Descending

Question 1

Large pyramidal cells of the cortex that stays in the CNS and synapses with lower motor neurons

Answer 1

Upper motor neurons

Question 2

Motor neurons that start in CNS and goes to muscle

Answer 2

Lower Motor neurons

Question 3

Tracts with upper motor neurons

Answer 3

Corticospinal

Corticobullar

Question 4

Lower motor neurons are present where?

Answer 4

Brainstem and spinal cord

Question 5

Cell columns and what they innervate?

Answer 5

Dorsal medial=intercostal, rectus abdominis- flexors

Ventral medial=erector spinae- extensor

Intermediolateral=autonimic visceral

Central=C3,4,5-diaphragm

Ventral lateral=flexors arm/thigh,extensor arm/thigh

Dorsolateral=extensors/flexors forearm/leg

Retrodorsal=flexors/extensors hand/foot

Question 6

3 cell types and their function

Answer 6

Alpha=lower motor neuron going to muscle

Gamma Motor= motor neuron going to intrafusal muscle cells. Also part of stretch receptor

Renshaw= interneurons that inhibit alpha motor neurons as part of neg feedback loop

Question 7

Pyramidal system

60-80% from primary motor cortex—> through coronal radiata/internal capsule—> crus cerebri—> pontine corticospinal fibers—> once in medulla called the pyramid

Answer 7

Corticospinal spinal tract

Question 8

What percent of corticospinal tract fibers decussate at pyramidal decussation?

Answer 8

80% as lateral corticospinal

Question 9

What percentage of corticospinal tract fiber continue as anterior corticospinal?

Answer 9

20%, however 13-15% eventually cross and 5-8% remain ipsilateral

Question 10

Where do the anterior corticospinal tract cross?

Answer 10

Ventral Gray commissure

Question 11

Targets of the lateral corticospinal

Answer 11

Limb motor neurons

Renshaw cells

Excitatory interneurons

Presynaptic inhibitory neuron

Question 12

Function of the reticulospinal tract

Answer 12

Maintain tone

Locomotion

Posture

Question 13

Two reticulospinal tracts

Answer 13

Medullary(lateral)

Pontine (medial)

Question 14

This tract is the dorsal part of the midbrain with fibers that crossed and its function is to act on axial motor neurons turning the head towards a stimulus

Answer 14

Tectospinal

Question 15

What is the path of travel for the tectospinal

Answer 15

From tectum(midbrain) —> C5

Question 16

This tract has fibers that are uncrossed

Functions for maintaining center of gravity (balance)

Starts in the lateral vestibular nucleus

Innervates muscles surrounding vertebrae

Answer 16

Vestibulorspinal

Question 17

This tract begins in the raphe nucleus

Travels to dorsolateral/posterolateral tract of Lissuar where the 1st order neurons enter

Has inhibitory function on the information between 1st and 2nd order neurons

Limits pain (analgesic affect)

Doesn’t have a motor function

Answer 17

Raphespinal

Question 18

What are the aminergic pathway?

Answer 18

Serotonin(5-HT)-raphespinal

Adrenergic-autonomic function

Noradrenergic-autonomic function

Question 19

Pathway with fibers that descend in intermediate gray matter (lamina 7)

In the intermediolateral cell column (preganglionic)
*Ex. Sympathetic (baroreflex)-T1-L2
Parasympathetic (Bladder function)-sacral

Answer 19

Central autonomic pathways