Function: mediates voluntary control of movement of the limbs and motor functions of CN IX, X, and XII.

Lesion: UMN paralysis affecting limbs and disruption of motor functions associated with CN IX, X, and XII.

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

Lesion: Loss of conscious proprioception, some pain and temperature from body and limbs; some ataxia of movement

Function: Signals from descending component (present at level of medulla) result in changes in position of the head in response to vestibular input; Ascending component regulates position of the eyes in response to vestibular input.

Lesion: Impaired adduction of eye CONTRALATERAL to lesion; nystagmus; possible disruption of reflexes mediating adjustment of head and neck in response to changes in posture.

Function: 1st-order neuron mediating somatosensory (esp. pain and temp) sensation from head to brain.

Lesion: loss of pain and temp. sensation from head region.

Function: mediates pain and temp sensation from body

Lesion: Loss of pain and temp sensation for OPPOSITE side of body.

Function: anterior and posterior spinocerebellar tracs mediate unconscious proprioception to cerebellum.

Lesion: Unknwon, because pure spinoerebellar tract lesions have not been reported, but it is believed that loss of spinocerebellar inputs may contribute to cerebellar disorders, i.e. hypotonia.

Function: Facilitates flexor motor neurons.

Lesion: Unknown, because pure rubrospinal tract lesions have not been reported.

Function: Modulates muscle tone via their actions upon alpha and gamma motor neurons.

Lesion: May contribute to spasticity and hypertonicity present in stroke patients.

Function: 2nd-order neuron mediating somatosensory sensation (esp. pain and temp) from head regions to thalamus and then to cerebral cortex.

Lesion: Loss of pain and temp sensation from the head.

Function: Cell body origin of CN XII that mediates movements of the tongue.

Lesion: deviation of tongue to SIDE OF LESION.

Function: 2nd-order neuron mediating conscious proprioception, vibration sensation and tactile impulses to the thalamus and then the cerebral cortex form lower and upper limbs, respectively.

Lesion: Loss of conscious proprioception from different limbs of the IPSILATERAL SIDE of body, some ataxia may be present as well.

Function: A key relay nucleus mediating information form red nucleus and spinal cord to cerebellum.

Lesion: unknown.

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

Lesion: Nystagmus, impaired adduction of eye CONTRALATERAL to lesion, possible ataxia due to loss of input to cerebellum.

Function: origin of parasympathetic inputs to heart, guy and other visceral organs.

Lesion: Disruption of parasympathetics.

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

Lesion: Disruption of cardiovascular regulation and taste sensation.

Function: Origin of MOTOR outputs from CN IX and X to larynx and pharynx.

Lesion: Dysphonia, hoarseness, difficulty in swallowing, asphyxia, oss of gag reflex.

Function: Mediates a wide variety of functions (i.e. motor, sensory, autonomic, behavioral, including sleep and wakefulness).

Lesion: Loss of consciousness and other functions that affect sensory, motor, autonomic and behavioral processes.

Function: Relay nucleus for transmission of auditory impulses from inner ear to higher regions of CNS.

Lesion: Partial deafness.

- DISSOCIATION of function between conscious proprioception and pain/temp sensations.

- Ipsilateral UMN paralysis below level of lesion

and ipsilateral LMN paralysis at level of lesion.

- Loss of conscious proprioception and two-point discrimination on the ipsilateral side below the level of the lesion

- Loss of pain and temperature sensation on the contralateral side one or two segments below the level of the lesion, and bilaterally at level of lesion.

Below level of transection:

- Loss of muscle tone

- Loss of motor function

- Loss of reflex activity

- Loss of visceral sensation

- Loss of somatic sensation

- Loss of bladder and bowel function (autonomics)

- First 1-6 weeks, spinal shock (attenuated reflexes)

- Then, Babinski sign positive, alternate flexor and extensor spasms, esp. extensors.

