoses with lateral sacral artery and provides sacral spinal branches.

45
Q

Veins of the pelvis and clinical correlations

A
  1. Venous plexuses (rectal, vesicle, prostatic, uterovaginal); ultimately drain to venae comitantes of arteries and then to internal iliac vein.
  2. CLINICAL CORRELATION: Anastomotic connections (lateral sacral veins) link the venous plexuses of the pelvic viscera to the internal vertebral venous plexuses, creating potential routes of transmission for infections and metastatic tumor cells.
  3. CLINICAL CORRELATION: There are also important portocaval venous anastomoses within the rectum (see rectum, below).
46
Q

Lymphatic Drainage of Pelvis and Perineum

A

A. Major lymph nodes

  1. External iliac
  2. Internal iliac
  3. Sacral
  4. Common iliac
  5. Lumbar

B. Smaller groups of lymph nodes are found along smaller vessels (pararectal, uterine, etc)

C. General path of drainage:

  1. Internal iliac nodes → external iliac nodes → common iliac nodes → lumbar nodes → cistern chili → thoracic duct
  2. IMPORTANT: Exceptions are the testes/ovaries which drain to lumbar nodes directly
47
Q

Lymphatic Connections of Major Lymph Nodes

1. Sacral Nodes

A

a. Lie in concavity of sacrum; along median sacral arteries
b. Receive: posterior portions of pelvic viscera (urinary bladder, prostate, rectum, vagina)
c. Drain to: primarily to common iliac nodes.

48
Q

Lymphatic Connections of Major Lymph Nodes

  1. Internal Iliac Nodes
A

a. Receive: All pelvic viscera (EXCEPT ovary; testes), deep perineal space, gluteal region, pelvic wall
b. Drain to external iliac nodes.

49
Q

Lymphatic Connections of Major Lymph Nodes

3. External Iliac Nodes

A

a. Receive: Internal iliac nodes, direct drainage from superior portions of bladder, uterus, lower limbs, some from anterolateral abdominal wall.
b. Drain to common iliac nodes.

50
Q

Lymphatic Connections of Major Lymph Nodes

  1. Common Iliac nodes
A

a. Receive: external iliac nodes, sacral nodes

b. Drain to lumbar lymph nodes of abdomen.

51
Q

Lymphatic Connections of Major Lymph Nodes

  1. Lumbar Nodes
A

a. Receive: indirectly, all lymph from lower limb, perineum, pelvis via common iliac nodes
b. Receive: direct, lymph from ovary, testes, uterine tube, part of uterus

52
Q

Lymph- clinical correlation

A

The high degree of interconnections between pelvic lymphatic channels makes it fairly easy for pelvic cancers to spread to other organs.

53
Q

Sacral plexus overview

A

A. This is a somatic nerve plexus.

B. Ventral primary rami of L4-S5 (+ C0, the coccygeal nerve).

C. Formed within pelvis within and anterior to the piriformis muscle.

D. The lumbosacral trunk (L4-L5), carries these lumbar ventral rami to the sacral plexus.

E. Sensory and motor innervation to pelvic body wall, perineum, and lower limb.

54
Q

Sacral Plexus Branches

A
  1. Sciatic nerve (L4-S3)
    a. Largest branch of sacral plexus (largest nerve in body).
    b. Exits the pelvis via the greater sciatic foramen to enter gluteal region
    c. Innervates posterior thigh, leg, and foot.
  2. Pudendal nerve (S2-S4)
    a. Primary nerve of perineum; providing motor and sensory innervation.
    b. Exists pelvis via greater sciatic foramen to enter gluteal region, then loops around ischial spine (with internal pudendal vessels) and reenters perineum via the lesser sciatic foramen.
  3. Superior gluteal nerve (L4,L5,S1)
  4. Inferior gluteal nerve (L5,S1,S2)
  5. Nerve to quadratus femoris (L4,L5,S1)
  6. Nerve to obturator internus (L5,S1,S2)
  7. Nerve to piriformis (S1,S2)
  8. Nerve to levator ani and coccygeus (S3,S4, S5) – to pelvic diaphragm
  9. Anococcygeal nerve (S4, S5,Coccygeal) – sensory to skin over anal triangle.
55
Q

Overview of the Perineum- boundaries, divisions

A

A. Diamond-shaped area between coccyx and pubis.

B. Boundaries

  1. Anterior – pubic bones and pubic symphysis
  2. Anterolateral – ischiopubic rami
  3. Lateral – ischial tuberosities
  4. Posterior lateral – sacrotuberous ligaments
  5. Posterior – coccyx and sacrum
  6. Superior (roof) – pelvic diaphragm
  7. Inferior (floor) – superficial fascia and skin

C. The perineum is divided into anterior (urogenital) and posterior (anal) triangles by a line connecting the two ischial tuberosities.

