Introduction to Neurology

What do oligodendrocytes do?

Make myelin

What are microglia?

Scavengers

What are astrocytes?

Brain support cells

Create blood brain barrier

What are ependymal cells?

Lining the ventricles

What are the types of neurons?

Glutaminergic

Cholinergic

Dopaminergic

GABAergic

What neurons smooth out actions?

Dopaminergic

What neurons maintain calm?

GABAergic

What neurons are used for communication?

Cholinergic

What is the telencephalon?

Cerebrum

What is the metencephalon?

Cerebellum and pons

What is the myelencephalon?

Medulla oblongata

What is the diencephalon?

Thalamus

Hypothalamus

What is the mesencephalon?

CN III and CN IV

What is the pons?

CN V, VI, VII (motor)

What is the medulla oblongata?

CN VI-XII (sensory) and CN VII-XII (motor)

What is the function of the cerebrum?

Consciousness, processing of sensory information

What is the function of the thalamus?

Relay center for all anatomic divisions of the brainW

What is the pyramidal system?

Consciously controlled movement

What is the extrapyramidal system?

Unconsciously controlled movement

What facilitates the function of all cranial nerves?

Cerebrum

What is the origin of upper motor neurons?

Cerebrum or brainstem

What is the pathway of upper motor neurons?

Spinal cord to connect the brain to the lower motor neurons

What is the function of upper motor neurons?

Synapse with the lower motor neurons that innervate the muscles

What happens if upper motor neurons are damaged?

Increased muscle tone

Exaggerated spinal reflexes

What is the origin of lower motor neurons?

CNS

What is the pathway of lower motor neurons?

Exit the CNS to form the cranial nerves and peripheral nerves

What is the function of lower motor neurons?

Final pathway to innervation and activation of muscular activity

What happens when lower motor neurons are damaged?

Decreased muscle tone

Diminished or absent spinal reflexes

What does ipsilateral mean?

On the same side

What does contralateral mean?

On the opposite side of the body

T/F most fibers decussate just rostral to the pons or in the midbrain?

True

What type of fibers are easier to compress and lose function?

Larger fibers

What is the first thing you lose when a nerve is damaged?

Proprioception

When is respiratory control lost?

After deep pain is lost

What are the functions of nerve fibers that are lost in what order?

1. Proprioception

2. Conscious motor

3. Superficial pain

4. Deep pain lost

What does loss of deep pain signify?

A severe spinal cord injury

Are are nerve fiber functions regained?

In opposite direction than the order they were lost (deep pain comes back first)

What is paralysis?

Complete loss of function

What is paresis?

Muscular weakness associated with neurological dysfunction

What does tetra mean?

Affecting all 4 limbs

What does hemi mean?

Affecting front and rear limbs on one side of the body

What does para mean?

Only affecting rear limbs

What does spino- mean?

Ascending tract of spinal cord

What are spinothalamic tracts involved with?

Pain, temperature, and pressure sensation

What does the lateral spinothalamic tract do?

Superficial pain sensation

What does the ventral spinothalamic tract do?

Deep pain sensation

What does the corticospinal tract do?

Conscious motor control over skeletal muscles

What does the vestibulospinal tract do?

Control muscle for posture and balance

What does the rubrospinal tract do?

Control flexor and extensor tone

What does the tectospinal tract do?

Responses to startling visual or auditory input

What does the reticulospinal tract do?

Respiratory muscles

What is an alert mental status?

Normal state of consciousness. Varies due to individual behavioral responses to situations

What is is inappropriate mental status?

All inclusive term including

• Depressed

• Obtunded

• Demented

• Delirious

What is depressed mental status?

Quiet and unwilling to perform normally but responds to environmental stimuli

What is obtunded mental status?

Dull and relatively nonresponsive but conscious

What is a demented mental status?

Unrecoverable loss of higher brain functions

What is a delirious mental status?

Temporary disturbance of higher brain functions characterized by inappropriate responses or behaviors

What is stuporous mental status?

Unconscious in the presence of normal environmental stimuli but can be roused with more intense stimuli

What is a comatose mental status?

Unconscious regardless of the intensity of the stimulus applied

What is ataxia?

Loss of muscular coordination

Describe sensory (proprioceptive) ataxia

Peripheral nerves, spinal cord, brainstem, cerebrum

Visual cures can help with compensation

Describe vestibular ataxia

Peripheral or central vestibular

Central vestibular disease may have components of sensory and vestibular ataxia

Describe cerebellar ataxia?

