Neuroanatomy and Motor Control Quiz

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Questions and Answers

What characterizes the muscle tone in non antigravity muscles affected by upper motor neuron lesions?

Decreased tone with flaccidity (correct)

Normal tone with no spasticity

Variable tone with fluctuating weakness

Increased tone with spasticity

What is the primary impact of spasticity on movement?

It results in a complete loss of voluntary movement

It is associated with weakness in voluntary movements

It produces a rhythmic contraction of the affected muscle

It leads to an increase in muscle tone beyond normal limits (correct)

Which structure begins the direct motor control pathway for voluntary movement?

Spinal cord

Cerebral cortex (correct)

Cerebellum

Brainstem

What is the role of the lateral corticospinal tract?

It influences distal limb muscle movements Signup and view all the answers

How does the presence of hyperactive reflexes relate to lower motor neuron dysfunction?

It signifies an intact reflex arc but disrupted cortical influence Signup and view all the answers

What is the result of a lesion affecting the somatosensory association area?

Attentional deficit to tactile/visual stimuli Signup and view all the answers

Which cognitive impairment is primarily associated with damage to the prefrontal cortex?

Impaired judgment Signup and view all the answers

Which artery primarily supplies regions that may experience prosopagnosia when damaged?

Posterior cerebral artery Signup and view all the answers

What characterizes central post-stroke thalamic pain syndrome?

Normal touch interpreted as pain Signup and view all the answers

Dysphagia is most commonly associated with which type of lesion?

Medullary brainstem lesion Signup and view all the answers

What is the primary function of the auditory association area?

Processing and interpreting sound Signup and view all the answers

Which type of stroke is characterized by pure motor hemiplegia?

Lacunar stroke Signup and view all the answers

What visual process remains intact despite damage to the visual association area?

Recognizing objects Signup and view all the answers

Which part of the brain is primarily responsible for sensory perception?

Parietal Lobe Signup and view all the answers

What type of stroke is characterized by interrupted blood supply to the brain?

Ischemic stroke Signup and view all the answers

What condition can result from atherosclerosis and contribute to ischemic events?

Plaque formation Signup and view all the answers

Which arteries primarily supply oxygenated blood to the anterior part of the brain?

Internal carotid arteries Signup and view all the answers

Which of the following best describes the primary cause of secondary hemorrhagic strokes?

Weakening of vessels due to atherosclerosis Signup and view all the answers

In an ischemic cascade, what happens after the blood supply is blocked?

Release of excess neurotransmitters Signup and view all the answers

What is a possible outcome of a transient ischemic attack lasting more than 24 hours?

Potential precursor for cerebral infarction Signup and view all the answers

Which of the following is NOT a category of stroke mentioned?

Microvascular attack Signup and view all the answers

What is the primary reason for contralateral hemiparesis in Anterior Cerebral Artery Syndrome?

Lack of blood supply to the primary motor cortex Signup and view all the answers

What type of sensory loss is expected with Anterior Cerebral Artery Syndrome?

Contralateral hemisensory loss primarily affecting the lower extremity Signup and view all the answers

Which pathway is responsible for the touch and temperature sensation that crosses at the spinal cord?

Anterior column pathway Signup and view all the answers

Which artery is most commonly associated with blockages leading to contralateral hemiparesis and sensory loss?

Middle cerebral artery Signup and view all the answers

What characterizes Broca's aphasia?

Difficulty in producing speech, often non-fluent Signup and view all the answers

Homonymous hemianopia results in which of the following?

Visual field cut affecting opposite sides in both eyes Signup and view all the answers

What aspect does the Functional Independence Measure scale evaluate?

Physical performance during rehabilitation Signup and view all the answers

Which cortical area is typically affected in patients with Wernicke's aphasia?

Posterior to the central fissure Signup and view all the answers

What phenomenon occurs when the resistance to passive movement increases with the speed of movement?

Hypertonicity Signup and view all the answers

Which reflex is triggered by tapping the tendon, resulting in knee extension?

