Anatomy of the pelvis Flashcards
1
Q
which bones make up the bony pelvis
A
- pair of hip bones laterally
- sacrum midline posteriorly
- coccyx midline posteriorly
2
Q
which bones make up the hip bone
A
ischium
ilium
pubis
3
Q
explain the 3 surfaces of the ilium
A
- iliac fossa (anteriorly)
- gluteal surface (posteriorly)
- sacral surface (articulation at sacroiliac joint)
4
Q
what attaches to the pubic tubercle
A
inguinal ligament
5
Q
the pair of pubic bones articulate in the midline at the
A
pubic symphysis
6
Q
which two bones make up the obturator foramen
A
inferior pubic ramus
ischial ramus
7
Q
the ischial spine delineates the
A
greater and lesser sciatic notch
8
Q
how many vertebra make up the sacrum
A
5
9
Q
what are the lateral masses made of in the sacrum
A
the fused original transverse processes of the 5 vertebra
10
Q
what is the promotary
A
the superior surface of the sacrum
11
Q
what is the sacral alar
A
the superior surface of the lateral masses of the sacrum
12
Q
what are the articulations of the sacrum
A
L5 joint
coccyx
13
Q
what delineates the lesser/true and greater/false pelvis
A
the iliopectineal line (posterior extension of the pectineal line)
14
Q
function of the greater/false pelvis
A
protection for the abdominal contents
15
Q
what bounds the lesser/true pelvis
A
from anterior to posterior:
- pubic symphysis
- pubic crest
- pectineal line of the pubis
- arcuate line of the ilium
- sacroiliac joint (anterior margin of the alar and sacral promontary)
16
Q
what are the four basic pelvic types (based on shape of inlet)
A
gynaecoid
anthropoid
android
platypelloid
17
Q
what are the typical pelvic shapes of males and females
A
males - android and anthropoid
females - gynaecoid
18
Q
explain the general structure of the pelvis in males and females
A
males - thick and heavy
female - thin and light
19
Q
explain the shape of the pelvic inlet in males and females
A
males - heart shaped
females - transverse oval
20
Q
explain the greater sciatic notch in males and females
A
males - narrow inverted v
females - almost 90 degrees
21
Q
explain the subpubic arch in males and females
A
males - acute angle
females - obtuse angle
22
Q
explain the acetabulum in males and females
A
males - large
females - small
23
Q
explain the obturator foramen of the pelvis in males and females
A
male - round
female - oval
24
Q
what is the easiest thing to look at pelvic bones and tell whether it is a female or male
A
females - the distance from the acetabulum to the pubic symphysis is greater than the width of the acetabulum
males - distance is about the same
25
what structures make up the pelvic outlet
- inferior margin of the pubic symphysis
- tip of the coccyx posteriorly
- ischial tuberosities either side
26
what is the shape of the pelvic inlet and outlet
inlet - heart (male) or oval (female)
| outlet - diamond
27
where is the plane of least dimensions of the pelvis
extends from S4 behind, through the ischial spine to the pubic symphysis
28
what is the advantage of the shape of the pelvic floor during childbirth
it helps the babies head rotate and flex during childbirth so it only presents the smallest diameter to the smallest proportional part of which ever part of the pelvis it is going through
29
what are the 2 joints of the pelvis
- pair of synovial sacroiliac joints laterally
| - secondary cartilagenous pubic symphysis in the midline
30
which ligaments help reinforce the sacroiliac joints
anterior SI ligament
posterior SI ligament
interosseous SI ligament
31
what extra function does the interosseous SI ligament play
tightens as the sacrum rotates forwards - locking the sacroiliac joint
32
what are the 3 accessory ligaments of the sacroiliac joint
iliolumbar ligament
sacrotuberous ligament
sacrospinous ligament
33
what is the combined function of the accessory ligaments of the sacroiliac joint
resist tendency of the sacrum to rotate
34
where does the iliolumbar ligament extend from/to
from the iliac crest to the transverse process of L5
35
where do the sacrotuberous and sacrospinous ligaments extend from/to
ST - from ischial tuberosity to sacrum
| SS - from ischial spine to sacrum
36
what is nutation and counternutation of the pelvis
nutation - top of the sacrum goes forwards (closing the pelvic entry and opening the pelvic outlet) --> "nodding"
counternutation - top of the sacrum moves out and the tip of the coccyx movs in (opens the pelvic inlet and closes the pelvic outlet)
37
