Pelvic Anatomy (4)

Question 1

What bones make up the pelvic girdle?

Answer 1

Innominate (= Ilium, Ischium & Pubis) x 2
Sacrum (5 fused bones)
Coccyx (4 fused bones)

Question 2

What are the (superior, inferior, lateral, anterior & posterior) borders of the pelvic cavity

Answer 2

Superior = Pelvic inlet
Inferior = Pelvic diaphragm (sits above the perineum) 
Lateral = Hip bones & Obturator internus muscle (covers the obturator foramen) 
Anterior = Pubic bones, Pubic symphysis 
Posterior = Piriformis muscle, Sacrum & Coccyx

Question 3

What is the Pelvic brim (inlet), and what is it formed by?

Answer 3

= marks the plane of the pelvic inlet - separates the true (greater) pelvis from the false (lesser) pelvis
Formed by:
- the promontory & the ala of the sacrum
- 2 x linea terminalis (= arcute line, pecten pubis & pubic crest)

Question 4

What are the sexual dimorphisms of the male/female pelves: sacrum, coccyx & greater sciatic notch?

Answer 4

Sacrum:
F = wider, shorter - sacral curve is more attenuated
M = narrow, longer - sacaral promottary more ventral
Coccyx:
F = more movable (for childbirth), straighter
M = less movable, curves ventrally
Greater sciatic notch:
F = wide & shallow
M = narrow & deep

Question 5

What are the sexual dimorphisms of the male/female pelves: pelvic inlet (brim), pelvic outlet & subpubic angle?

Answer 5

Pelvic inlet:
F = wider - oval from side to side
M = narrow - basically heart-shaped
Pelvic outlet:
F = wider - ischial tuberosities are shorter, further apart & everted
M = narrower - ischial tuberosities are longer, sharper & point more medially
Subpubic angle:
F = obtuse
M = acute