Vertebral column Flashcards
The vertebral column is made up of 5 structures.
What are they?
How many vertebrae in each?
Cervical spine (7) Thoracic spine (12) Lumbar spine (5) Sacrum (5, fused) Coccyx (4, fused)
Describe the curvature of the vertebral column.
Why does it curve in this way?
Alternating pattern of lordotic (concave posteriorly) and kyphotic (concave anteriorly). Lordotic - CS Kyphotic- TS Lordotic- LS Kyphotic- Sacrum
Alternating curves balance each other to create a stable system which maintains the COG in a balanced state
How does the cervical spine curve?
Lordotic (concave posteriorly)
When do the vertebral curvatures develop?
Kyphotic curvatures (thoracic spine and sacrum) develop in utero. Lordotic curvatures (cervical and lumbar spine) develop during childhood; associated with lifting the head and sitting upright.
How are the sacrum vertebrae (structure) adapted for function?
Fused, widened and concave anteriorly to transmit the weight of the body through the pelvis to the legs
What are the 4 functions of the vertebral column?
1) Protect the spinal cord and cauda equina
2) Support the weight of the skull, thoracic cage, upper limbs and pelvis.
3) Contribute to movement and posture
4) Provide a site of haematopoiesis
What shape is the lumbar vertebral body?
Kidney bean shaped
The vertebral bodies change size throughout the vertebral column. Why is this?
Bodies increase in size inferiorly to resist growing compression forces due to increasing load above
The vertebral body is largely made up of which type of bone?
90% cancellous, 10% cortical
Describe the vertebral end plates
Superior and inferior surfaces of the vertebral body. They’re coated in hyaline cartilage and are adjacent to intervertebral discs
What is the major load bearing structure in the vertebral column?
What is the minor?
Vertebral bodies carry 2/3rds of the load
(except in atypical C1 & C2)
Posterior elements carry 1/3rd
What are the posterior elements?
Everything posterior to the vertebral body
Which structures make up the vertebral arch?
What is the purpose?
The 2 lamina and 2 pedicles.
The lamina connect the transverse processes to spinous process.
The pedicles connect transverse processes to the vertebral body.
The arching shape creates a tunnel for the spinal cord to sit inside
How many processes are there on the lumbar vertebra?
Name them.
7 processes spinous (1) Transverse (2) Inferior articular processes (2) Superior articular processes (2)
Why do muscles and ligaments attach to the spinous and transverse processes?
To control the position of the vertebral bodies; to allow movement etc.
What is another name for the zygapophyseal joint?
What type of joint in this?
Facet joint
Its a synovial joint due to hyaline cartilage coating of the inferior and superior articular processes which make up the joint.
Where does the spinal cord terminate?
L1-2
The vertebral notch creates which foramen?
How?
The intervertebral foramen where nerves can exit the spinal cord to the periphery
The notch is the concave shape of the articular processes. When they articulate in the facet joint, a hole is created.
The facet joint prevents displacement of the vertebrae in which direction?
Antero-posteriorly (forward- backward)
What determines the movement permissible at the facet joints?
The angle of the articulating facets (surfaces)
The invertebral discs make up how much of the vertebral column? (fraction)
1/4
What’s the major component of intervertebral discs?
What are the 2 other components?
Water 70%
collagen 20 %
proteogylcans 10%
What are the two regions of the invertebral discs and where are they located?
Annulus fibrosus is the peripheral/ outer layer around the circumference
Nucleus pulposus is the central inner section
How is the annulus fibrosus adapted for function?
Made up of lamellae of annular (ring shaped) collagen in varying orientations which allows the disc to resist compressive (axial) forces
(Function is a shock absorber)
The intervertebral disc will not fracture under compressive forces. Which other vertebral structure will?
Why?
The vertebral body
It is the major load bearing structure within the column and is weaker than the discs (concerning axial (compressive) forces).
Name the three collagen types within the intervertebral discs and their locations.
