GA - Pelvic Viscera I

Question 1

What is the Perineal Body?

Answer 1

Perineal body is a fibro-muscular mass in the midline of the perineum.

It serves as an attachment point for muscles.

Normally a bone would be used as an attachment point, but babies need to come through the pelvis, and a bone would block the way

Question 2

What are the three Superificial Perineal Muscles, and what structure are they superior to?

Answer 2

Superificial Transverse Perineal M.

Bulbospongiosus M.

Ischiocavernosus M.

They are superficial to the Perineal membrane

Question 3

Describe the erectile tissue in males

Answer 3

There are three cylindrical masses of erectile tissue in the penis.

1 ventral cylinder, and 2 (paired) dorsal chambers

Question 4

Name the segments of the erectile tissue in males, and describe their location

Answer 4

The proximal portions of the paired dorsal cylinders of erectile tissue are called the Crura of the Penis (Left Crus of the Penis, Right Crus of the Penis).The crura fan out on either side of the penis along the Brim of the Pelvis.

The distal portions of the paired dorsal cylinders of erectile tissue are called the 
Corpora Cavernosa (plural) or Corpus Cavernosum (singular)

The proximal portion of the ventral cylinder of erectile tissue is called the Bulb of the Penis

The middle portion of the ventral cylinder of erectile tissue is called the Corpus Spongiosum

The distal portion of the ventral cylinder of erectile tissue is called the Glans Penis

Question 5

Describe the erectile tissue in females

Answer 5

Erectile tissue compartments are not cylindrical like the male, but like the males, there are of these compartments

1 unpaired compartment is superior to the genitalia (clitoris)

2 (paired) compartments are i deep to the labia majora

Question 6

Name the compartments of erectile tissue and females and describe their location

Answer 6

The clitoris has three parts to it:

• Glans Clitoris is the most superficial segment
• Body of the clitoris is just deep to the glans clitoris
• The Crura of the Clitoris fan out left and right along the pelvic brim

Bulbs of the Vestibule are a set of paired compartments of erectile tissue deep to the labia majora

Question 7

Where is the Bulbospongiosus M. found in the male?

Answer 7

The Bulbospongiosus M. is a thin layer of muscle tissue found on top of the Bulbs of the Penis (proximal end of the ventral cylinder of erectile tissue) and on top of the Corpus Spongiosus (middle portion of the ventral cylinder of erectile tissue)

Question 8

Where is the Ischiocavernosus M. found in the male?

Answer 8

Ischiocavernosus M. is a thin layer of muscle tissue found laying overtop the Crura of the penis.

Attaches somewhat to the ischium

Ischiocavernosus of the male is much larger than the ischiocavernosus of the female

Question 9

Where is the Bulbospongiosus M. located in the female?

Answer 9

Bulbospongiosus muscle is a thin layer of muscle tissue found on top of the Bulbs of the Vestibule.

Question 10

Where is the Ischiocavernosus M. found in the female?

Answer 10

The Ischiocavernosus M. is a thin layer of muscle tissue found laying overtop the Crura of the Clitoris

Ischiocavernosus of the female is much smaller than the ischiocavernosus of the male

Question 11

What is the action of the Bulbospongiosus M. in the Female?

Answer 11

Holds the Perineal Body in place from the anterior direction.

Compress the vaginal vestibules as well as the vagina

Question 12

What is the action of the Bulbospongiosus M. in the Male?

Answer 12

Holds the Perineal Body in place from the anterior direction.

Maintains erection by blocking venous drainage

Since the Bulbospongiosus surrounds the bulb of the penis, it is also capable of helping expel drops of urine/semen

Question 13

What is the action of the Ischiocavernosus M. in the male?

Answer 13

Maintains erection of penis by compressing venous drainage

Question 14

What is the action of the Ischiocavernosus M. in the female?

Answer 14

Maintains erection of the clitoris by compressing venous drainage

Question 15

What is the action of the Superficial Transverse Perineal M.?

Answer 15

Supports and fixes the Perineal Body from both lateral directions

Question 16

What are the Urogenital Diaphragm Muscles?

