Pelvic Anatomy Flashcards
Describe the differences between the pelvic inlet and outlet
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What is the clinical importance of the ischial spine?
Landmark for pudendal nerve and can be used to assess progress of labour
How can the progress of labour be assessed using the ischial spine?
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What is the clinical importance of the sacral promontory?
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What is the clinical importance of the iliopectineal ligament?
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Main differences between male and female pelvic anatomy
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What are the main joints of the pelvis
Sacroiliac and pubic symphysis
How is the sacroiliac joint stabilised
NO MUSCLES, only ligaments holding it together - anterior ileo-sacral ligaments and the posterior Ileo-sacral ligaments
What are the key features of the pubic symphysis
- Fibrocartilagenous disc - shock absorber (it can compress)
- There is a hormone called relaxin that allows more water to enter the ligaments and allows it to relax. The joints of the child do not detach but they slide over each other.
What are the main ligaments in the female reproductive tract?
Broad, Ovarian and Uterine
What is the broad ligament?
- a flat sheet of peritoneum, associated with the uterus, fallopian tubes and ovaries
- Extends from the lateral pelvic walls on both sides and folds over the internal female genitalia, covering their surface anteriorly and posteriorly
What are the subdivisions of the broad ligament
Mesometrium (uterus), Mesovarium (ovaries) and Mesosalpinx (fallopan tube)
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What are the other ligaments located in the broad ligament?
Ovarian ligament
Round ligament of uterus
Suspensory ligament of ovary (aka infundibulopelvic ligament)
Which ligaments are associated with the superior aspect of the uterus?
The broad ligament and round ligaments
Which ligaments are associated with the middle aspect of the uterus?
cardinal, pubocervical and uterosacral ligaments
Which structures support the uterus inferiorly?
levator ani, perineal membrane, perineal body
Where are the Cardinal ligaments found?
Situated along the inferior border of the broad ligament, housing the uterine
artery and uterine veins
What is the function of the pubocervical ligaments?
Bilateral structures attaching the cervix to the posterior surface of the pubic symphysis
What is the function of the uterosacral ligaments?
Bilateral fibrous bands attaching the cervix to the sacrum posteriorly
What is the innervation of the walls of organs in the pelvis?
PARASYMPATHETIC - smooth muscle walls
Why is any pain in the walls of pelvic organs poorly localised?
Referred pain occurs because the sensory nerves transmit signals up the same tracts of the dermatomes - wherever it enters at a particular level, the pain comes from that equivalent dermatome.
Where is most pain felt and why?
Most pain is felt in the MIDLINE – because the autonomic ganglia (SPLANCHIC NERVE GANGLiA) are near the vessels of the midline.
What are the main muscles of the pelvic diaphragm?
levator ani (puborectalis, pubococcygeus, iliococcygeus) and coccygeus
Damage to which muscle during delivery is a major cause of faecal incontinence?
Pubo-rectalis as normally, it puts a kink in the rectum which prevents faeces from exiting the rectum - this makes it more important than sphincters for faecal incontinence
What is used to quantify and describe the degree of uterine prolapse?
Pelvic Organ Prolapse Questionnaire - POP-Q
What are the nerve roots of the pudendal nerve?
S2-S4
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What does the pudendal nerve provide?
Motor to perineal muscles
Somatosensory to perineum and external genitalia
Why can a pudendal nerve block be useful prior to instrumental delivery?
Sensation in areas innervated by pudendal is usually specific and well localised so blocking it provides pain relief
What are the anatomical borders of the perineum?
Anterior: pubic symphysis
Posterior: tip of the coccyx
Laterally: inferior pubic rami and inferior ischial rami, and the sacrotuberous ligament
Roof: pelvic floor
Base: skin and fascia
What is the perineal body and where is it found?
An irregular fibromuscular mass located at the junction of the urogenital and anal triangles – the central point of the perineum.
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What is the function of the perineal body?
Acts as an attachment point for muscles from the pelvic floor and the perineum
In women, it acts as a tear resistant body between the vagina and the external anal sphincter, supporting the posterior part of the vaginal wall against prolapse
In the male, it lies between the bulb of penis and the anus.