Nuclei

Question 1

Pyramidal tract (includes small component of the corticobulbar tract)

Answer 1

Mediates voluntary control of movement of the limbs and motor functions of CN IX, X, and XII

Upper motor neuron paralysis affecting the limbs and disruption of motor functions associated with CN IX, X, and XII

Question 2

Medial lemniscus

Answer 2

Transmits conscious proprioception, pain and temperature from the body and limbs to the thalamus (and then to cerebral cortex)

Loss of conscious proprioception and some pain and temperature from the body and limbs; some ataxia of movement

Question 3

Medial longitudinal fasciculus

Answer 3

Ascending component is present at this level only: Regulates position of the eyes in response to vestibular input

Impaired adduction of eye contralateral to lesion; nystagmus

Question 4

Descending tract of CNV (in caudal pons only)

Answer 4

First-order neuron mediating somatosensory (especially pain and temperature) sensation from the head to brain

Loss of pain and temperature sensation from the ipsilateral head region

Question 5

Lateral spinothalamic tract

Answer 5

Mediates pain and temperature sensation from the body

Question 6

Trapezoid body

Answer 6

Mediates auditory signals from cochlear nuclei to the superior olivary nucleus

Likely partial CNS auditory deficits

Question 7

Rubrospinal tract

Answer 7

Facilitates flexor motor neurons

Unknown, because pure rubrospinal tract lesions have not been reported

Question 8

Medial reticulospinal tract

Answer 8

Facilitates muscle tone via their actions upon alpha and gamma motor neurons

Specific lesions of this pathway have not been reported but, in theory, loss of such inputs from this pathway to spinal cord might produce hypotonia

Question 9

Transverse pontine fibers

Answer 9

Mediates fibers from deep pontine nuclei to cerebellum as part of a two-neuronal pathway linking the cerebral cortex with cerebellar cortex

Largely unknown, but lesions of this pathway would likely affect coordination of purposeful movements associated with cerebellar functions

Question 10

Vestibular nuclei (lateral and superior)

Answer 10

Transmits vestibular inputs to spinal cord, cranial nerve nuclei mediating eye movements (i.e., CN VI, IV, and III), and to cerebellum

Nystagmus; impaired adduction of eye contralateral to lesion; possible ataxia due to loss of input to cerebellum

Question 11

Deep pontine nuclei

Answer 11

Origin of transverse pontine fibers that pass through middle cerebellar peduncle to cerebellar cortex, mediating inputs from cerebral cortex to cerebellar cortex

Largely unknown, but lesions of this pathway would likely affect coordination of purposeful movements associated with cerebellar functions

Question 12

Reticular formation

Answer 12

Nuclei and fibers mediating varieties of functions such as sleep and wakefulness, sensory, motor, and autonomic functions

Mainly loss of consciousness

Question 13

Abducens nucleus (CN VI)

Answer 13

Mediates lateral movement of the ipsilateral eye

Inability of ipsilateral eye to abduct, producing strabismus (inability of both eyes to focus on the same object)

Question 14

Facial nucleus and nerve (CN VII)

Answer 14

Motor nucleus mediates facial expression; superior salivatory nucleus (parasympathetic innervations of salivatory, pterygopalatine, lacrimal, and palatine glands)

Question 15

Main sensory nucleus (CN V)

Answer 15

Second-order neuron mediating somatosensory sensation from the head regions to thalamus and then to cerebral cortex

Loss of somatosensory sensation from the head on the side ipsilateral to the lesion

Question 16

Motor nucleus (CN V)

Answer 16

Mediates muscles of mastication (and jaw-closing reflex)

Loss of jaw-closing reflex

Question 17

Mesencephalic nucleus (CN V)

Answer 17

Mediates unconscious (from mainly muscle spindles of the jaw) to cerebellum and motor nucleus of CN V, contributing to monosynaptic jaw-closing reflex

Loss or disruption of jaw-closing reflex

Question 18

Nucleus locus ceruleus and raphe nuclei

Answer 18

Origin of major norepinephrine and serotonin innervations of the CNS, respectively

Disruption of sleep and wakefulness and varieties of other functions, in particular, those associated with control over emotional behavior

Question 19

Solitary nucleus

Answer 19

Mediates cardiovascular functions and also serves as a relay nucleus for taste impulses to the thalamus

Disruption of cardiovascular regulation and taste sensation

Question 20

Anterior, posterior, and flocculonodular lobes

Answer 20

Three lobes of cerebellum which receive selective inputs from spinal cord (mainly from anterior lobe), brainstem (anterior and posterior lobe), vestibular structures (flocculonodular lobe), and cerebral cortex (mainly posterior lobe) for regulation of balance, coordinated movements, and muscle tone

Depending upon the regions affected, lesions may cause loss of balance, hypotonia, or loss of coordination of movements

Question 21

Middle cerebellar peduncle

Answer 21

Transmits inputs arising from the contralateral deep pontine nuclei to cerebellar cortex (comprising a disynaptic pathway from the cerebral cortex to cerebellar cortex)

Question 22

Superior cerebellar peduncle

Answer 22

Major efferent pathway of cerebellar cortex whose axons target the red nucleus and thalamus (ventrolateral nucleus)

Believed to disrupt coordinated movements associated with functions of the cerebellum

Question 23

Dentate, interposed, and fastigial nuclei

Answer 23

Deep cerebellar nuclei; dentate and interposed nuclei project through superior cerebellar peduncle, targeting the red nucleus and thalamus, respectively (presumably for coordination of movements); fastigial nucleus projects to lower brainstem neurons, such as reticular formation and vestibular nuclei for regulation of muscle tone and balance

Loss of functions associated with cerebellum (i.e., coordination of movements, nystagmus, ataxia of movement, hypotonia)