CNS

Seite 1

CNS overview and gross anatomy

CNS vs PNS

Cluster/aggregate of neuronal cell bodies

CNS- nucleus

PNS- ganglion

Bundle of axons

CNS- tract

PNS- nerve

Revisit intro to NS

Brain

Surface anatomy + basic function

Cerebrum

Underlying deep nuclei

Basal ganglia control initiation of movement

Limbic system establish memory + emotional aspects of experience

Ofactory bulb

Involved in smell

Cerebellum

Folded

Involved in balance, co-ordination and the refinement of movement

Brain stem ?

Cerebral cortex

Cerebral hemisphere

Symetrical mainly

In humans LHS diff due to speech

Gyrus(p)

Gyri (s)

Elevated ridges

Sulcus

Sulci (s)

Shallow grooves

Medial Longitudinal fissure

Deep sulcus between hemispheres

Cruciate sulcus

Bisects medial longitudinal fissure

Separates the primary motor cortex from primary sensory cortex

Rabbit brain

No folded cortex

Relationship between folding and intelligence ?

Not fully accepted

Olfactory bulb

Receive input from olfactory nerves

Olfactory peduncle

Optic tract?

Hypothalamus

2 mammillary bodies

Brain stem

Optic and Olfactory nerves DONT come from brain stem

Others DO

Midbrain

Visual function

Pons (Bridge)

Allows communication between spheres of cerebellum

Medulla oblongata

Where lots of cranial nerves come from

Trapezoid body

To do with hearing

Periform lobe

Processing smell

Species variation in relative sizes + Cortical folding

Size depends on relative importance of each structure to that species

Degree of cortical folding

Intelligence

Constraints of brain expression within constrained space during development

SA increased

Corpus callosum

Giant bundle of axons that joins two hemispheres

Allows communication

Thalamus

Sensory processing

All sensory info eventually finds its way to thalamus

Relays info

Tectum

Part of midbrain

V developed in birds

Ventricle System

Shock absorber

Nutrient provision?

??

Fourth ventricle

Clinical importance

Frontal lobe

Rostral to cruciate sulcus

Sylvian gyrus is another useful

Parietal Lobe

Occipital lobe

Temporal lobe

Landmarks

Lesions in any of these areas there will be corresponding defects

Species variation in relative size of cortical areas

Association cortex dominates in humans

Primary cortical areas represent relatively larger proportions in other mammalian brains

Rat - V large olfactory cortex, more reliance on smell

Man - V smal olfactory cortes , less reliance on smell. Larger association cortex

Stimulation of association cortex gives unpredictable response

Highly folded

Folds narrower than cerebral cortex

Single fold = folium

Arbor vitae = white matter

Axons leaving cerebellum found here

Peduncles

3 attach cerebellum to brain stem

Rostral

Caudal

Cerebral

Colliculi

Rostral and caudal?

???

Deep Anatomy

Brain - subcortical structures

Integrative systems

?

Spinal cord

Grey matter

Neuronal cell bodies

Some unmyelinated axons

Split into horns

Dorsal horn receives somatic and visceral sensory neurones

Cell bodies reside in dorsal root ganglion

Lateral horn contains the cell bodies of preganglionic autonomic motor neurones

Ventral horn is the site of cell bodies of somatic motor neurones

White matter

Myelinated axons

Split into funiculi which are separated by motor + sensory roots

Funiculi - bundles of axonal fibres which project rostrally or caudally

Lateral = mixed

Dorsal = sensory

Ventral = motor

Spinal nerve

Dorsal median sulcus

Ventral median fissure

Sensory and motor sections as found in spinal cord

Cell bodies of neurons in the motor cranial nerves lie within brain stem in nuclei

Cell bodies of neurons within sensory cranial nerves within ganglia outside the brainstem

Cranial nerves innervate the head and neck

Grey and shite matter also found in brain

White matter on outside and inside

White matter on inside

Basal ganglia is grey matter

Movement

Caudate nucleus

?

Putamen and globules pallidus

Movement disorders in humans associated

Amygdala

To do with behaviour

Deep structures can be observed from different aspects

Deep cerebral nuclei

Produce movement disorders when damaged

Seite 2

CNS embryology

3 layers of the embryo

Ectoderm

NS develops from here (Neuro-ectoderm)

Mesoderm

Endoderm

Neural tube formation

Neural plate forms from the ectoderm

Neural groove forms

Groove deepens and dorsal lips fuse forming neural tube

Proliferation of superficial ectoderm gives rise to the neural CREST

Neural tube pinched off from surface

Neural tube = CNS

Superficial ectoderm = PNS

Notochord = cylinder of mesodermal cells

Responsible for inducing formation of neural plate through secretion of chemical signals

Stimulate there mesodermal cells to develop into vertebral bodies + intervertebral disc

Spina Bifida

Occurs when caudal neuro-pore fails to fuse

Impossible for vertebral arches to form + fuse normally above spinal cord

Not always serious

Manx cats

Bulldogs

Damage to underlying neural tissue can cause serious problems

Incontinence

Paralysation of hind legs

Maturation of spinal cord

Initially 3 layers of neural tube

Ventricular zone

Mantle layer

Marginal layer

Neurones and support cells made in ventricular zone

Then they migrate into mantle layer

Mantle layer forms grey matter

Myelinated axons lie in marginal layer

Sulcus limitans divides spinal cord into alar + basal plates

Alar plate forms dorsal horns of grey matter

Basal plate forms ventral horns of grey matter

Control of neural cell differentiation

Cells within neural tube secrete signalling factors that affect neighbouring cells

Somites responsible for development of skin , muscle and connective tissue?

Roof plate secretes bone morphogenetic proteins BMPs

Floor plate and notochord release Sonic hedgehog SHH

Floor and roof plates involved in partition of spinal cord into sensory and motor regions

Development of brain regions and ventricles

Subdivision occurs

Prosencephalon (forebrain)

Telencephalon

Forms the cerebral hemispheres

Diencephalon

Optic cups grow outwards

Forms thalamus and hypothalamus

Mesencephalon (midbrain) no division

Rhombencephalon (hindbrain)

Metencephalon

Forms pons

Forms cerebellum

Myelencephalon

Mature medulla oblongata

Mature brainstem formed from rhombencephalon and mesencephalon

Cylopia

Embryonic prosencephalon fails to subdivide properly

Division of the orbits of the eyes into separate cavities also fails

Malformed face

Nose either missing or malformed and non functioning

Due to faulty genes or intake of plant toxins

Corn lily

Failure of developing cells to respond to SHH

1/16000 born animals

1/250 embryos

Most spontaneously aborted

Development of the brain

slides?

7 wks

Folding occurs

Subdivision also occurs

11wks

Cerebral hemisphere enlarged

Subdivision ?

