Neuroscience: Reflexes and Nerve Function
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Questions and Answers

What reflex would most likely be affected by a lower motor nerve lesion?

  • Quadriceps – Patellar (correct)
  • Biceps brachii
  • Gastrocnemius/soleus - Achilles
  • Triceps brachii

What does a hyperactive reflex indicate?

  • A lower motor nerve lesion
  • A normal response
  • Peripheral nerve damage
  • A central nervous system lesion (correct)

How are reflexes graded when they are absent?

  • 2+
  • 1+
  • 0 (correct)
  • 3+

Which test would assess proprioception?

<p>Where your body is in space (D)</p> Signup and view all the answers

What is a characteristic of lower motor nerve lesions when testing reflexes?

<p>Decreased reflexes (B)</p> Signup and view all the answers

Which part of the brain is continuous with the spinal cord?

<p>Brain Stem (D)</p> Signup and view all the answers

What is the primary function of the spinal cord?

<p>Carrying signals between the brain and peripheral nerves (B)</p> Signup and view all the answers

Which cranial nerve is responsible for the sense of smell?

<p>Olfactory Nerve (C)</p> Signup and view all the answers

How many cranial nerves are there in humans?

<p>12 (B)</p> Signup and view all the answers

Which structure is located posterior to the brainstem?

<p>Cerebellum (C)</p> Signup and view all the answers

Which of the following is NOT a part of the diencephalon?

<p>Midbrain (C)</p> Signup and view all the answers

What is the function of the oculomotor nerve?

<p>Eye movement and pupil reflex (D)</p> Signup and view all the answers

Which cranial nerve is involved in throat sensation, taste, and swallowing?

<p>Glossopharyngeal Nerve (C)</p> Signup and view all the answers

What is the role of lower motor neurons (LMNs) in the motor pathway?

<p>They receive signals from upper motor neurons. (C)</p> Signup and view all the answers

Which of the following describes the corticospinal pathway?

<p>It travels through the brainstem and spinal cord. (A)</p> Signup and view all the answers

What typically results from damage to the corticospinal pathway?

<p>Motor deficits such as paralysis. (C)</p> Signup and view all the answers

What is a primary function of the motor pathways in the nervous system?

<p>To coordinate and control voluntary muscle movements. (A)</p> Signup and view all the answers

Where do upper motor neurons (UMNs) originate?

<p>In the primary motor cortex. (C)</p> Signup and view all the answers

Which pathway is NOT classified as a primary motor pathway?

<p>Somatosensory pathway. (C)</p> Signup and view all the answers

Which statement about motor pathway disruptions is correct?

<p>They may cause tremors or weakness in movements. (A)</p> Signup and view all the answers

What is the outcome when lower motor neurons (LMNs) receive signals from upper motor neurons (UMNs)?

<p>They innervate skeletal muscles to cause contractions. (A)</p> Signup and view all the answers

What is the primary role of the extrapyramidal pathway?

<p>Regulating muscle tone and involuntary movements (D)</p> Signup and view all the answers

Which spinal segment is primarily responsible for transmitting signals to and from the legs and feet?

<p>Lumbar Spine (B)</p> Signup and view all the answers

Which myotome is responsible for elbow flexion and wrist extension?

<p>C6 (A)</p> Signup and view all the answers

What do dermatomes primarily relate to?

<p>Areas of skin supplied by sensory fibers from a single spinal nerve (B)</p> Signup and view all the answers

Which spinal segment corresponds to knee flexion?

<p>S2 (A)</p> Signup and view all the answers

How many cervical spine segments are there?

<p>7 (A)</p> Signup and view all the answers

Which of the following structures is formed by fused vertebrae?

<p>Sacral segments (C)</p> Signup and view all the answers

Which myotome allows for shoulder elevation?

<p>C4 (B)</p> Signup and view all the answers

What function do myotomes serve?

<p>Providing motor fibers to specific muscles (C)</p> Signup and view all the answers

Which spinal segments are responsible for transmitting signals from pelvic organs?

<p>Lumbar and Sacral (B)</p> Signup and view all the answers

What is the primary characteristic of neonatal reflexes?

<p>They occur involuntarily in response to stimuli. (C)</p> Signup and view all the answers

At what age is the Moro (startle) reflex typically integrated?

<p>2 – 4 months (A)</p> Signup and view all the answers

Which reflex is responsible for an infant grasping an object placed in their palm?

<p>Palmar grasp reflex (B)</p> Signup and view all the answers

What is the potential outcome of retaining the asymmetrical tonic neck reflex?

<p>Poor head control and balance (B)</p> Signup and view all the answers

Which reflex is likely to cause feeding issues due to its retention?

