CNS Part 3 Flashcards
While the Corticospinal (Anterior & Lateral) and Corticobulbar
Pathways regulate the activity of the LMN, there are other descending
motor pathways that originate in the brainstem that regulate the —,
too.
LMN
The UMN from each of
these tracts synapse with
the LMN in the
ventral gray
horn (*) of the spinal cord
indirect tract: rubrospinal
location of UMN:
site of cross over:
function:
location of UMN: red nucleus in midbrain
site of cross over: midbrain
function: upper limb muscle tone and movement
indirect tract: tectospinal
location of UMN:
site of cross over:
function:
location of UMN: midbrain (superior and inferior colliculi)
site of cross over: midbrain
function: regulation of eye head, neck, and UL position in response to visual and auditory stimuli
indirect tract: vestibulospinal
location of UMN:
site of cross over:
function:
location of UMN: vestibular nucleus (pons and medulla)
site of cross over: none, control ipsilateral muscles
function: regulation of balance and muscle tone
indirect tract: reticulospinal
location of UMN:
site of cross over:
function:
location of UMN: medial RS (pons +) lateral RS (medulla -)
site of cross over: none, controls ipsilateral muscles
function: regulates muscles of the trunk and limbs maintaining posture and tone in response to ongoing body movements
The red nucleus in the
midbrain/mesencephalon receives fibers from
the
primary motor cortex (corticorubral tract)
The red nucleus give rise to the
— —, which crosses to
the opposite side of the brainstem and travels
alongside the corticospinal tract into the
lateral columns of the spinal cord
RUBROSPINAL TRACT
Rubrospinal Pathway functions as an
accessory route for transmission of signals from the primary motor cortex to the spinal cord. Fibers terminate on interneurons and motor neurons of the spinal cord involved in upper limb muscle tone and movement.
The TECTOSPINAL Tract arises
from the
superior and inferior colliculi
midbrain
the tectospinal pathway regulates the (4)
eye, head, neck and upper limb position in response to visual (superior
colliculus) or auditory (inferior colliculus) stimuli.
The Vestibular Nuclei (in Pons and Medulla Oblongata) transmit excitatory signals through the --- --- to control antigravity muscles (proximal limb extensors and head/neck muscles) to maintain balance and muscle tone.
VESTIBULOSPINAL
Tracts
Vestibulospinal Pathway controls
muscles on the same side of the
body (these fibers to not decussate)
Reticulospinal Pathway
Medial -
Lateral -
Pontine
Medullary
Pontine RS pathway activates
axial muscle of the body
(muscles of the vertebral column and extensors of the
limbs). Have a high degree of background activity.
Regulated by the Vestibular nuclei, cerebellar nuclei
and cerebral cortex.
Medullary RS pathway is an
antagonist to the activity of
the Pontine RS Pathway. The medullary reticular nuclei
receive strong input from the corticospinal tract and
rubrospinal tract.
Reticulospinal Pathway controls muscles on the
same side of the body (these fibers to not decussate)
UMN Activity is Regulated by the — — via
the Thalamus
Basal Nuclei
The Basal Nuclei are involved in
initiating and terminating movements,
suppressing unwanted movements and
establishing a normal level of muscle
tone
Parkinson’s Disease
A Hypokinetic Disorder • Loss of Dopaminergic neurons from the Substantia Nigra that project to the Striatum, where they inhibit Cholinergic neurons. • Clinical Manifestations: Bradykinesia, Cogwheel Rigidity, Pill Rolling, Tremor, Shuffling Gate, Stooped Posture, Depression, Dementia
Tremor can impact the tongue and lips
impacting
mastication, swallowing and speech.
Most common oral manifestations due to the
medications (targeted at dopamine) include
difficulty with oral hygiene, xerostomia, burning
mouth/mucositis, difficulty swallowing, drooling
and less caries/more teeth than age-matched
controls.
Huntington Disease
A Hyperkinetic Disorder • Autosomal Dominant Genetic Disease • Loss of GABAergic neurons, resulting in reduced inhibitory output from the Striatum. • Clinical Manifestations: Chorea (multiple, rapid, random movements), athetosis (slow writhing movements), personality changes, dementia
Grimacing, speech difficulties and
dysphagia can occur. Treatment can be
hindered by
involuntary mouth and jaw
movements. Sedation may be required for
treatment of some patients.
UMN Activity is Regulated by the — via
the Thalamus
Cerebellum
The Cerebellum is involved in
monitoring differences
between intended movements and movements actually
performed. It issues commands to UMN to reduce errors
in movements. It also coordinates body movements to
maintain normal posture and balance.
functional zone: spinocerebellum location in cerebellum: receives input from: function: effect of lesions:
location in cerebellum: vermis (trunk and proximal limbs) and intermediate zones (distal limbs)
receives input from: muscle spindles and GTOs via spinocerebellar tracts
function: coordination of body and limb movement; maintenance of muscle tone
effect of lesions: ataxia dysmetria intention tremor hypodontia
functional zone: vestiulocerebellum location in cerebellum: receives input from: function: effect of lesions:
location in cerebellum: flocculonodular lobe
receives input from: vestibular nuclei CN VIII, superior colliculi, and visual cortex
function: balance and eye movements
effect of lesions: vertigo, nystagmus
functional zone: cerebrocerebellum location in cerebellum: receives input from: function: effect of lesions:
location in cerebellum: lateral zones
receives input from: cerebral cortex and inferior olivary nucleus in medulla
function: planning and execution of movement; coordinating complex sequential movements
effect of lesions: abnormal coordination of ipsilateral movements, dysdiadochokinesia, dysmeria, intention tremor
Cerebellar diseases result in (3)
alterations
in gait, balance and coordination of
motor activities; not paralysis
functional zone: spinocerebellum
location in cerebellum:
function:
location in cerebellum: vermis (trunk and proximal limbs) and intermediate zones (distal limbs)
function: coordination of body and limb movement; maintenance of muscle tone
functional zone: vestibulocerebellum
location in cerebellum:
function:
location in cerebellum: flocculonodular lobe
function: balance and eye movements
functional zone: cerebrocerebellum
location in cerebellum:
function:
location in cerebellum: lateral zones
function: planning and execution of movements; coordinating complex sequential movements
Lesions of the medial part of cerebellum (vermis, flocculonodular lobe, and corresponding deep nuclei) affect
medial structures (i.e., axial and proximal limb musculature), resulting in symptoms including trunk ataxia and nystagmus.
Lesions of the lateral parts
of cerebellum (lateral
zones)
affect
lateral structures (distal limb musculature), resulting in symptoms such as ipsilateral limb ataxia.
The vestibulocerebellum is not shown in this diagram. It receives input from the
vestibular system and it adjusts the action of the Reticulospinal and vestibulospinal pathways.
The tectospinal tract is not shown here, but it rises from the
superior colliculus (midbrain) and it causes head turning in response to sudden visual or auditory stimuli.