At birth

Cerebral hemispheres and cerebellum v folded

Dicenp

Thalamus

Hypothalamus

Brainstem

??

Embryonic brain flexures

Expansion greater than cranial capacity

Initially 2 bends

Cephalic (Between mid brain and hind brain )

Cervical (Occurs at top of spinal cord)

3rd later in development = pontine

Cervical flexure less pronounced in quadrupeds than bipedals

image?

Spinal cord vs brainstem development

Lumen of neural tube expands to form cerebral ventricular system

Ventricles of brain are continuous with the central canal of the spinal cord

I wasn't listening - slide

Not a clue

Seite 3

Blood supply meninges + CSF

Meninges

Membranes = meninges

3 layers

Physical protection of brain + spinal cord

Facilitate flow of CSF

Provide a framework for blood vessels to supply CNS tissues

Outside layer - Duramater?

Two indistinguishable layers within the skull

Outer=endosteal

Inner=meningeal

Separated to form two folds which course into fissures between brain tissue

Falx cerebri (between hemispheres)

Tentorium cerebelli (between cerebral and cerebellum)

Contain venous sinuses

Pain sensitive

Own blood supply

Arachnoid

Potential space between this layer and duramater

Avascular

Space underneath - subarachnoid space

Blood vessels here

?

Piamater ?

V thin

Tightly adherent to tissue

Highly vascular

Bring blood vessels to Brain tissue

Dura separates from endosperm within vertebral canal creating the epidural space

Denticulate ligaments ?

Cuff zones

??

Meninges follow nerves up to a point then blend into perinuerium

This is the cuff zone

Clinical relevance

Cerebrospinal fluid

Communicates with ISF of neural tissue freely

Cell-free, protein-free, low amino-acid content, low and stable K+ content and relatively low glucose content

Must be kept stable

Provides nutrition

Shock absorber

Acts as a volume buffer

Accommodates some swelling

Facilitates flow of neurotransmitters

Circulates through subarachnoid space, ventricles of brain and central spinal canal

Ventricles and central canal lined by ependymal cells which possess cilia

Communication through inter ventricular foramen

Image? Stream?

CSF production and drainage

Choroid plexi ?? stream? all this slide?

Choroid plexi main source of CSF

Small amount from ultra filtrate of pill blood

CSF

Blood:brain barrier maintains CSF in a steady state

BBB prevents changes in blood affecting CSF

Tight junctions between endothelial cells

Thick BM

Astrocytes

Transporting ependymal cells covering plexi pump solutes into the CSF to draw water in by osmosis

Lipid soluble substances readily across into CSF

Drugs must be lipid soluble

Abnormal BBB means some drugs could enter - CARE

Water soluble materials must be actively transported into CSF

Drugs vary in their ability to pass into the CSF and the permeability of the BB varies in different disease processes

CSF sampling

Sub arachnoid space

Cerebellomedullary system

Lumbar system

V sterile

CARE - negative pressure cause problems

Death

Arterial supply

Cerebral arterial circle

Located at ventral part of brain

5 arteries come off this?

Image

Dog input from Basilar and internal carotid arteries

Source to circle differs between species but derived from combination

Internal carotid

Basilar artery

Maxillary artery

Vertebral artery

Source matters in terms of slaughter techniques- Halal, Shechitah

Position of animal during slaughter has effect

Either directly supplies circle or does so via rate mirabile

Slows blood down , loses some of pulse pressure

Cools blood down

Dog and horse - blood from internal carotid and and basilar arteries

Sheep and cat - blood mainly from maxillary artery via rete mirabile

Ox- blood from maxillary artery + vertebral artery via rete mirabile

Functional end arteries

There are a few inter-arterial anastomoses + little collateral circulation in the CS?

Spinal cord blood supply

Branches of vertebral artery and aorta??

Venous drainage of the brain

Blood filled spaces that receive venous blood of vein

Flow very slow

Vulnerable to bugs

2 dorsal sinuses

Straight

Dorsal sagittal sinus

Ventral sinuses

Cavernous sinus

Most rostral

V vunerable for infection

Drains nasal cavity and orbit

Petrosal sinuses

Dorsal drains to transverse

Ventral drains to basilar sinus

Basilar sinus

Transverse sinus

Confluence of sinuses

Drains whats left?

Systemic circulation in vertebral canal?

Venous drainage of the spinal cord

Drain out through signal vertebral veins

Azygous ein

Vertebral vein

Caudal +Cranial vena cava

Seite 4

Eye anatomy and vision

Structure of Mammalian Eye

Something to do with nerves? stream

Layers of the Eyeball

3 tunics

Retina = inner

Vascular (urea) = middle

Fibrous = outer

Development of brain regions

Nervous layer of retina

Light-sensitive layer (innermost layer)

Photoreceptor cells (Neuroepithelial cells)

Outer segments made up of disks which form ...

Rods

Cones

Bipolar neurons

Ganglion cells

Development of Eye

Represents a section through the developing brain as seen from above

Neural tube region containing the retinas starts to grow back towards the surface of the head , forming optic cups

Optic cups contain photoreceptor cells

Note how retinas end up back to front , cilia of neuroepithelial cells are at the back of the cup

Optic cup

Represents a section through the optic cup as seen from above

Narrowing forms optic stalk

Layers? Stream

Lateral indentation has now deepened

Cup also indents ventrally to form the choroid fissure

Axons of retinal ganglion cells form the optic nerve which . along with blood vessels supplying retina- becomes entirely enclosed when the lips of the choroid fissure

??YES stream

Failure of choroid fissure to fuse can lead to haemorrhage and blindness

Pigment layer of retina

Outerlayer

Epithelial cells

Inner layer

3 layers including light sensitive cells

Fovea? stream

Optic disc -

Where optic nerves leave eye

No photoreceptors

Blind spot

Rods ???

Low light condition

Night

Black and white

Cones

Bright light

Day

Colour

Fact file

Cats + Dogs 95% rods +5% cones

Light and shade but not much colour

Optic nerve may be as many as a million axons

More in both optic nerves than ALL dorsal roots of spinal cord

Stream?

Histological layers of the retina

Number of cells in each layer increases the further back you go?

Progressive retinal degeneration or atrophy

Image?

Greater visual sharpness cones? stream

Retina viewed through the pupil

Opthalamoscope

Fovea

Straight behind lens

High density of cones

Optimal visual axis (no blood vessels)

Blind spot

Where ganglion cell axons leave retina

No sensory cells

?stream

Progressive retinal atrophy

Caused by loss of Rods and Cones

Loss of rods - Night blindness

Incl

Irish (red) setter

Abyssinian + Siamese cats

Blood vessels progressively atrophy leading to blindness

Pupils dilate to compensate

Appear able to see in day but bump Inyo things at night

Vascular layer

Choroid

Heavily supplied by blood vessels

Made up of collagen

Heavily pigmented - absorbs stray light

Iris

Continuous with ciliary body

Ciliary body ? stream?

