Sem 2 - E - Pelvic walls&floor- Pelvic bones, SI joint ligaments- Psoas/iliacus/obturator internus/externus,piriformis- pelvic floor

Question 1

What is the pelvic diaphragm and what muscles make it up? State the nerve supply to these muscles?

Answer 1

Pelvic diaphragm is the musculuar part of the pelvic floor made up of the levator ani and coccygeus

Levator ani

• * Pudendal neerve (S2,3,4) & nerve to levator ani (S3,4)

Coccygeus

• * Direct bracnhes from sacral plexus S4,5

Question 2

What are the hip bones also known as?

Answer 2

The innominate bones or os coxae

Question 3

The pelvic skeleton is formed posteriorly (in the area of the back), by the sacrum and the coccyx and laterally and anteriorly (forward and to the sides), by a pair of hip bones. Each hip bone consists of 3 sections, ilium, ischium, and pubis. State what the arrows are pointing to

Answer 3

Brown - anterior superior iliac spine Green - acetabulum Blue - obturator foramen Yellow - ischial tuberosity Orange - lesser sciatic notch Black - ischial spine Red - greater sciatic notch

Question 4

State muscles which attach to the ASIS and AIIS? What muscles lie over the obturator membrane? What vessels run behind the ischial spine? What is the prominent bone which we sit on?

Answer 4

* Anterior superior iliac spine - sartorius (& tensor fascia latae) attaches here * Anterior inferior iliac spine - rectus femoris attaches here * Obturator internus lies on pelvic surface of obturator membrane * Obturator externus lies on external surface of obturator membrane * Internal pudendal vessels and pudendal nerve run behind the ischial spine * We sit on the ischial tuberosities

Question 5

What type of joint is the lumbosacral, sacroiliac and pubic symphysis joint?

What attaches from ASIS to pubic tubercle?

Answer 5

• Lumbosacral joint - secondary cartilaginous
• Sacroiliac joint - synovial plane
• Pubic symphyseal joint - secondary cartilaginous

The inguinal ligament runs from ASIS to pubic tubercle

Question 6

What are the wings of the sacrum known as? What are the three crests of the sacrum formed by?

Answer 6

Wings of the sacrum - ala

Crests on posterior surface of sacrum

• Median crest - the fused spinous processes
• Intermediate crest - the fused sacral articular processes
• Lateral crest - the fused transverse processes

Question 7

What is the attachment point of the sacrum and coccyx? What allows for the passage of nerves through the sacrum?

Answer 7

The sacrum and coccyx attach at the cornua of the bones The sacral foramina allows for passage of the sacral nerves into and out of the sacral canal

Question 8

What forms the pelvic boundaries? (roof, floor, lateral wall, posterior wall, anterior wall)

Answer 8

There is no structure at the roof of the pelvis - roof is just the pelvic inlet

• Floor of pelvis - muscular pelvic diaphragm
• Lateral wall - formed by oturator internus
• Posterior wall - sacrum, coccyx and piriformis
• Anterior wall - pubic bodies, pubic symphysis, pubic rami

Question 9

What are the ligaments involved in the sacroiliac joint?

What are the accessory ligaments involved in this joint?

Answer 9

Ligaments

• * Anterior sacroliac ligament
• * Posterior sacroliliac ligament

Accessory ligaments in sacroliac joint

• * Sacrospinous ligament
• * Sacrotuberous ligament * Iliolumbar ligament

Question 10

Is the anterior or posterior sacroliliac ligament fibrous?

Answer 10

Anterior sacroiliac ligament is synovial Posterior sacroliliac ligament is fibrous

Question 11

What are the attachments of the anterior and posterior sacroiliac ligament?

Answer 11

Anterior sacroiliac ligament - consists of numerous thin bands connecting the anterior surface of the lateral part of the ilium to the margin of the auricular surface of the ala

Posterior sacroliac ligament - attaches on posterior aspect of sacrum to ilium

Question 12

There are four basic pelvis shapes

• Gynecoid
• Android
• Anthropoid
• Platypelloid

Describe each and which is the typical male and female pelvis

Answer 12

• Gynecoid - classic female pelvis - round shaped pelvic inlet
• Android - classic male pelvis - heart-shaped pelvic inlet
• Anthropoid - oval pelvic inlet with greatest diameter AP
• Platypelloid - oval pelvic inlet with greatest diameter laterally

Question 13

What do the gynecoid and android pelvis allow for? What is the difference in the subpubic angle between males and females?