what are the ligaments that reinforce the pubic symphysis
superior pubic ligament
| inferior arcuate ligament
38
what separates the two bones of pubic symphysis
fibrocartilagenous disc
39
what other than ligaments help support the pubic symphysis
the criss-crossing muscles of:
- oblique abdominal muscles (and aponeurosis)
- rectus sheath
- adductor longus
40
what are the muscles of the walls of the pelvis and what are their positioning
- obturator internus - lateral wall
- piriformis - posterior wall
- pelvic floor
41
origin of obturator internus
arises from the internal surface of the obturator membrane, the adjacent margins of the obturator foramen, and extends up onto the posterosuperior aspect of the hip bone
42
route and insertion of obturator internus
goes through lesser sciatic foramen (collecting the lesser and greater gemeli) and appears into the gluteal region --> greater trochanter
43
origin of piriformis
arises from the middle 3 pieces of the sacrum and the adjacent parts of the lateral mass
44
route and insertion of piriformis
the fibres converge as they exit the greater sciatic foramen into the gluteal region
45
origin of the pelvic floor
one continuous lateral origin around the side wall of the pelvis (the internal aspect of the body of the pubic bone, along the side wall of the pubis, across the obturator membrane, halfway along obturator internus, and ending at the ischial spine)
46
insertion of the pelvic floor
central line of insertion into a midline raphe that extends from the tip of the coccyx to the anorectal junction (anococcygeal raphe)
47
what are the 3 muscles that make up the pelvic floor and which muscles make up the levator ani
pubococcygeus
iliococcygeus
ischiococcygeus
(pubo and ilio = levator ani)
48
what are the three parts of pubococcygeus
pubovaginalis/prostaticus - most medial/anterior
puborectalis - more lateral
most lateral fibres - most lateral
49
does iliococcygeus overlye or underlies pubococcygeus
underlaps
50
where does the ischiococcygeus muscle extend from/to
extends from the ischial spine towards the side of the coccyx (internal aspect of the sacrospinous ligament)
51
function of ischiococcygeus
nothing
52
what is the anorectal angle
80 degrees
53
explain the pelvic fascia
dense fascia overlies fascia over structures that dont move
| loose fascia on structures that need to expand or move
54
what is endopelvic fascia
loose CT that fills the spaces in the pelvis
55
what is special about the endopelvic fascia
condenses around the NV structures that help them go from the lateral wall into the viscera
56
where is the sacral plexus
on the surface of piriformis
57
which branch of the internal iliac artery supplies the pelvic viscera
anterior
| posterior gives only parietal branches
58
explain the peritoneum of the pelvis
- anterior pelvic peritoneum leaves the anterior abdominal wall and then drapes over pelvic viscera and invests them in part with a serous coat before onto the posterior abdominal wall
- between viscera it hangs in dependent folds or pouches
59
what structures cross the ureter in the male and female
male - vas deferens
| female - uterine artery
60
what are the 2 ligaments that stabilise the bladder
- pubovesical ligament
| - fascial condensation = lateral pelvic ligament
61
explain the orientation of the bladder
tipped forwards so that the apex points towards the pubic bone
- base is posterior
62
explain the orientation of the structures entering the bladder
- ureters entering at the base of the triangle
| - urethra exits at the apex of the triangle
63
explain the internal surface of the bladder
- have mucosal ridges overlying the detrusor muscle
| - bladder base (most posterior) is smooth (trigone)
64
what are the bilateral reproductive structures of male
- testis
- epididymus
- ejaculatory duct
65
what are the midline reproductive structures of the male
urethra
| penis
66
what are the accessory glands of the male
prostate
seminal vesicles
bulbourethral glands
67
what structures comes together to form the ejactulatory duct
vas deferens
| seminal vesicle
68
where is the prostate located
between the neck of the bladder and levator ani (above) and the perineal membrane (below)
69
what part of the prostate is palpable on PR exam
the posterior surface of the prostate
70
what things can you feel about the prostate gland on PR exam
size
hardness
contour
71
which part of the prostate gland is transversed by the ureter