Smooth muscle

Once optic nerve leaves eye it becomes myelinated

More nerves in optic nerves than all of PNS

Image?stream?

Optic Neuritis

Optic disc appears fuzzy

Inflammation of optic nerve

Oedema

Gives animal blurred vision

Tapetum Lucidum

Cells containing crystals lie between pigment layer of retina and choroid

Cells have no pigment - crystals instead

??stream

Triangular area of greenish-yellow, light reflecting , iridescent cells usuallydorsal to point where optic nerve leaves eye

Vitreous chamber

Contains vitreous humor

Maintains shape of eye

Holds retina back against the eye

Detached retina

Nervous portion of retina detaches from pigmented layer

Optic disc ALWAYS remains attached

Deprived of O2 and nutrients supplied by choroid

Without interventions = death

Causes

Blow to head

Bleeding in eye wall

Damage to vitreous humor

Sclera

Supporting

Continuous with cornea

Made of collagen

Thick layers running in many different directions

Ora serrata

Where photoreceptors finish

Lens

Sits behind pupil and iris

Image formation

Three processes involved

Refraction of light

Accommodation of lens

Constriction of pupil

Most refraction occurs at cornea and lens

Images focused in retina are inverted

Brain learns early in life to co-ordinate images with orientations of objects + corrects this

Accommodation

Distance vision

Relaxed ciliary body relaxed

Lens fibres taut

Lens flat

Close vision

Ciliary body contracted

Fibres slack

Spherical lens

Posterior chamber

Where?

Anterior chamber

Where?

Cataract

Lens becomes cloudy due to age, genetics or diabetes

Can be accompanied by lens luxation

Treatment = irreversible unless cataract removed but animal then has distance vision only. This can be restored by replacement with prosthetic lens

Diabetic cataracts

?

Drainage of aqueous humor

Humor formed by filtration of blood plasma by the ciliary processes

Fluid leaks through pupil from posterior chamber into anterior chamber

Fluid returns to circulatory system via venous plexus at transition between cornea + sclera

Stream this?

Proper notes needed from here on

Glaucoma

Raised intraocular pressure

Aqueous humour drainage blocked at limbus but production continues

Extreme pain

Blindness

Indirect causes

Pressure impedes circulation in ye , killing retinal cells and may compress and damage optic nerve

Treatment

Via eye drops

Drugs diffuse into eye, red humor secretion or improve drainage

In cats??

Cell types in cornea

Layers of collagen

Stratified simple epithelium ? on top

Healing v slow if wound deep into badly vascularised cornea

However cornea v innervated -- why things are v painful if they get in eye

stream?

Vascularisation + Keratinisation of the cornea

Keratoconjunctivitis sicca (dry eye)

Cornea starts to dry and becomes opaque

Autoimmune disease causing failure of tear production

Treatment: Artificial tears

?

Corneal ulceration

Deep wound into cornea

Treatment -

Bringing in blood supply

3rd eyelid over

Cornea transplant

Doesn't bring about immune reaction as no blood supply

Conjunctivitis

Inflammation of conjunctival membranes: sometimes discharge

Many causes:

Vrial and bacterial infection

Disorders of tear production

Exposure to foreign material

Allergy

Treatment

Tear drops

Ointment

Visual pathways + reflexes

Stream?

Cross at optic chasm

Stream?

Left visual field processed by right visual cortex

Right visual fields processed by left visual cortex

what

More fibres that cross over - better depth vision they have

Some axons?

Visual field

Horizontal field of vision

Carnivore eyes = frontal position = restricted monocular lateral field and large central binocular area

Herbivore eyes = lateral position = wide monocular lateral field and narrow binocular area

Pupillary light reflex

2 sets of Smooth muscle

Circular

Inner layer

Constricts pupil

Radial

Outer layer

Dilates pupil

Nerves supplying these muscles

Rostral

Some sympathetic

Healthy animal

BOTH pupils should constrict when light shone in eyes

If not something along visual pathway is wrong

Eyeball Positioning + strabismus

Work out from eye positioning where problem is in brain stem?

stream?

Which cranial nerves are problem?

Seite 5

Spinal cord and segments

Protective structures

Vertebral column

Meninges

Connective tissue (covers spinal nerves)

Foramen Magnum

Large hole at base of skull through which spinal cord passes

Spinal nerves emerge from vertebral foramina

Stream?

Autonomic nerves branch of into sympathetic chain

Transverse section through spinal cord

stream?

External Anatomy

Intumescences

Enlarged areas

More nuerones supplying area

Conus medullary

Caudal tapering

Cauda equina

Lumbar cistern

Spinal nerves

?

Number of pairs of nerves in each region varies with species

Anatomical + Functional region of canine spinal cord

Stream?

Spinal cord + Initial sections of spinal nerves in a mammal

Spinal column is longer than spinal cord itself

Spinal nerves angled downwards

This forms the cauda equina

Thoracic level = Epidural space filled with fat

Clinical relevance = site for injection of anaesthetic

Lumbar level = Lumbar cistern

Good place for sampling CSF

??STREAM?

Internal anatomy

?

Spinal cord segment

Each segment gives rise to one spinal nerve on each side, innervating muscles in that body segment

The number of segments = number of spinal nerves

Stream?

Motor axons exit via ventral root?

Transverse Sections of spinal cordite different levels

Images

Intumesenses?

Larger diameter at lumbar and cervical region

Stream?

Spinal Nerves

Branches = rami

Networks = plexuses

Brachial plexus supplies forelimbs

Lumbosacral plexus supplies hindlimb

Spinal nerve plexus

? stream

Dorsal and ventral branches??

Anatomical + Functional spinal cord regions + Main nerve plexi

Plexuses are generally to obvious or important except for ventral ones which form enlargements opposite the origins of the limbs = brachial + lumbosacral plexuses. These give rise to nerves distributed to forelimb and hindlimb structures respectively

Innervation of thoracic + pelvic limbs

Occurs from intumescences via plexi

Cranial part of the intumescence + plexus supplies the cranial and proximal muscles of the limb

Caudal part of the intumescence supplies the caudal and distal muscles of the limb

Clinical relevance

Injection sites for anaesthetic

Loss of feeling - where problem is

SEE adendum

Distribution of dermatomes in the dog

Regions of skin supplied by sensory parts of the skin

Clinical importance?

Spinal cord physiology

Sensory + motor pathways

Definition / concept

Nomenclature (origin and destination)

Ascending = sensory

Descending = motor

Locations pf major tracts

Sensory + Motor nerve tracts

Sensory nerve tracts from skin and musculoskeletal system to cerebral cortex

3 sets of neurones

Dorsal column

Spinothalamic tract

Motor nerve tracts from cerebral cortex to skeletal muscles

Stream??

