Lumbar Biomechanics Flashcards
0
Q
What is Type I mechanics?
A
Sidebending and rotation are coupled to opposite sides. Also known as neutral mechanics.
1
Q
Does the lumbar region follow Fryette mechanics?
A
Yes
2
Q
What is Type II mechanics?
A
Sidebending and rotation are coupled to the same side. Also known as non-neutral mechanics.
3
Q
What vertebrae are exceptions to Fryette’s rule?
A
L5/S1
4
Q
Explain the exceptions to Fryette’s rules.
A
L5/S1 has more connections, thus is less predictable. This segment is the site of more spinal anomalies than anywhere else in the spinal column. Anomalous facings of the facet joints negates Fryette mechanics. Trauma is common here, with loss of stability due to ligamentous or disc injury, again negating Fryette mechanics.
5
Q
Describe lumbar kinesiology.
A
Motion is permitted by bones & joints, restrained by ligaments, and produced & stabilized by muscles.
6
Q
What vertebrae make up the anatomical lumbar spine?
A
L1-L5
7
Q
What vertebrae make up the functional lumbar spine?
A
T11-L5
8
Q
What kind of curve and design does the lumbar spine have?
A
Lordotic curve; weight-bearing design.
9
Q
Describe the sagittal plane orientation of the facets.
A
Superior articular facet - faces posteromedially
Inferior articular facet - faces anterolaterally
Allows for good forward & backward bending
Discourages rotation & sidebending
10
Q
How much does each lumbar vertebra move in total flexion & extension?
A
L1 on L2: 9-16 degrees L2 on L3: 11-18 degrees L3 on L4: 12-18 degrees L4 on L5: 14-21 degrees L5 on S1: 18-22 degrees
11
Q
How much does each lumbar vertebra move in sidebending?
A
Approximately 10 degrees in each direction per segment.
12
Q
How much does each lumbar vertebra move in rotation?
A
L1-L3: about 2 degrees in each direction
L4-L5: about 3-4 degrees in each direction
13
Q
Intervertebral discs are thicker where, and what does this contribute to?
A
They are thicker anteriorly. This contributes to the shape of lumbar lordosis.
14
Q
To what and where do the discs attach?
A
They attach to hyaline cartilage at the vertebral end plates (which are parallel).
15
Q
What is the blood supply like for IV discs?
A
They are avascular (except at the periphery); receive nutrients by diffusion from vertebrae.
16
Q
What does motion loss impair and thus lead to?
A
It impairs nutrition, leading to premature disc degeneration.
17
Q
What is needed for normal disc development?
A
Motion
18
Q
IV discs make up how much of the length of the spinal column?
A
1/5
19
Q
What checks rotary motion and “screws” down the disc?
A
The fiber arrangement of annulus fibrosus.
20
Q
Where is the nucleus pulposus?
A
Near the posterior surface of the disc.
21
Q
If the IV discs are healthy and compressive forces are applied to the spine, what will happen?
A
The vertebrae will fractures before the discs give away.
22
Q
When does disc degeneration happen for men and women?
A
Men: begins 11-20 years of age
Women: begins 21-30 years of age
23
Q
By age 50, what percentage of lumbar discs show degenerative changes?
A
97%
24
Which disc sees the most common herniation?
L5-S1
25
What reinforces the strength of the disc posteriorly in the mid-line?
Posterior longitudinal ligament - becomes narrower and weaker as you descend the spine (goes postero-laterally), predisposing the lower discs to herniation.
26
What does ligamentous function do?
Allows adequate physiologic motion and fixed postural attitudes between vertebrae with a minimum expenditure of muscular energy. Example - relax while standing (minimal muscle energy used). Also provides stability to the spine within physiologic ranges of motion (shared task with musculature).
27
What do ligaments protect, and how do they do so?
They protect the spinal cord and cauda equina by restricting the motions within well-defined limits. Go to far - spinal cord damage. Must protect spinal cord in traumatic situations in which high loads are applied at fast speeds. All of this requires the absorption and dissipation of large amounts of energy.
28
What movements are check ligaments responsible for?
Forward bending
Backward bending
Lateral bending
Rotation
29
What movements are kinetic ligaments responsible for?
Absorbtion and re-dispersement of energy
30
What are the 8 ligaments to the lumbar spine?
```
Anterior longitudinal ligament
Posterior longitudinal ligament
Intertransverse ligaments
Capsular ligaments
Ligamenta flava
Interspinous ligaments
Supraspinous ligaments
Iliolumbar ligaments
```
31
Which ligaments are forward bending check ligaments?