median/medial lobe
72
what does an antiverted uterus mean
uterus bent forward over the vagina that is bent backwards
73
what are and where are the parts of the uterus
- above the uterine tubes = fundus
- below the entrance of the uterine tubes = body of the uterus
- cervix
74
which part of the cervix is visible on a speculum examination
external os
75
which part of the uterus is stabilised by ligaments
cervix
76
what are the 3 ligaments that attach to the cervix
- lateral cervical ligaments
- utero-sacral ligaments/recto-uterine ligaments
- pubocervical ligament
77
what is the most substantial ligament
lateral cervical ligaments
78
where are the ligaments that attach to the cervix
- lateral cervical - from side wall to the cervix (endofascial condensation surrounding NV structures)
- uterosacral ligament (backwards to the sacrum)
- pubocervical ligament (forwards to the pubic bone)
79
what is the cause of a prolapsed uterus
the ligaments supporting the cervix and vagina slacken (due to childbirth or advancing age)
80
how long are the uterine tubes
10-14cm
81
what is the broad ligament
the peritoneum that covers most of the anterior surface of the uterus, the uterine tubes and the posterior part of the uterus
82
where do the ovaries lie in relation to the broad ligament
on the posterior side
83
what are the 4 parts of the uterine tubes
intramural
isthmus
ampulla
fimbriae
84
which direction do the fimbriae of the uterine tube point
posteriorly towards the ovary
85
how and where are the ovaries connected to the uterus
connected by the ovarian ligament to the upper angle of the uterus
86
what are the three structures that attach to the upper angle of the uterus
fallopian tubes
ovarian ligaments
round ligaments
87
where does the ovary sit in relation to NV structures
sits between the bifurcation of the iliac vessels
88
which direction does the vagina sit
sits with an angulation backwards
89
which wall of the vagina is longer (ant or post)
posterior
90
where can you palpate the pouch of douglas
via vaginal examination - the posterior wall of the vagina at the superior asepct
91
what is the vaginal fornix
the expanded upper part of the vagina that surrounds the external os
92
what do the ant, post and lateral parts of the vaginal fornices relate to
ant - bladder
post - pouch of douglas
lateral - lateral structures
93
at what anatomical landmark does the rectum begin
at S3 - where the taenia change back to a longitudinal muscle coat
94
which part of the rectum stores the faeces
ampulla
95
what are the 2 arteries that enter the pelvis from above and what do they themselves branch from
```
ovarian arteries (abdominal aorta)
superior rectal artery (continuation of the inferior mesenteric artery)
```
96
what are the common (both male and female) visceral arterial branches for the pelvis and which structures do they relate to
superior vesical artery = bladder
| superior rectal artery
97
what are the visceral arterial branches of the plevis that are extra in the male
inferior vesical artery - reinforces the prostate, seminal vesicles etc
98
what are the visceral arterial branches of the pelvis that are extra in the female
uterine artery - uterus
| vaginal artery - vagina
99
where is the the nerve supply to the pelvic viscera derived from
the inferior hypogastric plexus (contains both SNS and PNS)
100
where is the PNS component of the inferior hypogastric plexus derived from
pelvic nerves S2-4 (part of sacral plexus)
101
where is the SNS component of the inferior hypogastric plexus derived from
the thoracolumbar nerves
102
where is the perineum and what are its borders
beneath the pelvic floor and the skin
| - diamond - from symphysis pubis to tip of the coccyx behind and ischial tuberosities either side
103
how is the perineum divided up
into 2 triangles by a line that joins the ischial tuberosities horizontally
- uritogenital triangle
- anal triangle
104
what further divides the uritogenital triangle of the perineum and what are the divisions called
the peroneal membrane
- superficial peroneal pouch
- deep peroneal pouch
105
what is and where is the peroneal membrane
it is a fibrous membrane that extends from one ischial pubic ramus to the other with a free posterior edge
106
what is important about the free posterior edge of the peroneal membrane
has a thickening in the midline of its posterior margin (peroneal body)
107
the free posterior edge of the peroneal membrane is reinforced by...