Spinal cord segment: Regions

Stream ?

Locations of major sensory + motor tracts

?

Seite 6

Development of the head

Intro

12 pairs of cranial nerves

Numbered as well having a name according to either function, anatomical characteristics and distribution

Clinically important to know functional anatomy

Development

In trunk cavitation of mesoderm results in splanchnic and somatic lateral plate mesoderm enclosing a coelomic cavity

In head cavitation doesn't occur

Lateral plate mesoderm remains as solid belt of tissue surrounding gut tube

Intermediate mesoderm fails to develop

Segmental Head

Adult trunk is clearly segmental

Head appears not to be but embryonically it was once

Seven segments

Ectoderm

Somites

Endoderm

Lateral plate mesoderm

Segmental arteries

Neuraxis

Nerves

Ectoderm

Form outer epithelial covering

Function of somatic sensation

Innervated by somatic afferents

Segments marked externally by lateral indentations (pharyngeal cleft)

1st segment exception

Equivalent to gill slits in fish

Deeply invaginated into segments 1 + 2

Forming stomodeum

Consequently 1+2 don't have ectoderm

Oral plate is thin plate tissue where stomodeal ectoderm meets pharyngeal endoderm

Lies at boundary between 2+3

Endoderm

Forms inner epithelial covering

Sensation supplied via autonomic afferents (visceral afferents)

Motor (sympathetic/parasympathetic) supplied via autonomic efferents

Cephalic part of fore-gut becomes pharynx

Flattened dorso-ventrally

Marked off into 6 divisions by 6 internal gill slits

In mammals theses are pharyngeal pouches

In fish these perforate into external gills slits

In mammals no perforation occurs

Lateral plate mesoderm

Belt of striated skeletal muscle which surrounds pharynx of all segments except 1

Each belt forms a donut

Separated from each other by pharyngeal cleft and pharyngeal pouch

Each belt known as pharyngeal arch

Forms special visceral muscle of the gut tube

Innervated by special visceral efferents

Also forms skeletal elements

Somites

Each segment has a pair of somites

Form striated muscle of eyeball + tongue

Innervated by somatic efferents

Segmental arteries

All but 1st segment have a pair of segmental arteries

Forms 6 pairs of aortic arches

Embedded in lateral plate mesoderm

Innervated by autonomic afferents /efferents

Neuraxis

Differentiated into brain

Each segment of neurosis referred to as a neuromere

Obliteration and migration

Obliteration

Somites 4 + 5 +associated nerves

Pharyngeal arch 5

Arterial arches 1+2

Pharyngeal clefts/ pouches 5+6

Ectoderm of segments 6+7

Fails to develop further

Endoderm of arch 2

Ectoderm of segments 3-5

Migration

Somites 6+7

Oral + nasal cavity

Vertical dotted line is boundary between ectoderm and endoderm

Paired nasal pits form

Right and left separated by septum

Nasal cavity breaks through into primitive oral cavity

Palatine process grows

Soft palate endodermal

If lateral palatine folds fail to develop= cleft palate

Tongue

Epithelium

Front of tongue = ectoderm of arch 1

Back of tongue = endoderm of arch 3

Muscle

Migration of paired somites 6+7

Pituitary + Thyroid glands

Pituitary gland

Anterior + intermediate lobes arise as diverticulum of ectoderm from arch 1

Posterior develops from brain stem

Thyroid gland

Arises as diverticulum of endoderm from arch 2

Thyroglossal duct is remnant of this

Larynx, Trachea + Lungs

Depression in floor of arches 4+6 forms laryngo-tracheal groove

Trachea + lungs develop from this

Epithelial linings = endodermal

Pharyngeal pouches + Clefts

Cleft 1 = external ear

Boundary = ear drum

Pouch 1= middle ear cavity / Eustachian tube

Clefts 2-4 disappear

Pouch 2 = palatine tonsil

Pouch 3 = parathyroid + thymus

Pouch 4 = parathyroid, thymus ultimobranchial body

Ectoderm

1 = skin of top of head

2 = the rest of skin of head

3,4 +5 = small area of skin in external ear

6+7 fail to develop

Somites

1-3 = extrinsic muscles of eye

1 = all rectus muscles (except lateral rectus) + ventral oblique

2= dorsal oblique

3 = lateral rectus + retractor oculi

4-5 disappear

6-7 = muscles of tongue

Intrinsic = tongue itself

Extrinsic attach tongue to other structures

Lateral plate mesoderm

Arch 1 = chewing muscles / malleus+ incus

Arch 2 = facial muscles / stapes + hyoid

Arch 3 = stylopharyngess muscle/ hyoid

Arch 4 = pharyngeal muscles + cricothyroid muscle/ laryngeal cartilages

Arch 5 disappears

Arch 6 = laryngeal muscles/ laryngeal cartilages

Aortic arches

1+2 disappear

3 = internal carotid, carotid sinus + body

4

Right = right subclavian

Left = aortic arch, aortic baroreceptor site + aortic bodies

5 disappears

6 = pulmonary trunk + ductus arterioles on left side

Each segment has a pair of cranial nerves

Each structure of the head requires a nerve supply

Seite 7

Cranial nerves

Segmental trunk nerves

Somatic nervous system under voluntary control

1 = afferent sensory

2-3 = inter neuron

4 = efferent motor

Primary afferent cell bodies in dorsal root ganglion

Dorsal and ventral roots fuse to form single spinal nerve carrying all 4 nerve types

Autonomic nervous system under involuntary control

1= afferent sensory

2 = inter-neuron

3 = pre-ganglionic efferent

4 = post-ganglionic efferent

Has additional ganglion where pre- and post-ganglionics synapse

Segmental head nerves

Similar of runs EXCEPT

Autonomic efferent neurons leave via dorsal root

Dorsal and ventral roots do NOT unite

Head as 5 th neuronal component

Striated muscle arising from somites supplied by somatic efferents as in trunk

Striated muscle arising from lateral plate mesoderm supplied by SPECIAL VISCERAL EFFERENTS leaving via dorsal root

Summary

Segment 1 has no pharyngeal arch therefore it borrows its dorsal root nerve from segment 2 = ophthalmic branch of V

Due to development of mouth dorsal root nerve of segment 2 splits into 2 major branches

Segments 4 + 5 lose their somites so don't have a ventral root nerve

Segment 6 loses its pharyngeal arch so doesn't have a dorsal root nerve

Segments 6+7 somites unite to form tongue muscles, so does their ventral root nerve