Knee jerk reflex Signup and view all the answers

What term describes the resistance pattern where there is high resistance at first but then it drops off?

Clasp-knife phenomenon Signup and view all the answers

Which condition is associated with abnormal limb synergies following a stroke?

Spasticity Signup and view all the answers

What best describes the characteristics of rigidity in muscle tone?

Consistently high muscle tone throughout motion Signup and view all the answers

Which movement pattern describes the extension synergy in the lower extremities post-stroke?

Hip extension, knee extension, ankle plantarflexion Signup and view all the answers

What characteristic defines the 'flaccidity' observed immediately after a stroke?

Decreased muscle tone Signup and view all the answers

In abnormal synergy patterns of the upper extremity, which of the following describes the pattern of flexion?

Shoulder abduction, elbow flexion, forearm supination Signup and view all the answers

Study Notes

The Brain

Components: Cerebrum, Cerebellum, Brainstem.
Lobes:
- Parietal Lobe: Responsible for sensory perception.
- Temporal Lobe: Influences emotions and memory.
- Occipital Lobe: Primarily responsible for vision.
- Frontal Lobe: Linked to personality, behavior, and motor control.

Stroke

Clinical syndrome
- Caused by abnormal cerebral blood circulation.
- Leads to persistent neurological deficit.

Arteries

Responsible for delivering blood to the brain.
The brain requires oxygenated blood.
- Internal carotid arteries (anterior):
  - Provide blood to the front of the brain.
- Vertebral arteries (posterior):
  - Provide blood to the back of the brain.
The two pathways function independently, ensuring blood supply even if one is compromised.

Mechanisms

Ischemic stroke: Caused by a blockage of a blood vessel, interrupting blood flow.
Hemorrhagic stroke: Caused by bleeding into the brain tissue.

Risk Factors

Atherosclerosis: A condition characterized by the build-up of fatty plaques in the arteries.
- Can result in ischemia or blockage of the arteries.

Ischemic Cascade

Clot Stops Blood Supply:
- Ischemia: Lack of blood flow to the brain.
- Release of Excess Neurotransmitters: Neurotransmitters are released in large quantities due to lack of blood flow.
- Disruption of Energy Metabolism: Increased energy demands that can't be met.
- Increased Calcium Ions:
- Formation of Substances that Damage the Brain: Release of harmful substances that further damage brain tissue.

Cerebral Thrombosis

A blood clot that forms in a cerebral artery

Cerebral Embolism

A blood clot that travels from elsewhere in the body to the brain

Hemorrhagic Cascade

Primary Nontraumatic Cerebral Hemorrhage:
- Atherosclerosis and Hypertension: Weakened blood vessels are unable to manage high blood pressure.
- Increased Blood Pressure: Microaneurysms, small bulges in blood vessels, can rupture.
- Microaneurysms/Arterial Necrosis:
  - Bleeding: Increased fluid in the space between brain and skull (intracranial pressure).
  - Adjacent brain tissue displaced: Leads to compression and ischemia.

Categories of Stroke

Major stroke: Significant neurological impairment.
Deteriorating stroke: Progressive worsening of symptoms.
Yang stroke: A variant with a higher risk of death.
Transient ischemic attack: Temporary blockage of blood flow to the brain, often a precursor to a major stroke.

Transient Ischemic Attacks (TIAs)

Involve retinal or cerebral ischemia.
Last less than 24 hours.
Don't usually cause permanent brain damage though they are a predictor of future stroke risk.

Anterior Cerebral Artery Syndrome

Cerebrovascular Accident (CVA) in the Anterior Cerebral Artery (ACA): Blockage of blood flow in the ACA.
- Contralateral Hemiparesis: Weakness or paralysis on the opposite side of the body.
  - Primarily affects the lower extremity, especially the leg.
- Contralateral Hemisensory: Loss of sensation on the opposite side of the body.
  - Primarily affects the lower extremity, especially the leg.

Anterior Cerebral Artery

Supplies the medial frontal and parietal lobes.
- Primary Motor Cortex: Responsible for voluntary movements.
- Primary Sensory Cortex: Responsible for sensory perception.