<p>Rooting reflex (C)</p> Signup and view all the answers

When is the Babinski reflex typically observed to disappear?

<p>8 – 12 months (C)</p> Signup and view all the answers

Which reflex is considered permanent and assists in orienting to auditory stimuli?

<p>Auditory orienting reflex (D)</p> Signup and view all the answers

How are developmental reflexes significant clinically?

<p>They reflect brain to spinal cord signaling. (A)</p> Signup and view all the answers

What is the primary location of upper motor neuron (UMN) lesions?

<p>Central nervous system (B)</p> Signup and view all the answers

Which of the following symptoms is characteristic of upper motor neuron lesions?

<p>Hyperactive reflexes (C)</p> Signup and view all the answers

What type of muscle tone is associated with lower motor neuron (LMN) lesions?

<p>Hypotonia (D)</p> Signup and view all the answers

Which of the following conditions is a typical example of an upper motor neuron lesion?

<p>Cerebral palsy (B)</p> Signup and view all the answers

What is a common outcome of lower motor neuron lesions?

<p>Atrophy of muscles (B)</p> Signup and view all the answers

Which symptom is typically absent in lower motor neuron lesions?

<p>Increased muscle tone (D)</p> Signup and view all the answers

What characterizes spasticity as it relates to upper motor neuron lesions?

<p>Increased muscle resistance during passive movement (B)</p> Signup and view all the answers

How does the location of lesions differentiate upper motor neuron lesions from lower motor neuron lesions?

<p>UMN lesions are within the central nervous system, while LMN lesions are in the peripheral nervous system (C)</p> Signup and view all the answers

Which of the following might be a symptom of both upper and lower motor neuron lesions?

<p>Muscle paralysis (B)</p> Signup and view all the answers

What phenomenon is commonly associated with upper motor neuron lesions, but not with lower motor neuron lesions?

<p>Hypertonia (C)</p> Signup and view all the answers

In cases of lower motor neuron lesions, reflexes are usually:

<p>Reduced or absent (D)</p> Signup and view all the answers

Which neurological condition is specifically a result of lower motor neuron damage?

<p>Amyotrophic lateral sclerosis (ALS) (D)</p> Signup and view all the answers

Hyperactive reflexes in upper motor neuron lesions are primarily due to:

<p>Disrupted inhibitory signals from the brain (D)</p> Signup and view all the answers

Flashcards

Spinal Cord

The part of the central nervous system responsible for relaying signals between the brain and the rest of the body.

Brainstem

The part of the brain directly connected to the spinal cord. It controls important functions like breathing, heart rate and blood pressure.

Cerebellum

Responsible for coordinating movement, balance and posture.

Cerebrum

The largest part of the brain, responsible for higher cognitive functions like thinking, language, and memory.

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Cranial Nerves

These nerves connect directly to the brain and control various functions of the head and neck.

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Olfactory Nerve (I)

This nerve is responsible for smell.

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Oculomotor Nerve (III)

This nerve controls eye movements and pupil size.

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Vestibulocochlear Nerve (VIII)

This nerve is responsible for hearing and balance.

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Motor Pathways

Neural pathways in the nervous system responsible for transmitting signals from the brain to muscles, leading to voluntary movements.

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Corticospinal Pathway

A primary motor pathway originating in the primary motor cortex, traversing through the brainstem and spinal cord, and ultimately controlling voluntary movements.

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Upper Motor Neurons (UMNs)

Neurons in the primary motor cortex that project down to the spinal cord, driving voluntary muscle contractions.

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Lower Motor Neurons (LMNs)

Neurons located in the spinal cord that receive signals from upper motor neurons and directly control muscle contractions.

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Muscle Contraction

The process of a muscle contracting in response to electrical impulses from lower motor neurons.

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Extrapyramidal Pathway

A motor pathway that influences movement indirectly, primarily responsible for fine motor control, posture, and balance.

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Hypoglossal Nerve

A cranial nerve that controls tongue movement, enabling speech and swallowing.

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Motor Impairments

Disruptions to motor pathways leading to impairments in movement, such as weakness, tremors, or difficulty controlling movements.

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Myotome

A group of muscles primarily innervated by the motor fibers of a single spinal nerve.

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Dermatome

The area of skin supplied by sensory fibers from a single spinal nerve.

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Cervical Spine

Transmits signals to and from the head, neck, shoulders, arms, and hands.

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Thoracic Spine

Transmits signals to and from parts of the arms, anterior and posterior chest, and abdominal areas.

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Lumbar Spine

Transmits signals to and from the legs, feet, and some pelvic organs.

