Vertebral Column Practical Flashcards
When the vertebrae are aligned into the vertebral column, what is the role of the vertebral foramen?
Align to form the vertebral canal
What attaches to the cranial and caudal endplates in life?
Annulus fibrosus of the intervertebral discs
What is the function of the dorsal and transverse spinous processes?
Increase surface area for muscle attachment
What is the function of the articular facets?
Articulate with adjacent vertebrae to form the vertebral column.
what are the structures
What structure is located in the intervertebral disc space and what is/are its function/s?
Intervertebral disc. Holds vertebral bodies together and provides shock absorption
What structure passes through the vertebral canal in life?
Spinal cord
What structure passes through the intervertebral foramen in life? In which species might this knowledge be of clinical use for performing abdominal surgery?
Spinal nerves
Cow & sheep – performance of paravertebral anaesthesia to allow a lateral flank surgical incision for operations such as caesarean sections to be performed.
what are these structures
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?
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.
Why do the rest of the cervical vertebrae have short dorsal and transverse spinous processes?
Large range of movement necessary in this region therefore short so don’t interfere with movement
Why do the thoracic vertebrae have long dorsal spinous processes and absent transverse ones?
Dorsal spinous processes – muscle attachment for forelimb and epaxial muscles
Absence of transverse processes to allow articulation with the ribs.
Why do the lumbar vertebrae have long transverse processes?
Attachment of abdominal wall muscles for support of abdominal contents
Why are the sacral vertebrae fused?
Efficient transfer of propulsive forces from the hindlimb to the vertebral column via the sacro-iliac joint
Which areas of the vertebral column are associated with most movement and therefore are most prone to damage?
Cervical region - especially atlanto-occipital joint
Lumbar region – especially thoracolumbar junction & lumbosacral junction
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?
Injection of contrast medium into subarachnoid space to perform myelogram or take CSF sample
what are the palpable features on the vertebral column
- transverse processes of C1/atlas
- dorsal spinous process of C2/axis
- dorsal spinous processes of thoracic vertebrae
- dorsal spinous processes of lumbar vertebrae
What is the vertebral formula for each of the skeletons present and are these always constant within a species?
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
What is the functional significance to humans of the horse having a longer thoracic region than other species?
support weight of human
What is the functional significance of the larger species having long and broad transverse processes?
Presence of rumen / hind gut fermentation means abdominal contents heavy so abdominal wall muscle attachments need to be strong
What are the defining features of the anticlinal vertebra and what is its function?
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)
Why do you need to know where the withers in the horse are located?
Used to measure the height of the horse and will provide information for a legal document
What is the function of the nuchal ligament?
Passive support of the weight of the head
Why do you need to know the location of the nuchal ligament in the horse and why is it used for this purpose?
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
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?
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
Which of the structure(s) highlighted here is / are most important in preventing movement of the disc material and why?
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.
What is the potential consequence of protrusion / herniation of the disc material?
If material enters the vertebral canal then it can cause compression of the spinal cord leading to neurological changes in the animal.
Which regions of the vertebral column are most vulnerable to protrusion / herniation of the disc material and why?
Areas with lots of movement – thoracolumbar junction ; lumbar region ; cervical region
Which regions of the vertebral column are least vulnerable to protrusion / herniation of the disc material and why?
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
what are the features of cervical vertebrae
- short dorsal and transverse processes
- transverse processes have ventral projections
- presence of transverse foramen
what are the features of C1 (atlas)
vertebral arch present but no vertebral body
no dorsal spinous process
2 large transverse processes/wings - palpable
what are the features of C2 (axis)
extra vertebral body - dens
small transverse processes
large dorsal spinous process - palpable
what are the features of the thoracic vertebrae
- short vertebral body
- long dorsal spinous process
- abscence of transverse processes
- presence of 4 costal fovea for articulation with ribs
what are the features of lumbar region vertebrae
- long vertebral body
- long transverse processes
- short dorsal spinous process
what are the features of the sacral region
- vertebrae fused to form sacrum
- no intervertebral disc spaces present
what are the features of the caudal/coccygeal region vertebrae
rudimentary cylinder of bone - most features lost
what are the species differences between dog and cat vertebrae
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
what are the views taken in order to view the vertebral column
lateral
ventrodorsal views
What are the layers of tissue you would incise down through to enter the abdominal cavity?
Skin, superficial fascia / fat, tunica flava abdominis, muscle (external abdominal oblique, internal abdominal oblique, transverse abdominus), peritoneum
Give at least 3 anatomical features of the appendicular skeleton that allow you to identify these as cats rather than dogs
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
How could you distinguish each of the muscle layers as you passed through it?
Fibre direction : external abdominal oblique – caudoventral ; internal abdominal oblique – cranioventral ; transverse abdominus – dorsoventral
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?
Nerves from L5-S2 give rise to the sciatic nerve that branches to innervate the biceps femoris, semitendinosus and semimembranosus muscles
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?
Ventral medial fissure. 4 =dorsal nerves, sensory. 5 =ventral nerves, motor.
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.
- development, elongation of vertebral column greater than the spinal cord that matures earlier.
- 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
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?
7 occupied by epidural fat. Cauda equina.
