UMN and LMN systems Flashcards
what efferent cells are necessary to connect the brain and the target organ
The first is the UMN
The second is the LMN
both are descending motor pathways
UMN:
upper motor neurons
LMN:
Lower motor neurons
where are the cell bodies of the UMN
in the cortex and brainstem
where do UMN terminate
UMN terminate and synapse on lower motor neurons in the spinal cord
How do UMN effect the LMN
UMN influence LMN activity (including reflexes)
where are the cell bodies of the LMN
LMN have cell bodies in the CNS spinal cord
What is the function of the LMN
LMN innervate motor unit (muscle)
Lesions to UMN and LMN cause predictable outcomes with regard to (6)
- motor function
- muscle tone
- reflexes
- muscle atrophy
- proprioception
- sensation
UMNs function to:
initiate voluntary activity of muscle
what two systems do the Axons of the UMN use to travel down the spinal cord
- Dorsalateral motor system
- Ventromedial motor system (funiculus)
what is the funiculus
the funiculuc is a bundle of nerves forming one tract of white matter in the spinal cord
What are the two ways LMN can be stimulated
- Concious effort
- UMN
- Reflexes
- interneuron
what does it mean when it says “UMN motor pathways have Somatotopy”
point for point correspondence of an area of the body (or function) to a specific point on the central nervous system
what is the function of the UMN dorsolateral system
- Fractionated
- fine/precise movements
- especially distal limb movements
what muscle systems does the UMN dorsolateral system focus on
- Distal more than proximal
- Flexors more than extensors
what is the muscle system focus of the UMN Ventromedial system
- Proximal more than distal
- Extensors more than flexors
what is the primary function of the UMN Ventromedial system
- Posture and balance
- Whole limb movement
what are the CS of damage to the dorsolateral motor system
decreased or absent voluntary movements of the fine motor (mostly flexor) systems caudal to the site of damage
What are the CS of damage to the Ventromedial Motor Systems
decreased or absent voluntary movement of the whole limb (mostly extensor) system caudal to the site of damage
Transverse damage to the spine will have CS from which neuron system
both UMN and LMN
with Transverse damage to the spine where will you see UMN CS
caudal to a spinal lesion
with transverse damage to the spine where would you see LMN CS
you will see LMN CS at the site of the spinal lesion
what are the CS of LMN damage
- Paresis or paralysis
- Decreased to absent muscle tone
- Decreased to absent reflexes
- Rapid onset muscle atrophy
- EMG and histological changes in affected mm
what are the CS of UMN damage
- Paresis to paralysis
- Normal to increased muscle tone clonus
- Normal to increased spinal reflexes
- Slow muscle atrophy
- EMG activity is unaltered and no histological changes in the affected mm.
what is the somatic innervation of the urinary bladder
Pudendal nerve (S1-S3)
what is the PSNS innervation of the urinary bladder
Pelvic n. (S1-S3)
what is the SNS innervation of the urinary bladder
Hypogastric n. (lumbar)
what does the pudendal nerve provide to the urethra
sensory/afferent innervation
what type of innervation does the pudendal nerve provide to the urethralis muscle
- motor/efferent
- (external urethral sphincter)
- providing voluntary control of micturation
What reflex does the pudendal n cause at the Urethralis and what type of nerve is it
Efferent n of the reflex closure of the urethralis m. at the external urethral sphincter
what sensory innervation of the bladder is provided by the pelvic n.
visceral afferent (stretch bladder wall)
what muscle of the bladder is innervated by the pelvic n. and its function
- Detrussor m.
- involuntary smooth muscle contraction of the bladder wall
what does the hypogastric n inhibit
inhibits the action on the detrussor m
What does the hypogastric n stimulate
stimulatory to smooth m of the sphincter at the bladder neck
what nerve is stimulated by urine filling and stretching the bladder wall
stimulates visceral afferents (pelvic n.)
afferents travel to cortex to make animal aware of the need to urinate
what nerve is stimulated by tiny amounts of urine leaking into the proximal urethra
stimulates the somatic afferent (pudendal n.)
-Afferents to the cortex make animal aware of the need to urinate
which nerve controls the reflex contraction of the urethralis m
efferent pudendal n
which nerve allows for somatic voluntary control of urethralis m.
efferent pudendal n
what nerve gives of sympathetic fibers that inhibit contraction of detrussor m.
hypogastric nerve
what are the two nerves that alert the animal to the need to urinate
- pudendal
- pelvic
what nerve handles the conscious voluntary motor relaxation of urethralis m
Pudendal n
Parasympathetic fibers of which nerve induce contraction of detrussor m.
pelvic n.
how can UMN an LMN damage affect the bladder
LMN and UMN damage can cause incontinence
Where would an UMN lesion be located to induce urinary incontinence
lesion is cranial to sacral spinal cord segments
Where would an LMN lesion be located to induce urinary incontinence
result from lesions of spine S1-S3 segments or nerves emanating from there (pelvic n. and pudendal n.)
what are the UMN bladder CS
- Severe bladder distention
- incontinent
- Resistance to manual expression
what are the CS of LMN bladder
- Continuous leakage