56
Q

Fascias of the perineum: superfiscial fascia

A

a. Fatty layer (Camper’s fascia)
1. Abdomen – superficial fatty layer (Camper’s fascia)
2. Female UG triangle – forms fatty tissue of labia majora and mons pubis
3. Male UG triangle – replaced with a smooth muscle layer called Dartos fascia found within of scrotum and penis.
4. In anal triangle – forms ischioanal fat pad

b. Membranous layer (Scarpa’s fascia)
1. Abdomen – superficial membranous layer (Scarpa’s fascia)
2. Female UG triangle – Colle’s fascia
3. Male UG triangle – Colle’s fascia; also forms Dartos fascia found within of scrotum and penis.
4. In anal triangle – none

57
Q

Fascias of the perineum: deep fascia

A

(UG triangle only)

a. Females
1. Perineal membrane

b. Males
1. Perineal membrane
2. Buck’s fascia of penis

58
Q

Perineal body

A

(central tendinous point)

a. Connective tissue structure which functions to support mid-line viscera and a site for muscle attachment.
1. Bulbospongiosus
2. External urethral sphincter
3. Superficial and deep transverse perineal muscles
4. Levator ani
5. External anal sphincter
b. Located at midpoint of ischial tuberosities.
c. CLINICAL CORRELATION – Trauma or tearing of the perineal body can occur during childbirth; can result in a weakness of the floor of perineum and increased risk for prolapse of pelvic viscera into the perineum.

59
Q

Spaces of the UG triangle: Superficial perineal space- borders and contents (females and males)

A

a. Inferior border – Colles fascia
b. Superior border – perineal membrane
c. Contents (female)
1. Clitoris and bulbs of the vestibule
2. Ischiocavernosus and bulbospongiosus muscles
3. Superficial transverse perineal muscle
4. Urethra
5. Branches of pudendal nerve, internal pudendal vessels
6. Greater vestibular glands
d. Contents (male)
1. Root of the penis
2. Ischiocavernosus and bulbospongiosus muscles
3. Superficial transverse perineal muscle
4. Urethra
5. Branches of pudendal nerve, internal pudendal vessels

60
Q

Spaces of the UG triangle: Deep perineal space

A

a. Inferior border – perineal membrane (inferior fascia of UG diaphragm)

b. Superior border (current description) – pelvic diaphragm
c. Superior border (previous description) – superior fascia of UG diaphragm).

d. Contents
1. Urethra and vagina (female)
2. Sphincter urethrae
3. Deep transverse perineal muscle
4. Bulbourethral glands (male)
5. Branches of pudendal nerve, internal pudendal vessels
6. Anterior recess of ischioanal fat pad

e. Urogenital diaphragm (previous description); muscles of deep perineal space (current description)
1. Deep transverse perineal m
2. Sphincter urethrae

61
Q

Pudendal Canal

A

(Alcock’s canal)

  1. Fascial tunnel along the lateral wall of the ischioanal fossa, created by a split in the fascia on the medial surface of the obturator internus m.
  2. Carries: pudendal nerve and internal pudendal vessels
62
Q

Vascular Supply of Perineum: Internal pudendal artery

A

a. Branch of internal iliac a.
b. Course
1. Exits pelvis via the greater sciatic foramen, inferior to the piriformis.
2. Loops around ischial spine to enter the perineum via the lesser sciatic foramen.
3. Enters pudendal canal along lateral wall of ischioanal fossa.
4. Travels forward into deep space of UG triangle.
c. Branches
1. Inferior rectal a. – supplies anal triangle
2. Perineal a.
a. Muscular branches
b. Posterior scrotal/labial a.
3. Artery of the bulb of the penis/vestibule
4. Dorsal a. of penis/clitoris – supplies deep pouch, skin of penis/clitoris
5. Deep a. of penis/clitoris – travels in corpus cavernosum; supplies erectile tissue

63
Q

Internal pudendal vein

A

drains perineum

64
Q
  1. Deep dorsal vein of penis/clitoris
A

drains directly to prostatic/uterovaginal venous plexus

65
Q

Pudendal nerve

A

(S2-S4)

a. Provides motor (including sympathetic) and sensory innervation to perineum.
b. Course: see course of internal pudendal a. above.
c. Branches
1. Inferior rectal n. – supplies external anal sphincter, perianal skin
2. Perineal n. – supplies superficial and deep pouch
a. Superficial branch → posterior scrotal/labial n.
b. Deep branch → supplies all muscles of UG triangle
3. Dorsal n. of penis/clitoris – primary sensory nerve of penis, clitoris

66
Q

Minor cutaneous nerves

A

ilioinguinal, posterior femoral cutaneous, anococcygeal nn.

67
Q

What nerve provides all motor innervation to the muscles of the UG triangle?

A

the perineal nerve

Endo Exam 2 (14 decks)

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