PELVIS

Question 1

what does the pelvis consist of?

Answer 1

bony pelvis + pelvic cavity

Question 2

what is the pelvic girdle and what 4 bones does it consist of?

Answer 2

a basin-shaped ring of bones that connect the vertebral column to the two femurs. surrounds the pelvis. composed of sacrum, coccyx, 2 x os coxae (hip bone).

Question 3

what are the primary functions of the pelvic girdle? (2)

Answer 3

1) transfer the weight from the axial to the lower appendicular skeleton for standing and walking.
2) bear the weight of the upper body when sitting and standing.

Question 4

how is weight transferred from axial skeleton to the ilia?

Answer 4

via sacro-iliac ligaments

Question 5

what 3 bones make up the hip bone after they fuse in puberty and where do they meet?

Answer 5

ilium, ischium, pubis - meet at the acetabulum

Question 6

what is the sacrum composed of and where do they articulate with the hip bones?

Answer 6

formed by the fusion of 5, originally separate, sacral vertebrae. articulate with os coxae at sacroiliac joints.

Question 7

what does the pelvic inlet do?

Answer 7

divides the pelvis into the greater (false) and lesser (true) pelves

Question 8

male vs. female pelvis

Answer 8

male = thick and heavy, female = thin and light
GREATER PELVIS: male = deep, female = shallow
LESSER PELVIS: male = narrow and deep and tapering, female = wide and shallow and cylindrical
PELVIC INLET: male = heart-shaped and narrow, female = oval and rounded and wide
PELVIC OUTLET: male = comparatively small, female = comparatively large
PUBIC ARCH AND SUBPUBIC ANGLE: male = narrow (< 70), female = wide (>80)
ACETABULUM: male = large, female = small
GREATER SCIATIC NOTCH: male = narrow (<70) inverted V, female = almost 90

Question 9

sacro-iliac joints purpose and characteristics

Answer 9

= link the axial skeleton and the inferior appendicular skeleton.
= synovial joints
- strong, weight-bearing compound joints
- limited mobility
- permits weight transfer from the vertebral column to the pelvis
- allows slight but significant movement during childbirth, when the pubis symphysis and the ligaments are softened by hormones

Question 10

what are the secondary functions of the pelvic girdle?

Answer 10

protection and support of a domino pelvic viscera and housing + attachment for structures of the genital and urinary systems.

Question 11

false (greater) pelvis

Answer 11

= greater, expanded blade-like portions of each ilium superior to the pelvic brim. bounded on each side by the ilium. situated above and in front of the pelvic brim.

Question 12

true (lesser) pelvis

Answer 12

• bounded in front and below by the pubic symphysis and the superior rami of the pubis. bounded above and behind by the sacrum and coccyx
• encloses pelvic cavity
• provides the skeletal framework for both the pelvic cavity and the perineum, which are separated by the pelvic diaphragm
• contains the pelvic colon, rectum, bladder, and some of the sex organs

Question 13

which ligaments help to support and immobilise the sacrum as it carries the weight of the body?

Answer 13

sacrospinous and sacrotuberous ligaments

Question 14

position of the pelvic cavity

Answer 14

• extends superiorly into the thoracic cage
• extends inferiorly into the pelvis
• lined with peritoneum
• drapes over the superior aspects of the pelvic viscera, but in most regions does not reach the pelvic floor
• bladder is anterior
• rectum is posterior
• funnel-shaped
• continuous with the abdominal cavity at the pelvic inlet

Question 15

what forms the floor of the pelvic cavity and what muscles does it consist of?

Answer 15

pelvic diaphragm - levator ani and coccygeus

Question 16

what muscles is the levator ani composed of?

Answer 16

iliococcygeus (outside)
pubococcygeus (inside)
puborectalis (underneath)

Question 17

main action, innervation, proximal and distal attachment of levator ani

Answer 17

main action: forms most of pelvic diaphragm that helps support pelvic viscera.
innervation: nerve to levator ani (branches of S4), inferior anal nerve, and coccygeal plexus
proximal attachment: body of pubis, ischial spine, tendinous chord of obturator fascia
distal attachment: perineal body, coccyx, anococcygeal ligament, walls of prostate/vagina, rectum and anal canal

Question 18

coccygeus main function, innervation, proximal and distal attachment

Answer 18

main function - forms small part of pelvic diaphragm that supports pelvic viscera. flexes coccyx
innervation - branches of S4 and S5 spinal nerves
proximal attachment - ischial spine
distal attachment - inferior end of sacrum and coccyx

Arises from the lateral border of the sacrum and coccyx, the fibres cross on the deep surface of the sacrospinous ligament and insert into the ischial spine.

Question 19

what muscles make up the lateral and posterosuperior walls of the pelvic cavity?

Answer 19

lateral - obturator internus

posterosuperior wall - piriformis

Question 20

obturator internus and piriformis function, where they arise from and pass through

Answer 20

both hip rotator muscles, arise within the pelvis and pass outward through the sciatic foramina.
Piriformis muscles pass through the greater sciatic foramina in order to enter the gluteal area

Question 21

function of parietal peritoneum and how is it separated from pelvic floor

Answer 21

linens the abdominal cavity, remains separated from the pelvic floor by the pelvic viscera and surrounding pelvic fascia.

Question 22

what is parietal pelvic fascia?

Answer 22

a membranous layer of variable thickness that lines the inner aspect of the muscles forming the walls and floor of the pelvis

Question 23

what is visceral pelvic fascia?

Answer 23

includes the membranous fascia that directly ensheathes the pelvic organs, forming the adventitial layer of each.

Question 24

adventitia definition

Answer 24

the outer layer of surrounding connective tissue surrounding an organ

Question 25

what is the Tendinous Arch of Levator Ani and where does it extend from/to?

Answer 25

a thickened portion of the obturator fascia on the medial aspect of the obturator internus that extends in an arching line from the pubis posteriorly to the ischial spine

Question 26

what is the Tendinous Arch of Pelvic Fascia?

Answer 26

a continuous bilateral band running from the pubis to the ischial spine

Question 27

anococcygeal ligament

Answer 27

the fibres of the levator ani which arise more posteriorly unite in this midline at this fibrous band

Question 28

what is the anterior wall of the pelvis formed from?

Answer 28

symphysis pubis, body of pubis, pubic rami

Question 29

what is the posterior wall of the pelvis formed from?

Answer 29

sacrum, coccyx, piriformis muscle

Question 30

what does the obturator canal do?

Answer 30

transmits the obturator nerve and vessels

Question 31

where does the obturator internus originate and insert?

Answer 31

originates at the pelvic surface of the ilium and ischium and the obturator membrane. inserts itself into the greater trochanter of the femur

Question 32

what bears the weight of the urinary bladder?

Answer 32

the anterior wall of the pelvis

Question 33

iliococcygeus location

Answer 33

Arises from ischial spine and the tendinous arch of levator ani and blends with the fibres of the anococcygeal body

Question 34

pubococcygeus

Answer 34

Arises from the lateral aspect of the posterior surface of the body of the pubis and inserts into the coccyx and the anococcygeal body.

Question 35

puborectalis location and function

Answer 35

The muscle fibres arise from the posterior aspect of the body of one pubic bone, wrap around the posterior aspect of the anorectal junction and insert on the posterior aspect of the other pubic bone. It is involved in maintaining faecal continence.

Question 36

what is the anococcygeal body?

Answer 36

a mass of fibrous tissue which lies between the anus and the coccyx