Intervertebral Disc and Functional Anatomy of the Back

Question 1

what are the two joints that the vertebrae articulate between

Answer 1

• 1 between the vertebral bodies via IV dsics

- 2 between articular facets – this is a synovial plane joint

Question 2

what type of cartilaginous joint is between the 2 vertebral discs

Answer 2

secondary

- symphysis

Question 3

describe the types of cartilage in the IV discs

Answer 3

• 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

Question 4

the joints between the vertebral bodies are…

Answer 4

The joints between the vertebral bodies are reinforced by longitudinal ligaments.

Question 5

describe the structure of the intervertebral disc

Answer 5

• 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

Question 6

what does the nucleus pulpsis do

Answer 6

• act as a shock absorber

- when compressed the pulpous becomes broader and thinner when stretched

Question 7

what do the longitudinal ligaments in the spine do

Answer 7

• Both longitudinal ligaments limit the amount of flexion and extension thus preventing hyperflexion and hyperextension

Question 8

what are the two longitudinal ligaments in the spine

Answer 8

• anterior

- posterior

Question 9

what does the anterior longitudinal ligaments do

Answer 9

• The anterior longitudinal ligament is thick and prevents hyperextension of the vertebral column.

Question 10

what does the posterior longitudinal ligament do

Answer 10

The posterior longitudinal ligament is weaker and prevents hyperflexion and is smaller

Question 11

what is stronger the anterior or posterior longitudinal ligament

Answer 11

anterior longitudinal ligament

Question 12

what is the optimum position for sitting

Answer 12

• 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

Question 13

how does the IV disc get blood supply

Answer 13

• 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

Question 14

what is the thickness of the cerebral discs as the column descends

Answer 14

• 3mm in cervical
• 5mm in thoracic
• 9-11mm in lumbar

Question 15

why do the IV discs get bigger

Answer 15

• The IV discs get larger as you go down the vertebral column as the loads and weights increase as you go down the column

Question 16

describe the thickness of IV discs

Answer 16

• 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

Question 17

where do the majority of herniations occur in the IV discs

Answer 17

95% of herniated disc occur between L4-L5 or L5-S1

Question 18

what is a disc herniation

Answer 18

• 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

Question 19

what are the stages of disc herniation

Answer 19

• 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

Question 20

what are the problems with a herniated disc

Answer 20

• 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

Question 21

what are the symptoms of a herniated disc

Answer 21

• 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

Question 22

where are the facet joints between

Answer 22

• between inferior and superior articular processes of adjacent vertebrae

Question 23

what do the facet joint do

Answer 23

they limit rotational movement of the spinal column so you are not twisting all the spinal nerves and damaging the nerve roots

Question 24

why are facet joints important

Answer 24

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

Question 25

what is another name for facet joints

Answer 25

zygopophysial joints

Question 26

what are the two ligaments in the spine

Answer 26

• interspinous ligament

- ligamentum flavurm

Question 27

where is the interspinous ligament

Answer 27

• between spinous processes

Question 28

describe the interspinous ligament

Answer 28

• Goes from one spinous process to the next spinous process
  o Joins adjacent spinous processes
  o Weak more like a thin membrane

Question 29

where is the ligametnum flavum

Answer 29

• Extends from lamina above to lamina below of adjacent vertebra

Question 30

what does the ligament flavum do

Answer 30

• Resists separation of the lamina
• Stops abrupt flexion
• High elastic content so assists with straightening the spinal column after flexion
• In between the two lamina, thick strong ligament

Question 31

what is the Atlanto-occipital joints

Answer 31

• Between the occipital condyles and the lateral masses of C1 is a condyloid synovial joint. This joint permits flexion and extension of the cervical spine
• They articulate with the occipital condyle that you find in the skull
• Allows you to nod your head

Question 32

what is the altato-axial joint

Answer 32

• Atlas and axis articulate together at a pivot type synoivla joint
• The joint is reinforced by the transverse ligament which encircles the dens of the axis – this stops the dens from going posteriorly into the spinal cord
• The joint permits rotation of the cervical spine
• Allows you to shake your head

Question 33

what are the superficial muscles in the back

Answer 33

trapezius
lattices dorsi
tires major

Question 34

what do the superficial muscles attach to

Answer 34

• They attach to the vertebrae and to other bony structures

Question 35

what do the deep muscles attach to

Answer 35

attach the vertebrae to themselves and attach vertebrae to other vertebrae

Question 36

what are the movements of the back

Answer 36

• Flexion and extension
• The mobility of the vertebral column results from the size and compressibility of the IVDs as well as the bony anatomy of the vertebrae
• Most extension is the lumbar region
• Most flexion is the cervical region
• Lateral flexion
• Thoracic region is limited in the ability to flex and extend – don’t want to compress lungs and heart, action that you can do the most is rotation

Question 37

what are the paraspinal muscles

Answer 37

• The paraspinal muscles attach to the individual vertebrae and are involved in posture and movements of the vertebral column.

Question 38

what are the paraspinal muscles innervated by

Answer 38

posture and movements of the vertebral column.

- Innervated by the dorsal rami of spinal nerves

Question 39

what do the doors rami innervate

Answer 39

innervate the paraspinal muscle and the skin in front of them