Lecture 11: Central Control of Movement Flashcards
What structures make up the forebrain
Cerebrum, thalamus and hypothalamus
What is the major relay center of the brain, master controller
Thalamus and hypothalamus
What structure in the CNS links the brain stem and cerebrum with ascending and descending fibers. Contains visual and auditory relay circuits
Midbrain
What structure in the CNS is derived from neural tube during development
Pons and cerebellum
What structure in the CNS contains fiber tracts and relays between cerebellum and cerebrum
Pons
What is the suprasegmental structure in the brain stem
Cerebellum
What structure in the CNS contains fiber tracts that relay circuits that control breathing, HR, and visceral function
Medulla oblongata
Describe the flow of information through the brain
- Information flows from sensory neurons to
- Primary sensory cortex to
- Sensory association cortex to
- Multimodal association cortices to
- Premotor cortex to
- Primary motor cortex
What does the multimodal association cortices do
Gives meaning to information, stores information in memory, decision making areas
The multimodal association cortices relays decisions to ___
Premotor cortex
What cortex results in movement and action
Primary motor cortex
What are three other important brain circuits send information to the cortex
- Basal nuclei and cerebellum
- Limbic system
- Reticular activating network
What is the function of the parietal lobe
Auditory processing
What is the function of the occipital lobe
Visual processing
What is the function of the temporal lobe
Auditory processing and memory
What is the function of the motor cortex
Motor processing, decision making, mood
What are the three regions of the motor cortex
- Premotor
- Supplementary motor
- Primary motor
Neurons in the ____ and ___ motor areas are linked to primary motor cortex
Premotor and supplementary motor
What is the motor homunculus
Map of body on the cortex, meaning nearby neurons have similar function
UMN and LMN connect cortex to ____
Target muscles
UMN start in motor cortex and reach LMN via the ___ or ___ tracts
Corticospinal or corticobulbar
What pathway has UMN terminate in the brain stem
Corticobulbar pathway
What pathway has UMN terminate in the spinal cord
Corticospinal pathway
CN I- name and function
Olfactory- smell
CN II- name and function
Optic- vision
CN III name and function
Oculomotor- eyeball and eyelid movement, pupil contradiction, focus of the lens
CN IV- name and function
Trochlear- eyeball movement and proprioception
CN V name and function
Trigeminal- chewing, somatic sensations of the face and mouth
CN VI name and function
Abducens-eyeball movement and proprioception
CN VII name and function
Facial- facial expression, secretion of saliva and tears, taste from front of tongue
CN VIII name and function
Vestibulocochlear- hearing and equilibrium
CN IX name and function
Glossopharyngeal- swallowing and secretion of saliva. Taste from back of tongue, somatic sensation in mouth
CN X name and function
Vagus efferent output for skeletal muscles of pharynx and larynx. PNS smooth muscles and glands of abdominal cavity. Cardiac regulation. Afferent input from thoracic and abdominal organs, blood pressure monitoring
CN XI name and function
Accessory- efferent output for skeletal muscles of the pharynx, larynx, neck and shoulder
CN XII name and function
Hypoglossal- tongue movement
Describe the corticobulbar tract
- UMN arise from lateral primary motor cortex
- Synapse on LMN in brain stem
- LMN run through cranial nerves and determine motor control of head and neck
Which cranial nerves are LMN
III- VII, XI- XIII
Which cranial nerves are tested in pupillary light reflex
II and III
Which of the two, CN II or CN III is efferent
CN II- afferent
CN III= efferent
Where do UMN decussate in the corticospinal tract
Caudal end of medulla
90% of UMN in corticospinal tract do what
Decussate- Cross the midline to enter the spinal cord on opposite side
10% of UMN in corticospinal tract do what
Continue down spinal cord without crossing
LMN are ___motorneurons that innervate skeletal muscles
Alpha-motor neurons
LMN from the lateral part of the ventral horn innervate ___
Muscles of distal limbs
LMN from the medial part of the ventral horn innervate ___
Axial muscles and muscles of the proximal limbs
Where are neurons in the extrapryamidal system located
Neurons are located in the nuclei of the brain stem:
- Red nucleus
- Reticular formation
- Vestibular nucleus
- Tectum
Damage to the extrapyramidal tracts is associated with ___ and ___ pathology
Hypertonic and hypotonic pathology
What is decerebrate rigidity
Condition of increased muscle tone and stretch reflexes, particularly the extensor muscles resulting in extensor hypertonia
*absence of flexor muscle activity
What is opsithotonus
Spasm of muscles causing backward arching of head and neck
What extrapyramidal dysfunction occurs is the decerebrate rigidity (commonly a result of HBC)
Damage to red nucleus—>rubrospinal tract
What extrapyramidal neurons receive information from motor cortices
Red and reticular
What extrapyramidal neurons receive information from sensory organs in head
Superior and vestibular nuclei
The red nucleus receives input from….
