Biomechanics of the Lumbar Spine Flashcards

1
Q

What is the most important characteristic of the lumbar spine?

A

it must bear tremendous loads created by body weight that interact with forces generated by lifting and other activities involving powerful muscle actions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The lumbar spine is largely responsible for what?

A

trunk mobility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the anatomy of the facets of the lumbar spine

A

large
thick
strong

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

L/S inferior articular processes are CONVEX and face what direction?

A

anterolaterally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

L/S superior articular processes are CONCAVE and face what direction?

A

posteromedially

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

In what plane are the L/S facets?

A

sagittal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What occurs to the facets at the lumbosacral junction?

A

they become more coronal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What do the facet configuration of the L/S limit? and allow?

A

limits: rotational flexibility
allows: for greater mobility in flexion and extension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the facet configuration of L1-4?

A

sagittal orientation

limits axial rotation (øy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the facet configuration of L5-S1?

A

coronal orientation

limit posterior/anterior shear (z translation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The lumbar facets normally carry ____% of axial load and up to ____% in extension.

A

18%

33%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the primary movement in the Lumbar spine?

A

Flexion/extension (øx)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What % of trunk flex/ext occurs in the L/S?

A

75%

TWICE as much FLEXION as extension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What rotation is limited in the L/S overall due to sagittal facet orientation?

A

øy Axial rotation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Lateral bending in the L/S is coupled with axial rotation; what side does the spinous go to?

A

ipsilateral (may switch at L4 and L5)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where is the nucleus located in the L/S?

A

somewhat posteriorly in the disc

17
Q

What is the disc height-to-body height ratio in the L/S?

A

1:3
(this relationship allows for more movement than T/S, but less movement than C/S and gives the disc greater resistance to axial compressive forces

18
Q

What does the L/S canal contain and protect proximally?

A

conus medularis

19
Q

What does the L/S cancel contain and protect distally?

A

cauda equina & spinal nerves distally

20
Q

Where does the spinal cord end?

A

L2; nerve roots continue down the spinal canal as the cauda equina

21
Q

CNS is tethered to the coccyx by what?

A

filum terminale

22
Q

NRs exit the dura slightly above the foraminal opening, causing their course to be more ___________ and their length to increase.

A

oblique

23
Q

When does the secondary lordotic curve of the L/S occur?

A

starts to develop ~ 9-12 months of age/beginning to sit up. Becomes established as they learn to stand (~18m)

24
Q

Where is the apex of the L/S lordotic curve?

A

L3-4 disc

25
Q

What should the normal lumbar lordosis angle be?

A

20-60 degrees

26
Q

Changes in the sacral angle can influence the depth of the ______ curves in the spine.

A

A-P

27
Q

What happens to the sacral base angle with an anterior pelvic tilt?

A

increases; resulting in an increase in the lumbar lordosis, which places more weight-bearing responsibility on the facets

28
Q

What happens to the sacral use angle with a posterior pelvic tilt?

A

decreases; resulting in a decreased lumbar lordosis, placing more weight-bearing responsibly on the disc and a decrease in spines ability to absorb axial compression forces

29
Q

What is the major stabilizer of the L/S?

A

(QL) Quadratus Lumborum

30
Q

How much is the QL lumborum active?
Heavy lifts?
isometrical lateral bending holds?
standing isometric twists?

A

74%
54%
42%

31
Q

What are the characteristics of the ALL & PLL of the L/S?

A

Restricts excessive flex/ext
Well developed (ALL>PLL)
Attached to the vertebral body and the annulus

32
Q

What are the characteristics of the Ligamentum Flavum in the L/S?

A

Highly elastic

Acts as a barrier to material that would otherwise encroach on cord during ROM

33
Q

What are the characteristics of the Lumbodorsal Fasica in the L/S?

A

Attachment for: Transverse Abdominis, internal oblique, lattissimus dorsi
Acts like a large extensor retinaculum to constrain long tendons of thoracic and lumbar extensors

34
Q

What are the characteristics of the Interspinous lig in the L/S?

A

Acts like a collateral lig, controls vertebral rotation to follow an arc through flexion range

35
Q

What are the characteristics of the supraspinous leg in the L/S?

A

provides resistance against excessive forward flexion

36
Q

What are the characteristics of the facets in the L/S?

A

Well developed
Restricts joint flex
Restrics distraction of facet surfaces during axial rotation

37
Q

What is lig damage in the L/S caused by?

A

joint laxity; joint degeneration follows

ligament damage mark the beginning of the end