L1 - Defining the pelvic region

Question 1

Four bones that form the pelvis

Answer 1

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

Question 2

Ligaments of the pelvis

Answer 2

• Sacroiliac : between the sacrum and the ilium, has an anterior and posterior components
• Sacrococcygeal : between the sacrum to the coccyx
• Sacrospinous : between the ischial spine and the sacrum/coccyx
• Sacrotuberous : posterior to the sacrospinous; between the lateral aspect of sacrum+coccyx onto medial margin of ischial tuberosity

Question 3

What is the perineum

Answer 3

• Refers to the space located at the pelvic outlet and inferior to the pelvic diaphragm(ie muscles of the pelvic floor)
• It can be said 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 posteriorly to the gluteal folds

Question 4

What does the transverse line joining the two ischial tuberosities split the perineum into

Answer 4

• Urogenital triangle
• Anal triangle
• The mid point of this line defines the perineal body

Question 5

What does the deep perineal pouch enclose

Answer 5

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

Question 6

What does the superficial perineal pouch enclose

Answer 6

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

Question 7

Main aspects of the pelvis

Answer 7

• Sacrum
• Ileum, pubis, ischium
• Ischial tuberosity
• Ischial spine

Question 8

Joints of the pelvis

Answer 8

• Sacroiliac
• Sacrococcygeal
• Pubic symphysis

Question 9

What is the pelvic brim formed by

Answer 9

• Promontory and ala(wing) of sacrum
• Right + left linea terminalis
• Arcuate line
• Pectineal line

Question 10

Posterior border of the pelvic cavity

Answer 10

• Sacrum/coccyx

Question 11

Anterior border of the pelvic cavity

Answer 11

• Pubic symphysis

Question 12

Inferior border of the pelvic cavity

Answer 12

• Pelvic floor

Question 13

Superior border of the pelvic cavity

Answer 13

• Pelvic brim

Question 14

Lateral border of the pelvic cavity

Answer 14

• Obturator internus m

Question 15

Contents of the pelvic cavity

Answer 15

• Reproductive organs/tracts
• Bladder
• Rectum

Question 16

Muscles that line the wall of the pelvis

Answer 16

• Piriformis

- Obturator internus

Question 17

Muscles that line the floor of the pelvis

Answer 17

• Coccygeus

- Leavtor ani (iliococcygeus, pubococcygeus and puborectalis)

Question 18

Origin and insertion of the piriformis

Answer 18

• From the anterior surface of sacrum; through the greater sciatic foramen ie over the ischial spine; inserts onto the greater trochanter of femur

Question 19

origin and insertion of the obturator internus

Answer 19

• From the internal surface of the obturator membrane; through the lesser sciatic foramen ie below the ischial spine; also inserts onto the greater trochanter of femur

Question 20

Origin and insertion of the coccygeus muscle

Answer 20

• From the ischial spine to the inferior end of the sacrum + coccyx

Question 21

Origin and insertion of the iliococcygeus

Answer 21

• From the tendinous arch - a line extending from the ischial spine to the posterior aspect of the pubic bone - to the annococcygeal body

Question 22

Origin and insertion of the pubococcygeus

Answer 22

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

Question 23

Origin and insertion of the puborectalis

Answer 23

• A continuous muscle that originates from the posterior aspect of the pubic bone and slings behind the rectum

Question 24

Arterial supply to the pelvic organs

Answer 24

• Anterior division of internal iliac, providing several branches, eg uterine, vesical or internal pudendal
• Gonadal, from abdominal aorta, supplying the gonads

Question 25

Venous drainage from the pelvic organs

Answer 25

• Internal iliac, to common iliac veins

- Gonadal, to IVC or L renal vein

Question 26

What are the somatic plexuses subdivided into

Answer 26

Lumbosacral (L4-S4 <=Note: joined by lumbar L4/5)
Coccygeal (S4-Co)
Function as motor or sensory
e.g. sciatic nerve, sup/inf gluteal, pudendal nerve

Question 27

What are the visceral plexuses subdivided into

Answer 27

Paravertebral/Prevertebral
Sympathetic/Parasympathetic/Visceral fibres
Erection/Ejaculation
e.g. inferior hypogastric plexus

Question 28

Origin of superior gluteal nerve

Answer 28

• Sacral plexus

Question 29

Origin of inferior gluteal nerve

Answer 29

• Sacral plexus

Question 30

Origin of the sciatic nerve

Answer 30

• Sacral plexus

Question 31

Origin of the pudendal nerve

Answer 31

• Sacral plexus

Question 32

Parasympathetic flow to the pelvic organs

Answer 32

• Pelvic splanchnic nerves (S2-4)

Question 33

Sympathetic flow to the pelvic organs

Answer 33

• Sacral sympathetic trunk

- Superior and inferior hypogastric plexuses

Question 34

Three main articulations of the hip

Answer 34

• Sacroiliac joint - Articulation with the sacrum
• Pubic symphysis - Articulation between the right and left hip bones
• Hip joint - Articulation with the head of the femur

Question 35

What is the deep perineal pouch

Answer 35

• Is the anatomic space enclosed in part by the perineum, and located superior to the perineal membrane