Vertebral Column 3

Question 1

how many articular facets are there per vertebra

Answer 1

4 –> 2 cranial and 2 caudal

Question 2

what is the orientation of the articular facets

Answer 2

cranial facets lateral/ventral to caudal facets

Question 3

what are the exceptions to the synovial joint features (3)

Answer 3

1. atlanto-occipital joint where the atlas or C1 articulates with the occipital condyles of the skull rather than adjacent vertebra
2. sacrum –> bones are fused into single bone unit –> articular facets and associated joints are absent
3. caudal/coccygeal region –> vertebra have reverted to more basic form and have lost many of features associated with typical vertebra including articular facets

Question 4

what are the features of synovial joints

Answer 4

synovial fluid is present between articular surfaces

produced by synovial membrane and contained within the joint capsule

stabilized by ligaments and movement across joints produced by action of muscle

Question 5

what is the intervertebral disc made up of

Answer 5

1. annulus fibrosus
2. nucleus pulposus

Question 6

what is the annulus fibrosus

Answer 6

series of concentric rings of fibrous tissue arranged in rigns (like onion)

fibres run between endplates of adjacent vert bodies –> holding them together + providing stability by restricting stretching of intervertebral disc space

Question 7

what is the nucleus pulposus

Answer 7

notochord remnant –> involved with embryological development of vert column

jelly filled cushion embedded within annulus fibrosis and surrounded by it –> shock absorption and resists compression of disc space

Question 8

where is the intervertebral disc space weakest

Answer 8

annulus thinnest dorsally

Question 9

what structures shown

Answer 9

1. annulus fibrosus
2. nucleus pulposus

Question 10

what are the intervertebral ligaments

Answer 10

1. dorsal longitudinal ligament
2. ventral longitudinal ligament
3. interspinous ligaments
4. interarcuate/yellow ligament
5. supraspinous ligament
6. nuchal ligament - dog

Question 11

where does the dorsal longitudinal ligament run

Answer 11

along the dorsal aspect of the vertebral bodies –> ventral floor of the vertebral canal

along the entire length of the vertebral column from the level of C2

Question 12

name the ligaments shown

Answer 12

1. dorsal longitudinal ligament
2. ventral longitudinal ligament
3. invertebral disc
4. interspinous ligaments
5. interarcuate/yellow ligament

Question 13

where does the ventral longitudinal ligament run

Answer 13

ventral aspect of the vertebral body and is present from the level of C2 to the sacrum

Question 14

where does the supraspinous ligament run

Answer 14

along dorsal aspect of dorsal spinous processes and is present from level of T1 to CC3

in dog it continues in cranial driection to caudal aspect of axis or C2 as a cord of fibroelastic material called nuchal ligament

Question 15

what is the function of the nuchal ligament

Answer 15

passive support for the large weight of head

Question 16

how does the nuchlar ligament differ in horses

Answer 16

heavier head –> 2 parts

1. funicular part = cord: fibro-elastic band of tissue (present in dog) is a continuation of supraspinous ligament runs all the way to nuchal crest of skull
2. laminar part = fenestrated sheet: run from funicular part of nuchal ligament to dorsal spinous processes of cervical vertebrae

Question 17

what is present near the nuchal ligament in horses

Answer 17

1. fluid filled bursa –> atlantal bursa (located between nuchal ligament and atlas/C1
2. supraspinous bursa –> dorsal to the dorsal spinous processes of the first few thoracic vertebrae

Question 18

what are the ribs held in place by

Answer 18

costal ligaments

Question 19

where does the intercapital ligament run

Answer 19

between the heads of each pair of corresponding left and right ribs

runs over dorsal surface of intervertebral disc space and merges with fibres of dorsal longitudinal and annulus fibrosis of intervertebral disc

Question 20

what is the function of the intercapital ligament

Answer 20

stabilizes the ribs and the intervertebral disc

Question 21

what ribs is the intercapital ligament associated with

Answer 21

1-10

Question 22

why do ribs 11-13 not have the intercapital ligament

Answer 22

they articulate only with the vertebral body of the corresponding vertebra and don’t span the intervertebral disc space –> ligament is absent

Question 23

what does the tuberculum of each rib held in place by

Answer 23

articulates with short transverse process of corresponding vertebra and held in place by costo-transverse ligament

Question 24

what ligament holds the ribs in place ventrally

Answer 24

radiate ligament that supports the joint capsule and merges with fibres of annulus fibrosus of intervertebral disc space

Question 25

how does the vertebral column move with minimal damage

Answer 25

restricted movement between bones cummulative effect over length of section transitional areas most susceptible to damage

