Development of the Vertebral Column Flashcards
(52 cards)
What is the starting material for the ossification of the centrum?
Mesenchyme (undifferentiated mesoderm)
The ossification process begins with mesenchymal cells differentiating into bone-forming cells.
Where does ossification of the centrum initiate?
Dorsal to the notochord
The notochord contains angiogenic inhibiting factors that prevent blood vessels from entering the area initially.
What shape does the developing centrum have due to vascular supply?
Donut-like shape
Bone forms around the periphery of the centrum, resulting in a central area that is initially devoid of bone.
What is true endochondral ossification?
Begins in the centre and progresses to the periphery
This type of ossification is characterized by the formation of cartilage that eventually transforms into bone.
When does ossification of the centrum first appear in the fetal development?
Between 9-10 fetal weeks
The process starts in the lower thoracic and upper lumbar regions.
What is the significance of blood supply in the ossification of the centrum?
Ossification requires blood supply for bone formation
Initially, the notochord area is devoid of blood vessels, which affects the early stages of ossification.
How does the ossification pattern progress?
Bidirectional progression - up and down spread
This means that ossification spreads in both directions from the initiation point.
What are the primary ossification centres for C1?
3 primary centres:
* 2 x Neural arch centres - 7th fetal week prenatal
* Anterior arch centre - 1-2 years of life
What are the primary ossification centres for C2?
5 primary centres:
* 2 x neural arch centres - 7-8 weeks prenatal
* 1 x centrum centre - 4-5 months prenatal
* 2 x centres for the odontoid process - 4-5 months prenatal
How many secondary ossification centres does C2 have?
5 or 6 secondary centres
These include flake-like epiphyses for transverse processes and plate-like epiphyses for bifid spinous processes.
What characterizes typical cervical vertebrae in terms of ossification?
3 primary centres:
* Neural arch centres - 2-3 months prenatal
* Centrum centre - 3-4 months prenatal
6 secondary ossification centres
By when are all 3 primary centres present in thoracic vertebrae?
By the end of the 3rd intrauterine month
This includes neural arch centres and centrum development.
What secondary ossification occurs in thoracic vertebrae?
Annular ring above and below vertebral body, transverse process, spinous process, costal surfaces
These structures contribute to the overall stability and movement of the thoracic spine.
When are all primary centres present in lumbar vertebrae?
By the 3rd intrauterine month
This includes neural arch centres and centrum development.
What is the pattern of sacral ossification?
Complex - 21 separate centres of ossification
Each sacral vertebra is represented by 3 primary centres.
At what age does the posterior arch of C1 typically fuse?
4-5 years
It may remain open, leading to conditions like spina bifida atlantis.
What is the first structure to fuse in C2?
Fusion of odontoid process centres occurs at birth
This is critical for the stability of the cervical spine.
What is the significance of neurocentral fusion in cervical vertebrae?
Occurs at 3-4 years of life
This leads to the formation of synovial uncovertebral joints of Luschka.
What are the primary curvatures of the spine?
Concave anteriorly (kyphosis):
* Thoracic
* Sacral/coccygeal
What triggers the development of cervical lordosis?
Development of postural muscles to hold the head up
This occurs at around 2-3 months of life.
What is a common pathological curvature characterized by an exaggeration of thoracic kyphosis?
Hunchback
This condition can lead to significant postural and respiratory issues.
What is the role of intervertebral discs in spinal curvatures?
Curvatures arise due to modification of shape of intervertebral discs
This occurs due to changes in loading, affecting the thickness of anterior and posterior parts.
What is the general learning objective regarding the vertebral column?
Be able to describe how the vertebral column ossifies and develops.
List the specific learning objectives related to the vertebral column.
- Describe the ossification process and pattern for each vertebral region
- Use correct developmental terminology for juvenile and adult vertebral column
- Describe the pattern of fusion for each vertebral level
- Describe the development of normal vertebral curvatures
- Describe common pathological vertebral curvatures and explain their origin
- Understand the importance of the intervertebral disc in vertebral curvature development.
