Vertebral Column Flashcards
how many vertebrae does the typical adult vertebral column have?
33:
- 7 cervical (C1 – C7)
- 12 thoracic (T1 – T12) articulate with ribs
- 5 lumbar (L1 – L5)
- 5 sacral (S1 – S5) fused into = sacrum – transfers weight to pelvis and lower limbs
- 4 coccygeal (Co) fused into one = coccyx
In adults, where does the spinal cord typically end?
L1-L2
What are vertebrae held together by?
- Facet joints
- Intervertebral discs
- Ligaments
What are facet joints? What do they connect?
- (also called zygapophyseal joints)
- connect the superior and inferior articular processes of adjacent vertebrae
- interlocking maintains stability
What passes through intervertebral foramen?
Spinal nerves
What are intervertebral discs? Function?
- Between all non-fused vertebrae
- Provide flexibility and act as shock absorbers
What is the function of the ligaments of the spinal cord?
Bind the vertebrae together and stabilise the vertebral column
function of vertebral canal?
- Protects spinal cord
- Supports body weight
- Semi-rigid axis 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
Curvatures are present along the spinal cord. What are these important for?
Allow flexibility and shock absorption
Describe 1ary and 2ary curvatures of the spine
Foetus:
- Thoracic and sacral kyphoses –> 1ary curvatures seen in foetus
Adult:
- Cervical and lumbar lordoses –> 2ary curvatures that develop later
What type of curvature is:
- cervical
- thoracic
- lumbar
- sacral
- 2ary
- 1ary
- 2ary
- 1ary
What is kyphosis?
Kyphosis is a spinal disorder in which an excessive outward curve of the spine (near neck) results in an abnormal rounding of the upper back.
What is lordosis?
An excessive inward curve of the lumbar spine (closer to low back)
What is scoliosis?
A sideways curvature of the spine
General plan of a vertebra:
- Anterior vertebral body
- Posterior section:
- Pedicles
- Laminae
- Superior and inferior articular processes
- Transverse processes
- Spinous process
- Project directly posteriorly
- These are little bones you can feel in your back
What is the function of the pedicles?
Attaches the transverse process to the body of the vertebra
What is the function of the lamina?
Attaches transverse process to spinous process
What is the function of the superior and inferior articular processes and facets?
Joints between adjacent vertebrae; alignment determines movement
Which vertebral segment is the smallest?
Cervical spine C1-C7
Which cervical vertebrae are considered ‘atypical’? Why?
- C1 and C2 –> these are highly modified
- 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
- C7 is considered typical BUT:
- Has a long spinous process (vertebra prominens) which may not be bifid
- Used as a landmark to count the vertebrae from
- The transverse foramina of C7 might be small, or even absent
- Has a long spinous process (vertebra prominens) which may not be bifid
Why are injuries to the C-spine common?
- the C-spine is flexible
- the head is heavy
What do injuries to the C-spine risk?
Damage to the cervical spinal cord or brainstem:
- Fractures and dislocations: traumatic, crush / compression
- Dislocations can cause fractures because of the interlocking joints in the VC
- Rupture of ligaments > can compromise stability
- Cord / spinal nerve injuries occur if fracture fragments or dislocations compress or sever the cord
- Hence C-spine injuries are the most catastrophic – can lead to death or tetraplegia
What feature distinguish the cervical vertebrae?
The cervical vertebrae have three main features which distinguish them from other vertebrae:
- Triangular vertebral foramen.
- Bifid spinous process – this is where the spinous process splits into two distally.
- Transverse foramina – holes in the transverse processes. They give passage to the vertebral artery, vein and sympathetic nerves.
Describe the articular facets of the cervical vertebrae
- The articulating facets in the cervical vertebrae face 45 degrees to the transverse plane and lie parallel to the frontal plane
- The superior articulating process facing posterior and up
- The inferior articulating processes facing anteriorly and down
What runs through the transverse foramina?
- Vertebral arteries
- Vertebral veins
- Sympathetic nerves
What is important to note about the size of the cervical vertebral foramen?
Is large relative to the size of the spinal cord –> therefore, injuries to the cervical vertebrae don’t always result in spinal cord damage due to wiggle room
Which transverse process of the cervical vertebrae does the vertebral artery not pass through?
The vertebral artery doesn’t travel through the transverse foramina of C7
What is C1 also referred to as?
The atlas
How is C1 highly atypical?
- Is a ring structure with 2 lateral masses
- No vertebral body or spinous process
- Has 2 lateral masses which are connected by an anterior and posterior arch
- Anterior arch has facet for articulation with the dens of C2
- Posterior arch has groove for vertebral artery and C1 spinal nerve
- Each lateral mass contains a superior articular facet (for articulation with occipital condyles) and an inferior articular facet (for articulation with C2).
What does C1 articulate with superiorly? What action does this allow?
The occiput of the head - allows us to nod our head up and down
The posterior arch of the atlas (C1) contains a groove for what?
Vertebral artery and C1 spinal nerve
What is C2 also referred to as?
‘axis’
How is C2 highly atypical?
- No vertebral body
- This is highly modified to form the odontoid process / dens/ peg
- Hens 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
- This is highly modified to form the odontoid process / dens/ peg
View of C2
What does the dens of C2 articulate with? What joint does this create? What movement does this allow?
- the inner aspect of the anterior arch of C1
- creates the medial atlanto-axial joint
- allows for rotation of the head independently of the torso