- FASCICULUS GRACILIS degeneration

- Loss of vibration sensation, two-point discrimination, and conscious proprioception

- Some ataxia. The loss of conscious proprioception results in ataxia

- Vit B12 absorption deficiency

- Degeneration in dorsal and lateral funiculi

- Paresthesia and Loss of vibration and conscious proprioception (dorsal columns)

- Weakness and ataxia in lower limbs

- Loss of UMN function (corticospinal)

- Pernicious anemia may also be seen

- Lesion to one dorsal root - not much

- Lesion to three consectutive dorsal roots = abolition of all sensory coming from a dermatome

- Loss of muscle tone in dermatome (reflexes interrupted)

- No motor functions of the muscles innervated by the affected segment

(cervical - hand muscles; thoracic - visceral organs)

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

Lesion: Largely unknown, but lesions would like affect coordination of purposeful movements associated with cerebellar functions.

Function: Transmits verstibular inputs to - spinal cord, cranial nerve nuclei mediating eye movement (CN III, IV, and VI) and cerebellum.

Lesion: Nystagmus, imparied adduction of eye contralateral to lesion, possible ataxia due to loss of input to cerebellum.

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

Lesion: Largely unknown, but lesions of this pathway would likely affect coordination of movements associated with cerebellar function.

Lateral Medullary Syndrome

Common cause: occlusion of PICA or vertebral artery

1) Vestibular nuclei -nystagmus, imbalance, vertigo

2) Spinal tract and nucleus of CN V - decreased ipsilateral facial sensation and corneal reflex

3) Nucleus ambiguus - dysphagia, dysathria (motor weakness in palate, larynx, and pharynx)

4) Dorsal nucleus of CN X - tachycardia, abnormal breathing

5) Inferior cerebellar peduncle - ataxia, ipsilateral incoordination

6) Spinothalamics - contralateral loss of pain/temp

7) Central sympathetics -ipsilateral Horner's syndrome

8) Nucleus solitarius - decreased taste

Medial Medullary Syndrome

Causes: obstruction of vertebral artery (paramedian branches)

1) Medial lemiscus - contralateral tactile and vibration sensation, conscious proprioception

2) Pyramid - contralateral hemiplegia, Babinski sign

3) Hypoglossal nerve - tongue deviates to side of lesion and atrophy

Cause: Obstruction of basilar artery (short and circumferential branches)

1) MLF - nystagmus, abnormal gaze

2) Nucleus of CN VI - ipsilateral lateral rectus weakness

3) Nucleus of CN VII - ipsilateral facial weakness

4) Spinal nucleus and tract of CN V - ipsilateral loss of facial sensation and corneal reflex

5) Medial lemniscus - contralateral loss of tactile/vibration sensation and conscious proprioception

6) Lateral lemniscus - (usually no clinical hearing loss)

7) Spinothalamic - contralateral loss of pain/temp

8) Central sympathetics - ipsilateral Horner's syndrome

9) Vestibular nuclei - vertigo

10) Middle cerebellar peduncle - ipsilateral incoordination

"Locked-in" syndrome

Cause: obstruction of basilar artery (circumferential branch)

1) Pyramids (corticospinal/bulbar) - contralateral hemiparesis

2) Abducens nerve - ipsilateral weakness of lateral rectus

Causes: obstruction of basilar artery (paramedian and short circumferential branches)

1) Middle cerebellar peduncle - ipsilateral incoordination

2) CN V - Ipsilateral loss of facial sensation and chewing weakness

3) Corticospinal tract - contralateral hemiparesis

Cause: obstruction of basilar artery (long circumferential branch)

1) Motor nucleus of CN V - Ipsilateral weakness in chewing muscles

2) Sensory nucleus of CN V - Ipsilateral loss of facial sensation

3) Spinothalamic - Contralateral pain/temp loss

4) Medial lemniscus - Contralateral loss tactile/vibration, conscious proprioception

Midbrain Peduncle Syndrome

Cause: obstruction of posterior cerebral a. (deep branches) or posterior choroidal a.

1) CN III - ipsilateral oculomotor weakness, dilated pupils

2) Crus cerebri - contralateral hemiparesis

Red Nucleus Syndrome

Causes: obstruction of basilar a. (interpeduncular branches) or posterior cerebral a. (deep branches)

1) Red nucleus - contralateral hyperkinesia (chorea, athetosis)

2) Medial lemniscus - contralateral loss of tactile/vibration, conscious proprioception

3) CN III - ipsilateral dilated pupil, oculomotor weakness

Function: Mediates lateral movement of ipsilateral eye.