Segments 5+7 share dorsal root nerve

Cranial nerves

Special sense nerves

CN I - Olfactory nerve

Olfaction/smell

CN II - Optic nerve

Vision /sight

CN VII - Vestibulo-cochlear nerve

Balance + hearing

The other cranial nerves

Each segment should have a dorsal and a ventral root

Dorsal roots innervate all structures

Contain SA, AA, AE + SVE neurons

Ventral roots innervated somites

Contain SE neurons only

Except CN III has small AE component to ciliary muscles + SVE to leave palpebrae superioris

Remember that during development pharyngeal arch 5 and somites 4+5 fail to develop as do their nerves

Segment 1

Ventral root nerve = III occulomotor

SE- Somite forming most orbital muscles

E to ciliary muscle

SVE to levator palpebrae superioris

Dorsal root nerve = ophthalmic branch of V

No pharyngeal arch so no dorsal root , borrows from segment 2

SA- ectoderm only, forms skin on top of head bone eyes

SVE, AA, AE - None

Segment 2

Ventral root nerve - IV trochlear

SE- somite forms dorsal oblique orbital muscle

Dorsal root nerve = V

Mouth splits trigrminal into 2 further branches - maxillary SA and mandibular SA + SVE

SA- ectoderm forms most of skin of face , rostral 2/3 of tongue

SVE - Pharyngeal arch 1 forms muscles of chewing

Segment 3

Ventral root nerve = VI abducent

SE- somite lateral rectus + retractor oculi

Dorsal root nerve = VII facial

SA - ectoderm forms small area of skin internal ear cavity

SVE- pharyngeal arch 2 forms muscles of facial expression

AA - taste from 2/3rds of tongue , palate

AE - to mandibular / subigual salivary glands, nasal cavity glands, lacrimal gland

Segment 4

Ventral root = NONE

Dorsal root nerve = IX glosso-pharyngeal

SA - ectoderm forms very small area in ear canal

SVE - pharyngeal arch 3 forms stylopharyngess muscle

AA - endoderm forms lining of pharynx / caudal 1/3 of tongue, aortic arch 3 forms internal carotid

AE - motor to parotid salivary gland

Segment 5

Ventral root nerve = NONE

Dorsal root nerve = X/XI vagal-accessory complex

SA- ? ectoderm forms very small area of ear canal

SVE - pharyngeal arch 4 forms rest of pharyngeal muscles + cricothyroid muscle

AA - endoderm forms lining of common pharynx and larynx , aortic arch 4 forms root of aorta/ right subclavian

AE- Endoderm of gastro-intestinal tract

Segment 6

Ventral root nerve = XII hypoglossal

SE- somite 6 forms muscles of tongue

Dorsal root nerve = NONE

Segment 7

Ventral root nerve = XII hypoglossal

SE- somite 7 forms muscles of tongue

Dorsal root nerve = X/XI vagal-accessory complex

SVE - pharyngeal arch 6 forms rest of laryngeal muscles

AA - endoderm forms lining of larynx caudal to vocal folds/ trachea/ lungs /gastro-intestinal tract , aortic arch 6 forms pulmonary artery/ ductus arteriosus

AE- endoderm of gastro-intestinal tract

Seite 8

Motor systems

Structures involved

Motor cortex

Basal nuclei

Thalamus + internal capsule

Red nucleus and substantial nigra

Nuclei in pons and medulla oblongata

Cerebellum

Cranial nerves, Spinal cord, spinal nerves

NMJ

Skeletal muscle

Somatic motor system

Upper motor neurone UMN

Lower motor neurone LMN

Neuromuscular junction NMJ

Skeletal muscle fibres

UMN + LMN

UMN exist wholly within the CNS

They synapse on LMN which have a cell body in CNS and axon in PNS

LMN run via spinal or cranial nerves to innervate skeletal muscle fibres

LMN for forelimb from cervical intumescence

LMN for hindlimb from lumbar intumescence

UMNs

UMNs initiate, regulate, modify nd terminate LMN activity

May synapse directly on LMN or via interneurons

LMNs can be influenced y >1 UMN

UMNs to LMNs supplying flexor muscles travel in the lateral funiculi of the spinal cord

UMNs to LMNs supplying extensor muscles travelling the ventral funiculi of the spinal cord

?

UMNs and LMNs

Extensor muscles are dominant in body to maintain posture against gravity

Tempered by effect of inhibitory UMNs on the LMNs which supply these muscles

Without this inhibition extensors would take over leading to spasticity

LMNs

Have cell bodies in the CNS, run from CNS to muscle fibres

AP in the LMN causes muscle contraction

Regulated UMNs - initiate , regulate and terminate LMN function

LMN can fire without UMN input - reflex action

In conscious animal LMNs have a constant sub-threshold depolarisation causes ACh release which causes muscle tone and trophic support

Motor unit

Motor unit = LMN + NMJ + skeletal muscle fibres

Small motor unit allows fine movement

Large motor unit = more force, less finesse

??

As long as it has an intact LMN , a muscle can be made to contract

The motor system is not an island

Motor function occurs in response to sensory input and/or through voluntary action governed by the cerebral cortex

Normal function of all components is required for the animal to mobilise normal

Somatic reflexes

A reflex is the functional unit of the nervous system

It is an innate reaction to a stimulus and is present from birth

Sensory input leads to motor output without input from higher centres - doesn't require UMN input

This is different to a response which is a learned behaviour

May be monosynaptic or polysynaptic

May send info to higher centres

May be ipsilateral or contralateral

May be intra segmental or intersegmental

Monosynaptic reflex

?

Patellar reflex

?

Muscle spindles and GTO

?

Voluntary movement

?

Polysynaptic reflex

?

Withdrawal reflex

?

Reflexes don't require the input of an UMN

Removal of UMN input often causes a reflex to be exaggerated ??

In an injury to the LMN , the muscle will lodestone, bulk and reflexes

In an UMN injury, reflexes will be normal or increases will tone, and any atrophy will be relatively ild and due to disuse. Co-ordination will be reduced , but strength will be normal

UMN tracts

Corticospinal tract fine motor skills

Coticonuclear tract from cortex to cranial nerve nuclei

Rubrospinal tract skilled movements

Cortical input means this can serve similar function to corticospinal traction non -primates

Tectospinal tract orientates head + eyes in response to sights + sounds

Vestibulospinal for maintenance of posture/balance

Reticulospinal stabilises body against gravity

Pyramidal + extrapyramidal

Corticospinal tract runs caudally in the ventral medulla. Tracts form triangular shape on the transverse section - called the pyramidal tract

All other UMN tracts are extrapyramidal

Pyramidal tract enables fine, voluntary movements

Extrapyramidal tracts mainly control posture + subconscious, rhythmic movements

Although rubrospinal tract does generate fine skilled movements in non-primate mammals

Feedback between different nuclei and tracts ensures balance between excitation and inhibition

Cerebellum

Coordinates and integrates sensory input and input from the cerebral cortex

Output to UMN nuclei

Cant initiate movement

Cerebellar cortical nuclei inhibitory to deep cerebellar nuclei

Deep nuclei excitatory UMN nuclei

Cerebellar dysfunction leads to loss of coordination

??

