28. Male and Female Perineum

Question 1

Viewed from below, the perineum is a diamond-shaped area located between the thighs — what are the lateral, posterior, and anterior boundaries of the perineum?

Answer 1

Lateral = ischiopubic rami and sacrotuberous ligament

Posterior = coccyx

Anterior = pubic symphysis

Question 2

The perineum can be described as a 3D structure which has superior and inferior limits. The superior boundary, or _____ _____ separates the perineum from the pelvic cavity. The inferior boundary is the surface of the skin associated with the ______ _____ and anal canal

Answer 2

Pelvic diaphragm; external genitalia

Question 3

The perineum can be divided into 2 triangles by drawing an imaginary horizontal line between the 2 _____ _______. In the midline, this line will pass through the ____ ______.

What are the 2 named triangles this line makes?

Answer 3

Ischial tuberosities; perineal body

Urogenital triangle; anal triangle

Question 4

What are the boundaries of the urogenital triangle?

Answer 4

Pubic symphysis
Ischiopubic rami
Imaginary line drawn between ischial tuberosities

Question 5

What are the boundaries of the anal triangle?

Answer 5

Coccyx
Sacrotuberous ligaments
Imaginary line drawn between ischial tuberosities

Question 6

The _____ ______ are wedge-shaped spaces on either side of the anal canal

Answer 6

Ischiorectal fossae

Question 7

What are the boundaries of the ischiorectal fossae including the lateral walls, superomedial walls, and bases?

Answer 7

Lateral wall = obturator internus and ischium

Superomedial wall = levator ani and anal canal

Base = skin of perineum

Question 8

The ____ ___ is 4 cm long and continuous with the rectum. It is oriented in a posteroinferior direction, due in part fo the anterior pull of the _______ m. It terminates at the anus

Answer 8

Anal canal; puborectalis

Question 9

2 sets of anal sphincters surround the anal canal. The _______ is a layer of circular smooth muscle found in the upper 2/3 of the anal canal; it is controlled by _______ fibers from ______ nerves

Answer 9

Internal anal sphincter; parasympathetic; pelvic splanchnic

Question 10

The ________ is composed of circular skeletal muscle which surrounds the lower 2/3 of the anal canal. These muscle fibers are attached to the _____ ligament posteriorly, and the ________ anteriorly. It is consciously controlled by the ______ n., a branch of the ______ n.

Answer 10

External anal sphincter; anococcygeal; inferior rectal; pudendal

Question 11

What anatomical distinction makes distension of the anal canal possible during defecation?

Answer 11

Made possible bc the ischiorectal fossae are filled with fat (in other words, there are no vital organs in close proximity to interfere with its distention)

Question 12

On the lateral walls of the ischiorectal fossae are the ____ _____, located on the medial surface of the ____ ___ m.

Answer 12

Pudendal canals; obturator internus

Question 13

Contained within the pudendal canals are the _____ n. and the _______ a. and v. Passing from the pudendal canal to the anal canal are the _______ artery, vein, and nerve which travel through the ischiorectal fossae

Answer 13

Pudendal; internal pudendal; inferior rectal

Question 14

The urogenital triangle can be divided into _____ and _____ spaces

Answer 14

Deep; superficial perineal

[pouches or spaces]

Question 15

The deep perineal pouch in the urogenital triangle include the _____ _____, a continuous sheet of muscle that spans the gap between the ischiopubic rami. The superior fascia and inferior fascia of the perineal membrane are fused along the anterior and posterior borders. The ____ _____ is attached to the midpoint of the posterior border

Answer 15

Urogenital diaphragm; perineal body

Question 16

In women, the urogenital diaphragm is split into two halves by the vagina. Contained within this diaphragm are the following:

The first part of the urethra in ______, and the membranous urethra in _____.

Deep perineal muscles: in males, the external urethral sphincter surrounds the _________ urethra. It relaxes to allow urination to occur or when ejaculation occurs. The ___________ m. inserts in the perineal body in both males and females.

The _______ glands in males have ducts which empty into the ______ urethra; during sexual excitement they secrete a clear mucous which lubricates the urethra prior to ejaculation

Answer 16

Females; males

Membranous; deep transverse perineus

Bulbourethral; penile

Question 17

The superficial perineal space is a potential space deep to the perineal skin that covers the external genitalia. In females, this space is split in 2 halves by the _____ of the vagina.

Answer 17

Vestibule

Question 18

What are the contents of the superficial perineal space in males?

Answer 18

Root of penis + right and left crura
Bulb of penis
Ischiocavernosus m.
Bulbospongiosus m.
Superficial transverse perineus m.

Question 19

In males, the _____ m. (bilateral) surround the free surface of each _____ of the root of the penis. They attach to the ischiopubic rami and insert into the _____ _____ which is comprised of erectile tissue

Answer 19

Ischiocavernosus; crus; corpora cavernosa

Question 20

How do the ischiocavernosus and bulbospongiosus mm. help to maintain an erection in males?

Answer 20

They compress the veins which drain the corpora cavernosa

Question 21

The _____ m. in males arises from the perineal body and raphe of the penis, then wraps around the bulb and posterior part of the _____ ______, which is also comprised of erectile tissue. It aids in compressing/emptying the urethra of urine or semen.

