Neurological Terms and Reflexes

Key Terms

• Sympathetic nervous system involves excitatory responses and functions as the fight-or-flight system
• Vertigo is an illusion of movement
• Agnosia is the inability to recognize objects via sensory input
• Ataxia is the inability to coordinate muscle movement
• Romberg test assesses cerebellar function and body positioning, a positive test indicates dysfunction after 20 seconds
• Babinski reflex is the reflex action of the toes, indicative of motor control abnormalities in adults
• Clonus involves abnormal alternating contraction and relaxation of a muscle
• Delirium is an acute confused state with disorientation
• Dendrites conduct impulses toward the cell body
• Flaccidity involves a lack of muscle tone
• The parasympathetic nervous system division controls visceral functions in non stressful conditions
• Postural sense is awareness of body position without looking
• Reflex is an automatic response to stimuli
• Rigidity involves increased muscle tone at rest
• Spasticity involves a sustained increase in muscle tension

Anatomy of the Nervous System

• The central nervous system (CNS) consists of the brain and spinal cord
• The peripheral nervous system consists of cranial nerves, spinal nerves, and the autonomic nervous system

Physiology of the Nervous System

• Controls motor, sensory, autonomic, cognitive, and behavioral activities

Cells of the Nervous System

• The neuron is the basic functional unit
• Neurons consist of dendrites, a cell body, and an axon
• Dendrites receive electrochemical messages
• Axons carry electrical impulses away from the cell body
• Ganglia/Nuclei include nerve cell bodies occurring in clusters, while centers are clusters with the same function
• Glial cells supports, protect, and nourish neurons and are 50x greater in number

Neurotransmitters

• Facilitate communication between nerve cells or from nerve cells to target cells
• They are created and stored in Synaptic vesicles
• Action potentials prompt neurotransmitter release into synapses
• Neurotransmitters travel through the synapse and bind to receptors on the postsynaptic cell membrane
• Target cell activity is excited or inhibited by neurotransmitters
• All brain functions are modulated through neurotransmitter receptor sites

Forebrain

Cerebrum Composition

• Two hemispheres, the thalamus, the hypothalamus & the basal ganglia

Frontal Lobe Functions

• Responsible for concentration, abstract though, information storage, and motor function
• Broca area handles motor control of speech and in the left hemisphere
• Judgement, affect, personality, and inhibitions

Parietal Lobe Functions

• Posterior to the frontal lobe
• Analyzes and interprets the information to the cortical areas
• Is essential to body awareness in space, recognize size and shape, and differentiate left from right

Temporal Lobe Functions

• Located below the parietal and frontal lobes
• Processes auditory information
• Key role in understanding language and music

Occipital Lobe Functions

• Located on the posterior portion of the parietal lobe
• Visual interpretation and memory

Corpus Callosum Functions

• Connects the two brain hemispheres with thick nerve fibers
• Transmits information from one side of the brain to the other
• Left side specializes in verbal, linguistic, and analytical functions
• Right side specializes in geometric, visual functions

Midbrain

Midbrain composition

• Pons and Medulla oblangata
• Connects the cerebrum with the cerebrellar hemisphere
• Contains sensory and motor pathways

Pons Functions

• A bridge between the two cerebellum
• Cranial nerves V - VIII
• Portions that regulate respiration

Medulla Functions

• Motor fibers carry signals from the brain to the spinal cord
• Contains respiratory reflex centers, bp, heart rate, and coughing,
• Reticular formation handles arousal and the wake/sleep cycle

Thalamus Functions

• Relay station for all except smell

Hypothalamus Functions

• Role in endocrine function, regulates pituitary secretion of hormones
• Influences metabolism, reproduction, urine production
• Fluid balance, temperature regulation

Basal Ganglia Function

• Fine motor movement, including hands and lower extremities

Cerebellum Functions

• Located below the occipital lobe, behind the midbrain and pons
• Enables smooth, coordinated movements
• Controls balance, proprioception

Brain Protection

Cranium composition

• Bony skull protects
• Frontal, temporal, parietal, occipital, and sphenoid cranial bones are present

Meninges Function

• Connective tissues that cover the brain and spinal cord
• Provide nourishment, support, and protection

Dura Mater Composition

• Outermost layer
• Covers the brain and spinal cord
• Tough and thick

Arachnoid Composition

• Middle membrane
• Thin delicate membrane like a spider web

Pia Mater Composition

• Inner most membrane
• Thin and transparent layer

Spinal fluid

• Clear colorless fluid
• Produced in the ventricles
• Absorbs excess pressure
• Important in immune and metabolic functions

Arteries - Blood Supply

• Common carotid supplies to anterior brain
• Subclavian supplies most of the posterior circulation

Veins - Blood Drain

• Veins reach brain's surface and empty into a dural sinuses
• Not have the valves
• The blood brain barrier protects the central nervous system

The Spinal Cord

• Links the brain to the periphery
• 45cm long at about a finger's thickness
• Ascending and descending tracts (white matter)
• H shaped gray matter core
• Fiber bundles conduct messages

Autonomic Nervous System

• Regulates the inner working of the body
• The two main divisions are sympathetic and parasympathetic
• Sympathetic creates excitatory responses
• Parasympathetic primarily controls visceral functions