Answer 16

Deep Transverse Perineal M.

External Urethral Sphincter M.

These muscles are JUST DEEP TO THE PERINEAL MEMBRANE

Question 17

What is different about the Deep Transverse Perineal M. in males and females?

Answer 17

In females, the Deep Transverse Perineal M. is composed of smooth muscle

In males the Deep Transverse Perineal M. is composed of skeletal M.

Question 18

What are the components of the External Urethral Sphincter?

Answer 18

The Compressor Urethrae M. extends from the Ox Coxa wall to midline where it holds the External Urethral Sphincter in place.

The Urethrovaginal Sphincter M. is found only in womem. Muscle fibers extend from the External Urthra and wrap around the vagina.

Question 19

What nerve innervates the External Urethral Sphincter M.?

Answer 19

Dorsal Nerve of the Penis (males)

Dorsal Nerve of the Clitoris (female)

This is an exception. All the other muscles of the Urogenital Diaphragm and the Superficial Perineal Muscles are innervated by Deep Perineal Nerves

Question 20

What nerve innervates the muscles of the Urogenital Diaphragm and the Superficial Perineal Muscles (except for one muscle, name the exception)?

Answer 20

Deep Perineal Nerves innervate the muscles of the Urogenital Diaphragm and the Superificial Perineal Muscles.

The only exception is the External Urethral Sphincter M., which is innervated by the Dorsal Nerve of the Penis (males) or the Dorsal Nerve of the Clitoris (females)

Question 21

What are the anal muscles?

Answer 21

Internal Anal Sphincter M. (smooth muscle)

External Anal Sphincter M. (skeletal muscle)

Question 22

What are the actions of the External Anal Sphincter M. ?

Answer 22

Holds the Perineal Body in place from the posterior

Prevents feces from exiting the rectum

Question 23

What nerve innervates the External Anal Sphincter M.?

Answer 23

The External Anal Sphincter M. is innervated by the Inferior Rectal N. (aka the Inferior Anal N.)

Question 24

What does the Pelvic Diaphragm Separate?

Answer 24

The pelvis and the perineum

Question 25

What are the components of the Pelvic Diaphragm?

Answer 25

Coccygeus M.

Levator Ani Muscles:

• Puborectalis M. (pubis to Rectum)
• Pubococcygeus M.
• Iliococcygeus M.

Question 26

Where do the Levator Ani Muscles orignate?

Answer 26

Levator Ani Muscles attach to the Tendinous Arch of Levator Ani (aka the Tendinous Arch of Obturator Fascia)

This tendinous arch crosses the internal surface of the Obturator muscle and is composed of Obturator Fascia

Question 27

What nerve innervates the Pelvic Diaphragm Muscles?

Answer 27

Coccygeus M., Puborectalis M., Pubococcygeus M., and Iliococcygeus M. are all innervated by:

The Nerve to the Levator Ani

Question 28

What are the Accessory Muscles of the Pubococcygeus M. in the Female?

Answer 28

The following muscles are composed of fibers that extend from the Pubococcygeus M. toward midline structures:

• Pubovaginalis M. (attaches to vagina)
• Puboperinealis M. (attaches to perineal membrane)
• Puboanalis M. (attaches to anus)

NOTE: puboanalis SHOULD NOT BE CONFUSED WITH puborectalis

Question 29

What are the Accessory Muscles of the Pubococcygeus M. in males?

Answer 29

The following muscles are composed of fibers that extend from the Pubococcygeus M. toward midline structures:

• Puboprostaticus (attaches to the prostate gland)
• Puboperinealis M. (attaches to the perineal membrane)
• Puboanalis M. (attaches to anus)

NOTE: puboanalis SHOULD NOT BE CONFUSED WITH puborectalis

Question 30

What is the action of the Obturator Internus M.

Answer 30

Lateral rotator

Externally rotates the thigh

Question 31

What is the action of the Piriformis M.?

Answer 31

Lateral rotator; externally rotates the thigh

Can also slightly abduct the thigh