Nerve conduction Flashcards
What are motor neurons?
Neurons that carry signal to spinal cord and muscle, cell bodies in CNS to muscles to contract.
What are upper motor neurons?
Carry info from brain to LMN (spinal cord/ brain stem).
What are lower motor neurons?
Carry info from UMN to skeletal muscles, cell bodies in ventral horn.
What is the difference between ventral and dorsal horn?
Ventral horn (front) contain cell bodies of MN, Dorsal horn (back) receives sensory info from receptors.
What are the types of LMN?
Alpha and Gamma.
What are the two muscle types of skeletal muscle? What are the MN controlling them?
Extrafusal: larger, highly contractile, controlled by alpha
Intrafusal: smaller, contains muscle spindles (proprioceptive receptors), signals length and rate of change in length, controlled by gamma.
What is alpha-gamma coactivation?
Signal sent to both alpha and gamma, seen in stretch reflex.
What is the implication of continued oscillation of leg after patellar reflex?
Issue with coordination of inhibition of movement, UMN or cerebellar impairment.
What are two examples of UMN lesions?
Cerebral infarction, corticospinal tract.
What are two examples of LMN lesions?
Peripheral nerve, nerve root.
What are the symptoms of UMN lesions?
Increased muscle tone, reflexes, no fasciculations(involuntary muscle twitch), no muscle atrophy.
What are the symptoms of LMN lesions?
Decreased muscle tone, reflexes, fasciculation (involuntary muscle twitch) present, muscle atrophy present.
What is ALS?
Amyotrophic Lateral Sclerosis, progressive neurodegenerative disease with no known cure.
Bilateral degeneration of UMN and LMN, more likely sporadic rather than hereditary.
What are the two types of ALS onsets?
Limb onset: appear in limbs, most common
Bulbar onset: appear in face or neck, faster progression
Can include multiple focal onsets.
What is SMA?
Spinal Muscle Atrophy, defect in SMN1 gene (survival of motor neuron protein) essential for production of SMN. Autosomal recessive.
What is autosomal recessive inheritance?
Non-sex, inheritance where two copies must be present (both parents are carriers).
What are the S&S of SMA?
Areflexia, muscle weakness, hypotonia, fasciculations, (LMN affected). Bell-shaped torso, compromise of the intercostal muscles for breathing.
What are the 4 types of SMA?
Infantile, intermediate, juvenile, adulthood.
What is Werdnig-hoffman?
Infantile SMA, onset 0 to 6 month, floppy baby.
What is Dubowitz?
Intermediate SMA, onset 6-18 month, impaired walking + muscle weakness.
What is Kugelberg-Welander?
Juvenile SMA, onset 18+ months, compromised walking.
What is adulthood SMA?
Onset in adulthood, weakness in muscles, compromised mobility.
What is the Apgar score?
Assess newborn babies, heart rate, breathing, muscle tone, reflexes, skin color, out of 10.
