Vertebral Column Practical

Question 1

When the vertebrae are aligned into the vertebral column, what is the role of the vertebral foramen?

Answer 1

Align to form the vertebral canal

Question 2

What attaches to the cranial and caudal endplates in life?

Answer 2

Annulus fibrosus of the intervertebral discs

Question 3

What is the function of the dorsal and transverse spinous processes?

Answer 3

Increase surface area for muscle attachment

Question 4

What is the function of the articular facets?

Answer 4

Articulate with adjacent vertebrae to form the vertebral column.

Question 5

what are the structures

Answer 5

Question 6

What structure is located in the intervertebral disc space and what is/are its function/s?

Answer 6

Intervertebral disc. Holds vertebral bodies together and provides shock absorption

Question 7

What structure passes through the vertebral canal in life?

Answer 7

Spinal cord

Question 8

What structure passes through the intervertebral foramen in life? In which species might this knowledge be of clinical use for performing abdominal surgery?

Answer 8

Spinal nerves

Cow & sheep – performance of paravertebral anaesthesia to allow a lateral flank surgical incision for operations such as caesarean sections to be performed.

Question 9

what are these structures

Answer 9

Question 10

What is the nature of the movement that is possible at the joints between C1 & the skull and C1 & C2 and what is the functional significance of this arrangement?

Answer 10

C1 & the skull - Dorsal and ventral movement – ‘Yes’ joint

C1 & C2 - Lateral rotation – ‘No’ joint

Allows wide range of movement between skull and vertebral column but spreads this over a relatively large area (occipito – atlanto-axial joints) so spinal cord not damaged.

Question 11

Why do the rest of the cervical vertebrae have short dorsal and transverse spinous processes?

Answer 11

Large range of movement necessary in this region therefore short so don’t interfere with movement

Question 12

Why do the thoracic vertebrae have long dorsal spinous processes and absent transverse ones?

Answer 12

Dorsal spinous processes – muscle attachment for forelimb and epaxial muscles

Absence of transverse processes to allow articulation with the ribs.

Question 13

Why do the lumbar vertebrae have long transverse processes?

Answer 13

Attachment of abdominal wall muscles for support of abdominal contents

Question 14

Why are the sacral vertebrae fused?

Answer 14

Efficient transfer of propulsive forces from the hindlimb to the vertebral column via the sacro-iliac joint

Question 15

Which areas of the vertebral column are associated with most movement and therefore are most prone to damage?

Answer 15

Cervical region - especially atlanto-occipital joint

Lumbar region – especially thoracolumbar junction & lumbosacral junction

Question 16

Why is it useful clinically to be able to palpate the transverse processes of C1, the dorsal spinous process of C2 and the lumbar dorsal spinous processes?

Answer 16

Injection of contrast medium into subarachnoid space to perform myelogram or take CSF sample

Question 17

what are the palpable features on the vertebral column

Answer 17

1. transverse processes of C1/atlas
2. dorsal spinous process of C2/axis
3. dorsal spinous processes of thoracic vertebrae
4. dorsal spinous processes of lumbar vertebrae

Question 18

What is the vertebral formula for each of the skeletons present and are these always constant within a species?

Answer 18

Dog & cat - C7 T13 L7 S3 CC17

Horse - C7 T18 L6 S5 CC 10

Cow – C7 T13 L6 S5 CC 12

Pig - C7 T16 L6 S4 CC9

Pig & sheep variable to provide extra cuts of meat

Question 19

What is the functional significance to humans of the horse having a longer thoracic region than other species?

Answer 19

support weight of human

Question 20

What is the functional significance of the larger species having long and broad transverse processes?

Answer 20

Presence of rumen / hind gut fermentation means abdominal contents heavy so abdominal wall muscle attachments need to be strong

Question 21

What are the defining features of the anticlinal vertebra and what is its function?

Answer 21

Shortest and most upright dorsal spinous process

Prevents overcrowding of dorsal spinous processes during extension.

(Marks transition from low movement thoracic to higher movement lumbar region)

Question 22

Why do you need to know where the withers in the horse are located?

Answer 22

Used to measure the height of the horse and will provide information for a legal document

Question 23

What is the function of the nuchal ligament?

Answer 23

Passive support of the weight of the head

Question 24

Why do you need to know the location of the nuchal ligament in the horse and why is it used for this purpose?

Answer 24

Site for microchip placement. Midway up neck on left side of horse. Reduces chances of microship migrating and also standard position means easier to locate when scanning for a microchip in a horse

Question 25

How does the composition of the components of the intervertebral disc relate to their function and why does this result in the nucleus pulposus bulging following sectioning?

Answer 25

The annulus fibrosis is composed of fibrous tissue. Its function is to hold the adjacent vertebral bodies together and contain the nucleus pulposus.

The nucleus pulposus is a relatively fluid filled gel cushion held under pressure and so functions as a shock absorber between adjacent vertebrae

Question 26

Which of the structure(s) highlighted here is / are most important in preventing movement of the disc material and why?

Answer 26

Dorsal longitudinal ligament & intercapital ligament.

