Flashcards in Lecture 18 DA Deck (29):
Where does piriformis originate and insert?
It originates from the three midsections of the sacrum and exits the pelvis through the greater sciatic foramen, and attaches on the lower limb.
Where does obturator internus originate from?
It originates from the obturator foramen, exits through the lesser sciatic foramen, just under the sacrospinous ligament.
What lines the obturator internus? What attaches here?
Obturator fascia lines it. In the middle of obturator internus, it is thickened, called tendinous arch. The levator ani attaches here.
How does the levator ani split the pelvic cavity?
It partitions it into the cavity above and the perineum below.
What is within the perineum?
Rectum, vagina and urethra.
What is the pelvic floor?
Levator ani, also known as the pelvic diaphragm as it acts like one, maintaining pressure.
Where does the levator ani project and what does it do to foetal heads?
It projects medially, and rotates the head 90 degrees.
What is found between the levator ani and the obturator internus?
The pudendal canal. Neurovascular bundle travels through here, the pudendals.
What is the major artery of the pelvis?
Common iliac artery.
Where do the internal and external iliac arteries supply?
External - lower limb.
Internal - Pelvis.
What is the raphe?
A tendinous line formed by the levator ani.
What is a consequence of a weak levator ani?
Visceral prolapse distally, as well as urinal and faecal incontinence.
What is a complication of prostatectomy or childbirth regarding internal viscera?
They can both cause distal prolapse.
What is a complication of prostatectomy regarding nerves?
Nerve supplying rectum and urethra can be damaged, resulting in faecal and urinal incontinence.
What happens in a prolapse?
Pelvic floor stretches, and viscerafall through.
Describe the pubococcygeus.
Found deeply. Has puborecalis within it. Under reflex control in children. When nervous system matures, it goes under voluntary control. Puborectalis is deep to pubococcygeus, and passes around the anal canal like a sling, causing a kink at the recto-anal junction. Prevents involuntary defaecation. Rectum is only somewhat straighter during defaecation.
Describe the structure and function of puborectalis, pubovaginalis and puboprostaticus.
Sling like, fuses with the deep part of the external anal sphincter.
Pubovaginalis/puboprostaticus stabilise the vagina or prostate. Puboprostaticus attaches from pubis to prostate.
What is the prostatic urethra?
Urethra within the substance of the prostate.
Describe the iliococcygeus.
In between pubococcygeus and ischiococcygeus. Sits on top of the sacrotuberous ligament.
It is the agitator caudae in animals, moving the tail. Commonly absent or very few fibres.
Describe the ischiococcygeus.
It is the most posterior component of levator ani.
What are the three components of levator ani from anterior to posterior?
Is the levator ani always under pressure?
Yes, especially during childbirth.
What is the peineal body?
Midline fibrous nodule, larger in females than males, and is in the perineum. Muscles merge with the perineal body and stabilise it.
What are thr functions of the pelvic floor?
Supports pelvic viscera.
Raises the pelvic floor.
Continence, faecal and unrinal.
Childbirth, creates a gutter to enable foetal head rotation.
What is the nerve supply to the pelvis?
Segmental from S3 and S4 above.
Pudendal from S2 and S3 below, enters the gluteal region with the gluteal artery, but exits via the lesser sciatic foramen.
What nerve is in danger if trauma occurs to the perineal region?
Pudendal nerve can be damaged.
What nerve is anaesthetised during childbirth by obstetricians, and what landmark is used to find it?
The pudendal nerve, ischial spine used as a landmark.
Where is the urogenital hiatus found, what what passes through it?
Found anteriorly, vagina passes through it.