Present without loss of motor function

What are the types of ataxia?

Sensory (proprioceptive) ataxia

Vestibular ataxia

Cerebellar ataxia

What is bunny hopping gait?

Pelvic limbs advance together

What can cause bunny hopping gait?

UMN spinal cord disease

Bilateral hip dysplasia

What do big circles indicate

Cerebral disease

• Circle towards the mass

• Rarely may circle opposite direction

• Thalamic and hypothalamic disease

Where are big circles localized to?

Cerebrum

Where are small circles localized to?

Vestibular or cerebellum

What are some other findings found with small circles?

Head tilt in the direction of the circling

Nystagmus

CN 7 deficits

Multiple cranial nerve and limb deficits

What is head tilt?

One ear is held lower than the opposite ear

The nose continues to point straight ahead

Disease of the vestibular or cerebellar systems

The tilt is generally toward the lesions

Where is the head tilt in paradoxical vestibular syndrome?

Opposite direction of the lesion

Describe head turn

Ears remain parallel to the ground

Nose is deviated toward one side

Cerebral lesion

Turn is toward the side of the lesion

Circling is common

What should you do if you have a head tilt and a head turn?

Ignore the head turn, the head tilt will help you localize the lesion

How can you test for conscious proprioception

Place paw where a footfall would land with the dorsal surface on the ground

Support the pets weight

T/F you can test conscious proprioception the same in dogs and cats?

False

What is the technique for hopping?

Slightly lift the leg opposite to the one being examined

Use this hold to push the dog toward the limb being examined

As the paw goes toward midline the patient will hop the limb laterally to maintain balance

What is wheelbarrowing?

Life the pelvic limbs off the ground and walk the patient forward

What is hemiwalking?

Lift the limbs on one side and push the limbs towards the other limbs

The limbs will correct to keep the patient from losing balance

What is extensor postural reaction

Hold the patient vertically and bring them down to land on the pelvic limbs

The patient will naturally step back so that they can land on their front feet

What does the quadriceps (patellar) reflex test for?

L4-L6 spinal cord and femoral nerve

T/F the Quadriceps (patellar) reflex gets worse with age?

True

T/Fa tense patient can make the Quadriceps (patellar) reflex harder to elicit?

True

What does the cranial tibial reflex test?

L6-L7 spinal cord segment and the peroneal branch of the sciatic nerve

What is the expected response of the cranial tibial reflex?

Flexion of the hock

What does the gastrocnemius reflex test?

L7-S1 spinal cord and tibial branch of the sciatic nerve

What are the 2 techniques of the gastrocnemius reflex?

Percuss tendon insertion causes extension of the hock

Flex the hock then percuss then contraction of the gastrocnemius

What does the flexor (withdrawal) response evaluate?

Sensory component, reflex arc, and motor component

What is the problem with the flexor (withdrawal) response?

Dependent on force applied and nature of patient

Very questionable interpretation

T/F during a flexor (withdrawal) response a flexion is lost with a LMN lesion and present with an UMN lesion?

True

What does the biceps reflex test?

C6-C8 spinal cord and musculocutaneous nerve

T/F all the reflexes in the thoracic limb are difficult to interpret?

True

What is the technique for the biceps reflex?

Index finger wrapped around insertion of the biceps tendon

Elbow is pulled caudally to stretch the tendon

Finger is tapped with the pleximeter and the examiner watches for contraction of biceps

What does the triceps reflex test?

C7-T1 spinal cord segment and the radial nerve

What is the technique for the triceps reflex?

1. Hold forearm and pull elbow caudally and rotate elbow outward to stretch triceps tendon

2. Tendon is percussed and look for contraction of triceps

3. Index finger wrap around the triceps tendon to tension it futher and finger tapped with pleximeter

What does the extensor carpi radialis reflex test for?

C7-T1 spinal cord and radial nerve

What is the technique of the extensor carpi radialis reflex?

Percuss the proximal muscle belly of the extensor carpi radialis

Extension of the carpus, limb is supported passively to elicit this reflex

How can superficial pain be elicited?

Pinching skin overlying in between the toes

How can deep pain sensation be evaluated?

Applying pressure to bone or joints

When can the crossed extensor reflex be elicited?

UMN lesion