Lower Motor Neurons

Front 1

what is the term for the alpha motor neuron and all the muscle fibers it innervates?

Back 1

motor unit

Front 2

the final common pathway for movement is what?

Back 2

the alpha motor neuron

Front 3

muscle tone is regulated by what?

Back 3

CNS centers especially through the gamma motor neurons

Front 4

axial muscles are innervated by alpha motor neuron nuclei from where?

Back 4

the medial nucleus of the anterior horn

Front 5

limb muscles are innervated by alpha motor neuron nuclei from where? At what spinal levels are these nuclei found?

Back 5

the lateral nuclei of the limb muscles. C5 to T1 and L1 to S4.

Front 6

the spinal accessory nucleus is found where?

Back 6

in the cord at levels C1 to C6

Front 7

all motor activities exhibit reciprocal innervation via interneurons found where?

Back 7

the intermediate zone of the cord

Front 8

what cells make recurrent inhibition of motor neurons possible? Where is recurrent inhibition found in the CNS?

Back 8

the inhibitory interneurons called renshaw cells. Throughout the CNS

Front 9

describe the path (including nuclei) of the gag reflex.

Back 9

The pharynx or palate stimulates the glossopharyngeal which synapses on the Nu solitarius and then sends an interneuron which forks to go to both Nu ambiguuses to stimulate the vagus to contract the pharyngeal and palatal muscles.

Front 10

distinguish between an indirect (consensual) reflex and direct reflex.

Back 10

direct is muscle action on the same side of the body that initially sensed to do the reflex while consensual is the contralateral muscle action (ex. is with corneal and gag reflexes)

Front 11

describe the path (including nuclei) of the corneal reflex.

Back 11

the opthalmic nerve senses croneal touching and synapses in the spinal nu of trigem and then sends an interneuron that forks to both motor nuclei of the facial and the alpha motor neurons signal for the orbicularis oculi to contract

Front 12

what are the spinal levels and names of the nerves containing the alpha motor neurons stimulated for the following reflexes: biceps, brachioradialis, triceps, patellar, achilles, and the jaw jerk?

Back 12

C5, musculoskeletal
C6 radial
C7 radial
L4 femoral
S1 achilles
trigeminal

Front 13

distinguish between fasciculations and fibrillations.

Back 13

fasciculations are spontaneous contractions involving one or more motor units that can be seen through the skin. Fibrillations are spontaneous contractions of individual muscle fibers that can only be detected through elctromyography

Front 14

lower motor lesions are located where in relationship to the deficit observed?

Back 14

on the same side and same level

Front 15

what disease leads to loss of voluntary muscle control by causing lesions on the lower and upper motor neurons?

Back 15

amyotrophic lateral sclerosis

Front 16

A tibial nerve lesion would cause what? where on the cord (if on the cord) would the lesion be located?

Back 16

flaccid paralysis and atrophy of gastroc and soleus, dorsiflexion of foot, shortening of extensor tendons, arthritic changes with pain, and impaired plantar flexion. Level of the sacral enlargement

Front 17

a lesion of the median nerve would cause what? If on the cord, where would this lesion be located?

Back 17

flaccid paralysis and atrophy of thenar emminence, wrist and finger flexors of digits 1 to 3. wrist and finger flexion impaired as well as thumb movement. Extension of digits 1through 3 and shortening of extensor tendons. Level of cervical enlargement.

Front 18

a lesion to the spinal accessory nerve would do what? where in the CNS would this lesion be located (if in CNS)?

Back 18

Flaccid paralysis and atrophy of sternocleidomastoid and trapezius resulting in impaired shoulder rising and turning head to contralateral side. Level of rostral cord to caudal medulla.

Front 19

what would a lesion to the hypoglossal do? Where in the CNS would this lesion be located?

Back 19

flaccid paralysis and atrophy of ipsilateral tongue musculature resulting in dysarthria and deviation of tongue ipsilaterally. Found at mid medulla.

Front 20

what would a lesion to the vagus nerve do? where in the CNS would this lesion be located?

Back 20

flaccid paralysis of the pharynx, larynx, and palate musculature ipsilaterally resulting in dysphonia (weak voice), dysphagia (impaired swallowing), contralateral deviation of the uvula, and impaired gag reflex. Level of mid medulla

Front 21

what would a lesion of the facial nerve do? where would this be located in the CNS?

Back 21

flaccid paralysis and atrophy of the muscles of facial expression, stylohyoid, posterior belly of digastric, and stapedius muscles resulting in facial paralysis (Bell's palsy), facial drooping, widening of palprebal fissure, hyperacusis (increased sensitivity to loud sounds), and impaired corneal reflex. located in the caudal pons.

Front 22

what pathogen can cause bell's palsy?

Back 22

herpes simplex virus

Front 23

what would a lesion to the trigeminal nerve do? where in the CNS would this lesion be located?

Back 23

flaccid paralysis and atrophy of muscles of mastication and MATT muscles thus impaired chewing, deviation of jaw ipsilaterally, impaired jaw jerk reflex and possible impairment of corneal reflex. located at the mid pons

Front 24

opthalmoplegia and diplopia are consistant with what cranial nerve lesions?

Back 24

abducens, trochlear, and occulomotor

Front 25

what would a lesion to the abducens nerve do? what level of the CNS would the lesion be located?

Back 25

flaccid paralysis and atrophy of the lateral rectus muscle, thus internal strabismus (medial deviation of ipsilateral eye). Located in the caudal pons.

Front 26

what would a lesion to the trochlear nerve do? where in the CNS would this be located?

Back 26

flaccid paralysis and atrophy of superior oblique nerve thus impaired ipsilateral downward gaze and eyeball slightly extorted. Note the trochlear nerve is weird bc it exits the brainstem posteriorly and the must cross to the contralateral side to reach its nucleus. Location is on the midbrain (inferior colliculi).

Front 27

what would a lesion to the occulomotor nerve do? where would this lesion in the CNS be located?

Back 27

flacid paralysis and atrophy of all the eye muscles this guy innervates. Thus external strabismus (lateral deviation of the left eye) and ptosis of eyelid. Note that parasympathetic defects may also be present. This lesion is in the midbrain (superior colliculus).