4.b) Pelvis Flashcards
What type of joint in the sacroiliac joint?
Synovial joint
What type of joint is the pubic symphysis?
Secondary cartilaginous joint
What is the name of the surface that articulates with the head of the femur?
Acetabular fossa
What is considered the ‘true pelvis’?
Within the pelvic inlet.
What constitutes the pelvic wall?
Sacrum
Coccyx
Pelvic bones
What are the 2 main ligaments in the true pelvis?
Sacrospinous (sacrum to the ischial spine)
Sacrotuberous (sacrum to the ischial tuberosity)
Describe the orientation of the pelvic cavity.
Axis of the pelvic cavity is at a 45 degree angle to the axis of the abdominal cavity
Antero-inferiorly inclined
Shape of pelvic cavity
Conical/ cylindrical
Which muscle lines most of the pelvic bone facing the pelvic cavity?
Obturator internus
Where does the obturator internus insert and what other muscle inserts here?
Medial surface of the greater trochanter of the femur
Piriformis also inserts here
What muscle overlays the sacrospinous ligament?
Coccygeus muscle
What are the 3 main muscles of the pelvic floor and what are they called collectively?
Iliococcygeus muscle
Pubococcygeus muscle
Puborectalis muscle
These muscles make up Levator Ani
What forms the border between the obturator internus and the levator ani?
Tendinous arch of obturator internus fascia
What other ligament is found adjacent to Levantor Ani muscle?
Anococcygeal ligament
What does the pelvic diaphragm consists of?
Bowl like pair of skeletal muscles (Levantor Ani)
Support pelvic organs
What is the nerve supply to the levator ani?
Pudendal nerve (S2-S4) and directly from S4
What are the openings in the levator ani?
Urethra
Vagina
Anal canal
What is the perineal membrane?
Inferior layer of the fascia of the urogenital part of pelvic diaphragm
What does the perineum contain?
Voluntary sphincters
External genitalia
What is the name of the fat-filled space between the levator ani and the obturator internus in a male?
Ischio-anal fossa
What are the 2 sphincters in the urethra of a male?
Internal urethral sphincter (Smooth muscle)
External urethral sphincter (Skeletal muscle)
What are the 4 parts of the male urethra? How long is it?
Preprostatic Prostatic Membranous Spongy 20 cm
Describe the arrangement of the uterus and the bladder in women.
The uterus sits on top of the bladder
What is different about the urethral sphincters in women?
Women have a poorly organised internal sphincter.
External urethral sphincter is skeletal muscle surrounding the urethra in the deep perineal pouch.
Where is the external urethral sphincter of women found?
In the deep perineal pouch
How long is the female urethra and vagina?
Urethra: 4 cm
Vagina: 8-12 cm
What are 2 additional groups of muscle found in females?
Sphinter urethrovaginalis
Compressor urethrae
Describe the shape of an empty bladder.
Tetrahedral
What are the structures are each corner of the tetrahedron of the bladder?
Posterior superior vertices: ureters enter
Anterior vertex: has the median umbilical ligament
Posterior inferior vertex: urethra exits
What covers the superior surface of the bladder?
Peritoneum
Where does the bladder expand?
Between transversals fascia and lining peritoneum
Describe the 2 sphincters of the bladders
Smooth muscle sphincter (vesicae) at neck
Skeletal muscle sphincter (urethrae) in perineum
Describe the structure of the rectum.
It has a double S bend.
There are 3 transverse rectal folds (superior, middle and inferior).
Keeps the load off the sphincter.
What vessels supply the rectum?
Superior, middle and inferior rectal arteries
Which nerves supply the rectum and which nerves supply the anal canal?
Rectum: autonomic nerves (Sensitive to filling)
Anal canal: somatic nerves (V. sensitive to injury)
Which muscle is most important for faecal continence and what does it do?
Puborectalis part of Levantor Ani muscle: it puts a sharp angle into the recto-anal junction.
What could badly injure the Puborectalis muscle?
Episiotomy
Describe the muscle types in the internal and external anal sphincters
Smooth muscle (internal) skeletal muscle (external)
Where is the “right-angle bend back” in the rectum/ anus?
Recto-anal junction
What main blood vessels supply all the pelvic organs? (except the ovaries)
Internal iliac artery
What constitutes the margin of the pelvic inlet?
Pubic symphysis Pecten pubis Arcuate line Ala of sacrum Body of sacrum
What constitutes the margin of the pelvic outlet?
Inferior pubic symphysis
Pubic arches
Sacrotuberous ligament
Coccyx
What are the anterior and posterior vertices of the wedge shaped true pelvis?
Sacral promontory to upper border of pubic symphysis
Lower border of pubic symphysis to coccyx
