Neuro Exam 3

What is the level of motor control at the spinal cord?

Spinal cord- reflexes

What is the level of motor control at the brainstem?

Brainstem- vegetative function

What is the level of motor control at the cerebellum?

Cerebellum- coordination

What is the level of motor control at the basal ganglia?

Basal ganglia - regulation (inhibition/exhibition)

What is the level of motor control at the motor cortex?

initiation and regulation of movement

What is the primary function of the pre-central gyrus?

motor homunculus and contralateral control

What is the primary function of the premotor and supplementary motor area?

Aid the primary motor cortex in selection, planning, and generation movement

What is the lobe that the precentral gyrus, premotor area, and supplementary motor area located in?

The frontal lobe, primary motor cortex

What are the inputs to the motor cortex?

Prefrontal (intention, motivation, goals)Primary somatosensory (current muscle status/position)

Somatosensory association (complex spatial aspects, where you are in space)

Thalamocortical (excitatory loop; integration with basal ganglia)

Limbic System (motivation, goals)

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What are all the componenets of the motor unit?

LMN and all innervated muscle fibers

What is the neurotransmitter involved at the neuromuscular junction?

Acetycholine (ACh)

What is a pyramidal tract?

direct connection between brain and muscles

Know the pyramidal tracts (corticobulbar & corticospinal \[both anterior & lateral\]) including the names of neurons, location of cell bodies, location of axons, location of crossover, location of synapses, and target of the pathway.

Pyramidal tract overview

Corticobulbar tracts (70%)

Upper Motor Neurons end in brainstem

Lower Motor Neurons = cranial nerves

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Corticospinal tracts (30%)

Upper Motor Neurons end in spinal cord

Lower Motor Neurons = spinal nerves

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Lateral corticospinal tract overview

makes up 90% that crossover

crosses over at pyramidal decussation

contralateral spinal cord

(limbs)

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Anterior corticospinal tract overview

makes up 10% in the ventral tract

remains ipsilateral down the spinal cord

cross over prior to synapse

most innervate trunk muscle

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Identify the landmarks on the spinal cord - dorsal/ventral horns, dorsal/ventral roots

What is a myotome?

Areas/muscles innervated by efferent nerves (spinal nerves) (Motor)

How does a reflex arc work?

\- It is a direct sensory-motor connection

\- Stimulation of sensory nerve ending afferent signal travels through dorsal root into dorsal horn

\- Synapses on motor nerve: efferent signal travels through ventral root out to muscle

\- Reciprocal inhibition: inhibition of antagonist muscle to allow movement of primary muscle

Label the caudate nucleus

Label the putamen

Label the globus pallidus

What is the role of the basal ganglia?

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“Fine-tuning” motor functions, also plays a role in cognition and reward

How does the indirect basal ganglia circuit modify movement?

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basal ganglia: indirect circuit -> INHIBITS MOVEMENT = LESS MOVEMENT

How does the direct basal ganglia circuit modify movement?

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basal ganglia: direct circuit -> FACILITATES MOVEMENT = MORE MOVEMENT

What is meant by “comparator” in relation to the cerebellum?

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“comparator” (compares intended movement with actual movement)

What are symptoms of UMN lessions: contralateral?

*UMN lesions: contralateral symptoms*

\- loss of discrete muscle control

\- muscle weakness

What are symptoms of UMN lessions: bilateral?

*UMN lesions: bilateral symptoms*

\- hypertonia

\- loss of discrete motor control of head/neck

What are symptoms of LMN lessions?

*LMN lesions signs*

\- flaccid paralysis (reduced/floppy muscle tone)

\- reduced reflexes

\- muscle fibrillations and atrophy

What are symptoms of Spinal Cord lessions?

\- Complete transection

Bilateral loss of all sensory & motor below the lesion

\- Spinal Hemisection(Brown-Sequard syndrome)

Damage to 1 side of spinal cord(R or L)

What are symptoms of Motor Programming System lessions?

Apraxia of Speech

What are symptoms of Cerebellum lessions?

Ipsilateral effects

Motor coordination affected

paralysis or weakness (bc cerebellum not involved in initiation)

Sensory functions intact

Hypotonia: reduced tone (appears ipsilaterally)

Ataxia: decreased coordination/order of movement

What causes ALS (amyotrophic lateral sclerosis)?

Caused by degeneration of motor neurons (upper and lower)

What are the symptoms of ALS?

Symptoms: total loss of speech production and full movement disorder

What causes Parkinson’s?

Loss of dopaminergic neurons from substantia nigra

What are the symptoms of Parkinson’s?

Symptoms: resting tremor, hypokinetic dysarthria

What causes Huntington’s?

Caused by damage to caudate nucleus

What are the symptoms of Huntington’s?

Symptoms: Unwanted, uncontrollable movements and writhing movements

Where is movement initiated?

In the motor cortex

What pathways are involved directly in motor control?

Pyramidal Tracts–Direct Motor System

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Which regions and pathways are involved in modifying motor processing?

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The extrapyramidal tracts

What is CNI?

olfactory

What is CNII?

Optic

What is CNIII?

Occulomotor

What is CNIV?

Trochlear

What is CNV?

Trigeminal

What is CNVI?

Abducens

What is CNVII?

Facial

What is CNVIII?

Auditory/Vestibular

What is CNIX?

Glossopharyngeal

What is CNX?

Vagus

What is CNXI?

Spinal accessory

What is CNXII?

