Unit 3 - Neuro (CN, Reflexes, Diagnostics, Definitions) Flashcards
What are the four functionally different anatomic areas of the nervous system?
Cerebrum
Cerebellum
Brainstem and cranial nerves
Spinal cord and peripheral nerves
What are the three etiological categories of nervous illnesses?
Acquired biologic
Acquired nonbiologic
Congenital or hereditary
What should be observed on distant neurologic examination?
Mentation, posture, and gait
What spinal reflexes can be assessed in all ruminants?
Panniculus, withdrawal of forelimb/hind limb, patellar, and perineal reflex
What are the 6 broad types of abnormalities in mentation in ruminants?
- Excitement, mania, or hyperesthesia
- Seizures
- Depression
- Aimless circling, stupor, or coma
- Abnormal vocalization
- Blindness
T/F: Aimless circling and tight circles associated with vestibular lesions are caused by the same process.
False - aimless circling is due to serevral disease
What is gait?
The coordinated functioning of the cerebral cortex, extrapyramidal basal nuclei, and red nuclei which stimulates the flexor muscles and simultaneous inhibition of extensor muscles
What can cause gait abnormalities?
Cerebellar, brainstem, spinal cord, and peripheral nerve lesions
How do you assess conscious proprioception in ruminants?
During ambulation by placing obstacles in enclosures/alleyways
If an animal is halter broke, how do you assess conscious proprioception?
Walking in tight circles, walking across/up a curb, walking up and down a hill, and pulling the tail while walking strait
What neurologic signs can suggest the possible presence of proprioception deficits and exaggerated spinal reflexes?
Presence of ataxia, hypermetria, and truncal sway
What is posture maintained by?
The trunk muscles and extensor muscles of the proximal limbs
What facilitates posture?
The vestibulospinal and reticulospinal tracts from the medulla and pons
What are the three main aspects of posture?
Head, body, and limbs
What processes sensory input from pressure/stretch receptors in the limbs/body, vestibular system, and visual inputs?
The brainstem, cerebellum, and cerebrum
Abnormal head posture (continuous head tilt) indicates what?
Central or peripheral vestibular disease
What can cause abnormal trunk posture?
Congenital or acquired disorders such as scoliosis, lordosis, and kyphosis
What are some abnormal limb postures that can result from UMN or LMN disease?
Inappropriate positioning, weakness, knuckling, and a base-wide stance
What does the menace response evaluate?
The entire visual pathway, CN VII, and the cerebellum
What cranial nerves are involved in the menace response?
CN II and CN VII
T/F: The menace response is often absent in neonatal ruminants.
True
What cranial nerves do pupillary reflexes assess?
CN II and CN III
If the intraparenchymal visual pathways are affected (central or cortical blindness) what will the menace response be? The PLRs?
Menace - absent on the contralateral side of the lesion
PLR - intact
If the extraparenchymal visual pathways (peripheral blindness) are affected, what will the menace response be? PLRs?
Menace - blindness on the size of lesion; absent
PLRs - abnormal
What muscles does the CN III control?
Dorsal, ventral, and medial rectus muscles
Ventral oblique muscle
Levator palpebrae muscle
What do lesions of CN III result in?
Ipsilateral ventrolateral strabismus and mydriasis
What muscle does CN IV innervate?
Dorsal oblique muscle
What do lesions of CN IV result in?
dorsolateral strabismus
What does CN VI innervate?
The lateral rectus and retractor bulbi muscles
What do lesions of CN VI result in?
Medial strabismus with a more forward positioning of the globe
Failure to retract the globe during assessment of the palpebral (or corneal) reflex
T/F: The eyes of ruminants should try to maintain focus straight ahead, the result being that the eye moves slowly in the opposite direction of the head movement and then ‘jump’ quickly back towards the direction movement.
True
What are the three branches of the trigeminal nerve (CN V)?
Ophthalmic, maxillary, and mandibular
While all branches of CN V have sensory fibers, which branch has motor fibers as well?
Mandibular
Lesions to the mandibular branch of CN V result in what clinical signs?
Muscle asymmetry/loss, flaccid or lowered jaw, inability to close the jaw, inability/reduced mastication with dropping of feed and drooling, and protrusion of the tongue.
What do the corneal and palpebral reflexes test?
Sensory - CN V
Motor - CN VII
What branch of the trigeminal is assessed by touching the medial canthus? Lateral canthus?
Medial canthus - ophthalmic branch
Lateral canthus - maxillary branch
How is sensory function of the mandibular branch of CN V tested?
Touching/pinching the face, including the base of the ear
How is the consciously mediated, coordinated movement of the head away from noxious stimuli assessed?
Applying stimuli to the nasal septum
What CN tests test CN VII?
Menace response, palpebral reflex, corneal reflex