Intervertebral Disc and Functional Anatomy of the Back Flashcards
(39 cards)
what are the two joints that the vertebrae articulate between
- 1 between the vertebral bodies via IV dsics
- 2 between articular facets – this is a synovial plane joint
what type of cartilaginous joint is between the 2 vertebral discs
secondary
- symphysis
describe the types of cartilage in the IV discs
- Each of the verberal bodies you have a thin layer of hyaline cartilage
- Between each layer of hyaline cartilage, you have a fibrocartilaginous intervertebral disc
the joints between the vertebral bodies are…
The joints between the vertebral bodies are reinforced by longitudinal ligaments.
describe the structure of the intervertebral disc
- The outer part is Annulus fibrous and this comprises of 15 to 20 collagenous type 1 laminae which run obliquely
• Thicker region of the annulus anterior than posteriorly
• Therefore, nucleus pulposus are positioned posteriorly rather than anteriorly
• The nucleus pulposus is composed of type II collagen, water and proteoglycans, nucleus pulposus contains approximately 85% water
what does the nucleus pulpsis do
- act as a shock absorber
- when compressed the pulpous becomes broader and thinner when stretched
what do the longitudinal ligaments in the spine do
- Both longitudinal ligaments limit the amount of flexion and extension thus preventing hyperflexion and hyperextension
what are the two longitudinal ligaments in the spine
- anterior
- posterior
what does the anterior longitudinal ligaments do
- The anterior longitudinal ligament is thick and prevents hyperextension of the vertebral column.
what does the posterior longitudinal ligament do
The posterior longitudinal ligament is weaker and prevents hyperflexion and is smaller
what is stronger the anterior or posterior longitudinal ligament
anterior longitudinal ligament
what is the optimum position for sitting
- When standing up it is the lowest strain
- As you flex or extend it increases pressure that you put on the disc
- Highest pressure on the disc is if you are leaning acutely forward
- When you lean backwards this is the optimum position for sitting
how does the IV disc get blood supply
- The inner layers of the annulus fibrosus and nucleus pulposus have neither innervation nor blood supply; they receive nutrition via diffusion across the vertebral body
- therefore IV disc is poor at any sort of repair
what is the thickness of the cerebral discs as the column descends
- 3mm in cervical
- 5mm in thoracic
- 9-11mm in lumbar
why do the IV discs get bigger
- The IV discs get larger as you go down the vertebral column as the loads and weights increase as you go down the column
describe the thickness of IV discs
- thicker anteriorly than posteriorly in the cervical and lumbar therefore you get lordosis
- in thoracic you get kyphosis this is because the IV disc is the same thickness throughout the whole way through
where do the majority of herniations occur in the IV discs
95% of herniated disc occur between L4-L5 or L5-S1
what is a disc herniation
- A herniated disc is when the nucleus pulpous pushes through the annulus fibrosis and pushes onto the spinal nerve when too much gravity is applied
what are the stages of disc herniation
- Normal
- Protruding – bulge in disc but no rupture
- Prolapsed – pulposis forced into outer part of annulus but no rupture
- Extruded – pulposis bulging through a hole In annulus
- Sequestered – pulposis fragment outside the disc
what are the problems with a herniated disc
- IVD is poorly innervated so pain doesn’t come from the disc itself but from surrounding structures
- Compression of surrounding ligaments causes localised pain
- Compression of nerve roots causes numbness, tingling and pain across the respective dermatome
- The nucleus pulposis impedes on the other structures surrounding the vertical column and puts pressure on those, comes from the anterior and posterior longitudinal ligament, can get pain from the ligaments themselves, the vast majority of herination appears posteriorly as the nucleus propulsis is more posteriorly located in the vertebral disc, posterior longitudinal ligament is weaker meaning that the herinations tend to happen posteriorly this causes compression of the nerve roots in the body
- If you get herination at L4-L5 get compression at the nerve root that leaves that spinal level. – pain in the foot and lower leg, can go down posterior aspect of the leg L5-S1
what are the symptoms of a herniated disc
- The symptoms produced by a herniated IVD depend upon the spinal level and the nerves compressed.
- Compression of spinal nerves results in numbness or tingling along the respective dermatome.
- The most common symptom is back pain.
- Dependent on what spinal nerve they occur at
where are the facet joints between
- between inferior and superior articular processes of adjacent vertebrae
what do the facet joint do
they limit rotational movement of the spinal column so you are not twisting all the spinal nerves and damaging the nerve roots
why are facet joints important
they are next to the emergence of the spinal nerve from the vertebral column. Therefore when these joints are diseased/form osteophtyes spinal nerves become compressed.
- As IV disc degenerates spinal nerve roots can be compressed especially in lumbar region – this is because you have the smallest intervertebral foramen with respect to the nerves going out of them
