Week 9 The pelvis and perineum

Question 1

What is the perinium?

Answer 1

Refers to an external surface area as well as a compartment of the body
The region is that which overlies the inferior pelvic outlet

Question 2

How is the perineum separated from the pelvic cavity?

Answer 2

By the pelvic diaphragm

Question 3

What is the perineal region?

Answer 3

The narrow area between the thighs when standing in the anatomical position
Is diamond shaped when the leg are abducted

Question 4

What sits in the perineal region?

Answer 4

Mons pubis anteriorly
Medial aspect of the thighs laterally
Gluteal folds and upper end of intergluteal cleft posteriorly

Question 5

What is the mons pubis?

Answer 5

A mound of fatty tissue overlying the pubic symphysis

Question 6

What is the:
Perineum
Peritoneum
Peroneal

Answer 6

Perenium:
Area between the thighs
Peritoneum:
serous membrane lining the abdominal cavity
Peroneal:
Relating to the fibula or surrounding area

Question 7

What are the Ossifiborous structures surrounding the perineum?

Answer 7

Pubic Symphysis anteriorly
Inferior Pubic Rami, Ischial Rami anteriolaterally
Ischial Tuberosities laterally
Sacrotuberous Ligaments posteriolaterally
Inferior aspect of the Sacrum and Coccyx posteriorly

Question 8

What are the names of the two triangular regions of the perineum?

Answer 8

Posteriorly is the Anal triangle

Anteriorly is the urogenital region or urogenital triangle

Question 9

What is the Perineal Body?

Answer 9

The midpoint of the line joining the ishial tuberosities (muscle)
It is an irregular fibromuscular mass
contains collagenous and elastic fibres

Question 10

Where is the Perineal body located?

Answer 10

Posterior to the bulb of the penis or vestibule of the vagina
Anterior to the anus and anal canal
It is attached to the posterior border of the perineal membrane, which is the attachment for the perineal muscles

Question 11

What muscles attach to the perineal body?

Answer 11

Bulbospongiosus
External Anal Sphincter
Superficial and Deep transverse perineal muscles

Question 12

What is the perineal membrane?

Answer 12

A sheet of deep fascia which stretched from the pubic arch and covers the anterior aspect of the pelvic outlet

Question 13

What is the anal canal?

Answer 13

The terminal part of the bowel, begins where the pubo rectalis muscle forms sling around the anorectal junction.

Question 14

Where does the anococcygeal ligament run?

Answer 14

Between the anococcygeal ligament and the perineal body

Question 15

What is the External anal sphincter?

Answer 15

Large voluntray band of muscle
Large voluntary band of muscle
Found either side of the inferior 2/3rds of the anal canal. Blends superiorly with the puborectalis muscle

Question 16

What supplies the external anal sphincter

Answer 16

S4 inferior rectal nerve

Question 17

What is the internal anal sphincter?

Answer 17

Involuntary muscle band
Surrounds the superior 2/3 rds of the anal canal
It is a thickening of the muscle (circular layer) within the bowel

Question 18

What is the internal anal sphincter supplied by?

Answer 18

Parasympathetic fibres from the pelvic splanchnic nerves

Question 19

Why is the internal anal sphincter always contracted? When does it relax?

Answer 19

To prevent leakage

To release pressure from faeces and gas

Question 20

what does the superior part of the mucous membrane of the internal anal sphincter contain? What are these?

Answer 20

Ridges called anal colums
These are layers of mucous membrane which contain the terminal branches of the superior rectal artery and vein

At the inferior end the columns are joined by anal valves

Question 21

What are superior to the anal valves?

Answer 21

Sinuses which when compressed release mucous to aid in defication

Question 22

What is the line produced by the anal valves called?

Answer 22

The pectinate line

Question 23

What does the pectinate line do?

Answer 23

Divides the anus into superior and inferior regions

Question 24

What is the arterial supply to the rectum?

Answer 24

Inferior rectal arteries

Internal pudendal arteries

Question 25

What is the venous drainage of the anus?

Answer 25

The internal venous plexus
Superior rectal vein
Inferior rectal vein
Middle rectal vein

Question 26

What innervates the rectum?

Answer 26

Sympathetic and parasympathetic fibres from the inferior hypogastric plexus (superior to the pectinate line)

Branches from the pudendal nerve (inferior to the pectinate line)

Question 27

What are the muscles of the perineum?

Answer 27

Levator ani
Coccygeus
These make the pelvic diaphragm

Question 28

What is the origin Insertion and nerve supply of levator ani? What muscles make up this muscle?

Answer 28

Origin- body of the pubis, obturator fascia, ischial spine
Insertion - perineal body, coccyx, anococcygeal ligament, walls of the prostate / vagina, rectum and anal canal
Nerve supply - S4 nerve to Lev Ani

Made up of:
Puborectalis
Pubococcygeus
Iliococcygeus

Question 29

What is the origin, insertion and nerve supply of coccygeus?

Answer 29

Origin - ischial spine
Insertion - inferior end of the sacrum, coccyx
Nerve supply S4,5

Question 30

What are the sex differences in the pelvis?

Answer 30

Male pelvis
generally heavy and thick
has more prominent bone markings
Female pelvis:
wider, shallower
larger superior and inferior pelvic apertures
broader sacrum, thus hips bones are wider apart
the ischial tuberosities are farther apart
sacrum less curved