Synapses become more efficient with practise

Particularly important for rapid /complex movements

Seite 9

Somatosensory systems

Sensory cells

Adaptation

Sensory receptors

Sensory neurons

Rapidly adapting

Slowly adapting

Somatic sensations

inner ear= had in space

muscles tendons joints = body in space

Touch

Rapidly adapting

Meissners corpuscle

Tactile hair

Slowly adapting

Expanded tip receptor

Ruffini's end organ

Pressure

Itch

??

Thermal

Sensory perception

Acute pain

Chronic pain

Nociceptive pain

Neurogenic pain

Control of pain transmission

Gate cell scan inhibit pain sensations

By releasing enkephalins

Pain sensitisation

Treatment of pain = Analgesia

Somatosensory pathways

Decussation

Dorsal column-medial lemniscal

Spinothalamic pathway

Seite 10

Locomotion and proprioception

Gait

Span = distance you move whilst foot is on ground

Span is limited

Stride = distance moved whilst leg isn't in contact with ground

Stride can be increased by a suspension phase

walk = 4 beat

trot = 2 beat diagonals

pace = 2 beat different sides

canter = 3 beat

gallop = 4 beat with greater suspension phase

Proprioception = sense that enabled good motor function

Conscious proprioception

Intension tremor - try to do something + then tremor

3 neurone system

Question

Subconscious proprioception

2 neurone system

Question

Spinal tracts

Stream

Kinaesthesia

the sense of the position and movement of the body

??

Horse hasn't realised that leg won't support its body

Problem with fine movement, know where its leg is

Cerebellum again

Confounding factor

?

Question

subconscious hind legs spread, front legs narrow

dragging feet - conscious?

swaying

front legs moving at faster pace than back legs

info

Question

Not brain - neurotically no other abnormalities

Not lumbar - forelimbs are abnormal

Cervical - instability, squishes spinal cord

Woblers syndrome

Seite 11

Ear + Hearing

Outer ear

??

Becomes progressively more bony

Tympanic membrane = eardrum

Ear wax

Must be flushed if overproduction

Otherwise can lead to ulceration

Sedation necessary

Otitis externa

Treatment - ear drops

Also include pain killer

Middle ear

Auditory tube leads to back of throat (nasopharynx)

Equalises pressure on back of ear drum

stirrup connects to inner ear via oval window

Otitis media

Horner's syndrome

Conduction deafness

stream ?

Inner ear

transduction = conversion of one form of energy to another

Bony + membranous labyrinths

Membranous labyrinth

stream

Bony labyrinth

Bipolar neurones

Stream

Oval window is where stirrup foot plate makes contact with the inner ear

number of turns varies with species

Round window

Stream

Prevents perilymph to leak out

Allows movement of perilymph?

Organ of corti

?

??

Mechanics of hearing

?

?

Frequency discrimination in the cochlea

NB frequency measured in Hz

Narrow and stiff near round window , flexible at end of cochlea

Nerve Deafness

Noise trauma can kill off all cells

Auditory pathway

Difference in timing between noises

Crossing over of nerves

Time taken for sound to reach other ear

Allows animals to know where a sound is from

LGM - vision

MGN - auditory

Trapezoid body

Sits just above the pyramids

Seite 12

Vestibular system

Vestibular cell

Vestibular Organs

Crista

Senses changes in rotation of head

Macula

Senses changes in linear direction

Has gelatinous mass containing otoliths

Stream

Otoliths

Simulation of otoliths

How they work?

Static balance

Head upright?

Head tilted/upside down

Force of gravity causes hairs to stretch , triggering nerve impulses

Location of inner ears

?

How ampullae work

Moves in opposite direction of rotation

Enables dynamic balance

Dynamic balance

Vestibular pathways

Connect with a number of diff nuclei and so give communicate with many diff pathways

All depusate

Communicate with many cranial nerves involved with eye

Relays in thalamus before finally vestibular cortex

Control of eye movements and posture

Righting reflex - allows animals to land on their feet when they're falling

Vestibular reflex

Tonic neck reflex

Righting reflex

Vestibulo-ocular reflex

Motion sickness

Vestibularsyndrome

Seite 13

Taste + Smell

Chemoreception

Pheromones - small smell particles within species

Papillae

species differences not exam

Gustatory

Mechanical

strem

Features of the tongue

Taste bud

Not shown in images e- stem cells

Tastants

Taste molecules

Bitter

Salty

Sweet

Umami

Sour

Gustatory pathway

Stream

Olfactory communication

Olfactory epithelium

Neuroepithelial cells are able to regrow their axons

Only part of CNS which can do this

Olfactory bulb neuron = mitral cells

Vomeronasal organ - accessory organ

Epithelia lining lined with ?

One end blind?

Olfactory + vomeronasal structure + function

Flehmen reaction

Cuts of nasal pathway

Not all species

Olfactory pathways - Canine

Conscious and subconscious pathways

anosmia - loss of sense of smell

Loss of appetite

Hypothalamus v involved in controlling appetite

Nursing sick animals

Seite 14

Learning, Memory + Behaviour

Limbic system

Highly interconnected brain areas coordinating

Homeostasis

Motivation

Emotion

Includes olfactory cortex

Route for olfactory info re

Feeding

Sexual behaviour

The hippocampus forms part of the limbic system and is important for memory formation

Amygdala = seat of aggression

Abnormal behaviour - limbic/forebrain lesions

The limbic system includes regions of the forebrain associated with emotional responses

Forebrain includes the frontal lobe , the seat of planning , decision-making and personality

Lesions cause changes in an animals normal habits, personality, attitude, reaction to the environment

Clinical signs

Depression

Lethargy

Listlessness

Stupor

Destructive behaviours

Pacing

Circling

Rabies

Contagious disease of virtually all mammals

Dogs = main vectors for virus (saliva)

Virus passes along nerves from bite or scratch and reaches CNS, directly affecting the hippocampus and other structures

Lesions in limbic system alter level of aggression such that docile and wild animals become the opposite

Resulting in 'dumb form' and then 'furious form' = two stages the disease

Animals goes from being morose and sulky to violent, refusing food, snapping at anything passing , easily excited , vacant stare, great salivation and finally paralysis

Conformation = histology

Negri bodies are cellular inclusions often found in the hippocampus and purkinje cells of the cerebellum as well as the medulla oblongata and various ganglia .

