THE PELVIS Flashcards
(26 cards)
What are the 3 joints of the pelvis and what type of joint is each one?
1) The sacroiliac (synovial)
2) Intervertebral disc (fibrous)
3) Pubic symphysis (cartilaginous)
Which bones fuse to form the hip (innominate) bone?
The ilium, ischium and pubis.
what are the superior and inferior boundaries of the true pelvis ? What does true pelvis contain?
superior: pelvic inlet
inferior: pelvic outlet (inferior pelvic aperture)
contains: rectum, bladder, reproductive organs
The false pelvis is also called the ____ and lies ____ to the ________ and is flanked by the _____. it is part of the ____ and contains ______, ______ and ____
greater pelvis superior superior pelvic aperture (pelvic brim/inlet) Ala of iliac bones abdomen appendix, ileum, sigmoid colon
pelvic outlet boundaries (4)
pubic symphysis
ischial tuberosities
tip of coccyx
sacrotuberous ligament
PITS
How is the superior pelvic aperture tilted?
Anteriorly since the ASIS and pubic symphysis are in the same vertical plane
What are the various diameters (conjugates) of the pelvis and between what bony landmarks do they extend?
1) Diagonal conjugate: sacral promontory to inferior aspect of pubis
2) obstetric (true) conjugate: 2 cm shorter than the diagonal
3) midpelvic (transverse) congugate: distance between ischial spines.
Which one, measured per vagina, is considered critical in obstetrics? Why?
The diagonal conjugate is measured per vagina from which the smaller - and more critical - obstetric conjugate is derived. The shortest diameter however, is the transverse conjugate.
Define the attachments of the sacrotuberous and sacrospinous ligaments.
Sacrotuberous: dorsal aspect of sacrum to ischial tuberosity
Sacrospinous: lateral aspect of the sacrum to the ischial spine.
What two foramina are formed by these structures?
Greater (via sacrospinous lig.) and lesser (via sacrotuberous lig.) sciatic foramena.
Name the muscles that form the walls of the pelvis?
Obturator internus and piriformis.
What are the attachments of the muscles that form the walls of the pelvis?
Obturator internus: rim of obturator foramen to greater trochanter
Piriformis: vertebrae S1-3 to greater trochanter. Lateral rotator of femur
What is the innervation of these pelvic wall muscles?
Obturator internus: n. to obturator internus (L5, S1.2); and piriformis: (S1,2).
What muscles form the floor of the pelvis?
Coccygeus and levator ani mm. (pubococcygeus + iliococcygeus - deeper fibers of the latter = puborectalis)
Where do the muscles of the pelvic floor arise?
Coccygeus: ischial spine to lateral
margin of sacrum & coccyx; and
levator ani: pubis and tendinous arch of obturator internus to coccyx.
What is the innervation of these pelvic floor muscles?
S2,3,4.
Pudenal nerve
What do these muscles form a sling around?
Lower rectum/upper anal canal.
What is the perineal body?
A connective tissue mass. Serves as an insertion point for muscles such as levator ani
Why is the perineal body clinically important?
It is either incised, or avoided, in episiotomies during childbirth.
90% of vessels that leave pelvis pass through _____
greater sciatic foramen
What is the tendonous arch?
A thickening of the deep investing fascia on the inner surface of the obturator internus muscle
What is subserous fascia?
Loose adipose fascia that interdigitates with the endopelvic fascia and acts as packing material
Where is the perineal body located?
Between the anus and the base of the scrotum in the male or the posterior aspect of the vagina in the female.
What is Alcock’s canal? Also known as pudendal canal
A canal compromised of investing fascia on the outer surface of the obturator internus muscle that allows passage of the pudendal nerve and internal artery and vein
