Pelvic anatomy lecture Flashcards
Male bony pelvis - General structure?
Thick + heavy
Male bony pelvis - Greater (false) pelvis?
Deep
Male bony pelvis - Lesser (true) pelvis?
Narrow and deep
Male bony pelvis - Pelvic inlet?
Heart-shaped
Male bony pelvis - Pelvic outlet?
Comparatively small
Male bony pelvis - Sub-pubic angle?
Narrow
Male bony pelvis - Obturator foramen?
Round
Male bony pelvis - Acetabulum?
Large
Female bony pelvis - General structure?
Thin + light
Female bony pelvis - Greater (false) pelvis?
Shallow
Female bony pelvis - Lesser (true) pelvis?
Wide and shallow
Female bony pelvis - Pelvic inlet?
Oval + rounded
Female bony pelvis - Pelvic outlet?
Comparatively large
Female bony pelvis - Sub-pubic angle?
Wide
Female bony pelvis - Obturator foramen?
Oval
Female bony pelvis - Acetabulum?
Small
Which part of the pelvis is termed the false pelvis?
The Greater pelvis (Pelvis major)
Which part of the pelvis is termed the true pelvis?
The lesser pelvis (Pelvis minor)
What type of joint is the sacroiliac joint?
Bicondylar synovial joint
What type of joint is the pubic symphysis?
Secondary cartilaginous
Diameter of the female pelvic outet - Anteroposterior?
13cm
Diameter of the female pelvic outet - Transverse?
11cm
Diameter of the female pelvic inlet - Anteroposterior?
11cm
Diameter of the female pelvic inlet - Transverse?
13cm
Diameter of the female pelvic inlet - Oblique?
12cm
What forms the anterior wall of the pelvis?
1) Bodies of the pubis bones
2) Pubic Rami
3) Pubic symphysis
What forms the posterior wall of the pelvis?
1) Coccyx and sacrum
2) The piriformis muscles with their coverings of the parietal pelvic fascia
What forms the lateral wall of the pelvis?
1) Hip bone
2) Obturator membrane
3) Sacrotuberous and sacrospinous ligaments
4) Obturator internus muscle and its covering fascia
What forms the inferior wall of the pelvis?
The pelvic diaphragm
Which nerve network lies on the piriformis muscle of the posterior wall of the pelvis?
The Sacral plexus (L4, L5, S1, S2, S3, S4)
What is the main nerve given off from the sacral plexus?
The Sciatic nerve
What are the two main divisions of the Sciatic nerve?
1) Common fibular (peroneal) nerve = L4, L5, S1 and S2
2) Tibial nerve = L4, L5, S1, S2 and S3
What is the perineal body?
A complex musculotendinous structure which gives an attachment of the perineal muscles. (Located immediately posterior to the urethral hiatus)
What is the anococcygeal body?
A complex musculotendinous structure which gives an insertion point for the Levator ani muscles. (Immediately posterior to the rectal hiatus and attaches to the coccyx)
What are the two major parts of the pelvic diaphragm?
1) Levator ani
2) Coccygeus muscle
What are the three muscles of the Levator ani, where do they all insert?
From medial to lateral:
1) Puborectalis m.
2) Pubococcygeus m.
3) Iliococcygeus m.
Insert on the anococcygeal body
What are the functions of the pelvic diaphragm?
1) Support of the abdominopelic viscera (E.g. bladder, intestines, uterus etc)
2) Resistance to increases in intra-pelvic/abdominal pressures (E.g. heavy lifting or coughing)
3) Urinary and faecal continence
What is the innervation of the Levator ani muscles?
Branches of the pudendal nerve (S2, S3, S4)
What is the innervation of the coccygeus muscle?
Anterior rami of S4 and S5
What is a cystocele?
Bladder prolapse into the vagina
What is a rectocele?
Rectal prolapse into the vagina
Injury to the pelvic floor in childbirth can lead to what?
1) Prolapse/herniation
2) Urinary stress incontinence
3) Rectal incontinence
Why may an episiotomy minimise long-term damage in childbirth?
Helps to prevent uncontrolled tearing of the perineal muscles.
E.g. If the midline fibres of the puborectalis are torn rectal herniation will often occur. This can be stopped with an Episiotomy
Is midline or mediolateral episiotomy preferred? Why?
Mediolateral are there is a decreased risk of deep perineal tears versus midline (7% versus 14.8%)