Annulus fibrosus:
Outer lamellae- Type 1 collagen
Inner lamellae- fibrocollagen
Type 2 collagen in the nucleus pulposus
The nuceus pulposus is gelatinous. Why?
How does its location change from infancy?
Type 2 collagen within the nucleus has a high osmotic content because water resists compressive forces.
Centrally located in child, becoming more posterior.
Why does the vertebral column shorten throughout the day?
When else does it shorten?
Water is forced out of the nucleus pulposus (within the intervertebral discs) throughout the day due to mechanical pressures
Column shortens with age
Why should you maintain a straight spine whilst lifting?
The intervertebral discs are very strong under axial (compressive) forces, but weaker in tangential loading.
Which 2 ligaments surround the vertebral bodies?
Which is stronger?
anterior longitudinal ligament
posterior longitudinal ligament
anterior is stronger
Where do the 2 longitudinal ligaments begin and end?
What is their function?
anterior; C1 to sacrum
posterior; C2 body to sacral canal
anterior- prevent hyperextension (leaning back) of the vertebral column
posterior- prevent hyperflexion (leaning forwards)
The lumbar spine is lordotic
What does this mean?
It is concave posteriorly
Above C2 (the axis) the posterior ligament is the ____ membrane?
Tectorial membrane of the atlanto-axial joint
Why does disc prolapse tend to occur laterally?
What is this called?
It occurs lateral to the posterior longitudinal ligament bc the ligament reinforces the annulus fibrosus centrally (it protects and contains it)
Paracentral disc prolapse
The ligamentum flavum is yellow, why?
Describe its position
high elastin content
Between the lamina of adjacent vertebrae (lamina connect the spinous process to the transverse process)
- Ligamentum flavum
- Interspinous ligaments
- Supraspinous ligaments
all prevent which movement?
Which is the weakest?
Which is strongest?
Hyperflexion of the spine (bending forward)
Weak- Interspinous (sheets of fibrous tissue)
Strong- Supraspinous (band of fibrous tissue)
Where are the interspinous ligaments and which other ligament do they fuse with?
Between the spinous processes of adjacent vertebrae
Fuse with the supraspinous ligament posteriorly
Where is the supraspinous ligament?
Runs along the tips of the spinous processes
When are these ligaments taut?
- Ligamentum flavum
- Interspinous ligaments
- Supraspinous ligament
What happens to the intervertebral bodies during this movement?
During spine flexion
They are compressed
along with vertebral bodies and anterior longitudinal ligament
Why are you at increased risk of back injury when lifting a load far from the body?
The force of the load is multiplied through the spine
Moment (Nm) = force (N) x distance (m)
Why do the facet joints bear more load as we age?
What does this cause?
Because the intervertebral discs dehydrate and shrink (so less weight borne through vertebral bodies)
Osteoarthritic changes
E.g. loss of cartilage and marginal osteophytes (bony spurs)
What does the cauda equina contain?
Where do these nerve arise from?
2nd-5th lumbar nerves*
1st-5th sacral nerves
coccygeal nerve
* lumbar nerves exit before sacral canal
end of the spinal cord (around L1/L2
height) the conus medullaris
What is senile kyphosis?
Why does it happen?
The secondary curvatures (lordotic cervical and lumbar spines) diminish with ageing leaving only the primary c shaped (kyphotic) spine that we have in utero.
This is why old people hunch over.
The intervertebral discs dehydrate and shrink causing loss of height + compression fractures commonly occur to create wedge shaped vertebrae
What do the 4 weak points of the vertebral column have in common?
- The centre of gravity of the body passes through these 4 sites when the person is stood
- pathology will commonly develop here
What are the 4 weak points of the vertebral column?
(Note; they are the borders of each spine) C1/2 C7/T1 T12/L1 L5/S1
Describe mechanical back pain
Risk factors?
Commonly lumbar back pain, occurs when the spine is loaded, worsens with exercise and alleviates with rest
Sedentary lifestyle with deconditioning of the core (paraspinal) muscles, obesity and incorrect manual handling
What is marginal osteophytosis?