Answer 13

Gynecoid pelvis - allows for the passage of the foetal head (classic female round shaped pelvis)

Android pelvis - allows for bipedal locomotion (classic male hear-shaped pelvis)

Males subpubic angle is smaller (<70 degrees) than female subpubic angle (80-90 degrees)

Question 14

Muscle we will be discussing in this lecture * Psoas, iliacus * Obturator externus and obturator internus * Piriformis * Pelvic diaphragm (levator ani and coccygeus)

State the attachment of the iiacus, its nerve supply and its function?

Answer 14

Iliacus - attaches from iliac fossa and joins with psoas to insert as iliopsoas into the lesser trochanter of the femur

Nerve supply - femoral nerve (L2-4) Function - Hip flexion

Question 15

State the attachment of the psoas, its nerve supply and its function?

Answer 15

• * Superficial fibres of psoas originate from vertebral bodies and IV discs of T12-L4
• * Deep fibres of psoas originate from transverse processes of L1-L5 vertebrae
• * Distally joins with iliacus to insert as iliopsoas onto the lesser trochanter of the femur

Nerve supply - Anterior rami of L1-L3

• Function
  
  • * Flexion of hip
  • * Unilateral contraction - lateral flexion of trunk
  • * Bilateral contraction - raises trunk from supine

Question 16

Now we will discuss the obturator internus and obturator externus Describe the attachments of the obturator internus?

Answer 16

Obturator internus attaches from the pelvic surface of the obturator membrane and margins of the obturator foramen to pass though the lesser sciatic foramen to insert into the medial side of the greater trochanter of the femur known as the trochanteric fossa

Question 17

Now we will discuss the obturator internus and obturator externus Describe the attachments of the obturator externus?

Answer 17

The obturator externus arises from the outer surface of the obturator membrane and margins of the obturator foramen where its fibres will travel posterio to the neck of the femur to insert into the trochanteric fossa of the femur

Question 18

What is the function of the obturator intenrus and externus? What is their nerve supply?

Answer 18

The obturator externus and internus are both lateral rotators of the hip joint Obturator externus - supplied by the obturator nerve (L3,4 roots) Obturator intenrus - supplied by the nerve to obturator internus direct from sacral plexus (L5,S1)

Question 19

What muscle forms part of the posterior wall of the pelvis? What are its attachments?

Answer 19

Piriformis forms part of the posterior wall of the pelvis

Attachments - Anterior surface of the sacrum (and sacrotuberous ligament) through the greater sciatic foramen to the superior border of the greater trochanter of the femur

Question 20

What is the function of the piriformis and what is its nerve supply?

Answer 20

Function - lateral rotation of the hip joint Nerve supply - nerve to piriformis (anterior rami of S1,2)

Question 21

Now we want to visualise the levator ani from above showing the floor of the pelvis Which muscles forms the roof of the anal triangle? What is the function of the pelvic diaphragm?

Answer 21

Levator ani forms the muscular roof of the anal triangle Function of the pelvic diaphragm is to prevent pelvic organ prolapse

Question 22

What is the attachment of the coccygeus?

Answer 22

Coccygeus originates at the ischial spines and travels along the sacrospinous ligament to the coccyx and lower sacrum

Question 23

What is the function of the coccygeus? What is its nerve supply?

Answer 23

Function of the coccygeus is to support the pelvic viscera and it also weakly flexes the coccyx Innervated by direct branches (S4-5) from the sacral plexus

Question 24

The levator ani is the main muscle of the pelvic diaphragm What are the different parts of the levator ani? (state what the medial fibres part can be divided into)

Answer 24

Levator ani parts

• Pubococcygeus which are the most medial fibres - can be divided into puborectalis and puboprostaticus (levator prostatae) / pubovaginalis
• Iliococcygeus which are the more lateral fibres sitting anterior to the coccygeus

Question 25

What is the function of the pubococcygeus fibres? When must the levator ani contract and relax?

