MSK 5 - The Lumbar Spine (anatomy + disorders) Flashcards

1
Q

Describe the gross structure of the vertebral column

A
  • 33 vertebrae (7 cervical, 12 thoracic, 5 lumbar, 5 sacral + 4 coccygeal)
  • Sacral + coccygeal vertebrae fused to give 2 innominate structures (sacrum + coccyx)
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2
Q

What are the 4 main functions of the lumbar spine?

A

1) Support - of the thoracic spine + pelvis
2) Protection - of the spinal cord + cauda equina
3) Movement - highly flexible structure
4) Haemopoiesis - in red marrow

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3
Q

Describe the structure of an individual lumbar vertebra and the functions of the individual parts.

A

Split into: (see slide 5)

1) Anterior region - consisting of vertebral body (largest part), kidney shaped. End plates superiorly + inferiorly lined with hyaline cartilage. Linked to adjacent vertebral bodies by intervertebral discs. Main weight bearing part of vertebra (80% of weight) - made from 90% cancellous and 10% cortical bone.
2) Posterior region - consists of vertebral arch and vertebral foramen. Arch linked to adjacent vertebrae by articular processes. Foramen contains conus medullaris, cauda equina + meninges. Posterior region has 2 pedicles, 2 lamina + 7 processes (slide 9)

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4
Q

Why does the size of the vertebral body increase from superior to inferior? (i.e.: down the column)

A
  • To resist the greater compressive forces distally (i.e.: there are more structure above it going further down the column so greater compressive force).
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5
Q

How are facet joints on the posterior region of lumbar vertebrae formed?
Which movements does their orientation allow?
What are the 4 primary movement of the lumbar spine?

A
  • Facet joints are paired to form zygapophyseal joints from articulation of the inferior and superior articular processes.
  • They are orientated at a 45* angle in the coronal plane, allowing flexion, lateral flexion + rotation//also preventing anterior displacement of vertebrae
  • Flexion/Extension, Lateral flexion + Rotation
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6
Q

How many fused vertebrae are the sacrum and coccyx formed from?
Where do the spinal nerve exit the sacrum?

A

Sacrum = 5
Coccyx = 4
- Spinal nerve exit spinal canal via sacral foramina and sacral hiatus
- Coccyx is the remnant of the tail, which humans are very rarely born with (removed surgically)

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7
Q

What are the 3 types of joint in the lumbar spine - give an example of each.

A

1) Fibrous - non-mobile - e.g.: sacroiliac joint
2) Secondary cartilaginous - partially mobile - e.g.: intervertebral discs
3) Synovial joints - highly mobile - e.g.: facet joints

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8
Q

Describe the composition, structure and role of intervertebral discs

A

Composition = 70% water, 20% collagen, 10% proteoglycans.

Structure = 1) Nucleus pulposus (central region), is the remnant of the notochord, made from gelatinous, type 2 collagen. 2) Annulus fibrosus - surrounds pulposus, made from type 1 collagen and layers of annular bands. it is avascular + aneural.

Role = Accounts for 25% length of the vertebral column Changes heigh throughout day and with age. Acts as shock absorbers, highly resilient under compression (force applied from the nucleus onto the annulus) and keeps vertebrae separate.

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9
Q

What are the 5 ligaments of the vertebral column? What are their common functions?
Which ligaments are stronger - the anterior or posterior ones?

A
  • Supraspinous, interspinous, ligament flavum, posterior longitudinal, anterior longitudinal (3 x posterior, 2 x anterior)
  • Provide stability and limits to ROM
  • Anterior ligaments are stronger.
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10
Q

What are the 2 anterior region ligaments of the lumbar vertebra, their positioning and their roles?

A

1) Anterior longitudinal ligament - anterior to vertebral body, mobile over intervertebral discs + prevents hyperextension
2) Posterior longitudinal ligament - runs throughout lumbar spine, weaker than the ALL, prevents hyperflexion.

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11
Q

What are the 3 posterior region ligaments of the lumbar vertebra, their positioning and their roles?

A

1) Supraspinous ligament - on the tips of the adjacent spinous/articulating processes. They are strong bands of white fibrous tissue, lax in extension and prevent hyperflexion.
2) Interspinous ligament - weak sheet of fibrous tissue that unite spinous processes.
3) Ligamentum flavum - contain elastin, found between laminae of adjacent vertebrae. Stretched during flexion.

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12
Q

What type of forces are applied through the spine during flexion?
How does force transmission change with age?

A
  • Compression through anterior side, tension through posterior side.
    Young = 80% of body weight through vertebral bodies, 20% through facet joints.
    Elderly = disc dehydration, leading to loss of disc height 65% through vertebral bodies, 35% through facet joints.
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13
Q

What are the natural curvatures of the vertebral column segments?

