ACTIVITY 3 : VERTEBRAL JOINTS

3.1. Identify a facet joint. – Zygapophysial joint

3.1.1. What type of joint is it? – Plane synovial joints

3.1.2. What is the orientation of thoracic & lumbar facet joints?
a) Thoracic
o T 5-T8 : articular facets are nearly coronally oriented that define an arc centered in the IV disc
o Superior facets : posteriorly and slightly laterally
o Inferior facets : anteriorly and slightly medially

b) Lumbar
o The articular facets are sagittally orientated initially but becoming more coronally orientated as the column descends
o The L5-S1 facets are orientated coronally
o Superior facets : posteriormedially
o Inferior facets : anterolaterally (laterally)

3.1.3. How is this orientation related to function?
a) Thoracic
o The arc permits rotation(greatest degree of rotation) and some lateral flexion of the vertebral column
o Attachment of the rib cage combined with the vertical orientation of articular facets and overlapping spinous processes limits flexion and extension as well as lateral flexion

b) Lumbar
o In the more sagittally oriented superior joints, the laterally facing facets of the inferior articular processes of the vertebra above are “gripped” by the medially facing facets of the superior processes of the vertebra below, thus facilitating flexion, extension and allowing lateral flexion but prohibiting rotation.

3.1.4. Identify and list the accessory ligaments of facet joints.
Ligamenta flava, Interspinous ligaments, Supraspinous ligaments, Nuchal ligament, Intertransverse ligament

3.2. Identify an intervertebral disc.
3.2.1. What type of joint is this? – Symphyses (secondary cartilaginous joints)

3.2.2. Where they are usually found? Between adjacent vertebrae bodies

3.2.3. What type of cartilage is involved? Fibrocartilage

3.3. What are the two major parts of the disc? Anulus fibrosus, nucleus pulposus

3.3.1. What is the centre of the disc a remnant of? Notochord

3.3.2. What is the only other remnant of this structure?

3.3.3. How are the shape and the thickness of a thoracic disc compare to a lumbar disc?

3.3.3.1. Why are these differences?


3.3.4. Where does a disc prolapse normally occur?
In the lower lumbar part of the spine.

3.3.4.1. Why? Stresses experienced by the spine are the greatest at these levels.

3.3.5. Which disc is most likely to prolapse? At L4-L5 and L5-S1 level

3.3.5.1. Why?
The sacrum does not stand vertically but is tilted backwards, so producing a sharp curve in this region and giving a wedge shape to the discs, which may concentrate the stresses in the back of the disc so making these lower lumbar discs particularly liable to damage.

3.3.6. Why do most young adults grow by a centimeter overnight?
Growth hormones are produced during sleep

nb : i left a few blanks cuz i couldn't find the answers...