Hypoglossal

What is cranial nerve nuclei?

cell bodies for the LMN of corticobulbar tract

What is the relation of cranial nerve nuclei with the corticobulbar tract?

They’re intimately connected, the corticobulbar provides the primary source of motor control to the cranial nerve nuclei

What is the function of CNI?

Sensory

The olfactory nerve transmits information regarding a person’s sense of smell to the brain.

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What is the function of CNII?

Sensory

The optic nerve transmits information to the brain regarding a person’s vision.

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What is the function of CNIII?

Motor

The oculomotor nerve helps control muscle movements of the eyes.

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What is the function of CNIV?

Motor

 also has a role in eye movement.

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What is the function of CNV?

Both

The trigeminal nerve is the largest cranial nerve and has both motor and sensory functions.

What is the function of CNVI?

Motor

 control eye movements.

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What is the function of CNVII?

The facial nerve also has both motor and sensory functions.

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* movement of muscles that produce facial expression
* movement of the lacrimal, submaxillary, and submandibular glands
* the sensation of the external ear
* the sensation of taste

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What is the function of CNVIII?

Both

helps  with a person’s hearing and balance.

What is the function of CNIX?

Both

The sensory function receives information from the throat, tonsils, middle ear, and back of the tongue. It also has a role in the sensation of taste on the back of the tongue.

What is the function of CNV?

Both

has a range of functions, providing motor, sensory, and parasympathetic functions.

What is the function of CNXI?

Motor

 provides motor function to some muscles in the neck.

What is the function of XII?

Motor

supplies the tongue muscles. It originates in the medulla.

What does CNI innervate?

enter brain directly

What does CNII innervate?

ganglion cell axons from retina

What does CNVIII innvervate?

the rectus muscle and oblique musclesup

What does CNIV inneravate?

superior oblique muscle

What does CNV innervate?

Three sensory branches: face, teeth, dura, mucous membranes

One motor branches:muscles of mastication, tenses the soft palate

What does CNVI innervate?

Innervates 1 of the 6 eye muscles

What does CNVII innervate?

Travels through internanl auditory meatus with CNVIII

What does CNVIII innervate?

Enter brainstem in upper medulla

What does CNIX innervate?

enters/exits at medulla

What does CNX innervate?

enters/exits at medulla

What does CNXI innervate?

Leaves brainstem at medulla

What does CNXII innervate?

leaves brainstem at lower medulla

What does lateral strabismus mean?

deviation of ipsilateral eye to lateral position which leads to double vision

What does Ptsosis mean?

Drooping eyelid

What does Mydriasis mean?

permanent dialation of pupil

Which cranial nerves are important for speech production?

CN X for voicing and movement of velum

CN XIII for movement of tongue

CN VII for movement of lips

Where does the blood supplying the brain come from?

• Blood supply to the brain comes directly from the heart, via the aorta

What is the anterior route?

• Anterior route (80%)

internal carotid arteries

from aorta, travel up the side of neck

branches supply anterior, medial & lateral structures

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What is the posterior route?

• Posterior route (20%)

vertebral arteries from aorta, travel up through vertebral column & along brain stem fuse to form basilar artery, branch to supply cerebellum, inferior & posterior surfaces/structures

What is the circle of willis?

structure of arteries at base of the brain

Label the circle of willis

Identify/label the areas of the brain supplied by the 3 cerebral arteries.

• 3 Cerebral Arteries • Anterior • Middle (supplies blood to language region of brain) • Posterior

What is meant by watershed region?

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#### • Watershed provides double coverage for areas of overlap between two vascular territories

• Watershed vessels are small diameter (terminal branches), so they are more susceptible to small vessel disease

 What is the difference between an artery and a vein?

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* Arteries carry oxygen-rich blood to the brain
* Veins carry oxygen-low blood to the heart for reoxygenation

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What is a stroke?

 CerebroVascular Accident (CVA)

• Interruption of blood flow to the brain that results in damage to brain tissue

• AKA stroke

What’s the difference between schemic and hemorrhagic stroke?

• Ischemic: inadequate blood flow to the brain

• Hemorrhagic: blood spills out of vessels

What factors determine the effects of a stroke?

Location!

What happens if a stroke affects the left peri-sylvian area?

Aphasia, dysarthria, apraxia of speech

What happens if a stroke affects the right hemisphere?

Cognitive-communication deficits

What happens if a stroke affects the occipital lobe?

Visual field cuts

What happens if a stroke affects the cerebellum?

Ataxia, balance/coordination deficits

What is the difference between a stroke and a TIA?

• CerebroVascular Accident (CVA)

* Interruption of blood flow to the brain that results in damage to brain tissue


* AKA stroke

• Transient Ischemic Attack (TIA)

* “mini stroke”
* Temporary (transient) arterial blockage

What are controllable risk factors of a stroke?

• Hypertension

• Heart disease

• Diabetes

• High cholesterol

• Smoking, drug use, excessive alcohol use

What are warning signs of a stroke?

All occur suddenly

• Weakness/numbness in face, arm, leg unilaterally

• Dizziness, loss of balance/coordination

• Loss of vision (one or both eyes)

• Sudden, severe, unexplained headache

• Difficulty speaking and/or understanding speech

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Why is it important to get immediate help if you suspect a stroke?

In one second 32,000 neurons can be lost so it’s important to get help right away and preserve as many neurons as possible

What is hemispheric specialization of the left hemisphere?

Speech and language perception and production (phonology, morphology, syntax)