Question 26

what is the atlanto-occipital joint

Answer 26

atlas/C1 and occipital condyles of skull limited to flexion and extension by wings of C1 (large transverse processes) 'yes' joint

Question 27

what is the atlanto-axial joint

Answer 27

formed between C1 and C2 dens of C2 sits on ventral floor of the vertebral foramen of C1 and held in place by transverse ligament large dorsal spinous process of C2 limits to lateral rotation 'no' joint --\> sideways shaking motion

Question 28

what is the occipito-atlanto-axial complex

Answer 28

combination of atlanto-occipital and atlanto-axial joints --\> allows a ful 360 range of movement but spreads it over the length of 2 joint spaces reduces the chance of spinal cord damage due to excessive movement

Question 29

how does disc degeneration occur

Answer 29

the intervertebral discs are subjected to compressive and distractive forces as they function like shock absorbers between the adjacent vertebral bodies can occur either as an age related change or spontaneously in some breeds such as the Dachshund which are predisposed to it nucleus pulposus becoming dehydrated and this reduction in fluid content means that it is no longer hyperintense or bright white on MR images but appears dark, similar to the annulus fibrosis. This results in the disc loosing some of its compliance which can predispose it to further damage.

Question 30

what is disc protrusion

Answer 30

disc material bulges dorsally from the disc space pushing the dorsal longitudinal ligament into the vertebral canal

Question 31

why does disc protrusion always occur in a dorsal direction

Answer 31

annulus fibrosis is thinner dorsally than ventrally

Question 32

how does disc protrusion occur

Answer 32

due to trauma but dogs with degenerative discs may be predisposed to this as the nucleus pupolsus is more rigid and less flexible than normal

Question 33

what is disc extrusion occur and why is it a serious condition

Answer 33

disc ruptures through the dorsal longitudinal ligament and disc material becomes located within the vertebral canal itself. not much space in the vertebral canal and therefore a very real risk that this material will cause compression of the spinal cord itself

Question 34

where are disc protrusion and extrusion most commonly found

Answer 34

degeneration can affect any disc along the length of the vertebral column but protrusion and extrusion --\> most movement possible --\> **cervical and lumbar regions and thoracolumbar junction (transition area of low motion to high motion)**

Question 35

why is the lumbo-sacral region not affected by disc problems

Answer 35

the spinal cord terminates in the lumbar region of the vertebral column, it would not be affected by disc disease at this level

Question 36

where are uncommon regions of disc disease

Answer 36

areas of low motion --\> thoracic (also because the intercapital ligament from T1-10 that helps stabilise the disc) sacrum is a single fused unit with no disc spaces and therefore will not be affected

Question 37

what are the diseases

Answer 37

1. disc degeneration 2. disc protrusion 3. disc extrusion

Question 38

what is the vertebral formula of the dog

Answer 38

C7 T13 L7 S3 CC variable

Question 39

name the vertebrae

Answer 39

cervical ? ? ?

Question 40

what is the vertebral formula of cat

Answer 40

C7 T13 L7 CC variable

Question 41

what are the differences in feline vertebrae

Answer 41

more slender bones vertebral bodies appear longer and finer on radiographs more flexible column

Question 42

what is the vertebral formula of the horse

Answer 42

C7 T18 L6 S5 CC variable

Question 43

what are the species differences in the horse vertebrae (9)

Answer 43

1. 18 pairs of ribs --\> 18 thoracic vertebrae 2. 6 lumbar vertebrae and 5 sacral vertebrae (fused to form sacrum) 3. cervical region remains flexible to allow large range of movement of head 4. longest dorsal spinous process is T6 (withers) 5. anticlincal vertebra is T16 (thoracic vertebra with shortest and most vertically orientated dorsal spinous process) 6. transverse processes are very large in the lumbar region --\> abdominal muscle attachment 7. intertransverse joints + ligaments to support abdominal weight 8. sacrum --\> dorsal spinous processes separate 9. lumbosacral joint --\> vulnerable to damage, propulsion from hindlimbs

Question 44

what is the vertebral formula in the cow

Answer 44

C7 T13 L6 S5 Cc variable

Question 45

what are the species variation of the cow vertebrae

Answer 45

1. fewer ribs than horse --\> fewer thoracic vertebrae (13) 2. dorsal spinous process of sacral vertebrae are fused as well as the vertebral bodies (unlike horse)

Question 46

what is the vertebral formula of the pig

Answer 46

C7 T14-16 L6-7 S4 Cc variable

Question 47

what is the vertebral formula in the sheep

Answer 47

C7 T13 L6 S5 Cc variable