Lecture 1: The vertebral column Flashcards
What does the vertebrae protect?
Spinal cord (nerves at risk if injured)
What type of pain can be a red flag for sinister causes?
Back pain
What are the sections of the vertebral column
Cervical vertebrae
Thoracic vertebrae
Lumbar vertebrae
Sacrum vertebrae
Coccyx vertebrae
How many vertebrae in cervical?
7 (C1 - C7)
How many vertebrae in thoracic?
12 (T1 - T12)
How many vertebrae in lumbar?
5 (L1-L5)
How many vertebrae in sacrum?
5 (S1 - S5)
How many fused vertebrae in coccyx?
4 fused into 1
Where does the spinal cord typically end in adults?
L1-L2
Where do intervertebral discs lie?
Between all non-fused vertebrae
What do intervertebral discs do?
Provide flexibility and act as shock absorbers
Where are intervertebral discs not found?
Sacrum
Coccyx
Where are facet joints located?
Connect the superior and inferior articular processes of adjacent vertebrae
What are the facet joints function?
Interlocking and maintains stability.
what is the intervertebral foramen?
Through which the spinal nerve passes
what are the ligaments function?
Bind and stabilise the vertebral column
What are the vertebraes function?
Protects the spinal cord
Supports body weight
Semi rigid axis for the body
Allows pivoting of the head
Attachment for supporting ligaments and muscles of the back that stabilise and move the vertebral column - supports posture and locomotion
What do curvatures in the body allow for?
Allow flexibility and shock absorption
What type of curvatures are thoracic and sacral lymphoses?
1 Primary curvatures
(Seen in the foetus)
What type of curvatures are cervical and lumbar lordoses?
2 secondary curvatures
(Develop later)
Names of excessive/ abnormal curvatures?
Excessive kyphosis
Excessive lordosis
Scoliosis
Body of the vertebrae function:
weight bearing portion, supports the vertebral column, connected to the IV disc
Transverse processes function:
muscle and ligament attachments
Spinous process function:
muscle and ligament attachments
Pedicles function?
attaches the transverse process to the body of the vertebra
Laminae function.
attaches transverse process to spinous process
Superior and inferior articular processes function:
joints between adjacent vertebrae; alignment determines movement
Are all vertebrae the same?
Vertebrae in the 4 different segments of the vertebral column have broadly the same features, but do look different to each other as they have some different functions
What are the 5 areas of the vertebral arch?
Transverse processes
Spinous process
Pedicles
Laminae
Superior and inferior articular processes
What is the smallest in the vertebral column?
7 vertebrae; C1 – C7
They have to support less weight at the top than the bottom
What are special about C1 and C2
C1 and C2 – highly modified and thus termed ‘atypical’
C1 articulates with occiput – allows us to nod our head up and down
C1 and C2 articulate with each other and form a pivot joint – allows us to turn our head from side to side
What is special with C7?
Considered typical
although has a long spinous process which may not be bifid
Used as a landmark to count the vertebrae from
What happens with the transverse foramina of C7
Might be small or even absent
why are injuries to the C- spine common?
the C-spine is flexible
the head is heavy
What do injuries to C- spine risk?
The cervical spinal cord or brainstem
what injuries are common to the C - spine?
Fractures and dislocations: traumatic, crush / compression
Dislocations
Rupture of ligaments
Cord/ spinal nerve injuries
Why can dislocations cause fractures?
Because of the interlocking joints in the vertebral column
What can rupture of ligaments compromise?
Stability
When do cord/ spinal nerve injuries occur?
occur if fracture fragments or dislocations compress or sever the cord
Why are C- spine injuries the most catastrophic?
– can lead to death or tetraplegia
what is the spinous process and the cervical vertebrae often listed as what?
Bifid
In which gender / race is bifid more common in?
White males (less common in females or people of African descent)
What is the function of the transverse formina?
Passage of the vertebral artery and vein to/from the brain
Which transverse foramina does the vertebral artery not pass through?
C7
What is C1 referred to as?
The atlas
what is C1 lacking?
no vertebral body or spinous process
what allows us to nod our head up and down?
Articulation between C1 and skull allows us to nod our head up and down
Features of C1?
C1 is highly modified
Is a ring – no vertebral body or spinous process
Has anterior and posterior arches
Lateral masses articulate with the occipital bone of the skull (at the occipital condyles).
what is C2 referred to as?
The axis
what does the C2 not have?
Vertebral body
Features of C2:
C2 is also highly modified
No vertebral body – this is highly modified to form the odontoid process / dens / peg – hence dens is an anterior structure
Dens articulates with the inner aspect of the anterior arch of C1 to form a pivot joint – allows us to turn head from side to side
Pars interarticularis between the two articular facets
What are the atlantoaxial joints between C1 and C2?
