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February 11, 2003 8am
Mark Dirnberger, D.O.
Cedric Pratt
Page 1 of 8
Functional Anatomy of the Lumbar Spine
Dr. Dirnberger mentioned that there would be a great deal of information that would
overlap with a future lecture from Dr. Gustowski
Developmental Curves
The C curve is the primary curve at birth and secondary curves develop later.
Secondary Curves:
•Cervical curve develops as the child begins to hold its head up
•Lumbar curve develops as the child begins to stand and walk
Lumbar Spine - Serves as a foundation for the entire spine and all parts attaching to
•Anatomical L1-L5
•Functional T11-L5
•Lordotic Curve
•Weight Bearing Design
•35° Ferguson’s Angle (were L5 sits on sacrum)
Sagittal plane orientation of the facets
 Allows good BB/moderate FB
 Discourages Rotation & SB
 Superior Articular Facet faces Posteromedially
 Inferior Articular Facet Faces Anterolaterally
Bony Asymmetry
• 40% of the population have congenital osseous asymmetry
– Facet asymmetry
– Sacralization L5 fuses with sacrum
– Lumbarization – S1 becomes L6 vertebrete
– Spina bifida occulta – lamina do not fuse over lower lumbar spine –failure of
neural arch to develop
• The most common of these is facet asymmetry
– One facet is in a different plane
Structure & Function Must remember this because it shows up on boards
•Wolfe’s Law-- bone formation occurs along lines of stress
•Area of weakess-- anterior triangle becomes weak link for compression fracture
Anulus Fibrosus - outer ring, not very well innervated (50/50 fiber arrangement)
February 11, 2003 8am
Mark Dirnberger, D.O.
Cedric Pratt
Page 2 of 8
•interlocking crosshatch
•Attachment to anterior & posterior longitudinal ligaments
Nucleus Pulposus – formed from the notochord, this portion of the discs dehydrates
overtime and causes osteoporosis
•Surrounded by anulus fibrosis
•reciprocal motion characteristics
•High water content
*Discs have three main characteristics:
•Decreased thickness under load
•Reabsorption increases thickness
•age decreases the ability to recover thickness
* Disc s under load:
•diseased disc can be more compressible
•Decreased disc thickness causes an increased weight load on the facet joint
-Compression of these discs causes encroachment on spinal nerves
Sitting and leaning forward you compress disk posterior laterely
Structural Integrity
•Anterior Longitudinal Ligament
•Limits extension
•Posterior Longitudinal Ligament
•Limits flexion
Iliolumbar ligaments
•Strong attachment at L4 and L5 to increase stability at the lumbosacral junction
•Commonly strained in lifting/traumatic injuries
Lumbar anatomy: the deep muscular layers
1. Transversospinalis mm.
2. Interspinalis mm.
3. Spinalis mm.
4. Serratus posterior inferior
5. Longissimus mm.
6. Iliocostalis mm.
7. Latissimus dorsi aponeurosis
February 11, 2003 8am
Mark Dirnberger, D.O.
Cedric Pratt
Page 3 of 8
Quadratus lumborum mm.
Anterior to posterior
1. costovertebral
2. iliovertebral fibers
3. iliocostal fibers
Psoas major m.
transverse processes to lesser trochanter of femur
Superficial Posterior Lumbar Anatomy
•Latissimus dorsi m.
Gluteus maximus m
Posterior Lumbodorasal fascia
Posterior Layer Rectus Sheath
Anterior Layer Rectus Sheath
Lumbar Sensory Nerves
Each level is innervated by the medial branch of the dorsal rami from the level were it is
and ½ from the above level.
There is duel innervation so when they block these for surgery they block the level
above and below
Lumbar ROM
Extention of 35 degrees
Forward flexion of 60 degrees
Fryette’s Principles of Physiologic Motion
1st Principle
• When sidebending is attempted from neutral (anatomical) position, rotation of
vertebral bodies follows to the opposite direction.
2nd Principle
• When sidebending is attempted from non-neutral (hyperflexed or hyperextended)
position, rotation must precede sidebending to the same side.
3rd Principle
• Motion introduced in one plane limits and modifies motion in the other planes.
Physiologic Motion may be on exam
• Fryette’s 1st Principle of Spinal Motion
– Neutral Mechanics (no extreme of FB or BB)
• sidebending “X” followed by rotation “Y”
• these occur in groups
February 11, 2003 8am
Mark Dirnberger, D.O.