Answer 25

Puboccygeus fibres attach to and support the vagina/prostate gland and rectum

Levator ani contracts when there is increased intra-abdominal pressure eg sneezing and coughing to preserve continence and relaxs to allow for urination and defecation

Question 26

Describe the levator prostate and pubovaginalis? What is the nerve supply to all parts of the levator ani?

Answer 26

Levator prostatae/pubovaginais - most medial fibres of the pubococcygeus in a male/female arising from the pubic bones passing around prostate/vagina and inserting into the perineal body

Nerve - Nerve to levator ani (S4)&pudendal nerve (S2-4)

Question 27

Describe the attachments of the puborectalis? Is it usually contracted?

Answer 27

The puborectalis extends from the pubic bones and mix with fibres of the external anal sphincter forming a sling around the rectum bending it anteriorly to help maintain faecal continence

The puborectalis is tonically slightly contracted around the anal canal

Question 28

What does the parietal pelvic fascia covering the internal wall of the pelvis thicken over the obturator internus to form?

Answer 28

The parietal pelvic fascia covering the internal wall of the pelvis thickens over the obturator internus to form the tendinous arch of the pelvis and levator ani

Question 29

What is the attachment of the iliococcygeus muscle?

Answer 29

The iliococcygeus attaches to the posterior aspect of the fascia of the obturator internus - this area of fascia of the obturator internus is known as the tendinous arch of the levator ani - and ischial spines to insert at the anococcygeal ligament

Question 30

What is the perineal body and where is it located? What muscles attach to the perineal body?

Answer 30

Perineal body is a small fibrous structure located at the posterior aspect of the urogenital diaphragm (centre point of perineum)

Muscle attaching:

• Pubovaginais / levator prostate (puboprostaticus)
• Bulbospongiosus and transverse perineal muscles
• External anal sphincter

Question 31

Pelvic floor is not just a muscular structure (pelvic diaphragm), it is also fascial * What does the parietal pelvic fascia covering the internal wall thicken to form anteriorly? * What does the parietal pelvic fascia covering the internal wall thicken over the obturator internus to form?

Answer 31

Parietal pelvic fascia thickens anteriorly to form the puboprostatic ligament and pubovesical ligament The parietal pelvic fascia thickens over the obturator internus to form the tendinous arch of the pelvis and the levator ani

Question 32

Does the tendinous arch of the pelvis or levator ani lie deeper?

Answer 32

The tenindous arch of the pelvis lies deeper than the tendinous arch of the levator ani

Question 33

Visceral pelvic fascia covers the organs When do the parietal and visceral pelvic fascia blend? What is the lateral extension of visceral pelvic fascia from the vagina known as and what does it blend with?

Answer 33

The parietal and visceral pelvic fascia blend as the organs pierce the pelvic floor

The lateral extension of pelvic visceral pelvic fascia from the vagina to the tendinous arch is known as the paracolpium

Question 34

What is the paracolpium and what is it continous with?

Answer 34

Paracolpium is the blending of the lateral vagina visceral pelvic fascia with the tendinous arch and it is continous with the uterosacral / cardinal ligament

Question 35

Endopelvic fascia acts as a packing material around the organs between the parietal and visceral pelvic fascia, 2 basic types: loose and condensed What does the loose endopelvic fascia do?

Answer 35

The loose endopelvic fascia fills in the ‘spaces’ in the pelvis for example the retropubic (pre-vesical) space and the retrorectal space (pre-sacral) Allows for expansion of the bladder and rectum

Question 36

Other parts of the endopelvic fascia have a fibrous consistency, the ligamentous fascia. These parts are often described as “fascial condensations” or pelvic “ligaments.” What is the condensed endopelvic fascia ?

Answer 36

The condensed endopelvic fascia is thickeninngs of the fascia eg the primary fascial condensation is the hypogastric sheaths running along the posterolateral walls of the pelvis or the cardinal ligament

Question 37

What are the pouches in males and females formed by peritoenum draping over the pelvic organs?

Answer 37

Females - vesicouterine pouch and rectouterine pouch (pouch of douglas)

Males - rectovesical pouch