Exam 2 Lumbopelvic Flashcards
What is the most important characteristic of the lumbar spine?
it must bear tremendous loads created by body weight, lifting, and muscle actions
In addition to bearing heavy loads, what other responsibility does the lumbar spine have that places significant biomechanical demand on this region?
trunk mobility
T/F: the inferior articular processes of the L/S are concave and face anterolaterally.
False; convex
Describe the superior articular processes of the L/S.
concave and face posteromedially
What plane do the lumbar facets lie in primarily?
the sagittal plane
What motion is limited in the L/S? increased?
rotation;
flexion/extension
Which facets of the L/S have a coronal orientation rather than sagittal? What motion does this limit?
L5/S1 facets;
limits posterior/anterior shear (Z translation)
T/F: the lumbar facets normally carry 18% of the axial load and up to 33% in extension.
True
Which region of the L/S has the greatest combined flexion/extension? Least?
L5-S1;
L1-L2
Which region of the L/S has the greatest range of lateral bending (ThetaZ)? Least?
L3-L4;
L5-S1
Which region of the L/S has the greatest one side axial rotation (Theta Y)? Least?
L1-L5 all have relatively equal axial rotation;
L5-S1 has the least axial rotation
What motions are coupled in the L/S? What does this mean for spinous?
lateral bending is coupled with axial rotation;
spinous to ipsilateral side
Is the nucleus of the IVD in the L/S more anterior, posterior, or in the middle?
posterio
What is the disc height-to-body height ratio in the L/S?
1:3; greatest resistance to axial compressive forces
What is the name for the enlargement of the spinal cord that is protected by the L/S? What other main structure is protected by the L/S distal to the lumbar enlargement of the spinal cord?
conus medullaris;
cauda equina
What bone is the CNS tethered to via the filum terminale?
coccyx
Where does the spinal cord end? What do the nerve roots continue down the spinal canal as?
L2:
cauda equina
T/F: Nerve roots exit the dura of lumbar spinal canal slightly below the foraminal openings to provide “slack” which prevents stretching of the nerve roots.
False; NRs exit the dura slightly above the foraminal openin, causing therir course to be more oblique and their length to increase
T/F: The Lordotic curve of the L/S is considered a primary curve.
False; secondary curve
Where is the apex of the Lumbar curve?
L3-4 disk
What range (in degrees) should the lumbar curve measure?
20-60 degrees
T/F: An increase in the sacral base angle will result in more weight bearing responsibility on the facets.
True; increasing the sacral base angel with an anterior pelvic tilt results in an increase in the lumbar lordosis which places more weight on the facets.
T/F: An increase in the sacral base angle will result in more weight bearing responsibility on the disc which will decrease the spine’s ability to absorb the axial compression forces.
False; A decrease in the sacral base angle will do this as it decreases the lumbar lordosis
What muscle is the major stabilizer of the L/S?
Quadratus lumborum
What motions are restricted in by the ALL and PLL? Which is more well developed?
Restrict excessive flexion/extension;
ALL>PLL
T/F: The lumbodorsal fascia acts like a large flexor retinaculum to constrain long tendons of thoracic and lumbar muscles.
False; acts as a large extensor retinaculum constraining thoracic and lumbar extensors
What ligament of the L/S guards against posterior shear, assists facet joints to remain in contact/gliding with rotation, and acts like a collateral ligament controlling vertebral rotation to follow an arc through flexion range?
Interspinous ligament
What motion does the supraspinous ligament provide resistance against?
excessive forward flexion
T/F: The facet capsule is well developed in the L/S, restricting joint flexion and distraction of facet surfaces during axial rotation.
true
What are the 3 pelvic joints?
2 SI joints and the pubic symphysis
T/F: SI joints are immobile syndesmotic joints.
False; they are mobile diarthrodial joints (though they were once thought to be immobile syndesmotic)
What are the main responsibilities of the pelvic joints?
support for the trunk, guide movement, and help to absorb the compressive forces associated with locomotion and weight-bearing
What is the keystone effect of the sacrum?
the sacrum is triangular and serves as a keystone in the arch between the two columns formed by the lower extremities effectively distributing axial compressive forces
When do the SI joint surfaces begin to roughen and develop their characteristic grooves and ridges?
teen years
What are the 2 most common pelvic types?
gynecoid and android
What are the 4 main ligaments of the pelvis?
Sacrospinous, anterior sacroiliac, sacrotuberous, and posterior sacroiliac ligaments
T/F: Although the SI joint was once thought to be immobile, it is now universally accepted as a movable joint, how it moves, how much it moves, and where axes of motion are located.
False; there is still a lot of controversy about the SI joint
T/F: The SI joint is most active while maintaining erect posture.
False; most active during locomotion
What direction does an innominate move as it flexes?
posteriorly and inferiorly
Which way does the sacral base move during nutation? counternutation?
anteriorly and inferiorly;
posteriorly and superiorly
T/F: The proposed axes of motion in the SI articulation allow a “gyroscopic” figure-4 movement.
False; figure-8 movement
T/F: Flexion of the SI joint incorporates anterior and superior movement of the PSIS and ipsilateral posterior and superior movement of the sacral base (counternutation).
False; this is true of extension
T/F: The Quadratus lumborum, erector spinae, gluteus maximus, gluteus minimus, piriformis, iliacus, and latissimus dorsi muscles all cross the SI joint.
False; no muscle crosses the SI joint, but all of these muscles listed have fibrous expansions that blend with the anterior and posterior SI joint ligaments which contributes to the strength of the joint capsule and ligaments.
T/F: the muscles impacting the SI joints help provide mobility.
False; provide stability, not mobility
If the left ilium has a PIEX listing, what orthogonal directions has it moved?
-thetaX and -thetaY
If the right ilium has an ASIN listing, what orthogonal directions has it moved?
+thetaX and -thetaY
If the left ilium has an ASIN listing, what orthogonal directions has it moved?
+thetaX and +thetaY
If the sacrum has a base posterior listing, what orthogonal direction has it moved?
-thetaX
If the sacrum has an SAL listing, what orthogonal direction has it moved?
+thetaZ
If the sacrum has a P-R listing, what orthogonal direction has it moved?
-thetaY