Primary Sensory Cortex

Receives sensory input from the opposite side of the body.

2 Pathways Sensory (Ascending)

Posterior Column Pathway:
- Second-order neurons cross to the opposite side of the brain in the medulla.
- Responsible for transmitting proprioception (sense of body position) and fine touch.
Anterior Column Pathway:
- Sensory neurons cross to the contralateral side in the spinal cord.
- Primarily responsible for transmission of pain, temperature, and pressure.

2 Pathways Motor (Descending)

Anterior Corticospinal Tract:
- Upper motor neurons (CNS) cross to the opposite side of the spinal cord.
- Contribute to the control of voluntary movements of the trunk and proximal limbs.
Lateral Corticospinal Tract:
- Upper motor neurons cross to the opposite side in the medulla, then descend in the lateral white matter.
- Primarily responsible for controlling voluntary movements of the limbs, especially fine movements of the hands.

Middle Cerebral Artery Syndrome

Most common location for stroke blockage.
Leads to cerebral edema and swelling.
Contralateral Hemiparesis: Weakness on the opposite side of the body.
Contralateral Sensory Loss: Loss of sensation on the opposite side of the body.
- Affects the face and upper extremity more than the lower extremity.

Face and UE More Than LE

The Middle Cerebral Artery supplies blood to the frontal, temporal, and parietal lobes.
- These areas of the brain are responsible for controlling facial movements and voluntary movements of the upper extremity.

Frontal Lobe

Contains the Primary Motor Cortex - responsible for voluntary movements.

Parietal Lobe

Contains the Primary Sensory Cortex, responsible for sensory input from the opposite side of the body.

Aphasia

Wernicke's Aphasia (left):
- Receptive speech impairment.
- Affects comprehension and language expression.
- Associated with stroke damage posterior to the central fissure.
Broca's Aphasia (left):
- Expressive speech (motor) impairment.
- Non-fluent aphasia, characterized by difficulties with word finding.
- Stroke damage anterior to the central fissure.
- Individuals struggle to express thoughts, with limited vocabulary.

Homonymous Hemianopia

Visual field cut in half either on the left or the right side of both eyes.

Functional Independence Measure (FIM)

Used to assess neurological damage in individuals with stroke.
Measures functional skills and independence:
- 1 = Total Assistance.
- 7 = Complete Independence.

Posterior Association Areas

These areas integrate incoming sensory information.
- Somatosensory association area:
  - Integrating information from senses to make sense of touch, pressure, and temperature.
- Visual association area:
  - Integrating information from visual input.
- Auditory association area:
  - Integrating information from auditory input.

Perceptual Impairments

Posterior Association Areas:
- Lesion can cause agnosia.
- Agnosia: Inability to recognize incoming sensory information.
  - Tactile Astereognosis: Difficulty identifying objects by touch.
  - Prosopagnosia: Difficulty recognizing people by their faces.
Posterior Cerebral Artery:
- Involved in memory processing.

Cognitive Impairments

Executive Functioning: Enables purposeful behaviors.
- MCA: Supplies the lateral frontal cortex.
- ACA: Supplies the frontal cortex, including areas important for executive function.
Prefrontal Cortex:
- Lesion can impact executive functioning, potentially resulting in impulsivity and decreased judgment.
Association Cortex:
- Integrates sensory information from different sources, forming the basis for cognition.
  - Damage to visual association cortex leads to difficulty recognizing objects even though the person can still 'see' them.
  - Damage to the auditory association cortex can impact the processing and understanding of sound.
  - Lesions to the somatosensory association area can lead to attentional deficits for tactile and visual stimuli on the contralateral side of the body, as well as neglect syndrome.

Posterior Cerebral Arteries

Supplies blood to the occipital, medial, and inferior temporal lobes.
- Temporal Lobe Ischemia: Can lead to memory deficits, particularly amnesia.
- Hypothalamus: Also supplies the hypothalamus, which is a key structure involved in memory.

