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
List in order which fibers lose function in response to a lesion, starting with the pathways that lose function first.
PMS - proprioception, motor, sensory (nociception)
Why are proprioceptive pathways the first to be affected in response to damage of spinal cord?
They have the largest diameter and are located superficially.
What are the two phases of gait?
Stance (postural - extensor) phase
Protraction (swing - flexion) phase
Describe what happens during the stance (postural - extensor) phase of gait.
Activation of extensors via vestibulospinal tracts that are ipsalateral.
Inhibition of flexors (influence of pontine reticulospinal tracts).
Describe what happens during protraction (swing-flexion) phase of gait.
Activation of flexors (activating our rubrospinal tract).
Inhibition of extensors (medullary reticulospinal tract)
What is spinal walking?
When limbs are moving as a result of reflexes in response to walking but patient has no control over those limbs.
What to look for in pattern recognition of abnormal gait?
- Lameness
- ataxia (incoordination) which can be caused by general proprioception, vestibular, or cerebellar dysfunction
- weakness
What are the symptoms of lameness in limbs in regards to gait?
Short stride on affected limb, long stride of contralateral limb, regular irregular gait, and associated pain with orthopedic or neuropathic problems
What type of gait pattern to patients with ataxia (incoordination) have?
Irregularly, irregular gait pattern
What type of gait pattern to patients with lameness in limbs have?
regularly, irregular gait patter
What are the three qualities of ataxia?
General proprioception (GP)
Vestibular
Cerebellar
List the symptoms of ataxia relating to general proprioception.
- Lack of sensory information reaching CNS for neck, trunk and limbs
- Onset of protraction (swing phase) is delayed, long stride
- Limb may abduct or adduct
- Clinical signs overlap with UMN dysfunction resulting in paresis because proprioceptive pathway (spinocerebellar tract) lies very close to descending motor tract)
List symptoms of ataxia relating to vestibular system.
- Loss of orientation of head with eyes, neck, trunk, and limbs
- loss of balance
- usually accompanied by head tilt and nystagmus
Why do we see crossing of limbs in regards to vestibular ataxia?
Because of the input from movement of fluid within semicircular canals has important sensory input into vestibular nuclei which influences descending input to the extensor muscles or excitatory input to extensor muscles.
List symptoms of ataxia relating to cerebellar systems.
Onset of protraction (swing phase) is delayed
-hypermetria - excessive flexion with foreful return
-hypometria
Spasticity
May see concurrent vestibular signs
Cerebellum regulates _____ activity.
Motor activity
Define monoparesis and monoplegia.
Monoparesis - weakeness in one limb
Monoplegia - paralysis in one limb
Define paraparesis and paraplegia.
Paraparesis - weakness in pelvic limbs
Paraplegia - paralysis in pelvic limbs
Define tetraparesis and tetraplegia.
Tetraparesis - weakness in all four limbs
Tetraplegia - paralysis in all four limbs
Define hemiparesis and hemiplegia.
Hemiparesis - weakness on one side (in regards to limbs) compared to the other
Hemiplegia - no movement on one side (in regards to limbs) compared to the other
What do we see in weakness as a result of an UMN lesion?
proximity of GP pathways and UMN tracts results in GP ataxia and motor weakness
stiffness and spasticity - because of release from inhibition, and delay in onset of limb protraction (floating limb)
What do wee see in weakness as a result of LMN lesion?
Difficulty supporting weight and deficiency in generation of gait (no initiation of gait) Short stride (bunny hopping)
List the six neuroanatomic localizations.
- Brain (forebrain, hindbrain)
- C1-C5
- C6-T2 (cervicothoracic intumessence)
- T3 - L3
- L4 - S3 (lumbosacral intumessence)
- Ccy
List the symptoms in regards to a lesion or dysfunction in the forebrain
- Gait is usually normal
- Ipsilateral wide circles (circles toward side of lesion)
- head turn ipsilateral; hemi-neglect sezures
- +/- abnormal mentation
- Contralateral visual and menace deficits
- Contrlateral postural reaction deficits
When we see head turn (NOT a head tilt), we think of a lesion in what area?
