Structure of the Pelvic Wall

Question 1

Sacral promontory

Answer 1

Anterior-superior margin of S1

Question 2

Sacral hiatus

Answer 2

Inferior site of entry to the sacral canal allowing access for an epidural to the cauda equina

Question 3

Pubic Arch

Answer 3

Is wider in females; formed by the inferior rami of the pubic bones

Question 4

Pelvic Rim Structures

Answer 4

Pubic Crest => Pecten pubis => Arcuate line of the ilium => Lateral mass of the sacrum

Pecten pubis + Arcuate line= illiopectineal line

Question 5

Pelvic Fracture

Answer 5

Must assume damage to bladder and urethra; lots of hemorrhage

Question 6

Sacroiliac joint

Answer 6

Composed of anterior sacroiliac ligament, interosseus ligaments, and posterior sacroiliac
ligament

*Transmits the weight of the trunk to the pelvis

Question 7

Sacrotuberal ligament

Answer 7

Attaches sacrum to ischial tuberosity; forms inferior boundary of the lesser sciatic foramen

*Lies posterior to the sacrospinous ligament

Question 8

Sacrospinous ligament

Answer 8

Connects the sacrum and the ischial spine; forms the superior boundary of the lesser sciatic foramen

*Lies anterior to the sacrotuberous ligament

Question 9

FNXN of sacrotuberous/spinous ligaments

Answer 9

Resist rotational forces of the trunk on the pelvis

Question 10

Pelvic Inlet

Answer 10

Formed by the pelvic brim borders; entry into the pelvic cavity

Question 11

Pelvic Outlet

Answer 11

Pubic symphysis => Inferior ramus of pubis => Ischial tuberosity => sacrotuberous ligament => coccyx

*Inferior opening of the pelvic cavity

Question 12

Diagonal conjugate diameter

Answer 12

Measures angle b/w pubic symphysis & sacral promontory

*OBGYN measures w/ hand and determines other diameters w/ this; measures maximum diameter of pelvic outlet

Question 13

Transverse diameter of the pelvis

Answer 13

Diameter b/w two ischial tuberosities

*Measurement of maximal width of pelvic inlet

Question 14

Fetus during partuition

Answer 14

Must move head 90 degrees b/w pelvic outlet and inlet

Question 15

Sex differences of pelvic cavity

Answer 15

Main thing to remember is male has pointed cavity; females have round ones for childbirth

*Male pelvic inlet = kidney-shaped

Question 16

Tendon of obturator internus

Answer 16

Must pass thru lesser sciatic foramen to attach to greater trochanter of femur

*Fascia consists of endopelvic fascia that is continuous w/ the endoabdominal fascia

Question 17

Anterior Wall of Pelvis

Answer 17

Formed by pubic symphysis and bone

Question 18

Posterior Wall of Pelvis

Answer 18

Formed by piriformis

*Tendon courses thru greater sciatic foramen and attaches to greater trochanter of femur

Question 19

Perineum

Answer 19

Region below the pelvic diaphragm; contains external genitalia and outlet of gut

Question 20

Levator Ani

Answer 20

Forms anterior 2/3 of pelvic diaphragm; attaches to coccyx, annococcygeal body, and perineal body

Question 21

Perineal body

Answer 21

Tendinous raphe of pelvic muscles; important in supporting structures of abdomen

*If torn as a child => prolapse of pelvic viscera

Question 22

Levator prostate/ sphincter vaginae

Answer 22

Forms a sling around perineal organs and inserts onto perineal body

Question 23

Puborectalis

Answer 23

Forms an important sling around the anorectal jnxn pulling the posterior wall anteriorly

-Located adjacent to deep part of the external anal sphincter

Question 24

Pubococcygeus

Answer 24

Inserts onto anococcygeal body and coccyx

Question 25

Illiococcygeus

Answer 25

Extends from ischial spine and Tendinous arch to insert on anococcygeal body and coccyx

Question 26

Coccygus

Answer 26

Forms posterior 1/4 of pelvic diaphragm; goes from ischial spine to coccyx

Question 27

Sciatica

Answer 27

Pain to lower limb due to compression of the lumbosacral plexus by a tumor or possibly a child’s head

Question 28

Sciatic Nerve

Answer 28

Composed of L4-S3; exits inferior to piriformis

Question 29

Pudendal Nerve

Answer 29

S2-S4; travels out of the pelvic cavity thru the greater sciatic foramen and back in thru the lesser sciatic foramen

*Provides somatic motor innervation to perineal muscles

(Bulbospongiosus, ischiocavernosus, sphincter urethrae)

*Somatosensory to lower anal canal and superficial skin of penis

Question 30

Lateral Mass

Answer 30

Fusion of the sacral processes that connects the sacrum to ilium

Question 31

Iliolumbar ligament

Answer 31

Travels from the transverse processes of T5 to the iliac crest

Question 32

Maximum measurement of the pelvic outlet

Answer 32

Anterio-posterior diameter

*Can be determined by finding the diagonal conjugate diameter

Question 33

Pelvic diaphragm innervation

Answer 33

Ventral rami of S4 and S5

Question 34

Endopelvic fascia

Answer 34

Covers the pelvic organs and is continuous w/ the endoabdominal fascia

Question 35

Nerve to Obturator internus

Answer 35

Also passes thru the greater sciatic foramen and back thru the lesser

Question 36

Pelvic splanchnic nerves

Answer 36

Consist of pre-ganglionic parasympathetic fibers that innervate the Hindgut derivatives

Question 37

Lumbosacral trunk

Answer 37

Consists of the ventral rami of L4-L5; part of lumbosacral plexus

Question 38

Lumbosacral plexus

Answer 38

Consists of Lumbosacral trunk and S1-S3

-S1-S3 leave the sacrum via the anterior sacral foramina