Chapter 20 – Nervous System Structures & Disorders

20 vocabulary flashcards summarizing brain regions, neural pathways, cerebrospinal fluid, and common neurological disorders for Chapter 20 Quiz 1 preparation.

Motor Area (Primary Motor Cortex)

Region of the cerebral cortex that initiates voluntary skeletal-muscle contractions; located in the precentral gyrus of the frontal lobe.

Cerebellum

Posterior brain region that fine-tunes voluntary movement, balance, posture, and motor learning.

Thalamus

Paired mass of gray matter that acts as the brain’s major sensory relay station, filtering and directing impulses to the cerebral cortex.

Hypothalamus

Autonomic control center that regulates homeostasis (temperature, hunger, thirst), emotions, and links the nervous and endocrine systems via the pituitary gland.

Association Areas

Cortical regions that integrate information from multiple senses and are responsible for higher functions such as memory, reasoning, judgment, and emotion.

Pons

Middle portion of the brainstem that connects cerebrum and cerebellum; houses respiratory centers and nuclei for cranial nerves V–VIII.

Medulla Oblongata

Lowest part of the brainstem containing vital autonomic centers for heart rate, blood pressure, and breathing, as well as reflex centers for coughing and swallowing.

Limbic System

Functional network (including hippocampus and amygdala) that governs emotion, motivation, and memory formation.

Cerebrum

Largest brain region composed of two hemispheres; responsible for conscious thought, sensory perception, language, and voluntary movement.

Sensory Areas (Primary Somatosensory Cortex)

Postcentral gyrus regions that receive and interpret tactile, pain, temperature, and proprioceptive input from the body.

Corpus Callosum

Broad band of white-matter fibers that allows communication between the left and right cerebral hemispheres.

Cerebrospinal Fluid (CSF)

Clear fluid found in ventricles, central canal, and subarachnoid space; contains water, ions, glucose, and proteins, providing cushioning, buoyancy, and nutrient delivery to the CNS.

Dorsal Nerve Root

Posterior spinal cord root that carries incoming sensory (afferent) nerve fibers into the spinal cord.

Ventral Nerve Root

Anterior spinal cord root that carries outgoing motor (efferent) nerve fibers from the spinal cord to muscles and glands.

Parkinson Disease

Progressive neurodegenerative disorder caused by loss of dopamine-producing neurons in the substantia nigra, leading to tremor, rigidity, and bradykinesia.

Dementia

General term for a decline in cognitive abilities—memory, reasoning, language—severe enough to interfere with daily life; Alzheimer’s disease is the most common form.

Cerebral Palsy

Group of non-progressive motor disorders resulting from prenatal or perinatal brain injury, characterized by spasticity, impaired movement, and possible speech difficulties.

Huntington Disease

Autosomal dominant, hereditary neurodegenerative disorder marked by involuntary choreiform movements and progressive cognitive decline.

Cerebrovascular Accident (CVA/Stroke)

Sudden loss of brain function caused by interrupted blood flow (ischemic or hemorrhagic), resulting in neurological deficits.

Poliomyelitis

Viral infection that destroys motor neurons in the anterior horn of the spinal cord, leading to flaccid paralysis and muscle atrophy.

How is CSF produced?

Clear, colorless fluid produced primarily in the lateral ventricles by the choroid plexus (ependymal cells + fenestrated capillaries).

What is the CSF circulation pathway?

Lateral ventricles → interventricular foramina → 3rd ventricle → cerebral aqueduct → 4th ventricle → median/lateral apertures → subarachnoid space → arachnoid villi → dural venous sinuses.

What is the volume and turnover rate of CSF?

Approximately 150 mL volume; turnover rate is about 3-4 times per day (~500 mL/day).

What are the functions of CSF?

Provides buoyancy, acts as a mechanical cushion, aids in waste removal, and maintains chemical stability.

Where is a lumbar puncture typically performed and why?

L3–L4, used to analyze CSF for conditions like meningitis or subarachnoid hemorrhage.

What is the function of the Dorsal (Posterior) Spinal Nerve Root and what happens if it's lesioned?