Supraspinous
Interspinous
Posterior longitudinal
Capsular ligaments
32
Which ligament is the first to tear when in violent flexion?
Supraspinous ligament
33
How do you know if you have a torn supraspinous ligament?
If you can put your finger in between 2 spinous processes
34
If area of injury is tender, swollen, and painful, what kind of tear is it?
Acute, non-palpable
35
Describe the capsular ligaments, as well as what they do.
Fibers are oriented at right angles to the facet joint surface. The ligaments provide increasing stability with increasing flexion of the spine.
36
What is the kinetic ligament?
Ligamentum flavum
37
Describe ligamentum flavum.
Yellow
Packed with elastic fibers
Purest form of elastic tissue in human body
In forward bending, it stores kinetic energy to assist the musculature in returning the spine to the upright posture.
38
What are the sidebending check ligaments?
Intertransverse check ligaments
39
Describe the intertransverse check ligaments.
They form from the thickening of the anterior layer of the lumbodorsal fascia, enclosing the intertransverse musculature in the lumbar region (think muscle sandwich). One subset is the lumbosacral ligaments (L5-S1).
40
What are the rotational check ligaments?
Iliolumbar ligaments
41
Describe the iliolumbar ligaments.
Heavy, thick condensations of the fascia that blend continuously with the superior end of the sacroiliac ligaments. These ligaments are injured in the classic lumbosacral sprain and strain.
42
Besides ligaments, what else can check rotation?
Discs; alternating direction of fibers in adjacent lamina of disc serve to check rotational movement (affects stability to spinal column).
43
What is the backbending check ligament?
Anterior longitudinal ligament
44
Describe the anterior longitudinal ligament.
Broad and flat; it reinforces the disc anteriorly. It is roughly twice as strong as the posterior longitudinal ligament.
45
You would get tenderness by palpating where to find an anterior longitudinal ligament tear?
Abdomen; if very painful in one location, it's probably a tear.
46
What causes osteophyte formation and anterior lipping (as seen in lateral lumbar radiographs)?
Traction on the anterior longitudinal ligament vertebral attachments
47
What happens to all biomechanical properties of the anterior longitudinal ligament with increasing age?
They decrease; the ligament weakens, loses elasticity, and ruptures at lower force loads. Thus it is easier for the elderly to injure and recovery takes longer.
48
What is thoracolumbar fascia critical for?
Maintenance of lumbar stability
49
Where is there always a positive pressure due to thoracolumbar fascia?
The abdomen; this helps keep the thoracolumbar fascia taut.
50
Where can you find thoracolumbar fascia?
It encircles the abdomen and supports the spinal column.
51
What generates instability in thoracolumbar fascia?
Weakness
Hernias
Incisions
Pregnancy
52
What can the vertebral column be considered to be like?
A series of short levers. Each vertebral segment represents as single lever. Compression causes it to buckle.
53
What stabilizes the vertebral column? What else does it/do they do?
Short muscles stabilize the column, ensuring efficient action of the long muscles.
54
What are characteristics of short muscles?
Involuntary
| Stabilize & balance the spine
55
What are characteristics of long muscles?
Voluntary
| Movers of the spine
56
Describe the deep paraspinal muscles.
Involuntary
Segmental stabilizers of the spine
Muscles that respond to viscero-somatic & somato-somatic reflexes, causing and maintaining segmental somatic dysfunction.
57
Reflex dysfunction starts as what?
A muscular event
58
What are the deep paraspinal muscles?
Intertransverse muscles
Interspinalis muscles
Rotatores Brevis
Rotatores Longus
59
What are the attachments, actions, and innervations of the intertransverse muscles?
Attachments: between lumbar transverse processes
Action: Segmental sidebending/stabilization
Innervation: Posterior primary division of the spinal nerves
60
What are the attachments, actions, and innervations of the interspinalis muscles?
Attachments: T11-S1; one on either side of the interspinous ligament
Actions: segmental extension/stabilization
Innervation: posterior primary division of the spinal nerves
61
What are the attachments of rotatores brevis?
Transverse process to spinous process one segment above
62
What are the attachments of rotatores longus?
Transverse process to spinous process 2 segments above
63
Are flexed segments usually traumatic?
Yes - no little muscles flex.
64
What are the actions and innervations of rotatores brevis?
Action: rotates segment(s) to the opposite side/segmental stabilization
Innervation: posterior primary division of the spinal nerve
65
What is flexion of the trunk initiated by?
Rectus abdominus muscle
66
In full flexion, spinal muscles are at what position? How is this maintained?
They are at rest. This is a passive posture maintained by the check ligaments and resistance to disc deformation.