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Sacral Spine

Transmits signals to and from the lower back, glutes, pelvic organs, genital areas, and some areas in the legs and feet.

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Coccygeal Segment

Located at the bottom of the spinal cord, transmitting signals to and from the tailbone.

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Deep Tendon Reflex

A reflex test where tapping a tendon stretches the muscle, triggering a reflex contraction.

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Dermatome and Myotome Relationship

Regions of the spinal cord are connected to specific skin areas and muscle groups.

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Hypoactive Reflex

A reflex that is either absent or abnormally weak.

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Hyperactive Reflex

A reflex that is abnormally strong or exaggerated.

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Clonus

A series of rapid, involuntary muscle contractions that occur when a muscle is stretched.

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Sensory Testing

Testing the ability to feel different sensations like touch, temperature, pain, vibration and position.

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Reflexes

Involuntary movements or actions that the body performs automatically in response to a stimulus.

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Neonatal reflexes

Inborn reflexes present at birth that help with survival and development.

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Reflex Integration

Reflexes disappear as the baby grows, controlled by higher brain functions.

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Moro Reflex

A reflex that causes the baby to extend arms and legs in response to a sudden loud noise or movement.

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Palmar Grasp Reflex

A reflex that causes the baby to grab onto anything that touches their palms.

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Stepping Reflex

A reflex that causes the baby to make stepping movements when held upright.

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Clinical Significance of Reflexes

Reflexes indicate how well the brain communicates with muscles for movement and posture.

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Reflex Retention

Reflexes that can be retained in some learning disorders, such as ADHD, autism, etc.

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Upper Motor Neuron Lesion (UMN)

A neurological issue that affects pathways in the brain or spinal cord, leading to increased muscle tone, hyperactive reflexes, and possibly spasticity or weakness.

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Lower Motor Neuron Lesion (LMN)

A neurological issue that affects nerves outside the spinal cord, leading to decreased muscle tone, reduced reflexes, possible atrophy, and weakness or paralysis.

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Hypertonia

The state of increased muscle tone, leading to stiffness and resistance to movement. It's often associated with UMN lesions.

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Hypotonia

The state of decreased muscle tone, leading to floppy muscles and lack of resistance to movement. It's associated with LMN lesions.

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Spasticity

Sudden muscle contractions or spasms, a common feature of UMN lesions. It makes muscles tense and jerky.

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Atrophy

A condition characterized by muscle wasting due to a lack of neural input. It's associated with LMN lesions.

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Reduced Reflexes

Reduced or absent reflexes typically seen in LMN lesions due to interrupted signals between the spinal cord and muscles.

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Location of Lesion

The location of the lesion is the key difference between UMN and LMN lesions. UMN lesions occur in the brain or spinal cord, while LMN lesions are in nerves outside the spinal cord.

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Muscle Weakness in UMN and LMN

Both UMN and LMN lesions can cause muscle weakness, but the symptoms differ. UMN lesions often lead to stiffness and spasticity, while LMN lesions often lead to floppy muscles and atrophy.

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Amyotrophic Lateral Sclerosis (ALS)

A type of neurological disorder that causes progressive weakness and atrophy (muscle wasting). It is an example of a LMN lesion.

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Cerebral Palsy

A condition in which there is damage to the central nervous system, causing stiffness, spasticity, and hyperactive reflexes. An example of an UMN lesion.

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Multiple Sclerosis (MS)

A condition that causes damage to the myelin sheath surrounding nerve fibers, often in the central nervous system, leading to stiffness and spasticity. An example of an UMN lesion.

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Stroke

Any neurological condition that affects the brain, leading to weakness, stiffness, spasticity, and hyperactive reflexes. An example of an UMN lesion.

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Spinal Muscular Atrophy

A type of neurological disorder that affects the nerves controlling voluntary movement, leading to weakness, atrophy, and reduced reflexes. An example of an LMN lesion.

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Study Notes

CNS Anatomy: Brain and Spinal Cord

  • The spinal cord connects to the brainstem and runs through the spinal canal.
  • Cranial nerves exit the brainstem, nerve roots exit the spinal cord.
  • The spinal cord transmits signals between the brain and peripheral nerves.
  • It controls various bodily functions including awareness, movement, thoughts, speech, memory, etc.

Major Brain Parts

  • Brainstem: Continuous with the spinal cord, containing the medulla oblongata, pons, and midbrain.
  • Cerebellum: Located posterior to the brainstem.
  • Diencephalon: Superior to the brainstem, containing the thalamus, hypothalamus, and epithalamus.
  • Cerebrum: The largest part of the brain, situated on the diencephalon.

