Integrated Motor Control - Gait Lecture Flashcards
What should we observe in an animal when evaluating integrated motor control?
Mentation, posture, abnormal movmenet, muscle tone, gait
What should we be looking for when observing gait in regards to evaluating integrated motor control?
Circling, ataxia, weakness (paresis/paralysis), lameness, stance, slow walk (stride length, cadence regularity or irregularity, observe all directions), trot, run (observe fatigue)
Upper Motor Neuron
From brain to spinal cord
Voluntary movement
Descending inhibition of reflexes
Lower Motor Neuron
alpha-motor neuron
From spinal cord to muscle
final common pathway
Signs of a lesion in UMN
Spastic paresis/paralysis -lose voluntary movmenet and postural reactions -increased extensor tone intact spinal reflexes disuse muscle atrophy
Why do we see an exaggerated response of reflexes in an UMN lesion?
Because LMN tracts are still intact, allowing for reflex arc to be intact, but since we have an UMN lesion, we also lose the inhibitory impact of these tracts, causing spasticity.
Signs of lesion in LMN
Since we get a loss of LMN influence on muscle, we see:
Flaccid paresis/paralysis where we lose voluntary movement and postural reactions and decreased tone
Reduced to absent reflexes
Rapid and severe muscle atrophy
As a physician, what do we look for when examining posture?
Stance, weight bearing, head position, neck carriage, recumbent patient, tail position
A wide-base stance can be the result of a dyfunction in which two tracts?
Vestibular or cerebellar
What three things could be causing problems with weight bearing?
Monoparesis, orthopedic cause (broken bone), radicular pain (nerve root signature - hurts to bear weight)
______ dysfunction results in a head tilt.
Vestibular dysfunction
______ dysfunction results in a head turn.
Forebrain dysfunction
Define torticollis
When neck is turned very tightly towards the body
Dysfunction in what results in torticollis?
Vestibular dysfunction, high cervical lesion
Low head carriage is reflective of what two things?
Weakness, or pain (animals reluctant to move because of pain)
Symptoms of increased muscle tone include:
Spasticity (UMN problem)
rigidity (unable to flex limbs)
myotonia (delayed relaxation/prolonged contraction)
Symptoms of decreased muscle tone include:
Flaccidity (LMN problem)
An increased tail tone results in:
spasticity
A decreased tail tone results in:
flaccidity, sacrocaudal lesion
Name the two systems involved in sensory input:
General proprioception
Nociception
List two types of general proprioception.
Conscious and unconscious
Where do the fibers run in conscious proprioception?
Dorsal funiculus (fasciculus gracilis and fasciculus cuneatus)
Where do the fibers run in unconscious proprioception?
Spinocerebellar tract
Where do the fibers run in regards to nociception?
Lateral spinothalamic tract
Is sensory input contralateral or ipsilateral?
Fibers are contralateral and cross in the caudal medulla after they synapse
What type of loss of function do we see with respect to damage of forebrain lesion?
Contralateral loss of function
List the four Motor (UMN) tracts.
- Motor cortex - lateral corticospinal tract
- Red nucleus - rubrospinal tract
- Reticular formation - pontine and medullary pathways
- Vestibular nuclei - vestibulospinal tract
What tract is the major gate generator in quadriceps and has the greatest influence on extension and flexion of the limbs?
Rubrospinal tract
What is the role of the pontine pathway in reticular formation?
facilitates extensors and inhibits flexors
What is the role of the medullary pathway in reticular formation?
inhibits extensors and facilitates flexors
The motor cortex/lateral corticospinal tract influences:
the red nucleus/rubrospinal tract
the reticular formation
and the facilitation of flexors
The rubrospinal tract does what in regards to flexors?
Stimulates flexors
The vestibular nuclei/vestibulospinal tract main function is to? But also …..
Main function is to facilitate ipsilateral extensor muscles, but the fibers can also cross and inhibit contralateral extensor muscles
Why can damage to the spinal cord often effect both proprioceptive pathways and descending motor tracts?
Because sensory fibers are next to descending motor tracts