Lecture 9: The Vertebral Column

Question 1

What are the functions of the vertebral column?

Answer 1

• The cervical vertebrae allow us to move our head
• Weight bearing - particularly lumbar and sacral regions
• Shock absorber
• Allows flexibility
• Allows movement and supports posture
• Protects the spinal cord
• Semi-rigid axis for the body

Question 2

Describe the normal curvatures of the spine.

Answer 2

At the cervical and lumbar regions there is a natural lordosis. These develop later in life. Seen when the child strengthens their muscles around the head to support its head.

A natural kyphosis is seen at the thoracic and sacral regions. This is seen in foetus.

Question 3

What are the distinguishing factors of the cervical vertebrae?

Answer 3

• The spinous process is bifid
• The body is quite small as it is not very weight bearing
• C1 and C2 are highly modified
• The transverse process is quite small
• The transverse process has a foramen inside it. This is important for transmission of the vertebral artery so they are protected.

Question 4

What are the distinguishing factors of the thoracic vertebrae?

Answer 4

• Vertebral body is heart-shaped with superior and inferior costal demi-facets for articulation with the head of the rib
  
  • The tubercle of the rib articulates the transverse facets
  • The thoracic vertebrae are less moveable than the cervical vertebrae due to articulation with the ribs and the sternum
  • We can get traumatic injuries causing problems at the vertebral column - T11 and T12 are more likely to be injured
  • At T11-T12 we have a change to a more flexible vertebrae

Question 5

What are the distinguishing factors of the lumbar vertebrae?

Answer 5

• Lumbar vertebrae have a large body for increased weight bearing
  
  • Spinous process is short and sturdy
  • Relatively narrow foramen
  • Significant traumatic forces usually required to fracture lumbar vertebrae

Question 6

Describe the structure of the atlas.

Answer 6

C1:

- A ring structure with an anterior and posterior arch - there is no vertebra body or spinous process
- Lateral masses articulate with the occiput of the skull (at the occipital condyles).
- Articulation between C1 and skull allows us to no our head up and down

Question 7

Describe the structure of the axis.

Answer 7

C2:

- Articulates with C1 and C3 
- Sometimes called the axis 
- It doesn’t have a vertebral body. This has instead been modified to form bony projections known as the dens (other names include the peg, odontoid process). The dens is an anterior structure. 
- The dens articulates with C1, the atlas, and allows us to move our head from side to side

Question 8

Describe the structure of the atlanto-axial joint. How might it be injured?

Answer 8

There is 2 lateral joints between the lateral masses of C1 and the superior facets of C2. There us also a median pivotal joint between the dens and the atlas. This is a synovial joint and so it can be affected by arthritis.

The joint is reinforced by ligaments which hold the dens in place – key ligament is the transverse ligament of the atlas - spans in front of the dens and helps to keep the dens in place.

Question 9

How does osteoporosis affect the vertebral column?

Answer 9

• Osteoporosis (metabolic - demineralisation of the bone) typically affects the thoracic vertebrae
  - The vertebral bodies become weaker in osteoporosis, they buckle and compress under the weight - we get compression of the anterior part (wedge compression)

Question 10

How does osteoarthritis affect the vertebral column?

Answer 10

• Degenerative changes also seen in the spine

- Osteophytes, sclerotic changes and joint space narrowing (and often asymmetry)

Question 11

Describe the movements that are possible at the vertebral column and the muscle groups involved.

Answer 11

• Flexion
  - Extension
  - Rotation
  - Lateral flexion
  - These movements are possible to different extents in different regions of the VC depending on factors including the orientation of facet joints and thickness of the intervertebral discs. Patient factors can also affect movement/flexibility such as fitness, soft tissue around etc.
  - Generally the cervical and lumbar spine are the most flexible with thoracic is the least flexible.

Muscle groups involved include the Erector spine. This is the chief extensor pf the back. It is a large muscle that runs longitudinally either side of the VC. It is composed of 3 muscles - longissimus muscle, iliocostalis muscle and spinals muscle. We then have deeper smaller muscles. They connect the transverse processes of the vertebrae to the spinous processes of more superior vertebrae

Question 12

Give an account of the intervertebral discs including:

• Location
• Function
• Composition
• Consequences of ageing

Answer 12

1. They lie between 2 vertebrae.
2. They contribute to flexibility, stability and act as shock absorbers.
3. They have a high water content. They have an outer part (annulus fibrosus) and an inner part (nucleus pulposus).
4. They are all water when you are born. As we grow they dehydrate and become thinner and stiffer. They do not deform as well. When the outer annulus fibrosus becomes dry and stiff it can develop cracks and fissure and allow the nucleus pulposus to herniate - slip disc. This can lead to compression of the spinal cord or spinal nerves. Compression in the lower part of the vertebral column is called cauda equina syndrome. It is a surgical emergency. Without intervention it can lead to incontinence or paralysis of the lower limbs. Compression of the cord is a surgical emergency.

