Week 1 lesson 3: The organisation of the vertebral column

What is the correct vertebral formula for the canine (dog)?

The formula is C7 T13 L7 S3 Cd20.

What is the correct vertebral formula for the equine (horse)?

The formula is C7 T18 L6 S5 Cd (about 20).

What is the correct vertebral formula for the bovine (ox)?

The formula is C7 T13 L6 S5 Cd18.

What is the correct vertebral formula for the ovine (sheep)?

The formula is C7 T13 L6-7 S4 Cd16-18.

What is the correct vertebral formula for the caprine (goat)?

The formula is C7 T13 L6-7 S5 Cd16-18.

What is the correct vertebral formula for the pig?

The formula is C7 T14-15 L6 S4 Cd20-23.

Where are the epaxial muscles located relative to the vertebrae?

They are dorsal to the transverse process of the vertebrae.

From which nerve branches do the epaxial muscles receive their supply?

They receive their nerve supply from the dorsal branches of the spinal nerves.

Where are the hypaxial muscles located relative to the vertebrae?

They are ventral to the transverse process of the vertebrae.

From which nerve branches do the hypaxial muscles receive their supply?

They receive their nerve supply from the ventral branches of the spinal nerves.

What are the three parallel systems of the epaxial spinal musculature?

The three systems are the iliocostalis, longissimus, and transversospinalis.

What is the general function of the epaxial muscle systems?

They extend the vertebral column and produce unilateral movement of the trunk.

Where is the iliocostalis system located relative to the other epaxial systems?

it is located most laterally.

What is the composition of the iliocostalis system?

It consists of lumbar and thoracis bundles of overlapping fibers between the lumbar and cervical vertebrae.

What is the primary action of the iliocostalis system?

Its primary action is lateral flexion of the trunk.

How is the longissimus system divided between the ileum and the head?

It is divided into thoracolumbar, cervical, and capital muscle fascicles.

Where is the longissimus system located relative to the iliocostalis system?

It is located medially to the iliocostalis system.

What are the primary actions of the longissimus system?

It acts as an extensor of the back and assists in expiration.

Where is the transversospinalis system located relative to the spinous processes?

It is the most medial system to the spinous processes.

What is the extent of the transversospinalis system?

It extends from the sacrum to the head.

Which epaxial system is commonly reflected during a laminectomy procedure?

The transversospinalis system is commonly reflected.

What is the primary action of the transversospinalis system in the thoracic region?

It stabilizes the thoracic region of the column.

Where is the interarcuate ligament located?

It is located between the vertebral arches.

Which clinical condition in dogs is associated with the interarcuate ligament?

It is associated with degenerative lumbosacral stenosis (DLSS).

Name two symptoms of degenerative lumbosacral stenosis in dogs.

Symptoms include hindlimb lameness, pain in the lumbosacral area, arched back, or urinary incontinence.

Where are the intertransverse ligaments located?

They are located between the transverse processes of lumbar vertebrae.

Where is the interspinous ligament located?

It is located between the spinous processes of the vertebrae.

In which equine disease is the interspinous ligament severed to relieve tension?

It is severed in "kissing spine" disease.

What structures are connected by the intercapital ligament?

It connects the heads of adjacent ribs in the thoracic region.

Between which vertebrae does the intercapital ligament help stabilize intervertebral discs?

It stabilizes discs between T2 and T11.

What is a primary protective function of the intercapital ligament?

It prevents intervertebral disc herniation.

Where is the dorsal longitudinal ligament located?

It is located on the floor of the vertebral canal from the axis to the sacrum.

What movement does the dorsal longitudinal ligament prevent?

It prevents hyperextension of the spine.

What structures does the dorsal longitudinal ligament protect and support?

It supports the spinal cord and intervertebral discs.

Where is the ventral longitudinal ligament located?

It extends from the axis to the sacrum.

What are the primary functions of the ventral longitudinal ligament?

it stabilizes the spine and reinforces the intervertebral discs.

What is the nuchal ligament?

It is an elastic connective tissue structure that is the cranial continuation of the supraspinous ligament into the cervical region.

What are the specific attachments of the nuchal ligament in the dog?

It extends from the apex of the first thoracic spine to the spine of the axis.

In which species is the nuchal ligament absent?

It is absent in the cat.

What are the two parts of the nuchal ligament in horses and oxen?

It consists of funicular and laminar parts.

What are the specific attachments of the funicular part of the nuchal ligament in the horse?

It extends from the spinous processes of the withers (T3–T4) to the external occipital protuberance of the skull.

Which long ligament is continuous with the funicular part of the nuchal ligament in the horse?

The supraspinous ligament.

What is the structure of the laminar part of the nuchal ligament in the horse?

It is a fenestrated sheath that fills the space between the funicular part and the cervical vertebrae.

What are the attachments of the laminar part of the nuchal ligament in the horse?

It runs from the funicular part and the spines of T2 and T3 to attach to C2-C7.

What is the primary function of the nuchal ligament regarding the head?

It supports the weight of the head and relieves load when the head is held high.

Which joints does the nuchal ligament support in ungulates?

It supports the atlantoaxial and atlantooccipital joints.

How many total nuchal bursae are found in the horse?

There are three total, consisting of two cervical and one thoracic.

Where is the cranial (atlantal) nuchal bursa located?

It is located between the dorsal arch of the atlas (C1) and the nuchal ligament.

Where is the caudal nuchal bursa located in the horse?

It is located between the spinous process of the axis (C2) and the nuchal ligament.

Where is the supraspinous bursa located in the horse?

