Week 4 - finished

Question 1

1. Outline the characteristics of a typical lumbar vertebra.

Answer 1

Vertebral body: - Kidney-shaped (convex anterior) and taller anteriorly (creates lordosis). - Lateral dimensions are greater than A-P dimensions. Pedicles: - Short and strong, become thicker caudally which effectively makes the tunnel of the IVF wider. - Attached more inferiorly than those of the thoracic spine. - Transfer load from the vertebral bodies to the Z-joints and pars interarticularis. The vertebral canal: - varies (oval to triangular) Transverse Processes: - Project postero-laterally from the junction of the pedicle and the lamina - Long, flat and thin Accessory Processes: - Project posteriorly from the junction of the TP and the lamina, providing attachment sites for longissimus thoracis and intertransversarii lumborum muscles. Articular Processes: - Articular facets are oriented vertically - Superior facets face posteriorly and medially in a concave curved or angled shape - Inferior facets face anteriorly and laterally with a convex shape (conforming to the superior facet) - This orientation allows for a significant amount of flexion and extension, but severely limits rotation and sidebending. **The inferior facets of L5 are oriented more coronally than others and the facet surfaces tend to be less curved

Question 2

2. List the three parts of the intervertebral disc and the functions of each.

Answer 2

Annulus Fibrosus – Primary weight-bearing structure, Composed of 10-20 collagen lamellae, lamellae can resist stress in all directions (esp. rotation); weakest at posterolateral portion. Innervated with both proprioceptive and pain sensitive fibres in the outer 1/3 Nucleus Pulposus – A hydrated gel in the centre of each disc (70-90% water), composed largely of water binding proteoglycans. With axial compression it expands radially, bracing the annulus fibrosus and transmitting weight between vertebral bodies. End plates – Plates of cartilage cover the superior and inferior aspects of the disc. Prevents nucleus from being pushed into the vertebral bodies and provide nutrition to disc

Question 3

5. What is the orientation of the lumbosacral facet joint? How does this affect the L5 intervertebral disc?

Answer 3

The inferior facets of L5 are oriented more coronal (frontal plane) than others and the facet surfaces tend to be less curved. The more coronal orientation of L5-S1 facets allows for greater motion and greater likelihood of annular injury. o To prevent the slippage of L5/S1. The L5 IVD is the smallest, and is wedge-shaped: thicker anteriorly than posteriorly to produce the lumbosacral angle.

Question 4

4. What is the normal orientation of the facet (zygopophyseal) joints in the lumbar spine?

Answer 4

Articular facets are oriented vertically: - Superior facets face posteriorly and medially in a concave curved or angled shape - Inferior facets face anteriorly and laterally with a convex shape (conforming to the superior facet)

Question 5

6. What structures are located in the lumbar intervertebral foramen (IVF)?

Answer 5

The IVF contains - the spinal nerve - recurrent meningeal nerve - lymphatic channels - artery - adipose tissue. Spinal nerve is located in upper third and occupies about 1/3 of the IVF. The L5 nerve root is the largest of the lumbar nerves while the L5 IVF is the smallest.

Question 6

7. Compression or entrapment of the spinal nerve at the IVF can cause sensory and motor signs and symptoms. Which is more likely?

Answer 6

Sensory is more likely as sensory fibres in the form of the dorsal root ganglion take up more room in the IVF than the motor fibres.

Question 7

6. How does movement affect the dimensions of the lumbar IVF?

Answer 7

Extension narrows the canal Flexion expands the canal

Question 8

8. Why is the L5 spinal nerve particularly susceptible to compression at the IVF?

Answer 8

The L5 IVF is the smallest and the L5 nerve root is the largest.

Question 9

9. Hypertrophy of which ligaments can encroach on the IVF?

Answer 9

Hypertrophy of PLL, Ligamentum flavum calcification

Question 10

10. What is the primary role of the iliolumbar ligament?

Answer 10

Serves to anchor L5 to the sacrum and prevent forward slippage and rotation.

Question 11

11. What are attachments and actions of the lumbar multifidi and rotatores?

Answer 11

Multifidus: - Origin: mamillary processes - Insertion: SPs, 2 to 4 segments above **Deep fibres attach to facet joint capsule, preventing capsular entrapment. - Action: Extends the lumbar spine. Rotation is produced by contraction of abdominal oblique muscles. Multifidus acts as a stabilising muscle to prevent flexion and create pure rotation Rotatores: - Origin: from TP of one vertebra - Insertion: onto lamina and base of SP of vertebra located 1-2 segments above. Similar action to multifidi + rotation. Both may function as organs of proprioception.

