The Pelvic & Hip Region Flashcards
What are some functions of the pelvis?
- contain and support visceral contents
- transmit and absorb forces (upwards and downwards)
What is the innominate?
either of the two bones forming the sides of the pelvis, each consisting of three consolidated bones, the ilium, ischium, and pubis.
What bones make up the pelvic girdle?
bones of the innominate (ilium, ischium, pubis) and the sacrum
How are the innominate bones attached at birth vs adulthood?
separated by hyaline cartilage at birth - by 25 years of age they are fully grown and fused
The sacrum is a large inverted triangle. Which half is non weight bearing?
the inferior half is non weight bearing
Sacrum differences in male vs female?
wider and flatter in females
The sacrum consists of # fused vertebrae and it articulates with what?
5
Articulates with the lumbar and coccygeal vertebrae
The sacroiliac joint is a ____ joint.
synovial
Does the SI joint have hyaline cartilage?
Yes - on both articular surfaces of the sacrum and ilium
What happens to the SI with age?
becomes stiffer and irregular
What is the movement of the SI joint? When can it be greater?
Small motion - 2-4mm approx.
Can be greater during 1st and 3rd trimester of pregnancy, as well as in blondes with fair skin
With age, what contributes to form closure of the SI?
reciprocal undulating hyaline articular surfaces on sacrum and ilium as well as ligaments
What are the three components of functional stability at the SI joint?
Passive system: osseous, capsule, ligaments
Active System: muscles
Neural System: sensory receptors, nerves, spinal cord and supra-spinal centers, reflexes and/in active system
Form vs Force closure for structural integrity?
Form: passive structures - interlocking articular ridges and grooves of the SI joint, reverse keystone configuration of the sacrum within the pelvic ring and fibrous ligaments suspend pelvis
Force: muscle activation - external dynamic forces created by contraction of the stabilizing muscles to produce a “self-locking” mechanism, resulting in increased joint stability
When does the keystone theory not work?
when looking from a superior view (as opposed to anterior-posterior)
How is the sacrum held to the ilium from a superior viewpoint?
by ligamentous support and force closure
“concept posits that the sacrum is the reverse of a keystone”
tensegrity - the sacrum is a hub!
Movements of the sacrum:
- ____ is sacral anterior rotation (flexion)
- ___ is sacral posterior rotation (extension)
nutation
counternutation
Standing on both legs performing flexion at the trunk we will have _____ of the sacrum and ____ rotation of the inominate
nutation
anterior
Standing on left leg while flexing right hip joint the right innominate will ____ rotate and the left inominate will not move, the sacrum will ____ on the right side more than left (indicating movement at SI joint)
posteriorly
counternutate
When standing and walking, the weight of the body is where?
through the sacrum to the SI joint to the pubic symphysis and the heads of the femurs
When sitting, where is the weight?
through the SI joint to the pubic symphysis and ischial tuberosities
the ____ ligaments are between the lateral sacral crest and the inner side of the iliac tuberosity
interosseous
Differences between anterior and posterior sacroiliac ligaments?
anterior SI ligaments are thinner and not as extensive as posterior ligaments