pair of superficial transverse peroneal muscles and a pair of transverse peroneal muscles
108
what is the ischiorectal fossi
the space on either side of the anal canal that is filled with fat in real life
109
what forms the pudendal canal
a split in the fascia overlying obturator internus (lateral wall of the anal triangle)
110
explain the lining of the anal canal
upper 2/3 lined by mucosa
| lower 1/3 lined by skin
111
explain the differences in arterial supply of the upper 2/3 and lower 1/3 of the anal canal
upper 2/3 = superior rectal artery
| lower 1/3 = rectal artery
112
explain the differences in portal drainage of the upper 2/3 and lower 1/3 of the anal canal
upper 2/3 - drains to portal system
| lower 1/3 - drains to system system (site of porto-systemic anastomoses)
113
explain the differences in nerve supply of the upper 2/3 and lower 1/3 of the anal canal
upper 2/3 = autonomic nerves
| lower 1/3 = somatic nerve supply
114
what are where are the 3 parts of the external anal sphincter
deep - directly related to the pelvic floor
superficial - part that is fixed anteriorly and posteriorly
subcutaneous - immediately deep to the skin
115
what are the anterior and posterior anchor points of the superficial part of the external anal sphincter
anterior - to the perineal body
| posterior - tip of the coccyx
116
where are the external sphincters involved with the urethra
in the deep perineal pouch on the deep surface of the membrane
117
what structures are associated with the superficial peroneal pouch and the superficial surface of the peroneal membrane
the anchor points for the external genitalia
118
what are the 4 parts of the male urethra
- pre-prostatic (associated with the internal urethral sphincter)
- prostatic
- membranous - tranverses the deep perineal pouch and deep surface of perineal membrane)
- spongy part
119
explain the tissue of the penis
pair of corpora cavernosa
| single corpora spongiosum
120
anchor points for corpora cavernosa
laterally to the pair of ischial pubic rami - come together in the midline and join spongiosum
121
what are the muscles that cover the tissues of the penis
ischiocavernosus
| bulbospongiosus
122
what is the major nerve of the perineum
pudendal nerve
123
explain the composition of the pudendal nerve
sensory, sympathetic and somatic (not PNS) - branch of sacral plexus (S2-4)
124
route of the pudendal nerve
- starts in sacral plexus on piriformis
- exits with piriformis via GSF
- winds around the back of the ischial spine and leaves through the LSF beneath the pelvic floor
- goes into the pudendal canal and lands on obturator internus
125
what are the 3 branches of the pudendal nerve
inferior rectal nerve
perineal nerve
dorsal nerve of the clitoris/penis
126
route of inferior rectal nerve and what does it supply
through ischiorectal fossa and supplies the anal canal
127
route of perineal nerve and what does it supply
splits into motor and cutaneous branches to all the structures associated with the urogenital triangle
128
which nerves could potentially be damaged with a fracture of the pelvis
sciatic
femoral
lateral femoral cutaneous
129
what structures might be injured if the sacrum is fractured or there is a disruption of the SI joint
internal iliac
nerves in sacral foramen
hip flexors