Question 12

12. Describe the anatomy of the thoracolumbar fascia.

Answer 12

Extends from thoracic region to sacrum Thin covering over ES in thoracic region but very strong in lumbar region with three layers: - Posterior layer: Attaches to SPs and interspinous ligaments and the sacral crest. - Middle layer: Attaches to tips of TPs and intertransverse ligaments and extends from iliac crest to rib 12 - Anterior layer: Covers anterior of QL (forms lateral arcuate ligament of diaphragm) , anterior surface of TPs, ilium and iliolumbar ligt. The ES is b/w posterior and middle layers (can have compartment type syndrome). At lateral aspect of ES three layers join and form origin of transversus abdominus. Lumbosacral aponeurosis and thoracolumbar fascia blend so lumbar spine is functionally attached to gluts, hamstrings and via ITB to lower extremity. The TL fascia is also an attachment point for lat dorsi

Question 13

13. List the abdominal muscles. How do these muscles affect the thoracolumbar fascia?

Answer 13

Rectus abdominus Internal oblique External oblique Transversus abdominus Contraction of internal obliques and TA which is attached to the lateral raphe of TL fascia tightens the ‘stabilizing corset’ and provides important static bracing to lumbar structures when lifting.

Question 14

14. Which nerve roots form the lumbar and sacral plexuses?

Answer 14

Lumbar: Anterior Rami L1-L4 Sacral: Anterior Rami of L4-L5 as well as S1-S4

Question 15

15. Which muscle do the nerves of the lumbar plexus traverse?

Answer 15

Psoas major and minor

Question 16

16. Outline the dermatomes of the lower extremity. (draw on board)

Answer 16

Question 17

17. What is sclerotomal pain?

Answer 17

Sclerotomal pain is vague, deep, toothache like.

Arises from ligaments, bone or joints that share the innervation of the irritated nerve root. Eg Knee pain from L3 nerve root, ligaments in L3 region, pubic symphysis, hip or knee (all share L3 sclerotome)

Question 18

Carla is an active 34 year-old mother of 3 young children. She tells you she gained a few kilos after the birth of each child and would like to lose 10-12kg now that she doesn’t plan on having anymore.

She recently rejoined the gym and has developed increasingly severe LBP over the three weeks since returning to exercise. She describes a chronic history of low grade LBP, of at least 8 years duration but tells you it’s become much worse since having children.

Pain is worst first thing in the morning and last thing at night and is aggravated by bending activities; particularly vacuuming, changing the beds and cleaning the bath. Heavy lifting (especially the kids) is also problematic.

Historically she has experienced no pain associated with coughing or sneezing and no lower extremity symptoms.

Carla’s LBP has become more severe and more constant than is typical and she has experienced a dull pain in the posterior thigh and buttock that is not as constant or severe as the back pain.

Answer 18

xx

Question 19

18. Which structures resist shear force in the low back?

Answer 19

Ligaments:

• Iliolumbar ligament
• ALL

Bone/Articulations:

• IVD (annulus fibrosis)
• Articular facets

Myofascial support:

• Thoracolumbar fascia & abdo mm form bracing corset
• Eccentric action of lumbar ES (segmental control of trunk flexion)

Question 20

19. How do the abdominal muscles influence the lumbar spine?

Answer 20

Flex the spine

Rotate the spine (although this mostly happens in the Tx because of the orientation of the facets)

Transversus abdominus acts to pull on the TL fascia and create stability during Lx loading and movement

Question 21

20. What other muscles indirectly affect the lumbar spine by influencing pelvic tilt?

Answer 21

Psoas

Iliacus

Rectus femoris

Adductors

Piriformis

Gluteals

QL

Lat dorsi

Hamstrings

Question 22

21. How can hip flexor or extensor shortening influence IVD degeneration?

Answer 22

Hip flexor shortening:

Anterior pelvic tilt causes an increased lumbar lordosis. This puts extra compressive strain on the posterior aspect of the IVD, and tensile strain on the anterior part of the IVD. Increased compressive load in certain areas will cause more rapid IVD degeneration in these parts.

