Motor Pathways Flashcards
Paresis
partial loss of voluntary motor function. The P has loss of strength but still some voluntary movement
Ambulatory Paresis
P is weak but still able to walk
Nonambulatory Paresis
P has feeble voluntary movement but is not strong enough to walk on their own
Upper Motor Neuron
wants to contract muscle, sends AP to lower motor neuron what to do
Where is the LMN Located?
gray matter of spinal cord for limbs
Muscle Tone
resistance to muscle stretch
Paralysis
total loss of voluntary movement.
Will a paralyzed patient still have spinal cord reflexes?
yes because spinal cord reflexes are not voluntary
Mono-
one limb is involved
Para-
both pelvic limbs
Tetra-
all four limbs are affected
Segments of the Spinal Cord
8 cervical 13 thoracic 7 lumbar 3 sacral 5 caudal
Cervical spinal cord
C1-C8
Thoracic vertebrae
T1-T13
Lumbar Vertebrae
L1-L7
Sacral Vertebrae
S1-S3
Intumescences
Regions of the spinal cord that innervate all the muscles of the limbs and therefore contain many more LMN cell bodies and are larger in diameter
Where are the LMN for thoracic limbs?
C6-T2
Where are the LMN for the pelvic limbs
L4-S3
Where are the cell bodies for the UMN?
the brain
Where are the axons for the UMN for the thoracic and pelvic limbs?
C1-C5
Where are the axons for the UMN for pelvic limbs?
T3-L3
Signs of a LMN lesion
- paresis or paralysis
- weak to absent reflexes
- weak to absent muscle tone
- rapid, severe muscle atrophy
Signs of a UMN Lesion
- paresis or paralysis
- normal to exaggerated reflexes
- normal to increased muscle tone
- only mild muscle atrophy
Crossed Extensor Reflex
withdrawal reflex in one limb causes the other limb to extend while recumbent
Clonus of the Patellar Reflex
alternating extension and flexion of the stifle in response to a single tap of the patellar tendon
Spasticity
increased muscle tone. Characterized by increased tone in the extensor muscles such that the patient does not flex the limb normally during the protraction phase of the gait (when the limb is moving forward), resulting in a stiff stilted gait
What does a focal spinal cord lesion cause?
- lower motor neuron deficits at the level of the lesion
- Upper motor neuron deficits caudal to the lesion
- sensory deficits at the level of and caudal to the lesion
Forebrain/brainstem Lesion
tetraparesis/tetraplegia with normal to increased reflexes and muscle tone in all limbs
C1-C5 Lesion
tetraparesis/tetraplegia with normal to increased reflexes and muscle tone in all limbs
C5-T2 Lesion
tetraparesis/tetraplegia with weak to abesnt reflexes and decreased muscle tone in the thoracic limbs and normal to increased reflexes and muscle tone in the pelvic limbs
T3-L3 Lesion
Paraperesis/paraplegia with normal to increased reflexes and muscle tone in the pelvic limbs
L4-S3 Lesion
paraparesis/paraplegia with decreased to absent reflexes and muscle tone in pelvic limbs
Diffuse LMN Lesion
tetraparesis/tetraplegia with weak to absent reflexes and muscle tone in all limbs