Forebrain
Basal ganglia are important for what?
The initiation of movement. They influence corticospinal pathways to intitiate gate.
List the symptoms in regards to a lesion or dysfunction in the hindbrain.
- +/- abnormal mentation
- +/- vestibualr signs (tight circles ipsilateral)
-cranial nerve deficits (V-XII) ipsilateral
-Ipsilateral hemiparesis, tetraparesis
-Ipsilateral postural reaction deficits
(Ipsilateral because fibers don’t decussate)
When animal is circling in tight circles towards the lesion, this lesion is located in the _____ .
Vestibular region (hindbrain)
When animal is circling in wide circles towards the lesion, the lesion is located in the _____.
Forebrain
Cerebellum is important for learning what function?
Motor function/muscle memory - processes the learning the walking.
Define abasia.
Animal never learns to walk because was born with a problem in the cerebellum.
Signs of dysfunction in the cerebellum:
normal mentation, cerebellar ataxia, decerebellate posture, intention tremor, wide-base stance, titubatio, +/- vestibular signs, meance defici with normal vision, possible abasia in young animals
Lesion within C1-C5 region results in _____ to thoracic and pelvic limbs. (UMN or LMN)
UMN signs to thoracic and pelvic limbs.
Describe an animal’s posture with lesion in C1-C5 region.
Normal, horizontal neck carriage, recumbent
Describe an animal’s gait with lesion in C1-C5 region.
Long stride in both TL and PL; spastic, GP UMN ataxia, PL > TL, hemi- or tetraparesis/plegia
Describe postural reactions with lesions in C1-C5 region.
Normal, mild-severe deficits, PL>TL
Describe animal’s spinal reflexes with lesions in C1-C5.
Normal to hyperflexia.
Lesions within C6 to T2 region results in ____ signs to thoracic limbs and _____ signs to pelvic limbs.
LMN signs to TL and UMN to PL
Describe animals posture in regards to lesion in C6-T2 region.
Normal, horizontal neck carriage, recumbent
Describe animals gait in regards to lesion in C6-T2 region.
Spastic, GP UMN ataxia in PL (long stride in PL as a result of UMN signs), short choppy stride in TL as a result of LMN signs; hemi- or tetraparesis/plegia
Describe animal’s postural reactions in regards to lesion in C6 - T2.
Normal, mild-severe deficits PL>TL
Describe animal’s spinal reflexes in regards to lesion in C6 to T2.
Normal to hyperflexia PL; hyporeflexia TL
Lesions within T3 to L3 result in ____ signs to the pelvic limb.
UMN signs
Describe an animal’s posture in regards to lesion in T3-L3.
Normal, falling PL, Schiff-sherrington
Describe an animals gait in regards to lesion in T3-L3.
Long stride PL; spastic, GP UMN ataxia PL; hemi- or paraparesis/plegia
Describe an animal’s spinal reflexes in regards to lesion in T3-L3.
normal to hyperflexia
Lesions within L4 to Ccy result in ____ signs to pelvic limb and tail.
LMN
Describe an animal’s posture with lesion in L4-S2 region.
Normal, falling PL, tucked pelvis
Describe an animal’s gait with lesion in L4-S2 region.
Short, choppy stride PL or lameness, hemi- or paraparesis/plegia
Describe an animal’s spinal reflexes with lesion in L4-S2 region
Normal to hyporeflexia, +/- perineal reflex
What does a lesion in UMN result in?
It releases inhibition on exentsors, so it increases tone, increases stride length, normal to hyperreflexia, disuse muscle atrophy
What does a lesion in LMN result in?
Decrease tone, short choppy gait, hypo-to areflexia, neurogenic muscle atrophy
