UMNL LMNL Flashcards
where is LMNL located
Located in the brainstem (cranial nerve nuclei) and spinal cord (anterior horn cells/ alpha motor neurons).
what are clinical features of LMNL
• Weakness (loss of muscle strength due to denervation of motor units = less # of fully functional motor units)
• Muscle atrophy (wasting of muscles)
• Hyporeflexia (absent reflexes)
• Hypotonicity/flaccidity: loss of N muscle resistance to passive movements
• Fasciculations: spontaneous contractions of muscle fibers belonging to a single motor unit
• Muscle Cramps: abrupt, involuntary, and painful shortening of the muscle
sensations are intact
what is poliomyelitis
-Caused by poliovirus (ssRNA enterovirus) pure motor disorder wont affect sensory (polioMyelitis)
-LMN lesion; damage in anterior horn cells
• Symptoms: weakness & atrophy of lower limbs; no sensory deficit; absent deep tendon reflexes; fasciculations; muscle paralysis & atrophy
Spinal muscular atrophy
-autosomal recessive disease
-Degenerative disease with different types depending on age
• Werdnig-Hoffmann Disease in infants: generalized muscle involvement (floppy muscles) = respiratory involvement (respiratory muscle weakness)
amyotrophic lateral sclerosis
• Disorder of both upper and lower motor neurons = shows signs of both
• Ex: Hoffman’s sign, extensor plantar reflex, fasciculations, wasting,
clinical features of UMNL
- No muscle wasting, except from disuse
-Spasticity (Hypertonia): clasp-knife spasticity Clonus present
-Brisk (exaggerated) tendon jerks
-Extensor plantar reflex (Babinski sign) (dorsiflexion of the big toe and fanning out of the other toes)
-No fasciculation
-Paralysis affect movement rather than muscles
-hoffman sign
-superficial abdominal refkex absent
