Chapter 2 Flashcards Preview

Biomechanics II > Chapter 2 > Flashcards

Flashcards in Chapter 2 Deck (163)
Loading flashcards...

Are the biomechanics of the pelvis a confirmed and highly agreed upon?

no, it is a controversial area
Debate on amount of SI motion
For years it was thought that there was no motion.


What is the motion classification of the SI joint?

Upper 1/3 is an amphiarthrosis


What is the Importance in SI joint in relation to low back pain

Much so-called "low back pain" is caused by sacroiliac problems.

b) Often undiagnosed or incorrectly diagnosed.


Major mechanical functions of pelvis

a) Attaches the spine to the lower extremities and transfers weight to them

b) Shock absorption

c) Gyroscopic action during gait

d) In females, important in the birth process


what makes up the pelvis joints?

Pelvis consists of a three joint complex
a) 2 SI joints
b) Pubic symphysis


What kind of joint is the SI joint and what kind of surfaces does it have?

Synovial joint with atypical surfaces


What kind of joint is the pubic symphysis?

Pubic symphysis classified as a fibrocartilaginous joint
a) Amphiarthrosis


What 3 surfaces make up the SI joint?

Auricular surface
Iliac surface
Sacral surface


What is the appearance of the auricular surface?

(1) Ear (auricular) shaped or boot shaped
(2) Cephalad portion
(a) Referred to as the "upper joint"
(3) Caudad portion
(a) Referred to as the "lower joint"


What plane is the auricular surface in?

Predominantly in the sagittal plane (10° to sagittal plane)


What are the characteristics of the iliac surface?

(1) Fibrocartilage
(2) Central convex ridge
(3) Large rough bony surface posterior and superior to joint for ligamentous attachment
(4) Iliac tuberosity behind the joint
(a) Roughened area behind jt.


What are the characterics of the sacral surface?

(1) Hyaline cartilage
(2) Three times thicker than iliac surface
(3) Central groove (concavity)
(4) Wedge shaped superior to inferior (viewed P-A, A-P)
(5) S-shape anterior to posterior (viewed from side)


What is the pubic joint characteristic?

a) Articulation in median plane
b) Amphiarthrosis
c) Contains interpubic fibrocartilaginous disc


What are the intrinsic ligaments of the pelvis?

- bind sacrum to the ilium
Anterior ligament
(a) Anterior superior
(b) Anterior inferior

Posterior SI ligament
(a) Dorsal ligaments
(b) Interosseous SI ligament


What are the extrinsic ligaments of the pelvis?

(1) Sacrotuberous ligament
(2) Sacrospinous ligament
(3) Iliolumbar ligaments


What muscle crosses the SI joint?

None, no muscle crosses the SI joint


What muscles influence SI motion?

(1) Multifidus, erector spinae (SI ligament)
(2) Hamstrings, gluteus max., and piriformis have fibrous attachment to sacrotuberous ligament
(3) Psoas (anterior joint capsule)
(4) Quadratus lumborum (iliolumbar ligaments)


What is the innervation of the pelvis?

Exact innervation is debated1, but neural elements have been identified in the joint capsule and adjoining ligaments suggesting innervation for both pain and proprioception


What is the joint architecture of the SI joint?

(1) Synovial diarthrodial joint
(2) Auricular (ear) shape
(3) Corresponding groove/ridge
(4) Locking sacral wedge shape, plus interlocking sacral S configuration


Which gender has a greater "S" shape in their SI joint and what does this lead to?

Males have an increased "S" and it associates with decreased mobility


How does the SI joint appear at birth?

a) Joints undeveloped, smooth and flat, glide in any direction; stability provided by ligaments
b) Begin to develop during walking


How does the SI joint appear in the teens?

a) Roughening of surfaces, development of grooves and ridges
(1) Male more pronounced than female
b) Track bound movement develops


What occurs in the SI joint in the 3rd to 4th decade?

a) Articular changes in surface anatomy are well established.
b) Joint surfaces become more irregular.
c) enlargement of iliac tuberosity
d) beginning of joint surface erosions
e) possible osteoarthrosis (DJD) on iliac surface (more in males)


What occurs in the SI joint in the 5th and 6th decade?

a) Joint surfaces become more irregular.
b) Each individual joint is unique in its topography to varying degrees (more pronounced in males).
c) possible osteoarthrosis (DJD) developing on sacral surface and continuing on iliac surface (more in males)
d) possible development of joint adhesions, osteophytes, and fusion


What occurs in the SI joint in the 7th decade and beyond?

a) interarticular adhesions
b) high prevalence of bony ankylosis (fusion)
(c) Fusion occurs mainly in the superior part of the joint.


What are the two weight bearing arches of the pelvis?

Anterior and posterior arch


What is the function of the posterior arch?

Posterior arch

(a) Major weight bearer

(b) First three sacral segments

(c) Two pillars of bone running through
the SI and acetabular fossa


What resists the gravitational forces acting on the posterior arch in terms of weight bearing in the pelvis?

It is a down and posterior force which is resisted by:
(a) wedge shaped sacrum
(ii) Down and anterior; resisted by: (a) "S" shaped joint (b) posterior ligaments (c) interosseous ligaments (d) sacrotuberous ligaments


What is the anterior arch of the pelvis?

(a) Pubic rami
(b) Connects posterior arches and acts as a compression strut


What part of the SI joint promotes stability through form closure?

(1) Wedge shape of the sacrum
(2) Interlocking groove (sacrum) and ridge (ilium)
(3) S-shaped joint surfaces