Frontal lobotomy

Lesions the frontal lobe

Performed on humans and animals to alleviate violent and aggressive behaviours that are destructive in nature

Humans show extensive changes in personality and loss of intellect as well, so procedure is infrequently used

Results in dogs are variable

Performed as a last resort

Can be performed by inserting a sharp tool through eye socket

GA not needed - brain has no pain fibres

Amygdala

Experimental destruction of amygdala leads to variable alteration in animals' responses

In cats - unfriendliness, fear, rage , tendency to attack animate and inanimate objects

In other animals- tame them

Lesions in temporal lobe can cause psychic seizures bringing about bizarre and hallucinatory behaviour - aggressive response to things that aren't there

Seizure disorders - epilepsy

Spontaneous discharge of activity by hippocampal neurons

Characterised by fits

Sudden , complete lossof consciousness

Muscular convulsions

Eyeballs may roll

Lots of salivation

Particularly a disease of dogs

Causes

Genetic

Trauma

Infections

Treatment

Sedatives

Tranquillizers

Ascending reticular activating system (ARAS)

Reticular formation core throughout brainstem of neurons regulating vegetive function , such that lesions here are fatal .

A vast array to external and internal environmental information is passed via the RF to wide-ranging areas of cortex, to determine the arousal level of the animal and control the sleep-wake cycle

Consciousness + sleep

Transition sleep to consciousness due to activity in the RF

RF neurons recieven info from sensory organs and neurons commanding muscles also extend to cortex

Continuous sensory info will cause RF to bombard cortex + keep animal awake

When ready to sleep, animal lies quietly to reduce sensory stimulation

The RF is the main target of drugs for GA

ARAS functions by ranking incoming info in terms of importance

Enables animal to focus

Filters garage of sensory info

Clincally - decreased consciousness can be due to focal lesions of RF or diffuse lesions of cerebrum

Levels of consciousness

Normal - bright, alert + responsive

Obtunded - dull, tends to fall asleep

Stuporous - sleepy

Comatose - unconscious

Brain dead - no cortical electrical activity or brainstem function

Hypothalamic lesions

Abnormal

Water consumption

Appetite

Pica = eating non foods

Temperature regulation

Hemi-neglect = animal ignores one side of body

Causes not all fully understood

Memory and learning

Memory is the storage of info in the NS

To benefit, retrieval must also be possible

Learning is changes in behaviour based on previous experience

Forms of learning depend on consequences of different stimuli

Habituation - natural reactions to stimuli are suppressed

Occurs gradually over time

Sensitisation - natural reactions to stimuli are enhanced

Classical conditionings

Animal is trained to associate 2 different stimuli with one another

One is an unconditioned stimulus which causes a reflexive reaction

One is a conditioned stimulus that evokes the same reaction as the UCS

Operant conditioning - learning by trial and error

Obedience training based on this

Aid of repeated rewards at strategic timing

Forms of memory

Short term

Stores info from a few seconds to hours

Limited capacity - events registered here are either lost or transferred to long term memory depending on factors like concentration + motivation

Based on electrical activity in neuronal networks

Long term

Lasts for days and up to many years

Almost unlimited capacity

Result of physical or chemical changes in cells

Declarative

Information about what something is and what has happened

Primarily connected to cerebral cortex

Memory store in cortex aren't limit

Factual knowledge organised into networks making it simpler to remember new facts or events if they can be associated with others that are already remembered

As memory grows it actually becomes increasingly easy to remember new info

Procedural

Provides info about how something is done

WRT movements

Working

Includes info recently required to make decisions or solve current problems

Contains elements of both short and long term memory

Contents continuously being uploaded as individual faces new problems and has to make new decisions

Hippocampus

Where transition from short to long-term memory occurs,

Unsure how this occurs

Unsure how memories are received and transferred to working memory

Consolidation is the reinforcement of memory resulting from frequent retrieval of a piece of information

Plasticity is capability of brain to change functionally and structurally as a result of experience .

Deteriorates with age

Senility

Cognitive dysfunction

Collectively , cognitive disorders refer to dementia , failure to recognise owners, familiar environments and objects , inability to learn.

Cognition = act of knowing

Companion animals living long enough for these disorders to occur

Seite 15

Histology

Neuronal stains

Commonly - Nissl

Stains RER in cell body

Special stains needed to reveal ramify processes of neurons

Fuzzy appearance is due to dendritic spine

If nervous tissue gets lesion - retrograde degeneration occurs

Nerve degenerates from point of lesion back to cell body

Nissl disappears

Spinal Cord

Meninges

Pia mater - invests the tissue

Blood vessels sit in subarachnoid space

Sensory neurons in the DRG

Large + small cell bodies

Rounded

Unipolar neurons

Crowded at periphery of ganglion

Uninterrupted axon bundle

Motor Neurons in ventral horn

Huge cell bodies

Nucleus not always visible

In another plane of section

Multipolar

Polygonal

Many initial dendritic or axonal branches

Don't know which from routine stains

Ependyma

Type of epithelial cells

Cilia on apical surfaces that face into lumen of ventricles

Cells are cuboidal/columnar

Protective

Nutrient sensing

Keep concentrations of?? stable

Brain

H+E staining of grey matter in the cerebral cortex reveals the nuclei of glia and neurones but not neuronal processes

Nuclei of ?? appear granular due to DNA transcription

Dark staining nucleic from support cells

Astrocytes

Oligodendrocytes

Blood vessels present in subarachnoid space

Cerebellum

Nissl staining of a section through the cerebellum reveals

Layered + highly folded cortex

Cerebellar nuclei deep to cortex

Cerebellar peduncle

Cerebellar nuclei give rise to axons extending to other brain centres + spinal cord

Peduncle = stalk of cerebellum

Folds = folia (leaves)

Arrangement of a cerebellar folium

Purkinje cell dendrites + granule cell axons lie in the molecular layers

Purkinje cell axons synapse on the cerebellar deep nuclei located within the white matter

Layers of cerebellar cortex

Molecular layer

Composed of granule cell axons + Purkinje cell dendrites

Purkinje neurons

Send their axons into underlying white matter providing sole output of cerebellum

Granular layer

Vast numbers of densely packed small neurons

Eye

Lacrimal Gland

Produces tears

Serous gland produces many lysozyme

Lumens hold tear

Protects surface of eye

Histologically lacrimal gland has similar appearance to serous salivary gland

Tears are secreted into the lumen of each secretory unit and drain onto the eye from each gland via many small ducts

Whole Eye

Choroid is distinguishable even at low magnifications due to its high pigment content

The suspensory ligament by which the lens attaches to the ciliary body isn't preserved

Cornea

Anterior epithelium

Moderately thin layer of stratified, non-keratinised squamous epithelium

Microvilli on top layer of cells?

