21. The cervical and thoracic spine Flashcards
(48 cards)
How many cervical vertebrae are there?
7 (C1-C7)
Which cervical vertebrae are typical and which are atypical?
C1, C2, C7 —> atypical cervical vertebrae
C3 - C6 —> fairly uniform, typical cervical vertebrae
What is the structure of typical cervical vertebrae?
• Body that is small and broad from side to side.
• Large triangular vertebral (neural) foramen
• Bifid spinous process (except C7)
• Transverse foramen in the transverse process; a
conduit for the vertebral artery, vein and sympathetic plexus (except C7)
• Articular facets orientated in the coronal plane and at 45° to the axial plane.
How are the articular facets orientated in typical cervical vertebrae?
- superior articular facet faces upward and backward
- inferior articular facet faces downward and forward
What is the structure of the C1 vertebra?
- the atlas
- a bony ring with anterior and posterior arches connected by two strong lateral masses
- widest cervical vertebra
- does not have a vertebral body or spinous process
- anterior arch occupies 20% of the circumference of the ring
- posterior arch occupies 40% of the circumference of the ring
- vertebral arches are thick and strong and form a powerful lateral mass
which vertebrae are the smallest?
Cervical
what is the difference between cervical and thoracic in terms of mobility?
- Cervical Spine – Mobile
* Thoracic Spine - Immobile
what is the difference between typical cervical vertebrae and the lumbar spine?
• Majority of features of cervical is the the same as Lumbar Spine
Except, cervical has:
• Bifid Spinous Process
• Transverse Foramen
Where are the articular facets found on the atlas?
- positioned on the lateral mass
- the superior articular facets are cup-shaped and articulate with the occipital condyles of the skull
- the inferior articular facets articulate with the superior articular facets of the C2 vertebra
What attaches as the anterior and posterior arches of the atlas?
- The anterior arch is the site of attachment of the anterior longitudinal ligament
- The posterior arch contains the posterior tubercle which is a site of attachment of the ligamentum nuchae
which is the widest cervical vertebra and why?
C1 - bears the weight of the skull and tries to transmit it to the rest of the vertebrae
Where is the atlanto-occipital joint and what is its function?
- Between the occiput of the skull and the atlas vertebra
- permits nodding of the head and contributes to half of the total range of flexion and extension of the head and neck
Where is the atlanto-axial joint and what is its function?
- between the atlas and the axis (C2)
- responsible for 50% of the total rotation of the head and neck
What is the axis, its structure and its function?
- C2 - provides a pivot on which the atlas rotates
- strongest cervical vertebra and has a rugged lateral mass and a large spinous process
What is the odontoid process, its structure?
- aka the dens or odontoid peg
- projects vertically upwards from the axis body and attaches to its articular facet for the dens on the atlas
- vestigial remnant of the atlas body
- held in place by the transverse ligament of the atlas and acts as a pivot joint
- the atypical ligament attaches between the odontoid process and the base of the skull superiorly
What is the function of the odontoid process?
the odontoid process and transverse ligament together prevent horizontal displacement of the atlas on the axis below
Why is it difficult to see the odontoid process on an x-ray?
Sometimes covered by the skull
What is atlantoaxial instability?
- Excessive movement between the C1 and C2 vertebrae
- can be congenital but mostly results from acute trauma or degenerative changes in RA
- can cause the spinal cord/ adjacent nerve roots to be compressed which can cause neurological symptoms
What is the vertebra prominens?
C7
What is the structure of the vertebra prominens?
- has the longest spinous process of the cervical vertebrae
- only cervical vertebra that does not have a bifid spinous process
- large transverse process with a small transverse foramen which only transmits the accessory vertebral veins
How do spinal nerves pass through the cervical region?
- there is a groove that runs across the superior aspect of the vertebral pedicle and then between the anterior and posterior tubercles of the transverse process
- the spinal nerve passes posterior to the vertebral artery which ascends through the foramina transversaria in C1-C6, together with the vertebral vein and sympathetic plexus
Where do cervical spinal nerves exit?
- above their corresponding vertebrae until the C7/T1 junction, where the C8 nerve root is the ‘exiting nerve root’
- the neural segments are much more in line with their respective vertebrae (than in the lumbar spine), so the spinal nerve roots leave the cord more horizontally to pass through the intervertebral formamina
What type of nerve root tends to be compressed by disc herniation in the cervical spine
when comparing the effect of intervertebral disc prolapse in the cervical spine with that in the lumbar spine, as there is no traversing nerve root in the cervical spine and it is the exiting nerve root that tends to be compressed by the disc
What is the ligamentum nuchae?
- A thickening of the supraspinous ligament:
- extends from the external occipital protuberance of the skull and the median nuchae line to the spinous process of C7
- from its anterior border, a fibrous lamina attaches to the posterior tubercle of the atlas and to the spinous processes of all seven vertebrae
- continour inferiorly with the supraspinous ligament
