Vertebral Column

Vertebral formula, vertebral column, vertebrae, anticlinal vertebrae, ligaments, articulations, spinal cord, cervical vertebrae, thoracic vertebrae, muscles, ribs, sternum

Vertebral formula: dog/cat

C7, T13, L7, S3, Cd (varible)

Vertebral formula: horses

C7, T18, L6(5), S5, Cd 15-21

Vertebral formula: ox

C7, T13, L6, S5, Cd 18-20

Vertebral canal

The passageway for the spinal cord collectively formed by all of the vertebral foramina

Atlas & Axis

Atlas = C1
Axis = C2

Atlanto-occipital jt

skull → C1

A: ventral flexion & extension (yes (knod) movement)

Atlanto-axial jt

C1 → C2

A: rotaion (no (turn) movement)

Intervertebral foramina

formed by cranial & caudal vertebral notches of neighboring vertebrae

Vertebral body

All vertebrae except the atlas (C1) possess a more-or-less cylindrical vertebral body. The bodies articulate with one another at specialized fibrocartilaginous joints called intervertebral disks.

Vertebral arch: Pedicles

The flattened, dorsal part of the arch consists of right and left laminae; these are attached via pedicles to the body.

Vertebral arch: Laminae

The flattened, dorsal part of the arch consists of right and left laminae; these are attached via pedicles to the body

Vertebral foramen

Large passageway for the spinal cord seen in each vertebra

Vertebral notches (cranial & caudal)

The caudal vertebral notch of one vertebra aligns with the cranial vertebral notch of the next (caudal) vertebra, together creating an intervertebral foramen through which a spinal nerve will pass.

Transverse foramina (C1-C6)

cranial→caudal direction (green)

passageways for vertebral aa. & vertebral nn.

Lateral vertebral foramina of C1 (only in C1)

medial → lateral direction (blue)

passageways for 1st cervical spinal nn.

Spinous process

Projects dorsally from arch

Transverse process

project laterally from arch

Articular process (cranial & caudal)

form synovial ht in b/w cranial & caudal

Anticlinal vertebrae: dog/cat

T:11

Anticlinal vertebrae: horse

T16

Anticlinal vertebrae: ox

T13

Sacral vertebrae

fused into 1 bone = sacrum

pelvic & dorsal sacral foramina transmit sacral spinal nn. rather than intervertebral foramina

Caudal (coccygeal, Cd) vertebrae

vertebrae of the tail, variable in number

Nuchal ligament (ungulates: laminar & funicular parts)

elastic ligament on dorsal midline of the neck

A: provides passive support for the head against gravity

canine: spinous process of T1-C2 or skull in large animal

Nuchal ligament: Eq/Bov

funicular part = rope/cable shaped; dorsal

laminar part = flat, wide sheet; ventral

Supraspinous ligament

T1 → 3rd caudal vertebra

Interspinous ligament

tissue intersped with bundles of the interspinalis muscle

Dorsal longitudinal ligament

Ventral longitudinal ligament

Ligamenta flava (yellow ligament)

elastic sheets filling the interacuate spaces b/w arches of adjacent vertebrae

Articulations: caudal & cranial articular processes

Synovial jt

Articulations: intervertebral discs

Annulus fibrosus & nucleus pulposus = fibrocartilaginous jt

Articulations: sacroilliac jt

Synovial jt

Epidural space

b/w dura & vertebrae (Real space, fat & veins, epidurals are given here)

Spinal nerves

Dorsal root ganglion

Dura mater

Subdural space

b/w dura & arachnoid (potential space)

Arachnoid mater

Subarachnoid space

arachnoid & pia (real space, cerebrospinal fluid here) (lumbar cistern)

Pia mater: denticulate ligament

lateraly anchor spinal cord

Pia mater: filum terminale

caudally anchors S. C.

Conus medullaris

caudal end of spinal cord

Lumbar Cistern (purple)

Lumbar cistern space: holds cerebrospinal fluid (CSF), where spinal taps occur

Cauda equina (green)

Spinal nerve root & CUDal to conus mendullaris

8th cervical spinal nn.

emerging from the intervertebral foramina b/w C7 & T1

1st cervical spinal nn.

passing through the lateral vertebral foramina of the atlas (C1)

Epaxial vs. Hypaxial mm.

Epaxial muscle systems

I Love Taco’S

Transversopinalis mm.

Longissimus mm.

iliocostalis mm.

Transversopinalis mm.

most dorsal group

short muscles spanning b/w neighboring vertebrae

included splenius m.

Longissimus mm.

middle group

wing of ilium → skull

iliocostalis mm.

most ventral group

wing of illum → ribs

Epaxial muscle actions

extension of vertebral column (Bilateral contraction & lateral flexion (unilateral contraction)

Serratus ventralis m.

possible Epaxial or Hypaxial mm. because location-wise epaxial but unknown. Just in the muscle section of the long list with the Epaxial & Hypaxial mm.

Epaxial vs. Hypacial muscle innervations

Epaxial mm. - dorsal rami of spinal nerves

hypaxial mm. - ventral rami of spinal nerves

Hypacial mm.

Scalenus m.

Sternothyroideus m.

Sternohyoideus m.

Scalenus m.

Sternothyroideus m.

Sternohyoideus m.

Spinal cord functions

1. sensory input & Processor to brain & different spinal cord regions

2. motor outflow & processor

3. relexes

Spinal cord functions: sensory input & Processor to brain & different spinal cord regions

Brain: brainstem, cerebellum, cerebrum

Different spinal cord regions: ipsilateral vs. contralateral & Cervical, thoracic, lumbar, sacral, caudal

Spinal cord functions: motor outflow & processor

lower motor neurons (LMNs): “final common pathway” & receive input from - UMNs (brain) & interneurons

Spinal cord functions: reflexes

A stereotyped motor event driven by a sensory stimulus & local circuit - can operate without consciousness (without UMN from brain)

reflex arc = 1. receptor 2. afferent neuron (sensory) 3. interneuron 4. efferent neuron (motor) 5. target (muscles/glands)

Spinal cord: root vs. rami (branches)

spinal cord: external anatomy

2 spinal cord enlargements: 1. cervical enlargement - throacic limbs 2. Lumbosacral enlargement - pelvic limbs & some Autonomatic for Urogenital fxn

Why? more muscles & skin in those regions & they need more neurons to innervate them

Spinal cord vs. Vertebrae

differential growth rates: spinal cord stops growing but vertebral column keeps growing

Spinal cord: internal anatomy

white matter & gray matter

White matter

Neuron axons (myelinated)

Gray matter

neuron cell bodies

Meninges

Connective tissue members surrounding spinal cord (NOT nervous tissue)

Support & Protect CNS
Suspend CNS
3 layers: 1. dura mater (outermost layer) 1. Arachnoid (middle later) 3. pia mater (innermost layer)

Spinal cord injuries

spinal cord/nerves

Spinal cord injuries

flaccid paralysis: at region supplied by damaged LMN

loss of sensations from body caudal to injury

no effect above injury