Cedric Pratt
Page 4 of 8
Type I Mechanics for Thoracic and Lumbar spine.
Side bending – Around A-P / Within coronal
Rotation -- Around vertical / within horizontal
Normal Motion
• Fryette’s 2nd Principle of Spinal Motion
– Non-Neutral Mechanics (extremes of FB and BB)
• rotation “X” followed by sidebending “X”
• this occurs at one segment
Lumbar Somatic Dysfunction
• What if you don’t return to neutral?
• Somatic Dysfunction persists.
• Can be attributed to multiple causes
• How do I know it is Somatic Dysfunction?
Differential Diagnosis for Low Back Pain
•Lumbar disk herniation
•Muscular/ligamentous strain/sprain (muscle/ligament)
•Degenerative changes (arthritis)
•Spondylolisthesis (slippage of vertebrate on top, on the one below)
•Somatic Dysfunction
How do we narrow it down?
History and risk factors.
•IV drugs, manual labor, trauma (infection)
•Smoker (dehydrates discs, decreases blood flow to disc)
•Hormone replacement
Disc Herniation
Posterior disc herniation will push on the posterior longitudinal ligament as it exits the
disc space and can emptiy its contents. The posterior movement of the disk applies
pressure on the nerve.
•Most common herniation
February 11, 2003 8am
Mark Dirnberger, D.O.
Cedric Pratt
Page 5 of 8
–L5-S1 ( may seen more)
Mentioned that we should look at the color of the discs in X-ray or MRI films b/c water is
white and as the disc looses water it becomes more dark.
Intervertebral Foramina
•Vertebral Bodies
•Inferior Articular Process Posterosuperiorly
•Superior Articular Process Posteroinferiorly
•Intervertebral Disk
•Extension Narrows Foramina
•Adjacent Pedicles
•Flexion Enlarges Foramina
Nerve Root Exits a Foramina Inferior to the Superior Pedicle and Superior to the
Intervertebral Disc
So in the lumbar region the nerve root below will be compressed.
Eg. Between L4-L5 is the L5 nerve root.
X+1 Rule
• Herniation at disc X affects nerve root X+1
• WHY?
• Nerve root X will have already exited the foramina and will be unaffected
Neurologic Examination
Straight leg raise test
Babinski reflex
•Foot inversion (tibialis anterior m.)
•Patellar reflex
•Medial aspect of foot sensation
•Great toe extension (extensor hallicus longus m.)
•No reflex
•Dorsum (top) of foot sensation
Have patient raise big toe
February 11, 2003 8am
Mark Dirnberger, D.O.
Cedric Pratt
Page 6 of 8
•Foot eversion (peroneus longus m.)
•Achilles tendon reflex
•Lateral foot sensation
Straight Leg Raise Test
Hamstring Pain vs. Nerve Root Pain
•1. Raise affected leg until pain is experienced
•if pain begins <80° flexion go to step 2
•2. Lower leg 5° and add foot dorsiflexion
•pain elicited by dorsiflexion indicates nerve root irritation
Hamstring pain is usually only in posterior thigh, nerve root pain can go down to the foot
Hip-drop test
• Assessing sidebending of lumbar spine
• Pt stands straight and unlocks one knee without lifting heel
• Lack of 20-25 degree drop of ipsilateral hip or non-smooth lumbar curve
Trendelenburg Test
• Test for gluteus medius weakness
• Ask patient to stand on one leg
• Positive is hip drop to side of lifted leg
• Compare to hip drop test: Hip drop = lumbar SB; T’s = GM weakness
Hoover’s Test
• Good test to spot malingering patients!
• Hold patients heels and instruct to lift one leg
• Should feel counter-force upon effort in other hand
• If not, they’re not trying
A good way to remember this test is that if a patient has a positive test they suck! ( He
said it not me)
Babinski Reflex
Positive Babinski reflex indicates upper motor neuron problems
•brain damage
•Multiple sclerosis
February 11, 2003 8am
Mark Dirnberger, D.O.
Cedric Pratt
Page 7 of 8
Viscerosomatic Considerations - Think about these with chronic back pain
Left Colon
Lower Extremity
Possible GI Influence
•Increased Sympathetics
•Abd Pain
•Increased Parasympathetics
•IBS (both inc)
Continued with slides that showed pathology for the remainder of the lecture.
February 11, 2003 8am
Mark Dirnberger, D.O.
Cedric Pratt
Page 8 of 8