W1L2: Vertebral Column

Canine (dog) vertebral formula

C7 T13 L7 S3 Cd20

Equine (horse) vertebral formula

C7 T18 L6 S5 Cd (about 20)

Bovine (ox) vertebral formula

C7 T13 L6 S5 Cd18

Porcine (pig) vertebral formula

C7 T14-15 L6 S4 Cd20-23

Epaxial muscles: Location & Innervation

Dorsal to transverse processes; innervated by dorsal branches of spinal nerves.

Hypaxial muscles: Location & Innervation

Ventral to transverse processes; innervated by ventral branches of spinal nerves.

Three epaxial muscle systems

Iliocostalis (lateral), Longissimus (intermediate), and Transversospinalis (medial).

Iliocostalis system: Location & Action

Most lateral epaxial system; produces lateral flexion of the trunk.

Longissimus system: Action

Extends the back and assists in expiration.

Transversospinalis system: Action

Stabilizes thoracic region and elevates head and neck.

Interarcuate ligament: Clinical relevance

Located between vertebral arches; affected in degenerative lumbosacral stenosis (DLSS).

Intercapital ligament: Location & Function

Connects heads of adjacent thoracic ribs (T2-T11); stabilizes intervertebral discs.

Dorsal longitudinal ligament: Location

Runs along the floor of the vertebral canal from axis to sacrum.

Ventral longitudinal ligament: Location

Runs along the ventral surfaces of vertebral bodies from axis to sacrum.

Nuchal ligament: Dog vs Cat

Extends T1 to axis in dogs; completely absent in cats.

Nuchal ligament: Horse & Ox parts

Consists of paired funicular (cord-like) and laminar (fenestrated sheet) parts.

Poll evil

Septic bursitis of the cranial (atlantal) nuchal bursa.

Fistulous withers

Septic bursitis of the supraspinous bursa in horses.

Zoonotic organism associated with septic bursitis

Brucella spp.

Vertebral arch structure

Consists of two pedicles (walls) and two laminae (roof).

Intervertebral foramen: Function

Opening formed by adjacent pedicle notches allowing passage of spinal nerves.

Atlas (C1): Distinct features

Lacks a spinous process and body; features wide lateral wings.

Axis (C2): Distinct feature

Possesses a large elongated spinous process and the dens (odontoid process).

C6 vertebra: Peculiarity

Has expanded, flap-like ventrolaterally projected transverse processes.

Intervertebral disc absence in neck

Absent between C1 (atlas) and C2 (axis).

Wobbler syndrome (CVM)

Narrowing of cervical vertebral canal causing spinal cord compression in horses/dogs.

Anticlinal vertebra: Definition

Vertebra where spinous processes transition from caudal inclination to cranial inclination.

Anticlinal vertebra locations by species

Dog: T11; Horse: T16; Ox: T11-T13.

Sacrum composition

Formed by fusion of three sacral vertebrae in dogs.

Hemal arches / Chevron bones

Ventral structures on cranial caudal vertebrae protecting the main tail artery.

Atlanto-occipital joint: Movement

Allows flexion and extension in the sagittal plane (nodding 'yes').

Atlanto-axial joint: Movement

Allows rotation around the longitudinal axis (shaking head 'no').

Intervertebral disc: Key components

Inner gel-like nucleus pulposus and outer fibrous annulus fibrosus.

Dorsal laminectomy procedure

Surgical removal of dorsal spinous process and lamina to relieve cord pressure.

Spinal meninges (outer to inner)

Dura mater, arachnoid mater, pia mater.

Epidural space: Location

Between the dural tube and the inner periosteum of the vertebral canal.

Subarachnoid space: Content

Located between arachnoid and pia mater; contains cerebrospinal fluid (CSF).

Cerebellomedullary cistern: Location

Widening of subarachnoid space between cerebellum and medulla (atlanto-occipital space).

Primary CSF collection site in dogs/cats

Atlanto-occipital space (cerebellomedullary cistern).

Lumbar CSF collection site

Lumbosacral space (commonly L5-L6).