67
What are the extenders of the spine, from lateral to medial?
Hint: I Love Sex More
Iliocostalis lumborum
Longissimus thoracis
Spinalis thoracis
Multifidus
68
When acting unilaterally, voluntary muscles become what?
Sidebenders of the lumbar column.
69
When combined with the pull of internal oblique muscles, voluntary muscles become what?
Rotators
70
What are other important muscles of the lumbar region?
```
Diaphragm
Psoas major
Quadratus lumborum
Latissimus dorsi
Serratus posterior inferior
```
71
Flexed dysfunction of the diaphragm without a history of trauma may indicate what?
A respiratory issue
72
Where do the crura of the diaphragm attach?
To the anterior surface of the bodies of L1-L3.
Right: attach to L1-L3
Left: attach to L1-L2
73
What will tend to create flexed dysfunctions of the upper lumbar segments?
Diaphragmatic overuse (e.g. asthma) or chronic hypertonicity (COPD)
74
What causes the symptom of shortness of breath?
Upper lumbar somatic dysfunction that mechanically interferes with the function of the diaphragm.
75
The psoas major muscle is usually what in the standing position?
Silent
76
When does the psoas major become active?
As part of balance in the seated position
77
What will tend to shorten the psoas muscles with anterior tilt of the pelvis and increase in lumbar lordosis?
Prolonged sitting
78
Lumbar nerve roots leave what before passing anteriorly between what?
Neural foramina of the lumbar spine; proximal attachments of the psoas muscle
79
Lumbar nerve roots are vulnerable to what?
Compression and irritation by hypertonicity or spasm of the psoas major (radicular pain).
80
Acute psoas spasm will sidebend the trunk to which side and flex the trunk in which direction?
The side of spasm; forward at the waist.
81
What is the net effect of a psoas spasm when lumbar segments ae in a Fryette type II dysfunction (typically affecting L1, L2, or L3)?
Segment is flexed and rotated & sidebent to side of psoas spasm.
82
What tends to cause a somato-somatic reflex resulting in acute psoas spasm? What would you treat first?
Extended dysfunctions of L1-L3. Treat the flexed segment first.
83
Flexed dysfunctions tend to be the result of what? What would you treat first?
Psoas spasm; treat psoas first.
84
Somatic dysfunction can be either the _______ or ________ of a spasm.
primary trigger or result
85
What is the consequence of hypertonicity of the quadratus lumborum?
Sidebending of the lumbar column to the side of hypertonicity
86
What kind of curve would you get with a hypertonic quadratic lumborum? Why?
Group curve; muscle attachments are nearly on line with neutral mechanics.
87
When the arm is fixed in what position, the latissimus dorsi can influence what?
contraction....lower thoracics, all the lumbar segments, and the pelvis depending upon which portions of the muscle are firing at the time of injury
88
Where do lumbar and lower thoracic problems commonly transfer?
The shoulder
89
The serratus posterior inferior muscle is typically what?
An accessory muscle for forced exhalation.
90
If ribs are held in fixed inhalation posture, what will happen?
Unilateral contraction of serratus posterior inferior will rotate L1-L3 away from the side of muscle contraction.
91
What can cause fixed inhalation posture?
Emphysema
92
Air-trapping diseases tend to do what?
Create flexed posture to the thorax with a compensatory increase in lumbar lordosis. This extended position may be enough to provoke the production of a Type II dysfunction.
93
What are the veins of the spine and what makes them special?
Batson's Veins/Plexus - valve-less venous plexus; they are the route of travel for infections from the bladder/pelvis to reach the vertebrae or epidural space with osteomyelitis or epidural abscess formation as the result.
94
In children, Batson's veins also supply what, resulting in what?
IV discs....infectious discitis
95
Batson's veins are the principle route of what?
Metastasis of pelvic cancers to the spinal column, especially from the prostate.
96
How long are L1 nerve roots?
60mm
97
How long are S1 nerve roots?
170mm
98
Axons from S1 level of spinal cord to final destination in the foot may exceed what length?
100cm
99
Stretching a nerve root causes what?
Blood flow ceases = ischemia = dead nerve
100
Why must the nerve root complex be extremely mobile?
To accommodate lumbar flexion, sidebending, and rotation.
101
Nerve roots are limited in motion by what?
Fibrosis
| Intraspinal/extraspinal entrapment - becomes ischemic when stretched
102
What happens to the blood flow in the vasa nervorum when a nerve root is stretched just 8% of its total length?
It is significantly reduced
103
What happens to the nerve root when the nerve is stretched by 15% of its entire length?
Blood flow ceases entirely