Dysphagia

Impaired swallowing: Difficulty swallowing.
Patients with Medullary Brainstem Lesions:
Vertebrobasilar Artery Syndrome:
- Can manifest as dysphagia as this artery supplies cranial nerves involved in swallowing.

Pain

Thalamic Nuclei: Responsible for regulating pain signals and transmitting them to the cortex.
Posterior Cerebral Artery (PCA): Supplies the thalamus.
- Stroke in PCA:
  - Central Post Stroke Pain Syndrome: Intense, spontaneous pain.
  - Hyperalgesia: Exaggerated pain in response to normal stimuli.
  - Allodynia: Pain in response to non-painful stimuli, such as touch.

Lacunar Stroke Syndromes

Strokes in the small arteries that penetrate deep brain structures.
Associated with: Diabetes and hypertension.

Symptoms

Pure Motor Hemiplegia:
- Paralysis or weakness on one side of the body.
- Usually due to lesions in the pons or internal capsule.
Pure Sensory Stroke:
- Loss of sensation on one side of the body.
- Usually due to lesions in the thalamus.
Consciousness/Language Impairment: Higher-order cortical areas are typically spared in lacunar stroke.
Faster Recovery is common as these strokes often involve smaller areas of brain tissue.

Paresis

Weakness of voluntary movement:
- Often resulting from upper motor neuron lesions (UMNS).
- Increased Tone:
- Non-antigravity Muscles Weakened:
  - Muscles responsible for specific movements.
- Antigravity Muscles: Muscles that counteract gravity.
  - Increased Tone: Often leading to spasticity (increased resistance to movement).

Arms

Flexed and Pronated:
- Common after stroke due to the influence of the upper motor neuron system (CNS) on ascending pathways.

Legs

Extended: After stroke, the legs will likely be extended due to the influence of UMN and descending pathways.

Hyperactive Reflex

Increased reflex response:
- Passive Stretch:
  - Occurs due to lesions affecting lower motor neurons (LMNS) and their influence on the ventral spinal cord (VSC).

UMNL

Lesions affecting the upper motor neuron pathway above the anterior horn of the spinal cord:
- Impacts the UMN, often leading to spasticity and weakness.

Direct Motor Control

Corticospinal Tract:
- Responsible for precise voluntary movements.
  - Upper Motor Neuron (UMN): - Collateral motor neurons:
    - Impart signals to the brainstem. - Influences motor nuclei.
  - Pathway Starts at Cerebral Cortex:
  - Terminates at Lower Motor Neurons: In the spinal cord. - Influences distal extremity muscles.
- Lateral Corticospinal Tract: Primarily controls limb movements.
- Anterior Corticospinal Tract: Primarily controls proximal muscles (trunk).

Indirect Motor Control:

Corticospinal Tract:
- Influences UMN innervating distal extremity muscles (specifically fingers and feet).
Medullary Control Brainstem Motor Centers:
- This pathway is influenced by collateral motor neurons, regulating tone and movement.

Spasticity

Increased muscle tone.
Impacts Movement: Difficult to move normally.

Rate Dependent

The faster the movement, the greater the resistance (spasticity)

Hypertonicity

Increased resistance to passive movement.

Rigidity

Another type of hypertonicity, but not rate-dependent.
Consistent resistance throughout the entire range of motion.
Often associated with basal ganglia disorders.

Knee Jerk Reflex

Tendon Tapped:
- Stimulus creates a stretch in the muscle.
Stretch Recognized by Receptors:
- Sensory receptors send signals to the spinal cord.
Spinal Cord Connects:
- The spinal cord synapses with motor neurons.
Motor Neurons Signal Muscle:
- The muscle contracts.
Lower Leg Extension:
- Results in a kick forward.

Characteristics of Spasticity

Resistance to Passive Movement: The faster the joint is moved, the greater the resistance felt.
"Clasp-Knife" Phenomenon: Significant resistance, followed by a sudden letting go.

Stiffness

Increased Muscle Tone
Hyperactive Stretch Reflex: Overactive reflex response to stretching.