Lecture 4 (B) - Pelvis Flashcards
What axis is the pelvis on?
Anterior-inferiorly inclined.
What part makes up the majority of the pelvic girdle?
Iliac fossae - form shallow basins containing the lower abdominal viscera.
What artery supplies most of the pelvic organs?
Internal iliac artery - does not supply the ovaries/testis, the pelvic walls or much of the gluteal region.
Where can a synovial joint be found in the pelvic girdle?
At the sacro-iliac joint - marks the border between the sacral spinal cord and the pelvis.
What is the pelvic wall composed of?
- Sacrum and coccyx
- Pelvic bones
- Sacrospinous and sacrotuberous ligaments
Which two muscles are attached to the greater trochanter of the femur (highest point of femur)?
- Piriformis muscle
- Obturator internus muscle
What muscle makes up the majority of the pelvic diaphragm?
Levator ani
What does the pelvic diaphragm do?
Supports the pelvic organs (bladder, cervix, uterus and rectum/prostate in males) as well as forming the divide between the pelvic cavity and the perineum.
What is found in the perineum?
Voluntary sphincters and external genitalia.
Where are the openings in the elevator ani?
- Urethra
- Vagina
- Anal canal
What is found between the vagina and the anus?
Perineal body (a fibromuscular mass)
What is found inferior to the levator ani?
Perineal membrane (forms the inferior layer of fascia of the urogenital part of the pelvic diaphragm)
What nerves innervate the pelvic diaphragm?
Via the pudendal nerves (S2-4) and directly by S4.
How is the external urethral sphincter controlled?
Under voluntary control (skeletal muscle).
How is the internal urethral sphincter controlled?
Under non-voluntary control (smooth muscle)
What is the difference between the urethral sphincters in men and women?
- Internal urethral sphincter is not well organised in females
- There are two additional groups of muscles found in females (sphincter urethrovaginalis and compressor urethrae)
Describe the structure of the bladder.
- Tetrahedral in shape (when empty)
- Attached to a structure at each corner of the tetrahedron
- Ureters enter at the supero-posterior angles
- Urethra leaves through the inferior angle
- Median umbilical ligament is attached supero-anteriorly
Where is the internal sphincter found?
At the neck of the urethra, just below where it exits the bladder.
Where does the bladder begin and end?
Expands between the transversals fascia and the lining of the peritoneum (superior surfaced is covered in peritoneum).
What is the shape of the rectum and what is the significance of this?
Has a double S bend, which is thought to be a functional structures as an anti-gravity device, keeping the load off the sphincter.
How are the rectum and anal canal innervated?
Rectum - autonomic nerves
Anal canal - somatic nerves
What structure is important in faecal continence?
The puborectalis part of the levator ani, which puts a sharp angle into the recto-anal junction. The skeletal muscle sphincter surrounding the anal canal is actually much less important.
How can the puborectalis be damaged?
Can bee damaged in a poorly performing episiotomy.
What is an episiotomy?
A surgical cut made at the opening of the vagina during childbirth to aid difficult delivery and prevent rupture of tissues - it is sutured back up agin after delivery.
