Motor Pathways

Question 1

Spinal cord parts:

1. Conus medullaris
2. Filum terminale
3. Cervical and lumbar enlargements
4. Cauda equina

Answer 1

1. Inferior end of spinal cord
2. Long filament of connective tissue that attaches to the coccyx inferiorly
3. Where nerves for upper or lower limbs arise
4. Collection of spinal nerve roots

Question 2

Dorsal vs ventral root

Answer 2

D: contains sensory fibers, cell bodies located in dorsal root ganglion
V: contains motor fibers arising from anterior gray column

Question 3

Rami communicantes

Answer 3

Connect to the base of the ventral ramus

Leads to the sympathetic chain ganglia

Question 4

Monosynaptic (knee-jerk) stretch reflex

Answer 4

2 neurons and a single synapse

Question 5

Polysynaptic withdrawal reflex

Answer 5

Has more than 2 neurons and so has at least 2 synapses

In pain

Question 6

Lumbar cistern

Answer 6

Enlargement of the subarachnoid space between the conus medullaris of spinal cord and inferior end of subarachnoid space and dura mater

Question 7

Pyramidal path:
Lateral corticospinal
(location (funiculus), origin, termination, function)

Answer 7

L: lateral
O: Pyramidal neurons of motor cortecx of the cerebrum, cross over in pyramids of the medulla
T: By synapse with ventral horn interneurons that influence motor neurons, and occasionally with ventral horn motor neurons directly
F: Transmits motor impulses from cerebrum to spinal cord motor neurons (which activate skeletal muscles on opposite side of body); voluntary motor tract to limb muscles

Question 8

Pyramidal path:
Ventral corticospinal
(location (funiculus), origin, termination, function)

Answer 8

L: Ventral
O: pyramidal neurons of motor cortex, cross over at spinal cord level
T: By synapse with ventral horn interneurons that influence motor neurons, and occasionally with ventral horn motor neurons directly
F: Transmits motor impulses from cerebrum to spinal cord motor neurons (which activate skeletal muscles on opposite side of body); voluntary motor tract to axial muscles

Question 9

Rubrospinal path
(location (funiculus), origin, termination, function)

Answer 9

L: Lateral
O: red nucleus of midbrain, fibers cross just inferior to red nucleus
T: ventral horn - as others
F: Transmits motor impulses concerned with muscle tone of distal limb muscle (mostly flexor) on opposite side of body

Question 10

Tectospinal path
(location (funiculus), origin, termination, function)

Answer 10

L: ventral
O: superior colliculus of midbrain, fibers cross
T: ventral horn - as others
F: Turns neck so eyes can follow a moving object

Question 11

Vestibulospinal path
(location (funiculus), origin, termination, function)

Answer 11

L: ventral
O: Vestibular nuclei in medulla of brain stem, fibers do not cross
T: ventral horn - same
F: transmits motor impulses that maintain muscle tone and activate limb and trunk extensors and muscles that move head - maintains balance

Question 12

Reticulospinal

location (funiculus), origin, termination, function

Answer 12

L: ventral and lateral
O: Reticular formation of brain stem, crossed and uncrosses fibers
T: ventral horn - same
F: Transmits impulses concerned with muscle tone and many visceral motor functions - may control most unskilled movements