When does it occur?
Bony spurs (syndesmophytes) develop adjacent to the end plates of the vertebra
Ageing
Why do osteoarthritic changes in the facet joints cause pain?
the joints are innervated by the meningeal branch of the spinal nerve (transmits pain sensation)
What is radicular pain and why can it occur during ageing?
Pain which radiates along the dermatome of a nerve due to inflammation/ compression of the nerve root
Disc generation and osteoarthritic changes in the vertebral bodies (marginal ostephytosis) and facet joints may
narrow the intervertebral foramen compress the spinal nerves
Two most common sites for a slipped disc and why?
Medical term for a slipped disc?
Bottom of the lumbar spine due to mechanical loading
L4/L5
L5/S1
Disc herniation
Most common type of disc herniation?
Which type can cause cauda equina syndrome?
Paracentral prolapse (disc herniates posterolaterally)
Central prolapse
- transversing nerve root
- exiting nerve root
where do they emerge?
Transversing nerve root emerges below the level of the disc
Exiting nerve root emerges at the same level as the disc
Which nerve root is at risk of compression during an L4/L5 paracentral disc herniation?
- Paracentral herniations damage the transversing root
- Transversing root emerges below the disc
- L5root nerve at risk
Which nerve root is at risk during an L4/L5
far lateral disc herniation?
- far lateral herniations damage the exiting nerve
- exiting nerve emerges at the same level as the disc
- L4 nerve root at risk
What do nerves of the cauda equina innervate?
Pelvic organs (bladder) and lower limbs
Which nerve roots contribute to the sciatic nerve?
L4-S3
L4 sciatica pain
Medial leg, anterior leg, anterior thigh
L5 sciatica pain
Lateral leg, lateral thigh, dorsum of foot
S1 sciatica pain
sole of foot, heel, posterior leg and posterior thigh
What causes cauda equina syndrome
Compression of the lumbar and sacral nerve roots in the spinal canal
E.g. disc prolapse, tumour, spinal infection/abscess, spinal stenosis caused by arthritis, etc.
Red flag symptoms of cauda equina?
Bilateral sciatica Painless urine retention Incontinence Perianal numbness (saddle anaesthesia) Erectile dysfunction
Treatment for cauda equina syndrome?
Surgical decompression within 48 hours of sphincter symptoms
Why can cauda equina syndrome cause a numb bum?
Why is immediate treatment important?
Because the S3 and S4 sacral nerve roots supply the dermatomes around the buttocks
Untreated can cause lower limb weakness (wheelchair), faecal incontinence, self-catheterisation to pass urine, impaction
How can the ligamentum flavum cause spinal stenosis?
Who does spinal stenosis generally affect?
Which type is most common?
Hypertrophy can narrow the spinal canal
The elderly
lumbar stenosis; then cervical
Symptoms of spinal stenosis
Discomfort whilst standing
Numbness/ weakness below the level of stenosis
Bilateral symptoms
Neurogenic claudication
What is neurogenic claudication?
What triggers it?
Literally means a limp caused by the nervous system
The patient feels pain/ pins and needles in the legs causing them to limp
Prolonged standing or walking, relieved by rest
What is the pathology behind neurogenic claudication?
It’s a common symptom of ___?
Ischaemia of the lumbosacral nerve roots secondary to compression from surrounding structures
Spinal stenosis
Why is neurogenic claudication (symptom) not experienced if the patient cycles?
Cycling involves flexion of the spine which enlarges the spinal canal
(an erect spine (extended) narrows the canal).
What is spondylolisthesis?
Anterior displacement of the vertebra above on the vertebra below
What is a lumbar puncture?
What is it used for?
Which vertebrae is the needle inserted between?
Withdrawal of CSF from the subarachnoid space of the lumbar cistern
To diagnose CNS disorders like Multiple sclerosis and meningitis
Bottom vertebrae of the lumbar spine; Either L4/L5 or L3/L4