Sensory/Afferent fibers carrying sensory information from the periphery to the spinal cord; lesions can cause anesthesia or paresthesia in a dermatomal pattern.

What is the function of the Ventral (Anterior) Spinal Nerve Root and what happens if it's lesioned?

Motor/Efferent fibers conducting axons of lower motor neurons to skeletal muscles, with lesions leading to flaccid paralysis and loss of reflexes.

What is the underlying cause of Parkinson's Disease?

Progressive movement disorder due to degeneration of dopaminergic neurons.

What is the most common cause of dementia?

Most commonly Alzheimer's disease.

What is Cerebral Palsy (CP)?

Non-progressive motor disorders resulting from early brain insults; manifests as abnormal muscle tone and delayed milestones.

What type of disorder is Huntington's Disease?

Genetic disorder causing progressive chorea and dementia.

What is a CVA (Stroke) and how is it acutely managed?

Sudden neurologic deficit due to brain ischemia or hemorrhage; acute management includes tPA and thrombectomy.

What is Poliomyelitis?

Viral infection leading to paralysis; vaccination has significantly reduced incidence.

Why is understanding neuroanatomy important?

Crucial for clinical localization and management.

What ethical issues are raised by neurodegenerative diseases?

Autonomy, resource allocation, and genetic counseling.

What is the public health significance of stroke?

Stroke prevention education, as strokes are a leading cause of death in the US.

Give an example of global health equity in neurology.

Polio eradication campaigns highlighting disparities in vaccination coverage.

What is the total CSF volume?

150 mL

What is the CSF production rate?

~500 mL/day

What percentage of corticospinal fibers decussate?

About 90%

What is the prevalence of Alzheimer’s in the US?

Over 5 million Americans affected; incidence doubles every five years after age 65

How many stroke cases occur annually in the US?

Approximately 795,000 cases annually

How many stroke deaths occur annually in the US?

About 140,000 deaths annually

Where is the Motor Area located?

Primary Motor Cortex – Pre-Central Gyrus

What is the primary function of the Motor Area?

Generates voluntary movements by sending descending signals through corticospinal and corticobulbar tracts.

What is the motor homunculus?

Topographic map in motor area where larger cortical areas are allocated for fine motor control (e.g., hands, face).

What is the effect of an UMN lesion in the Motor Area?

Results in contralateral flaccid paralysis, potentially progressing to spasticity.

What is a clinical test for an UMN lesion?

Hyperreflexia, tested with the Babinski sign.

Where is the Sensory Area located?

Primary Somatosensory Cortex – Post-Central Gyrus.

What is the function of the Sensory Area?

Receives sensory information (proprioception, touch, pain, temperature) from the contralateral body via thalamic relay.

What is the sensory homunculus?

Topographic map in sensory area that parallels the motor map.

What is stereognosis and how is it enabled?

Object recognition by touch, enabled by integration of sensory area with association cortex.

What happens if there is damage to the Sensory Areas?

Can cause loss of discriminative touch and proprioceptive deficits.

What is the function of Association Areas?

Integrate incoming data with memory, emotion, and reasoning to produce context, comprehension, and planning.

What is the Prefrontal Cortex known for?

An example of an association area involved in executive functions.

What is Wernicke’s Area?

An example of an association area involved in language comprehension.

What are the Parietal-Temporal-Occipital Areas?

Examples of association areas involved in multimodal integration.

What are the effects of lesions on Association Areas?

Can lead to neglect syndromes, agnosias, and aphasias.

What is the Cerebrum composed of?

Contains cortical gray matter, basal nuclei, and limbic structures.

What are the Cerebrum's primary responsibilities?

Conscious thought, perception, and intellect.

What is the function of fissures and sulci in the cerebrum?

Increase surface area of the cerebrum (~2,500 cm²).

What functions are associated with the Left Hemisphere?

Associated with language and analytic tasks.

What functions are associated with the Right Hemisphere?

Linked to visuospatial skills and emotions.

What is the cerebellum's primary function?

Produces skilled muscle movements, helps with spatial orientation, and controls posture.

What is the mechanism of the cerebellum?