Cranial Nerves

  • Twelve cranial nerves emerge from the skull.
  • They transmit sensory and motor information and include the olfactory, optic, oculomotor, trochlear, trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, accessory, and hypoglossal nerves.

Motor Pathways

  • Motor pathways transmit signals from the brain to muscles, enabling voluntary movements.
  • The corticospinal and extrapyramidal pathways are primary motor pathways.
  • Corticospinal Pathway: Originates in the primary motor cortex, involves upper motor neurons (UMNs) traveling through the internal capsule, brainstem, and spinal cord, synapsing with lower motor neurons (LMNs) in the spinal cord, which then signal to muscles, causing their contraction.
  • Extrapyramidal Pathway: Involves multiple subcortical nuclei and brain regions, controlling muscle tone, posture, and involuntary movements, having more complex connections than the corticospinal pathway.

Spinal Segments

  • The spinal cord is divided into segments: cervical (7), thoracic (12), lumbar (5), sacral (5), and coccygeal (1).
  • Each segment transmits signals to and from specific body parts. These include parts of the arms, chest, abdomen, and legs, as well as pelvic organs and genital areas in their respective zones.

Dermatomes & Myotomes

  • Dermatomes: Areas of skin innervated by a single spinal nerve, carrying sensory information (pain, temperature, touch) to the spinal cord and then to the brain.
  • Myotomes: Groups of muscles primarily innervated by a single spinal nerve, enabling voluntary muscle movement.

Deep Tendon Reflexes

  • Deep tendon reflexes assess spinal cord integrity and differentiate between upper and lower motor neuron lesions.
  • UMN lesions cause hyperactive reflexes, while LMN lesions lead to decreased reflexes.
  • Reflexes are tested for asymmetry, stimulus threshold, and hyperactivity/hypoactivity.

Assessments: Sensory Testing

  • Sensory testing involves evaluating touch, temperature, pain perception, two-point discrimination, and proprioception (body position in space).
  • Comparisons are made between sides and from proximal to distal extremities

Assessments: MMT

  • Muscle strength testing (MMT) establishes baselines for treatment, diagnosis, and injury rehabilitation programs.
  • Tests examine muscle strength in different gravity-related positions.
  • Muscle strength is graded from 0 (no contraction) to 5 (normal).

UMN vs. LMN Lesions

  • Upper Motor Neuron (UMN) Lesions: Damage within the central nervous system (CNS) results in increased muscle tone (hypertonia), hyperactive reflexes, spasticity, and possible weakness/paralysis. Common conditions include stroke, traumatic brain injury, multiple sclerosis, and cerebral palsy.
  • Lower Motor Neuron (LMN) Lesions: Damage within the peripheral nervous system (PNS) causes decreased muscle tone (hypotonia), reduced or absent reflexes, and possible muscle atrophy (wasting) and weakness/paralysis. Common conditions include amyotrophic lateral sclerosis, spinal muscular atrophy, and peripheral nerve injuries.

Neurological Signs & Symptoms

  • Spasticity vs. Rigidity: Spasticity is velocity-dependent increased muscle tone during stretching, while rigidity is increased muscle tone throughout the range of motion (ROM).
  • Flaccidity: Reduced or absent muscle tone.

Other Neurological Terms

  • Dysarthria: Defective speech due to muscular dysfunction.
  • Dyskinesia: Impaired voluntary movement.
  • Dysphagia: Difficulty swallowing.
  • Dysphasia: Impaired speech production or comprehension.
  • Dyspraxia: Disturbances in the control or execution of voluntary movements.
  • Dystonia: Prolonged muscle contractions leading to twisting and repetitive movements.
  • Dysesthesia: Abnormal sensation on the skin.
  • Ataxia: Defective muscular coordination.
  • Paresthesia: Numbness, prickling, or tingling sensations.
  • Dysreflexia: A life-threatening uninhibited sympathetic response in individuals with T6 or higher spinal cord injury.
  • Aphasia: Inability to speak or comprehend language.
  • Paralysis: Temporary or permanent loss of motor function and/or sensation.

Developmental Reflexes

  • Developmental reflexes are involuntary actions that aid in postural control and movement.
  • These reflexes emerge during fetal development and typically disappear as the nervous system matures.
  • They are clinically significant as problems in their development or persistence can indicate underlying developmental or neurological disorders.

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Description

This quiz covers essential concepts in neuroscience, focusing on reflexes, lower motor nerve lesions, and cranial nerves. Delve into the anatomy of the nervous system and assess your understanding of how various structures interact in motor pathways. Test your knowledge with questions on proprioception, nerve functions, and damage effects.

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