Answer 21

Bulbospongiosus; corpus spongiosum

Question 22

______ _____ fascia covers the muscles in the superficial perineal space

Answer 22

Deep perineal

Question 23

What muscle is located in the superficial perineal space, along the posterior border of the UG diaphragm?

Answer 23

Superficial transverse perineus m.

Question 24

The body, or shaft, of the penis consists of skin and three bodies of erectile tissue, including the _______ and bilateral _______. ____ fascia covers the 3 sets of erectile tissue

Answer 24

Corpus spongiosum; corpora cavernosa; Buck’s

Question 25

The superficial perineal space in females contains the vulva or external genitalia, which includes what major structures?

Answer 25

Labia majora
Labia minora
Mons pubis
Vestibule of vagina
Clitoris
Bartholin’s glands
Superficial transverse perineus m.

Question 26

The labia majora unite anteriorly to form the ______. The labia minora surround the vestibule of the vagina, which contains the external urethral orifice, vaginal orifice, openings of the _____ glands, and the ________ _____ glands. The urethra contains an external urethral sphincter which relaxes to allow urination to occur.

Answer 26

Mons pubis; paraurethral; greater vestibular

Question 27

The clitoris is the female homologue to the penis in males. What are the major parts of the clitoris?

Answer 27

Two crura
Two corpora cavernosa
One body
One glans clitoris

Question 28

Each crus of the clitoris is continuous with a ________, which is composed of erectile tissue. These 2 parts are surrounded by an _________ m., which contracts during sexual arousal to slow the return of venous blood from the corpus cavernosum

Answer 28

Corpus cavernosum; ischiocavernosus

Question 29

In females, the 2 corpora cavernosa unite to form the ______. The _______ is attached to the body and is axternally visible

Answer 29

Body of the clitoris; glans clitoris

Question 30

In addition to the vulva, the superficial perineal space in females includes several important strucures which are deep to the skin. These include:

The _____ of the vestibule, which are located deep to the skin of the labia minora and are comprised of erectile tissue. Each one is covered by a _______ m., which is attached to the perineal body. During sexual arousal this muscle compresses the bulbs of the vestibule to slow the return of venous blood.

_______ glands, which produce a clear mucous during sexual arousal which lubricates the vulva

_______ mm. which attach to the perineal body

Answer 30

Bulbs; bulbocavernosus

Greater vestibular (Bartholin’s)

Superficial transverse perineus

Question 31

Arterial supply to the perineum is provided by two major vessels:

The ______ a., which is a branch of the ______, enters the perineum via the lesser sciatic foramen and then enters the pudendal canal. It gives branches to the anal canal and ischiorectal fossa, deep perineal space, and superficial perineal space. Included in its important branches are the _____ arteries, which supply the erectile tissues and dorsal arteries of the penis and clitoris.

The ______a., a branch of the _______, sends deep and superficial branches to the scrotum and penis in the male, and the labia majora and clitoris in the female

Answer 31

Internal pudendal; internal iliac a.; helicine

External pudendal; femoral

Question 32

The _______ n. Sends branches to all perineal structures supplied with blood from the internal pudendal a.

Answer 32

Pudendal n. (S2-S4)

Question 33

What 4 modalities are included in the pudendal n. (S2-4) supplying the perineal region?

Answer 33

Preganglionic parasympathetics (GVE) — glands and smooth muscle

Somatic motor fibers (GSE) — skeletal m.

Somatic sensory fibers (GSA) — sensation in perineal skin, distal portion of anal canal, distal vaginal canal

Postganglionic sympathetic fibers (GVE) — glands and smooth muscle

Question 34

In addition to the pudendal n., what other n. supplies the perineal region with cutaneous branches?

Answer 34

Posterior femoral cutaneous n.

Question 35

The superficial perineal space, distal portions of the vagina, and anal canal (below the pectinate line) drain to the _______ nodes.

The deep perineal space, proximal portion of vagina, proximal portion of anal canal (above pectinate line) drain to _____ nodes

Answer 35

Superficial inguinal

Internal iliac

Question 36

_______ = surgical incision made in the area between the vagina and anus during the last stages of labor and delivery to expand the opening of the vagina to prevent a perineal tear during delivery

Answer 36

Episiotomy

Question 37

What are the 4 types of episiotomy, which one is the most common?

Answer 37

Mediolateral episiotomy

Question 38

What structures are cut during a typical episiotomy?

Answer 38

Posterior vaginal wall
Bulbocavernosus m.
Superficial transverse perineus m.
Skin and associated subcutaneous fascia

Question 39

To repair an episiotomy, the obstetrician places 3 layers of sutures in what order?

Answer 39

1. Vaginal wall
2. Muscle layer
3. Subcutaneous fascia and skin

Question 40

What are the 4 types of episiotomy?

Answer 40

Medio-lateral (most common)
Midline
Lateral
J-shaped

Question 41

What autonomic plexus supplies the prostate, vesicle, utero-vaginal region, and rectum?

Answer 41

Inferior Hypogastric plexus

Question 42

What foramina do the internal pudendal vessels and pudendal n. pass through?

Answer 42

Greater and lesser sciatic foramina