The nucleus pulposus is located towards the dorsal aspect of the annulus fibrosis so if there is movement or bulging of disc material then it occurs in a dorsal direction. Both of these ligaments cross the dorsal aspect of the disc space and blend with the fibres of the annulus fibrosis thereby helping to stabilise the disc and prevent movement of material in a dorsal direction.

Question 27

What is the potential consequence of protrusion / herniation of the disc material?

Answer 27

If material enters the vertebral canal then it can cause compression of the spinal cord leading to neurological changes in the animal.

Question 28

Which regions of the vertebral column are most vulnerable to protrusion / herniation of the disc material and why?

Answer 28

Areas with lots of movement – thoracolumbar junction ; lumbar region ; cervical region

Question 29

Which regions of the vertebral column are least vulnerable to protrusion / herniation of the disc material and why?

Answer 29

Thoracic region - little movement in these regions & presence of intercapital ligament from T1-10 provides additional stabilisation of disc.

Sacral – fused so no discs

Caudal / coccygeal – spinal cord no longer present at this level so no relevant

Question 30

what are the features of cervical vertebrae

Answer 30

1. short dorsal and transverse processes
2. transverse processes have ventral projections
3. presence of transverse foramen

Question 31

what are the features of C1 (atlas)

Answer 31

vertebral arch present but no vertebral body

no dorsal spinous process

2 large transverse processes/wings - palpable

Question 32

what are the features of C2 (axis)

Answer 32

extra vertebral body - dens

small transverse processes

large dorsal spinous process - palpable

Question 33

what are the features of the thoracic vertebrae

Answer 33

1. short vertebral body
2. long dorsal spinous process
3. abscence of transverse processes
4. presence of 4 costal fovea for articulation with ribs

Question 34

what are the features of lumbar region vertebrae

Answer 34

1. long vertebral body
2. long transverse processes
3. short dorsal spinous process

Question 35

what are the features of the sacral region

Answer 35

1. vertebrae fused to form sacrum
2. no intervertebral disc spaces present

Question 36

what are the features of the caudal/coccygeal region vertebrae

Answer 36

rudimentary cylinder of bone - most features lost

Question 37

what are the species differences between dog and cat vertebrae

Answer 37

dog: prominent ventral projection of C5 transverse processes (visible on radiograph)
cat: bones larger and more slender than dogs
horse: has more thoracic vertebrae than other sp, withers = highest point approx T6, unfused dorsal spinous processes of sacrum
cow: fused dorsal spinous processes of sacrum

sheep and pig: some variability in their vertebral formula

Question 38

what are the views taken in order to view the vertebral column

Answer 38

lateral

ventrodorsal views

Question 39

What are the layers of tissue you would incise down through to enter the abdominal cavity?

Answer 39

Skin, superficial fascia / fat, tunica flava abdominis, muscle (external abdominal oblique, internal abdominal oblique, transverse abdominus), peritoneum

Question 40

Give at least 3 anatomical features of the appendicular skeleton that allow you to identify these as cats rather than dogs

Answer 40

Clavicle, suprahamet process, square olecranon process, similar diameter distal ends of radius & ulna (una tapers distally in dog), hyperextended DIP joints , pointed patella, box shaped pelvis(not visible in these rads) etc

Question 41

How could you distinguish each of the muscle layers as you passed through it?

Answer 41

Fibre direction : external abdominal oblique – caudoventral ; internal abdominal oblique – cranioventral ; transverse abdominus – dorsoventral

Question 42

Follow the nerve roots that arise from the region of the spinal cord indicated with pins marked 3. They give rise to the pelvic plexus including the large nerve also marked 3. Can you name this nerve and the muscles that are innervated from branches from this nerve?

Answer 42

Nerves from L5-S2 give rise to the sciatic nerve that branches to innervate the biceps femoris, semitendinosus and semimembranosus muscles

Question 43

This is a section of equine spinal cord. Can you name the fissure marked 6. What term is given to the nerve rootlets in the position marked 4 and 5 and indicate which of these receive sensory inputs or supply motor innervations to muscles?

Answer 43

Ventral medial fissure. 4 =dorsal nerves, sensory. 5 =ventral nerves, motor.

Question 44

Note the nerve roots associated with segments of the spinal cord. At the more caudal region of the spinal cord the nerve roots are more distant from their associated vertebral foramen, why is this? There are two regions where the spinal cord is enlarged (between pins marked 1 and pins marked 2). Can you name these regions and give an explanation why they are enlarged.

Answer 44

1. development, elongation of vertebral column greater than the spinal cord that matures earlier.
2. Cervical (C6-T1) intumescences and lumbar (L4-L7) intumescences. Greater white matter and cell body content due to the innervations of the thoracic (cervical) and pelvic

Question 45

This is the caudal region of the spinal cord in the dog. What would occupy the space marked 7 in the live animal? The segments of spinal cord form an elongated cone marked 8 named the conus medullaris? Caudal to this region a strand of glia and ependymal cells form the terminal filament that is enveloped in dura matter. This extends to the sacrum and attaches to the vertebra. Nerve roots continue to stream caudally, what is the collective name for these nerves?

Answer 45

7 occupied by epidural fat. Cauda equina.