Bowmans membrane

Anterior limiting lamina

Substantia propria (stroma)

Thick layer of highly regular, dense collagen in thin layers

Bright pink in H+E

Splitting of collagen plates to reveal small spaces is artifactual

Descemet's membrane

Posterior limiting lamina

Thick collagen/elastic basement membrane

Posterior epithelium

Squamous cells

Anterior chamber

Just right amount of hydration to maintain transparency

Ciliary body + surrounding structures

Cornea

Canal of Schlemm

Lined by squamous epithelium

Anterior chamber

Iris

Loose CT tissue

Trabeculae

Meshwork of fine collagenous material with slit-like spaces

Lined by simple squamous epithelium

Ciliary body

Main component is ciliary muscle

Bundled of smooth muscle fibres arranged in different directions

Ciliary processes

Lined with a double layer of cuboidal epithelium

Deep layer holy pigmented

Surface layer is not pigmented

Lens

Lens centre

Examination at high power shows cells devoid of organelles

Cells are living

Unknown how

Epithelium

Cuboidal

Single layer lining mature lens under the capsule

Secrete collagen

Capsule

Thick layer of collagen secreted by underlying epithelial cells

Layers in the wall of eyeball

Choriod isn't highly pigmented in order to reflect light

Cones often not found in animals

No tapetum is this region of choroid - heavily pigmented

Retina and optic nerve

Myelination occurs outside eye

Seite 16

Neurology exam

Starts before they've entered the consult room

Gait

Posture

Appearance

Don't forget the full basic clinical examination

Top to toe examination

Tailor exam to patient

All body systems

Neuro signs can often be a manifestation of systemic disease

I.e liver disease

Mentation, Posture, Symmetry

Tilted to one side?

Turned to one side?

Let animal wander in consult room

Moving normally?

Gait

Space where owner can walk them up and down?

Dragging toes

Tracking up?

Turning corners?

Conscious proprioceptions

Information about fine positioning movements

Feet right way up?

Enough force?

Paw righting reflex

Normal = immediately correct

Don't use whole leg (subconscious proprioception)

Test motor neuron function

Subconscious proprioception

Information that allows you to maintain the right posture

Step reflex

Q

Dorsal

Spinocerebellar

Q

Subconscious

Q

Subconscious?

Q

Sight

UMN

LMN

Symmetrical movement

Muscle tone

Proprioception

Q

Can tell if she can feel it without looking at face to see if she's showing a pain response

Myotactic reflex

Pressure on tendon causes limb to extends

Q- Muscle spindle

Q- proprioception

Q- Golgi tendon organ

Q

No effect / increased

Q

Reflexes absent / reduced

Cutaneous trunci

Pinching skin should cause symmetrical contraction

Allows localisation

Perineal reflex

Testing muscles of perineum

Testing sacral segments of spine

Bowel + Bladder function

History v important

Episodic

Might not occur during exam

Squat properly

Emptying bladder properly

Vision + eyelid/facial movements

Menace response

Don't create a breeze or ear around skin

Tests facial response

A response

Tests optic response

Vestibular function + eye movements

Vestibular reflex

Abscense normal

Occurs at rest

Abnormal

Asses for strabismus

Check both eyes

Q

Cat

Round dark optic discs

Dog

Triangular

Pain?

Pressing on edges of page vertebra to see if it hurts

Animals often stoic

If sore

Stay rigid

If not

Dip down a bit

Remember

Not able to perform all tests on all patients

DO NO HARM

Asses for pain

There may be other things that inhibit / affect examination

Now what

Localise the lesion

Next steps are taken to endeavour to identify the disease process

Blood tests

Haematology/biochemestry

Endocrine testing

Serology

Toxicology

Urinalysis

Enables interpretation of blood findings

Assits identification of concurrent disease

Diagnostic imaging

Ultrasound

Of abdomen if non-CNS disease is suspected

Of eye to examine retina, rostral optic nerve and retrobulbar area

Radiography

Plain

Contrast study

E.g. myelogram

Not is raised intracranial pressure

After CSF tap

Don't show whats inside bones v well

Fluoroscopy

A moving radiograph

Alimentary tract mobility

Advanced imaging

Computed tomography (CT)

Magnetic resonance imaging (MRI)

Better for CNS

Magenets make protons in body line up , blast them with radio waves , then the protons give of radio signals that are used to make and image

CSF tap

?

Pharmacological testing

Stream

Electrical testing

Cataracts

Cant see back of eye

Test retina function

Electromyogrophy

Test muscle itself

Deafness? stream

Lesion = area of damage

Seite 17

Clinical cases

4 yr 5 m female entire JRT

Acute onset tetraparesis

2 days duration

Started suddenly no apparent cause

Vaccines up to date

Not been out of UK

3 months from last season

No known access to toxic substances

Feeding constant

No trauma

DUDE normal

No seizures / history of neurological issues

No paw righting reflex on right fore

Unable to initiate movement well

Left side more effective

UMN?

Patella reflex present

my-tactic reflex present

Feels pain in legs

Back leg + other side LMN normal

LMN deficits in right fore limb

Cutaneous trunci reflex reduced on RHS

Everything else normal

UMN signs all 4 limbs

LMN in right fore

Intact deep pain

Right sided loss of spinal segment reflexes caudal to forelimb

Normal cranial nerves and mentation

Cervical intumescence affected

UMN deficits in all legs

LMN deficits right fore limb

Everything else normal

Bloods and urine normal

Nothing detected on radiography

MRI

Oedema in spinal cord - C6

Haemorrhage on RHS

Diagnoses

Fibrocartilage??

?

Treatment

hydro + physiothearpy

5y 2m male neutered

Cut onset neck pain + head turn to left

Duration 4 days

No known cause

Only turns left

Vacant / depressed

Head carried low

Vaccinated and parasite control up to dat e

feeding nchanged

No known toxins

No known trauma

Onset overnight

DUDE

Quieter than normal

No righting reflex on right hind and right fore

testing conscious proprioception -- deficits

Uneven hops - more on right , irregularly spaced

No signs of weakness

Segmental spinal reflexes fine

Cutaneous truni normal

Cranial nerve examination showed reduced menace on RS

Rest was unremarkable

Reduced mentation

Neck pain

Left sided head turn

circle to left -

RHS conscious proprioceptive deficits

Reduced menace on right

Pathways affected

Proprioceptive

Optic

Linked only by brain

Forebrain

All cross

Left forebrain

All pass through thalamus

Left sided lesion of thalamus

Left Circling = hemineglect as left side of brain not working properly , can't see that right is there

Neck pain = swelling

Blood and urine wnl

MRI - oedema in brain around a mass I left thalamus

Neoplastic? Inflammatory?

NO CSF - Raised pressure

Treatment yon presumed inflammatory disease

Steriods

Gastro protectants

Gabapentin = pain

2 weeks later better

4 weeks corticosteroids reduced

Relapse

Treatment restarted

Doing well!

Seite 18