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

Function: Motor nucleus - mediates facial expression;

Superior salivatory nucleus - parasympathetic innervations of salivatory pterygopalatine, lacrimal and palatine glands

Lesion: Loss of ipsilateral facial expression and diminished salivation

Function: 2nd-order neurons mediating somatosensory sensation from the head regions to the thalamus and cerebral cortex

Lesion: Ipsilateral loss of sensation from head

Function: Mediates muscles of mastication

Lesion: Loss of jaw closing reflex

Function: Monosynaptic jaw-closing reflex; mediates unconscious proprioception from muscle spindles of jaw to motor nucleus of CN V and cerebellum

Lesion: Loss of jaw closing reflex

Function: Origin of major norepinephrine and serotonin innervations of CNS, respectively.

Lesion: Disruption of sleep wakefulness and varieties of other functions, esp. control over emotions.

Function: Mediates cardiovascular functions and also serves as relay nucleus for TASTE impulses to thalamus

Lesion: disruption of cardiovascular regulation and taste sensation

Function: to receive inputs

Anterior lobe - spinal cord and brainstem

Posterior lobe - brainstem and cerebral cortex

Flocculonodular lobe - vestibular structures

Lesion: Loss of balance, hypotonia, incoordinated movements (depends on regions affected)

Function: Transmit inputs from CONTRALATERAL DEEP PONTINE NUCLEI to cerebellar cortex (disynaptic pathway from cerebrum to cerebellum)

Lesion: Largely unknown, but probably affect coordination of purposeful movements associated with cerebellar functions

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

Lesion: Believed to disrupt coordinated movements associated with functions of cerebellum

Function: Dentate and interposed nuclei - project through superior cerebellar peduncle, targeting the red nucleus and thalamus, respectively (coordination of movements)

Fastigial nucleus - project to lower brainstem neurons, i.e. reticular formation, vestibular nuclei (muscle tone and balance)

Lesion: loss of functions associated with cerebellum (coordination, nystagmus, ataxia, hypotonia)

Function: contains corticobulbar, corticospinal and corticopontine fibers

Lesion: UMN paralysis affecting limbs and disruption of motor functions associated with cranial nerves

Function: Site of descending sympathetic fibers to lower brainstem autonomic neurons;

Site of descending fibers mediating inhibition of pain, regulationof emotional behavior (i.e. fear, flight, anxiety, rage)

Lesion: Disruption of sympathetic regulation, possibly Horner's; disruption of expression of some meotional behaviror and pain inhibitory pathway (intense pain following nociceptive stimulation)

Function: Gives rise to rubrospinal tract, facilitates contralateral flexor motor neurons

Lesion: largely unknown, but likely affect coordination of purposeful movements associated with cerebellar functions

Function: mediates medial movement of ipsilateral eye

Lesion: Diplopia, esp. when downward gaze is attempted

Function: contains both GSE (most extraocular eye muscles) and GVE (ciliary ganglion and constrictor/radial muscles of eye) for control of accommodation and pupillary light reflexes, respectively

Lesion: Loss of ability to direct eye medially and loss of up/down movment; disruption of pupillary and accommodation reflexes.

Function: Auditory relay nuclues mediating auditory signals to medial geniculate nuclues of thalamus

Lesion: some CNS hearing loss

Function: receives some visual inputs form optic tract fibers, descending fibers from tectospinal tract, which plays a role in tracking movements of the eyes and reflex movements of the head/neck

Lesion: largely unknown

Function: contains both dopaminergic (pars compacta) and GABAergic (pars reticulata) neurons for regulation of motor control.

Dopamingeric - project to neostriatum

GABAergic - project to thalamus

Lesion: loss of pars compacts results in Parkinson's disease

Receives: the mamillary bodies and the hippocampus (mamillothalamic tract)

Main target : cingulate gyrus.

Receives: motor inputs from substantia nigra and globus pallidus

Receives: Motor inputs from substantia nigra, globus pallidus, and cerebellum

Projects to: primary motor cortex and premotor cortex

Receives: Spinothalamic and medial lemniscus tracts.

Projects to: primary somatosensory cortex