Hip extensor shortening:

Posterior pelvic tilt will create a decreased lumbar lordosis, and more of the weight bearing force will be put through the lumbar facets instead of through the IVD. *?*

Question 23

22. How does posture influence pain and degeneration of the lumbar spine?

Answer 23

Sequence of changes:

o Chronic postural changes increases strain on structures

o Hip flexor tightness increased ant pelvic tilt & Lx lordosis

o Hip extensor tightness increases post pelvic tilt & kyphotic sitting posture which increases compression

force on IVD anteriorly

o Need ligs to stabilize lumbar spine (e.g. iliolumbar or ALL, which become stretched)

o Facet joint capsular stretching and become less stable

o Increases stress on IVD (e.g. annulus resisting shear develops fissures)

Question 24

23. How do the clinical presentations of ligament sprain and muscle strain differ?

Answer 24

Ligament Sprain:

o Pain comes on almost immediately, is more localised, deep & specific to an injury

o Difficult to observe swelling

o Passive structure, pain comes on at end range

• Ligament tear will make a snapping sound and the pain will be instant.
• Ligament pain will have a very localised source of the pain, usually at the attachment site.
• If ligament is completely torn there will be an increased ROM with no/little pain.

Ligaments usually tear at end range while muscles tear at mid range.

Muscle Strain:

o Pain comes on several hours later, more diffused and relieved by heat

o Active structure, pain comes on anywhere in range of motion.

• It will hurt but the pain will settle quickly, and then will gradually build up again in the next 24 hours.

Question 25

24. What happens to the intervertebral disc with age?

Answer 25

Gradually loses water content, becomes more rigid and brittle (fissures develop in annulus) and reduced disc height. It is suggested that this is actually becaue of vertebral end place patholigy causing a reduction of nutrition to the annulus fibrosis and nucleus pulposis.

Question 26

25. How does aging of the IVD influence other bony and soft tissue structures of the vertebral unit?

Answer 26

􀁸 Reduces IVF space

􀁸 Ligamentum Flavum subjected to less tension, can buckle and encroach IVF space

􀁸 More load is transferred to posterior elements (pedicles, facet joints)

􀁸 Degenerative changes of facets

􀁸 Osteophytic encroachment of narrower IVF

􀁸 Bone spurs develop where annulus is attached

Question 27

26. How can degeneration of the IVD and osteoarthritis of the facet joints impact the structures of the IVF?

Answer 27

Structures of IVF can be impacted by compression or chemical/inflammatory irritation. This can also cause compression of the recurrent meningeal nerve which supplies posterior IVD, PLL, periosteum of the Vertebral bodies and and anterior dura, causing pain.

Clinical Presentation:

o Pain in lumbar or LS region

o Referral to buttocks

o Trunk held in flexion (keep IVF open)

o Difficult or painful to return to extension

o Morning stiffness

o Ease in hot shower

o Aggravated by sustained sitting or standing.

Question 28

27. What is lateral canal stenosis? How and where may this cause pain?

Answer 28

􀁸 Narrowing of IVF space

􀁸 Doesn’t produce ssx unless the spinal cord itself or adjacent nerve roots become irritated, or compressed.

􀁸 If posterior ramus is compressed, affects post structures (ES, facets, skin and muscles of posterior trunk)

􀁸 If recurrent meningeal nerve is compressed, affects PLL, post vertebral body and disc

􀁸 If nerve root= radiculopathy down low limb (dermatomal and myotomal pattern)

􀁸 Note with SLR, if pain comes on >50 degrees = facet joint hypertrophy.

o If pain comes on earlier, likely to indicate disc bulge

o Lateral stenosis tends not to be aggravated by valsalva

Question 29

28. What mechanisms may be responsible for this patient’s acute pain episodes?

Answer 29

• Overuse Injury due to unaccustomed activity (lifting, bending)

o Results in acute inflammation and oedema around or within joint capsule

• Acute Facet Lock (entrapment of synovial fold)

o Freq associated with some rotation or side-bending (trivial), pain felt immediately. Movement suddenly restricted (if in flexion, difficult to straighten up fully)

o No gross protective posture or widespread spasm. Limited AROM but not equally in all directions. Any attempt to move joint meets immediate resistance.

• Acute Disc Prolapse

o Flexion almost always markedly limited, may or may not have pain on extension

• Internal disc derangement
• SIJ?