Coordinates timing, force, and precision of skeletal muscle contractions; adjusts postural tone through an error-correction loop.

How does the cerebellum perform its error-correction?

Compares intended and actual movements using proprioceptive feedback.

What is ataxia?

Wide-based gait, a damage effect of the cerebellum.

What is dysmetria?

Inability to accurately estimate the range of motion, a damage effect of the cerebellum.

What is nystagmus?

Involuntary eye movement, a damage effect of the cerebellum.

What is the acute effect of alcohol on the cerebellum?

Alcohol consumption acutely depresses cerebellar function.

What is the Thalamus's role and location?

Acts as a bilateral relay station atop the brainstem, filtering and amplifying sensory (except olfaction) and motor signals.

What sensory signal is an exception to the thalamic relay?

Does not relay olfaction (smell) signals.

What is the Thalamus's role in sleep?

Participates in sleep-wake regulation via the reticular activating system (RAS).

When might Thalamic Pain Syndrome occur?

Pathology that can occur if RAS is disrupted.

What can cause a coma related to the thalamus?

Can occur if RAS (Reticular Activating System) is disrupted.

What is the primary function of the Hypothalamus?

Major center for visceral control and homeostasis, regulating temperature, hunger, thirst, circadian rhythms, and autonomic output.

How does the Hypothalamus connect to the pituitary gland?

Regulates autonomic output through its connection to the pituitary gland.

What is the function of the Supraoptic Nuclei?

Produces antidiuretic hormone (ADH) in the hypothalamus.

What is the function of the Paraventricular Nuclei?

Produces oxytocin in the hypothalamus.

What causes Diabetes Insipidus related to the hypothalamus?

Can be caused by a lesion in the hypothalamus affecting ADH production.

What can cause obesity related to the hypothalamus?

Can be caused by a lesion in the hypothalamus affecting hunger regulation.

What can cause thermoregulatory failure related to the hypothalamus?

Can be caused by a lesion in the hypothalamus affecting temperature regulation.

What is the function of the Pons?

Acts as a bridge of fibers between the cerebrum and cerebellum; contains nuclei for cranial nerves V–VIII.

Which cranial nerves have nuclei in the Pons?

Nuclei for cranial nerves V (Trigeminal), VI (Abducens), VII (Facial), and VIII (Vestibulocochlear) are located here.

What is the Pons's role in breathing?

Modulates respiratory rhythm through pneumotaxic and apneustic centers.

What reflexes are associated with the Pons?

Involves corneal blink and mastication reflexes.

What causes locked-in syndrome?

May result from damage to the pons if corticospinal tracts are bilaterally destroyed.

What is the function of the Medulla Oblongata?

Connects the brain to the spinal cord and houses vital autonomic centers for cardiovascular and respiratory functions.

Where does decussation occur in the brainstem and what percentage of fibers cross?

Approximately 90% of corticospinal fibers cross here, leading to contralateral control.

What happens with a high lesion in the Medulla Oblongata?

Can result in respiratory arrest.

What are the components of the Limbic System?

Hippocampus, amygdala, cingulate gyrus, and fornix.

What is the function of the Limbic System?

Governs emotion, motivation, and memory consolidation.

What is amygdala hyperactivity linked to?

Linked to PTSD.

What is the effect of hippocampus damage?

Can cause anterograde amnesia (e.g., in Alzheimer’s disease).

What is the Corpus Callosum?

The largest commissural fiber bundle linking the left and right cerebral hemispheres (approximately 200 million axons).

What is the role of the Corpus Callosum?

Enables bilateral integration of functions such as language (left) and prosody (right), as well as bimanual coordination.

What is a corpus callosotomy and what does it lead to?

Surgical procedure to treat intractable epilepsy, leading to “split-brain” phenomena.

What are "split-brain" phenomena?

Results from corpus callosotomy due to severed communication between hemispheres.

What is the composition of CSF?

Low protein content (<45 mg/dL), glucose around 60% of serum levels, and optimized ion milieu for neuronal excitability.

What is the choroid plexus?

Produces CSF, composed of ependymal cells + fenestrated capillaries.