2 lateral: between the lateral masses of C1 and the superior facets of C2
1 median - a pivot joint between the dens and atlas. Synovial – which means it can be affected by rheumatoid arthritis
What are the atlantoaxial joints reinforced with?
The joint is reinforced by ligaments which hold the dens in place – key ligament is the transverse ligament of the atlas
What do we look for in a C - spine X ray?
look for normal alignment
trace around all the vertebrae looking for signs of fracture
Look for uniformity in the thickness of the spaces between vertebral bodies
What is axial loading?
Application of weight or force along the course of the long axis of the body.
what can axial loading cause?
‘Axial loading’ can cause a burst fracture of the C1 ring –a “Jefferson fracture”
The occipital condyles impact into the lateral masses of C1 and cause it to break in at least 2 places (anterior and posterior)
Does axial loading always cause a spinal cord injury?
Not necessarily
when will axial loading cause a spinal cord injury?
However, if fracture fragments impact on the spinal cord, it can be a catastrophic injury
What can cause axial loading?
Any direct blow to the top of the head can cause axial loading
What percentage of C- spine fractures does fracture of the Dens attribute for?
Accounts for 10-15 % of all C-spine fractures
What can fracture of the dens be caused by?
Can be caused by hyperflexion or hyperextension injuries
Biomedical age distribution: elderly (Over 70s)?
= low-energy trauma (e.g. falls from standing height) +/- osteoporosis
Biomedical age distribution: Young (20-30yr)
= high-energy trauma (e.g. RTA, diving injuries, falls from height, blunt trauma to the head)
What is the dens supported by?
by the transverse ligament of atlas, therefore the spinal cord is usually not affected when the dens fractures
What happens of the transverse ligament of atlas ruptures?
But if the dens fractures and the ligament ruptures, the dens may be driven into the brainstem
What happens in non- fatal cases of dens fractures?
In non-fatal cases, dens fracture often requires surgery as non-union is a problem
what are ‘Hangman’s fractures’?
Known as traumatic spondylolysis of C2 or Hangman’s fractures
Can be caused by hyperextension of the head (rather than hyperextension of head and neck > whiplash)
Bilateral fracture of the pars interarticularis
Body of C2 sometimes displaced anteriorly
Injury to brainstem or spinal cord likely
Which part of the vertebrae’s is the most likely to dislocate?
C - spine
Vertebral foramen relatively wide therefore subluxation may not compress spinal cord
Why might not subluxation not compress the spinal cord at the C- spine?
Vertebral foramen is relatively wide
What is the vertebral body?
– heart-shaped with superior and inferior costal demi-facets for articulation with the head of the rib
what is spinous process?
Long and extends postero-inferiorly
What is the transverse process?
has a costal facet for articulation with tubercle of a rib
What are articular facets?
superior faces posteriorly, inferior faces anterior
What does the tubercle of the rib do?
The tubercle of the rib articulates with the costal facet on the transverse process
what does the head of the rib do?
The head of rib articulates with the superior demifacet of the corresponding (same number) vertebra and the inferior demifacet of the vertebra above
What are the most commonly fractured regions of the thoracic spinal column?
T11 and T12
What is Osteoporosis?
A condition when bone strength weakens and is susceptible to fracture. It usually affects hip, wrist or spine.
Compression (‘wedge’) fracture, concavity of vertebral body
Who is osteoporosis most common in?
Postmenopausal women
How common is Osteoporosis?
Very common – leads to excessive thoracic kyphosis, height loss, pain, and reduced mobility
What is Osteoarthritis?
Degenerative changes also seen in the spine
Osteophytes, sclerotic changes and joint space narrowing (and often asymmetry)
Why is the vertebral body large in lumbar vertebrae?
Vertebral body – large for increased weight-bearing
Movements of the vertebral column?
These movements are possible to different extents in different regions of the vertebral column depending on factors including the orientation of facet joints and thickness of the intervertebral discs
which spines are the most flexible?
C and L spine most flexible
Which part of the spine is rotation possible?
T-spine – flexion limited, but rotation possible
What is the erector spinae?
Erector spinae is the chief extensor of the vertebral column
Large muscle that runs longitudinally either side of vertebral column
Composed of 3 separate muscles
What do the intrinsic muscles of the back do and what are they innervated by?
Move the vertebral column
Innervated by the posterior rami of spinal nerves
What are the function of the muscles that lie deep to erector spinae?
Connect the transverse processes of the vertebrae to the spinous processes of more superior vertebrae
What are the two parts of the intervertebral discs?
Outer annulus fibrosus – fibrocartilage ring attached to the rim of vertebral body
Inner nucleus pulposus – gelatinous ‘shock absorber’
= flexibility, shock absorption and stability
What determines the flexibility of the vertebral column?
Thickness of discs determines flexibility of the vertebral column – relatively thicker in C and L spine, hence why these regions are most flexible
Where does the phrase ‘grow over night’ come from?
High water content and they dehydrate with age – become thinner and stiffer
