29. Bony Pelvis and Pelvic Wall

Question 1

The _____ and _____ lines delineate the pelvic brim

Answer 1

Pectineal; arcuate

Question 2

Which ligaments of the pelvic girdle are strong and extensive, supporting the sacrum as it acts as a wedge separating the hip bones?

Answer 2

Sacroiliac ligaments

Question 3

What 2 ligaments prevent rotation of the sacrum/coccyx and together with the hip bone create the greater and lesser sciatic foramen?

Answer 3

Sacrotuberous ligament

Sacrospinous ligament

Question 4

AP compression produces fractures of what part of the hip bones?

Answer 4

Pubic rami

Question 5

Lateral forces on the pelvis squeeze the ____ and ____ together, breaking both

Answer 5

Acetabulum; ilia

Question 6

What are the weak areas of the pelvis subject to injury?

Answer 6

Pubic rami
Acetabulum
SI joints
Ala

Question 7

What are the borders of the lesser or “true” pelvis?

Answer 7

Superior: pelvic brim (pelvic inlet)

Inferior: muscular pelvic diaphragm

Lateral and anterior: lower 1/2 of hip bones

Posterior: sacrum + coccyx

Question 8

What region is considered the greater or “false” pelvis?

Answer 8

Superior to pelvic brim; occupied by abdominal viscera

Question 9

What bone associated with the pelvis provides predominant support for abdominal weight?

Answer 9

Pubic bone

Question 10

______ pelvis = normal male type

______ pelvis = normal female type

Answer 10

Android

Gynecoid

Question 11

Compare the greater sciatic notch in males vs. females

Answer 11

Males: narrow (~70 degrees); inverted V

Females: almost 90 degrees

Question 12

Compres the obturator foramen in males vs. females

Answer 12

Males: round

Females: oval

Question 13

Compare the pubic arch and subpubic angle in males vs. females

Answer 13

Males: narrow (~70 degrees)

Females: wide (greater than 80 degrees)

Question 14

Compare the pelvic outlet in males vs. females

Answer 14

Males: comparatively small

Females: comparatively large

Question 15

Origin/insertion/innervation of obturator internus

Answer 15

Origin: ilium/ischium surface; obturator membrane

Insertion: greater trochanter

Innervation: obturator n.

Question 16

Origin/insertion/innervation of piriformis m.

Answer 16

Origin: S2-4 surface, superior margin of greater sciatic notch; sacrotuberous ligament

Insertion: greater trochanter

Innervation: S1-S2

Question 17

Origin/insertion/innervation of coccygeus m.

Answer 17

Origin: ischial spine

Insertion: inferior end of sacrum and coccyx

Innervation: S4-5

Question 18

Actions of coccygeus m.

Answer 18

Support pelvic viscera; flex coccyx

Question 19

In addition to being part of the pelvic wall, the ________ and ________ mm rotate the thigh laterally (both attach to the greater trochanter of femur)

Answer 19

Piriformis; obturator internus

Question 20

The pelvic diaphragm is made up of 4 mm. named for their ____

Answer 20

Origin

Question 21

What are the 4 muscles that make up the pelvic diaphragm (and their origins)?

Answer 21

(Ischio) coccygeus m. — ischial spine

Iliococcygeus m. — tendinous arch

Pubococcygeus m. — pubis

Puborectalis m. — pubis

Question 22

Of the 4 muscles that make up the pelvic diaphragm, the iliococcygeus, pubococcygeus, and puborectalis mm. elevate the anal canal and together are called the ____ _____

Answer 22

Levator ani

Question 23

The tendinous arch of the levator ani is a thickening of the ______ fascia between the ischial spine and body of pubis

Answer 23

Obturator

Question 24

What muscle helps maintain fecal continence, relaxing during both urination and defecation, and is distinct from the external and internal anal sphincters?

Answer 24

Puborectalis m.

Question 25

The ________ is the passageway for the rectum, urethra, and in females the vagina. it is formed by the anterior gap between the levator ani muscles

Answer 25

Urogenital (levator) hiatus

Question 26

What muscles associated with the urogenital hiatus are the most susceptible to tearing during birth being most medial and large parts of the levator ani?

Answer 26

Pubococcygeus m. | Puborectalis m.

Question 27

The _____ _____ sits inferior to the pelvic floor, is diamond-shaped, and is filled primarily with fat

Answer 27

Ischiorectal fossae

Question 28

The ischiorectal fossae can be divided into 2 triangles: the _____ triangle and _____ triangle

Answer 28

Anal | Urogenital

Question 29

The _____ membrane spans between rami in the ischiorectal fossae

Answer 29

Perineal

Question 30

The ischiorectal fossae allows movement of the ____ _____ and expansion of the _____ canal. It contains ________ to the anal canal and some to the perineum

Answer 30

Pelvic diaphragm; anal; neurovasculature

Question 31

The anal canal begins at the level when the rectum ‘perforates’ the ______ ____. The ____ _____ are the associated longitudinal ridges The ____ _____ are the associated folds at the base of the above structures The ____ _____ are small recesses adjacent to the above structures, and function to exude mucus facilitating defecation

Answer 31

Levator ani Anal columns Anal valves Anal sinuses

Question 32

The internal anal sphincter is made up of inner circular _____ muscle, which is involuntary. It is kept in _____ contraction except when feces fill the rectum It is responsible for ______% of resting anal tone

Answer 32

Smooth; tonic 55-85%

Question 33

The external anal sphincter is made up of ______ muscle, which is voluntary. It is responsible for _____% of resting anal tone

Answer 33

Skeletal; 15-30

Question 34

What are the 3 parts of the external anal sphincter?

Answer 34

Subcutaneous Superficial Deep (puborectalis)

Question 35

______ are essentially enlarged and collapsed varicosities of normal venous anatomy that may be a major clinical consequence of portal hypertension

Answer 35

Hemorrhoids

Question 36

_________ ________ = prolapse of rectal mucosa; due to weakened muscularis mucosa (bleeding often bright red due to abundant arteriovenous anastomoses within internal rectal venous plexus)

Answer 36

Internal hemorrhoids

Question 37

Describe external hemorrhoids

Answer 37

External venous plexus covered with epidermis

Question 38

What anatomical landmark is used to classify type of hemorrhoids as external vs. internal?

Answer 38

Pectinate line

Question 39

How is the pectinate line used to classify whether hemorrhoid is external or internal? Which type is painful vs. not painful?

Answer 39

Internal hemorrhoids are above the pectinate line and are NOT painful External hemorrhoids are below the pectinate line and are painful

Question 40

How does rectal innervation differ above vs. below the pectinate line?

Answer 40

Above: inferior hypogastric plexus (visceral) Below: inferior rectal nn (somatic)

Question 41

How does venous drainage differ in the rectum above vs. below the pectinate line?

Answer 41

Above: primarily to superior rectal vein (portal) Below: primarily to inferior rectal veins (systemic)

Question 42

How does destination of lymph drainage differ above vs. below the pectinate line?

Answer 42

Above: internal iliac LNs, inferior mesenteric Below: superficial inguinal LNs

Question 43

How does embryological epithelial origin differ in the rectum above vs. below the pectinate line?

Answer 43

Above: endoderm Below: ectoderm