A
  • Cervical = lordosis (anterior curve)
  • Thoracic = kyphosis (posterior curve)
  • Lumbar = lordosis
  • Sacral = kyphosis
  • Coccyx = kyphosis

3 x kyphosis, 2 x lordosis.

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14
Q

Describe the structure of the vertebral column in the foetus and the evolution that occurs in the first 18 months.

A
  • C-shaped (flexed in single curvature) - in a kyphosis - known as the primary curvature. This is retained throughout life in thoracic, sacral and coccygeal regions.
  • Primary curvature is remodelled to add 2 x secondary curvatures
  • 1) Cervical lordosis - when young child begins to lift its head
  • 2) Lumbar lordosis - when the child begins to stand up and walk (this allows up to stand upright/separates us from other animal)
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15
Q

What happens to the shape to the vertebral column in old age?
What curvature exaggeration occurs in pregnancy + why?

A
  • Secondary curvatures start to disappear + loss of disc height
  • Continous primary curvature re-established.
  • Exaggeration of lumber lordosis, allows pregnant women to keep head centred over pelvis as foetus growth causes shift in centre of gravity.
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16
Q

What are the 3 scanning techniques used to look at the vertebral column + their adv/disadv’s?

A

1) X-ray - doesn’t image soft tissue well
2) CT - still not great for soft tissue but 3 planes rather than 2
3) MRI - excellent for soft tissue

NB - Need to be able to identify key anatomical features on these images (see slide 40-42)

17
Q

How common is mechanical back pain and what are the causes?

A
  • 80% of UK population experience LBP lasting >24 hours in lifetime - abnormal not to experience mechanical LBP
  • Posture (pressure on intervertebral discs while slouching) - although exercise strengthens core muscles effective in reducing chance of mechanical back pain.
18
Q

When do the symptoms of mechanical back pain arise, what are the aggravating/alleviating factors ?

A
  • Pain when spine is loaded (sitting, standing NOT lying)
  • Worse w/exercise, relieved by rest
  • Can be triggered by innocuous activity, by unhealthy life style/being overweight or having poorly conditioned core muscles.
19
Q

What physiological changes occur to the spine with ageing?

A
  • Nucleus pulposus of IV discs dehydrates, leading to loss of disc height + disc bulging
  • Increased load stresses leads to reactive ‘marginal osteophytes’ (syndesmophytes) at endplates
  • Increased load stress on facet joints cause facet joint osteoarthritis
20
Q

What is a prolapsed intervertebral disc (slipped disc) and the 4 different kinds of prolapse possible?

A
  • Protrusion of the nucleus pulposus into the spinal canal leading to compression of nerve roots.
    1) Degeneration - disc bulge (due to ageing)
    2) Prolapse - Protrusion of nucleus pulposus with slight impingement into spinal canal
    3) Extrusion - nucleus pulposus breaks through annulus but remains in disc space
    4) Sequestration - nucleus pulposus breaks through annulus and separates from main body into spinal canal.
21
Q

Who in and where does slipped discs usually occur in?

A
  • 30-50 year olds
  • 90% resolved by 3 months
  • most commonly at L4/5 or L5/S1
  • Usually herniated paracentrally.
22
Q

What is Sciatica?

What are the different types of sciatica?

A
  • Sciatica is pain caused by irritation or compression of one or more of the nerve roots contributing to the sciatic nerve (L4 –> S3)
  • L4 - affects anterior thigh, knee and medial leg
  • L5 - affects lateral thigh, lateral leg, dorsum of foot
  • S1 - affects posterior thigh, posterior leg, heel, lateral border and sole of foot.
23
Q

What can cauda equina syndrome be caused by?

What are the symptoms?

A
  • Can be caused by a canal filling prolapse, compressing the cauda equina nerves
  • Bilateral sciatica, perianal numbness, painless retention of urine, incontinence + ED.
  • It is a surgical emergency
24
Q

What is spondylolisthesis?

What is it caused by?

A
  • Slipping of the spine (spondylo = spine, listheis = slip)
  • Caused by disconnection of the vertebral body from the vertebral arch
  • Can present in many ways including back and leg pain
  • Usually a forward displacement
25
Q

At what anatomical level is a lumbar puncture performed?

What are the structures the needle must pass through from the skin to the subarachnoid space?

A
  • L2/3, L3/4, L4/5 - below conus medullaris so only mobile spinal nerve roots not spinal cord affected - least chance of neurological damage
  • Skin, Subcutaneous fat, Ligamentum Flavum, Epidural fat, Veins, Dura mater, Arachnoid mater, Subarachnoid mater, ending in sub-arachnoid space.