Nerve conduction

Question 1

What are motor neurons?

Answer 1

Neurons that carry signal to spinal cord and muscle, cell bodies in CNS to muscles to contract.

Question 2

What are upper motor neurons?

Answer 2

Carry info from brain to LMN (spinal cord/ brain stem).

Question 3

What are lower motor neurons?

Answer 3

Carry info from UMN to skeletal muscles, cell bodies in ventral horn.

Question 4

What is the difference between ventral and dorsal horn?

Answer 4

Ventral horn (front) contain cell bodies of MN, Dorsal horn (back) receives sensory info from receptors.

Question 5

What are the types of LMN?

Answer 5

Alpha and Gamma.

Question 6

What are the two muscle types of skeletal muscle? What are the MN controlling them?

Answer 6

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.

Question 7

What is alpha-gamma coactivation?

Answer 7

Signal sent to both alpha and gamma, seen in stretch reflex.

Question 8

What is the implication of continued oscillation of leg after patellar reflex?

Answer 8

Issue with coordination of inhibition of movement, UMN or cerebellar impairment.

Question 9

What are two examples of UMN lesions?

Answer 9

Cerebral infarction, corticospinal tract.

Question 10

What are two examples of LMN lesions?

Answer 10

Peripheral nerve, nerve root.

Question 11

What are the symptoms of UMN lesions?

Answer 11

Increased muscle tone, reflexes, no fasciculations(involuntary muscle twitch), no muscle atrophy.

Question 12

What are the symptoms of LMN lesions?

Answer 12

Decreased muscle tone, reflexes, fasciculation (involuntary muscle twitch) present, muscle atrophy present.

Question 13

What is ALS?

Answer 13

Amyotrophic Lateral Sclerosis, progressive neurodegenerative disease with no known cure.

Bilateral degeneration of UMN and LMN, more likely sporadic rather than hereditary.

Question 14

What are the two types of ALS onsets?

Answer 14

Limb onset: appear in limbs, most common

Bulbar onset: appear in face or neck, faster progression

Can include multiple focal onsets.

Question 15

What is SMA?

Answer 15

Spinal Muscle Atrophy, defect in SMN1 gene (survival of motor neuron protein) essential for production of SMN. Autosomal recessive.

Question 16

What is autosomal recessive inheritance?

Answer 16

Non-sex, inheritance where two copies must be present (both parents are carriers).

Question 17

What are the S&S of SMA?

Answer 17

Areflexia, muscle weakness, hypotonia, fasciculations, (LMN affected). Bell-shaped torso, compromise of the intercostal muscles for breathing.

Question 18

What are the 4 types of SMA?

Answer 18

Infantile, intermediate, juvenile, adulthood.

Question 19

What is Werdnig-hoffman?

Answer 19

Infantile SMA, onset 0 to 6 month, floppy baby.

Question 20

What is Dubowitz?

Answer 20

Intermediate SMA, onset 6-18 month, impaired walking + muscle weakness.

Question 21

What is Kugelberg-Welander?

Answer 21

Juvenile SMA, onset 18+ months, compromised walking.

Question 22

What is adulthood SMA?

Answer 22

Onset in adulthood, weakness in muscles, compromised mobility.

Question 23

What is the Apgar score?

Answer 23

Assess newborn babies, heart rate, breathing, muscle tone, reflexes, skin color, out of 10.