Compression on the cord typically occur L1-2 followed by C-spine.

Question 13

Describe the major ligaments of the vertebral column? What is the result of injury?

Answer 13

Important for stability.

	- Anterior longitudinal ligament - runs anterior to the vertebral body. Starts at the occipital bone and C1 and runs to the sacrum. It limits hyperextension.
	- Posterior longitudinal ligament - runs posterior to the IV discs- found inside the vertebral canal. It prevents the interverbal discs from bulging out backwards. It limits also excessive flexion 
	- Ligamentum flavum found between adjacent vertebral lamina. It is transversed when you do a lumbar puncture. It gives characteristic resistance and a popping when you enter.

There are also other small ligaments. Supraspinous ligaments that join the tips together. These help to strengthen and reinforce the vertebral column. Others include the interspinous ligamentum.

Question 14

What is whiplash?

Answer 14

• This is rapid, forceful hyperextension followed by hyperflexion occurs particularly in high speed impact in RTA
  - This can cause anything from a mild muscular strain to a severe injury - ligaments can be ruptured or bone can be fractured
  - This can cause a tear in the anterior longitudinal ligament - this can pull away a bit of bone as it does so - this is known as a tear drop fracture
  - Part of a vertebral body may be avulsed and posterior part of the vertebral body dislocated leading to compression of spinal cord
  - Most patient in RTAs have a mild movement and get a bump from behind. The neck moves a little and they get muscular strains

Question 15

At what point in the vertebral column end in adults?

Answer 15

L1-L2

Question 16

How are the vertebrae held together?

Answer 16

Facet joints - connect the adjacent vertebrae. We have articular processes on each vertebrae and articulate with the vertebrae above and below. These are small joints, they keep the vertebral columns stable. There is only a little bit of movement. Where the vertebrae join we form an intervertebral foramen for the spinal cord to travel.

Intervertebral discs are in between the body of the vertebra. They are important for flexibility and give stability. They can compress and deform.

Ligaments help to stabilise the joint.

Question 17

What is scoliosis?

Answer 17

An abnormal curvature of the spine in which the vertebral column is not in the midline.

Question 18

Why do some textbooks regard C7 as atypical?

Answer 18

C7 has a very long spinous process (vertebral prominenns) It can be felt at the back of the neck. In addition to this the vertebral artery does not go through the foramina in the transverse process of the cervical vertebrae.

Question 19

Where does the tubercle of the rib articulate at the thoracic vertebrae?

Answer 19

At the transverse processes of the thoracic vertebrae.

Question 20

How is the sacrum organised?

Answer 20

There is fusion of the bone -fusion of the transverse processes creates the ala or the wings. There is no intervertebral discs also. The apex articulates with coccyx. There is a large facet for articulation with the pelvic bone and a superior articular process and fact for articulation with L5.

Question 21

How is the vertebral column organised?

Answer 21

We have 33 vertebrae:

• 7 Cervical
• 12 Thoracic
• 5 Lumbar
• 5 Sacral fused into 1 sacrum this transfers weight to the pelvis and lower limbs
• 4 coccygeal fused into one - coccyx

Question 22

Why is kyphosis seen particularly in the elderly?

Answer 22

There is collapse of the vertebral body anteriorly. This can be quite difficult to repair and rectify.

Question 23

Why does injury to the vertebrae not necessary lead to injury to the spinal cord?

Answer 23

The vertebral foramen is quite large in terms of the size of the spinal cord travelling through it and so injury to the vertebrae may not cause injury to the spinal cord.

Question 24

What can result due to a C spine injury?

Answer 24

• Injuries to the C spine are quite common as the C spine is the most flexible part and the head is heavy - trauma or high speed energy cause the head to be thrown
  - Injuries to the C spine risk the cervical spinal cord or the brainstem
  - They can lead to tetraplegia or death
  - We can get fractures and dislocations through trauma, crush and compression
  - Dislocations can cause fractures because of the interlocking in the VC
  - Ruptures of ligaments can compromise stability

Question 25

Why can burst fractures of C1 spare the spinal cord?

Answer 25

Burst fracture occurs when the forces squeezes and cracks the vertebra. It doesn’t necessarily cause spinal cord injury, this is as the foramina is big. It tends to widen the vertebral foramen that the spinal cord sits in. In some case there are other associated injuries and it can be fatal. This is called a Jefferson fracture.

Question 26

How can the axis and atlas be injured?

Answer 26

The atlas can be fractured due to axial loading - impact directly on top of the head. Multiple fractures of C1 are common.

The dens can also be fractures in the elderly due to low trauma due to osteoporosis. In the young it can also result due to high energy trauma.

Under normal circumstances the transvers ligaments secures the median atlatlanto-joint. If the ligament is torn the dens can fracture and may be driven into the upper spine or the brainstem or the lower part of the spinal cord.