Motor cortex and cerebellum
rubrospinal tract neurons provide excitation to LMN that control ___muscles in neck and proximal limbs, but inhibit ____muscles in limbs
Excite flexors, inhibit extensors
Is the rubrospinal activation voluntary or involuntary
Involuntary
Damage to the rubrospinal tract causes extensor ___
Extensor hypertonian(can’t provide inhibition to extensors and can’t activate flexors so get excessive extension of limbs)
Is the reticulospinal tract voluntary or involuntary
Involuntary extensor and flexor control
What is the pontine reticulospinal tract
Neurons excite alpha and gamma neurons to extensor muscles
What is the medullar reticulospinal tract
Neurons inhibit pontine tract, therefore inhibit extensor muscles
The reticulospinal tract allows for balance in descending influences onto ___ and ___ muscles and ___co-activation
Balance extensor and flexors
Alpha-gamma co-activation
Lesions to the reticulospinal tract will decrease ___ control
Postural
Injury to excitatory fibers of the reticular formation can result in ___
Hypotonia (flaccidity)
Injury to inhibitory fibers of the reticular formation can result in ___
Hypertonia (spasticity)
Where does the vestibular nucleus receive information from
Vestibular apparatus of the inner ear and cerebellum
The vestibulospinal tract controls __
Body position and balance
Damage to the vestibulospinal tract causes ___
Hypotonia
The tectospinal tract (superior/rostral colliculus) receive input about ___
Visual, auditory and somatosensory inputs about environmental stimuli
The tectospinal tract is involved in reflex orientation of ____ and ___ towards environmental stimuli
Head and eyes
The tectospinal tract controls the ___ and ___ musculature of the head
Axial and proximal
Damage to the tectospinal tract results in
Inability to orient head towards and fix gaze on an object
Do UMN in pyramidal tract transfer voluntary or involuntary motor action
Voluntary
Which tract exert control on LMN to increase fine control
Extrapyramidal tracts
Damage to ___ can cause inability to move, inappropriate movements (hyperreflexia), increased muscle tone and possible muscle atrophy
UMN
Damage to __ can cause inappropriate or absence of movement, hyporreflexia, flaccid muscles, paraplegia, muscle atrophy and reduced muscle tone
LMN
In feline diabetic neuropathy are LMN or UMN affected
LMN
LMN neuropathy occurs in feline diabetics because….
Axons die due to lack of delivery of metabolites
*longest axons most susceptible
What is muscle tone
Refers to resting level of tension in the muscle
Appropriate muscle tone allows muscle to…
Respond to nerve commands, maintaining posture and activity
Muscle tone is a result of resting level of discharge of ___motor neurons
Alpha
What is the major regulator of alpha motor neurons in maintaining muscle tone
Afferent muscle spindles
What is the role of alpha-gamma co-activation in muscle tone
Gamma efferent system regulates the resting level of activity in spindle afferents and establishes baseline level of alpha motor neuron activity in absence of muscle stretch
Reduced muscle tone is a result of damage to
Alpha-motor neuron (LMN)
Increased muscle tone is a result of damage to
UMN, lesion disturbs balance of supraspinal inhibitory and excitatory producing state of net disinhibition
Decerebrate rigidity is a result of trauma/lesion to where
Head trauma, specifically lesion to midbrain
In relation to other structures in the brain where is the damage located in decerebrate rigidity (above and below what structures)
Above the pons, medulla and vestibular nuclei, below the red nucleus
Where do pyramidal tracts descend from
Spinal cord or brain stem (corticospinal and corticobulbar)
__% of corticospinal tracts decussate in medulla and __% cross in the spinal cord
90%, 10%
What is the function of the lateral pyramidal tract
Fine movement
What is the function of the ventral pyramidal tract
Postural movement
Where do the extrapyramidal tracts originate
Brain stem nuclei
All of the extrapyramidal tracts cross to the Contralateral side except ___
Vestibulospinal
What are the functions of the vestibulospinal tract
Body posture, involuntary movements, modulation
What are the reflexes like in damage to UMN
Hyperreflexia
What is the atrophy like in patients with UMN damage
Late and mild
What is the tone like in patients with UMN damange
Weakness, spasticity, increased tone, loss of fine voluntary movement
Where is the location of UMN syndrome
Brain, C1-C5, T3-L3
What are the reflexes like in LMN syndrome
Hyporreflexia
What is the atrophy like in LMN syndrome
Rapid and severe
What is the tone like in patient with LMN syndrome
Weakness, paralysis, decreased tone, fasciculations, and fibrillations
Where is the location of LMN syndrome
C6-T2, L4-S3