It is located over the prominent spinous process of the withers (T2, T3, or T4).

What is the clinical condition "poll evil"?

It is septic nuchal bursitis involving the infection of the cranial nuchal bursa.

What is the clinical condition "fistulous withers"?

It is septic supraspinous bursitis involving the infection of the supraspinous bursa.

Why is the isolation of Brucella spp. in bursitis cases a special consideration?

It is a zoonotic pathogen that can be transmitted to humans.

What is the foramen magnum?

It is the large opening into the cranial cavity through which the spinal cord continues as the brainstem.

What occurs to the meninges at the margin of the foramen magnum?

They split from the inner surface of the skull to form a free tube separated from the vertebral canal by the epidural space.

What are the two main portions of a typical vertebra?

The ventral body and the dorsal vertebral arch.

What two structures form the walls and roof of the vertebral foramen?

The two pedicles form the walls and the two laminae form the roof.

What is the transverse process of a vertebra?

It is a lateral extension of the vertebral arch.

What is the spinous process of a vertebra?

It is a dorsal projection of the vertebral arch.

Where is the mamillary process located on a vertebra?

It is located between the transverse and cranial articular processes of caudal thoracic and cranial lumbar vertebrae.

Where is the accessory process found if present?

It is found between the transverse and caudal articular processes.

How is the intervertebral foramen formed?

It is formed by the caudal and cranial notches of the pedicles of adjacent vertebrae.

What is the function of the intervertebral foramen?

It allows for the passage of spinal nerves.

What is the vertebral canal?

It is the space formed by all the vertebral foramen lined up, housing the spinal cord.

Which cervical vertebrae are considered unique and different from C3-C5?

The first two (C1, C2) and last two (C6, C7).

What is the name of the first cervical vertebra (C1)?

It is known as the Atlas.

Which joints are formed by the atlas articulating with the skull and the second vertebra?

The atlantooccipital joint and the atlantoaxial joint.

What are the primary structural peculiarities of the atlas?

It has winglike lateral expansions, lacks a spinous process, and has a reduced body.

What is the name of the second cervical vertebra (C2)?

It is known as the Axis.

What is the distinctive feature of the spinous process of the axis in the dog?

It has a vast, elongated dorsal spinous process that projects cranially like a blade or fin.

What is the "dens" or odontoid process?

It is a pointed, cranial projection of the dorsal aspect of the axis vertebral body.

Which cervical vertebra has the highest spinous process among C3-C6?

The sixth cervical vertebra.

Through what structure do the vertebral vessels and nerve pass in the cervical vertebrae?

They pass through the transverse foramen.

What distinguishes the seventh cervical vertebra (C7) from the others?

It has a taller spinous process, an unperforated transverse process, and facets for articulation with the first rib.

What is the clinical risk of giving IM injections too close to the vertebral column in the equine neck?

It can result in pain and neurological problems.

What is Cervical Vertebral Malformation (CVM) or "Wobbler syndrome"?

It is a condition characterized by stenosis of the cervical vertebral canal leading to neurological deficits.

What is the anticlinal vertebra in the dog?

It is typically the 11th thoracic vertebra where the spinous process orientation changes.

How are the spinous processes oriented relative to the anticlinal vertebra?

Processes cranial to it are inclined caudally, while those caudal to it are inclined cranially.

What is a distinctive surgical landmark of the first thoracic vertebra?

Its large dorsal spinous process.

What are common features of lumbar vertebrae?

They have greater length, uniform bodies, an absence of costal facets, and interlocking articular processes.

How many vertebrae are fused to form the sacrum in the dog?

Three vertebrae.

What is the median sacral crest?

It is a ridge on the dorsal surface of the sacrum representing the fusion of three spinous processes.

What is the "wing" of the sacrum?

It is the enlarged lateral part that articulates with the ilium.

What is the average number of caudal (coccygeal) vertebrae in the dog?

The average number is twenty.

What movement is permitted by the atlanto-occipital joint?

It causes extension and flexion, or nodding, in the sagittal plane.

What movement is permitted by the atlantoaxial joint?

It causes rotation about a longitudinal axis, or side-to-side movement.

What is the clinical significance of a ruptured atlantoaxial ligament?

It allows the axis to strike against the spinal cord, which may be fatal.

What are the two parts of an intervertebral disc?

The nucleus pulposus and the anulus fibrosus.

What is the function of the nucleus pulposus within the fibrous ring?

It absorbs shock and spreads compressive forces over a wider part of the vertebrae.

What is the result of calcification of the nucleus pulposus?

It diminishes the normal resilience and flexibility of the spine.

In which regions is degenerative disc disease most severe in large animals?

The neck and the lumbosacral region.

What is a dorsal laminectomy?

It is a surgical procedure where the dorsal spinous process and lamina are removed to relieve pressure on the spinal cord.

What are the three continuous membranes (meninges) surrounding the spinal cord?

The dura mater, arachnoid, and pia mater.

Where is the epidural space located?

It is between the wall of the vertebral canal and the dural tube.

What occupies the epidural space?

It is occupied by fat and the internal venous vertebral plexus.

What structure separates the dura mater from the arachnoid?

The subdural space.

What is the function of the denticulate ligaments?

They attach the inner meninges to the dural tube to indirectly sling the spinal cord.

Which of the meninges is the innermost and directly attached to the brain and spinal cord?

The pia mater.

What is the cerebellomedullary cistern?

It is a dorsal widening of the subarachnoid space between the cerebellum and the medulla.

What is the most common site for collecting cerebrospinal fluid in dogs and cats?

The atlanto-occipital space (cerebellomedullary cistern).