Small Animal Spinal Column

Clinical Antomy section 2 lecture 8

How many cervical vertebrae does a dog and cat have?

7 cervical vertebrae

How many thoracic vertebrae present in the dog and cat?

13

How many lumbar vertebrae are present in the dog and cat?

7

How many sacral vertebrae are present in dogs and cats?

3

True or False: Dogs and cats have the same amount of vertebrae

False - Dogs can possess 20-23 coccygeal vertebrae, and cats can possess 18-21 vertebrae

C1 is referred to as what?

The Atlas

C1 (Atlas) is identifiable based on what structure?

Elongated wings

Muscle-wise, what is the Atlas’ function?

Site of neck muscle attachment

The Atlas’ shape allows for what?

Rotation of the head

What are the 4 defined features of all vertebrae?

Spinous Process

Articular Facets

Vertebral Arch

Vertebral Body

What lies between the 3 spinous pricesses on the vertebrae?

Epaxial Muscles

What important structure exit from the Articular Facets on a vertebrae?

Nerves

The Vertebral Arch protects what structure?

Spinal Cord

What structure lies between 2 vertebral bodies?

Intervertebral disks

What is the name for C2?

The Axis

What prominant structure identifies the Axis?

An enlarged spinous process

Movement-wise what is the Axis’ function?

Allows movement of the head, along with C1

What structure of the Axis allows articulation with the Atlas?

The Dens or the Odontoid Process

True or False: There is no vertebral disk between the Atlas and the Axis

True

What structure on the ventral aspect of vertebrae prevents spinal tissue hernation?

Ventral Longitudinal Ligament

Instead of a vertebral disk, what lies between C1 and C2?

A synovial joint

What is the name of the joint that contains C1 and C2?

Atlantoaxial joint

Atlantoaxial subluxation is a disease that is the result of what?

A hypoplastic Dens

A hypoplastic dens causes what disease?

Atlantoaxial subluxation

What impact on ligaments does a Hypoplastic Dens result in?

Loss of or weakening of ligamentous structures related to the joint

A malformation of the Dens will likely result in what disease?

Atlantoaxial subluxation

What symptoms are present in a A-A subluxation?

Cervical pain and/or neuro deficits

A patient presents with neuro deficits and cervical pain, what would you suspect?

A-A subluxation

What is the role of the Dorsal Atlantoaxial Ligament?

It keeps C1 and C2 together and in place

The Transverse ligament attaches to what structure on C2?

The Dens

How does an A-A subluxation lead to neuro deficits

Subluxation of C1 and C2 leads to spinal cord compression

Tearing of the Dorsal Atlantoaxial ligament can lead to what disease?

A-A subluxation

C6 is identified by what structure?

Its large transverse process

The Cervical intumescence contains what vertebrae?

C6-T2

A concentration of what structure is contained within the cervical intumescence

Lower motor neurons

A cerebrospinal fluid tap is collected from where?

The snyovial capsule between C1 and C2

What landmark structures are needed to correctly perform a CSF tap?

The wings of the Atlas and the Occipital Protuberance

Along with the Dorsal A-A ligament and the Transverse Ligament, what other ligament helps hold C1 and C2?

The Alar Ligament

True or False, damage to any of the 3 A-A ligaments will result in A-A subluxation

True

How many cervical nerves are present?

8

Which cervical vertebrae are important for knowing where you are in a neck radiograph?

C2 and its large spinal process and C6 with its large transverse process

The venous sinus in the vertebral column is located where respective to the spinal cord

Ventro-lateral

When obtaining radiographs of the thoracic vertebrae, which vertebrae is used as a marker to know where you are?

T11 - Its spinous process points cranial while T1-T10 point caudally

Where does the Dorsal longitudinal ligament lie in thoracic vertebrae

On the floor of the vertebral canal

The Dorsal longitudinal ligament runs between which 2 spinal structures?

The Dens in C2 to the Sacrum

The intercapital ligaments run between which structures?

Between rib heads

Which thoracic vertebrae are the intercapital ligaments present in?

T2-T11

When looking at a cranial view of a thoracic vertebra, what ligament lies directly ventral, underneath the Dorsal longitudinal ligament?

The intercapital ligament

The dog and cat thoracic vertebrae differ anatomical in 3 ways, what are they?

The thoracic vertebrae in cats are longer, the vertebae’s transverse processes are longer, and the intervertebral disk spaces are more narrow

The sacrum is formed by the fusion of what vertebrae?

S1, 2, 3

The sacrum wings articulate with what other boney structure

The Ilium of the pelvis

What is the name of the articulation between the sacrum and ilium?

The Sacroiliac articulation

How may ligaments are present on the sacroiliac articulation?

2

What are the 2 sacroiliac ligaments?

The Dorsal Sacroiliac ligament

The Sacrotuberous ligament

What species does not possess a sacrotuberous ligament?

Cats

Which sacroiliac ligament is used to help with perianal hernia surgery?

The Sacrotuberous ligament

Which sacroiliac ligament is palpable on rectal exam?

Sacrotuberous ligament

What is the process of a Myelogram

Injection of contrast material into the subarachnoid space in the spinal column. A CT is then taken for imaging

True or false: The Lumar spinal canal is wider than the cervical canal

False: The cervical canal is wider

Tip: Think about how many nerves enter/exit from the brain versus how many go to the legs

The lumbosacral spine includes which vertebrae?

L7-S1

Why can a Myelogram not be performed by injecting contrast past L7?

The spinal cord ends at L5/L6

What are the 3 landmarks when performing an epidural?

L7 Spinous process

Sacral vertebrae (S1)

Ilial wings

An epidural can include what 3 types of injections?

1.) Lidocaine injection for anesthesia

2.) Analgesic injection

3.) Corticosteroid injection

What structures are present in a spinal intumescence?

The Brachio plexus and Lumbar plexus

What are the 4 segments that the vertebrae are broken into?

C1-C5

C6-T2

T3-L3

L4-S3

The spinal cord contains thousands of axons which are protected by a sheath called what?

The Meninges

Since the spinal cord ends around L6, what structure continues to provide caudal innervation?

Cauda Equina

Cauda Equina Syndrome is also known as what?

Lumbosacral Stenosis

What nerves can be impacted by Cauda Equina Syndrome?

Femoral, Sciatic, Pudendal, Pelvic, and Coccygeal

A dog with Cauda Equina Syndrome would exhibit what symptom?

Inability to walk

Block vertebrae is the result of what occurrence?

Fusion of 2 or more vertebral bodies

What vertebral region is at highest risk for block vertebrae disease?

Cervical region

True or False: Block vertebrae has no relation to intervertebral disk disease

False: Block vertebrae can increase risk of disk disease

What dog breed is more vulnerable to block vertebrae?

Bulldogs

True or False: The Sacrum is considered a normal block vertebrae

True: It is the ONLY normal block vertebrae

What is Hemivertebral disease?

Incomplete formation of a vertebrae

Which vertebral structure is mostly impacted by Hemivertebrae?

Vertebral body

What does Hemi vertebrae lead to?

Spinal cord compression