1. Defining the pelvic region

Question 1

What is the articulated pelvis?

Answer 1

The four bones that together (including the ligaments) make the pelvis (os coxa)

Question 2

What makes up the articulated pelvis?

Answer 2

• Two innominate bones: ilium, ischium and pubis
• Sacrum, formed by fusion of the 5 sacral vertebrae
• Coccyx, formed by the fusion of the 4 coccygeal vertebrae

Question 3

What are some key features of the articulated pelvis?

Answer 3

L5
Sacrum
Coccyx
Posterior sacral foramina
Sacrococcygeal joint
intervertebral disc
sacroiliac joint
pubic symphysis (interpubic disc and ligaments)

Question 4

What are the ligaments of the pelvis and which bones do they articulate?

Answer 4

Sacroiliac - between sacrum and ileum (has anterior and posterior components)

Sacrococcygeal - between the sacrum and coccyx

Sacrospinous - between the ischial spine and sacrum/coccyx

Sacrotuberous - posterior to sacrospinous, between lateral aspect of sacrum and coccyx onto medial margin of ischial tuberosity

Question 5

What is the perineum?

Answer 5

The perineum is the space located at the pelvic outlet

inferior to the pelvic diaphragm (muscles of the pelvic floor)

Can be used to describe the narrow region between the thighs.

Diamond-shaped surface extending from the mons pubis (in females) to the medial surface of the thighs and posterior to the gluteal folds

Question 6

How can the perineum be split and what is the perineal body?

Answer 6

The perineum can be split into two triangles by a transverse line joining the two ischial tuberosities

• urogenital triangle
• anal triangle

The perineal body is the midpoint of this line

The perineal body is where several sphincter and perineal pouch muscles converge

Question 7

List key features of the pelvis when viewed from beneath

Answer 7

Pubic symphysis
Inferior pubic ramus
Obturator foramen
Pubic arch
Inferior pubic ligament
Ischial tuberosity
Perineal membrane

Question 8

Describe the deep perineal pouch

Answer 8

The space enclosed in part by the perineum, superior to the perineal membrane

Question 9

What are the contents of the deep perineal pouch?

Answer 9

Urethra
Vagina (in females)
Glands, such as bulbourethral (Cowper) glands in males
Perineal muscles that act as sphincters e.g. compressor urethrae or urethrovaginal sphincter in females

Question 10

What is enclosed by the superficial perineal pouch?

Answer 10

Urethra
Vagina in females, root of penis in males
Glands such as Bartholin in females (equivalent to Cowper glands in males)
Perineal muscles that provide support to the external genitalia, such as the bulbospongiosus or ischiocavernosus muscles

Question 11

Name two glands which are the equivalent of each other in either sex

Answer 11

Bulbourethral (Cowper) glands in males

Bartholin glands in females

Question 12

Joints of the articulated pelvis

Answer 12

sacroiliac, sacrococcygeal, pubic symphysis

Question 13

What forms the pelvic rim aka the pelvic inlet

Answer 13

Promontory and ala (wing) of sacram

Right and left linea terminalis made up of the arcuate lines and the pectineal lines

Question 14

What are the borders of the true pelvic cavity?

Answer 14

Posterior - sacrum/coccyx
Anterior - pubic symphysis
Inferior - pelvic floor
Superior - pelvic brim
Lateral - obturator internus muscle

Question 15

What are the contents of the true pelvic cavity?

Answer 15

Reproductive organs/tracts
Bladder
Rectum

Question 16

List the pelvic musculature

Answer 16

Muscles lining the wall:
- piriformis
- obturator internus
Muscles lining the floor:
- coccygeus
- levator ani (iliococcygeus, pubococcygeus and puborectalis)

Question 17

Describe the pelvic wall

Answer 17

Formed by piriformis and obturator internus

Piriformis:
origin - anterior surface of sacrum, through the greater sciatic foramen (over ischial spine) into greater trochanter of femur (insertion)

Obturator internus:
origin - internal surface of the obturator membrane, through the lesser sciatic foramen (below ischiatic spine) inserts onto the greater trochanter of femur

Question 18

What can you see from a superior view of the pelvic floor?

Answer 18

Tendinous arch
Urethra
Vagina
puborectalis muscle (most medial)
pubococcygeus muscle
iliococcygeus muscle (most lateral)
coccygeus muscle
piriformis muscle (most posterior)
Coccyx

Question 19

What can you see from the inferior view of the pelvic floor that you can’t see from the superior view?

Answer 19

Sacrospinous ligament

Sacrotuberous ligament

Question 20

Where does the coccygeal muscle go?

Answer 20

From the ischial spine to the inferior end of the sacrum & coccyx

Question 21

Where does the iliococcygeus muscle go?

Answer 21

From the tendinous arch to the annococcygeal body

Question 22

What is the tendinous arch?

Answer 22

Line extending from the ischial spine to the posterior aspect of the pubic bone

Question 23

Where does the pubococcygeus muscle go?

Answer 23

From the posterior aspect of the pubic bone and inserting to the coccyx (lateral fibres) or merging with the contralateral medial fibres

Question 24

Where does the puborectalis muscle go?

Answer 24

a continuous muscle originating from the posterior aspect of the pubic bone and slinging behind the rectum

Question 25

What muscles make up the levator ani?

Answer 25

puborectalis, pubococcygeus, ileococcygeus

Question 26

List and describe the pelvic arteries

Answer 26

Anterior division of the internal iliac which provides several branches e.g. uterine, vesical or internal pudendal

Gonadal, from abdominal aorta, supplying the gonads

Question 27

List and describe the pelvic veins

Answer 27

Internal iliac to common iliac veins

Gonadal, to IVC or L renal vein

Question 28

Describe the somatic plexuses of the pelvis

Answer 28

Somatic plexuses (L4-Co) subdivided into:

• lumbosacral (L4-S4 (joined by lumbar L4/5))
• Coccygeal (S4-Co)

Function as motor or sensory e.g. sciatic nerve, sup/inf gluteal, pudendal nerve

Question 29

Describe the visceral plexuses of the pelvis

Answer 29

Paravertebral/prevertebral
Sympathetic/parasympathetic/visceral fibres
Erection/Ejavulation e.g. inferior hypogastric plexus

Question 30

Lumbosacral trunk

Answer 30

superior gluteal
inferior gluteal
sciatic
pudendal

Question 31

Visceral plexuses

Answer 31

Paraysympathetic flow: pelvic splanchnic nerves (S2-S4)

Sympathetic flow: sacral sympathetic trunk; superior and inferior hypogastric plexuses

Question 32

Posterior pelvis nerves (gluteal)

Answer 32

sciatic nerve
pudendal nerve
gluteal vessels (superior and inferior)

Question 33

Pudendal nerve

Answer 33

dorsal nerve of clitoris
deep perineal nerve
superficial perineal nerve
pudendal nerve (nearsacrotubular ligament)