Nervous System

Overview and Functions

The nervous system is a complex network responsible for coordinating body activities and transmitting signals between different parts of the body. It is divided into the central nervous system (CNS) and the peripheral nervous system (PNS).

• CNS: Consists of the brain and spinal cord; interprets stimuli and controls body functions.

• PNS: Acts as a communication highway, conveying messages to and from the CNS.

• Functions are divided into voluntary (skeletal muscle control) and involuntary (cardiac muscle, smooth muscle) activities.

Structures of the Nervous System

Main Components

• Brain: Center for interpretation of thoughts, movement, and coordination.

• Cerebrum: Largest portion of the brain, divided into right and left hemispheres.

• Ventricles: Spaces within the brain containing cerebrospinal fluid (CSF).

• Cerebellum: Located under the posterior brain; coordinates skeletal muscles and maintains balance.

• Brainstem: Connects the brain with the spinal cord; controls respiration and heart rate.

• Pons: Bridge connecting the cerebrum with the cerebellum and brainstem.

• Medulla oblongata: Located between the pons and spinal cord; controls respiration, heart rate, and blood pressure.

• Spinal cord: Pathway carrying impulses to and from the brain.

• Dura mater: Tough outer covering of the brain.

• Cerebrospinal fluid (CSF): Clear fluid that cushions the brain and spinal cord.

• Nerve: Cord-like structure carrying impulses; 12 pairs of cranial nerves, 31 pairs of spinal nerves.

• Neuron: Nerve cell that carries impulses.

Medical Terminology: Word Parts

Combining Forms

Disease and Disorder Terms

Built from Word Parts

• Cerebellitis: Inflammation of the cerebellum.

• Cerebral thrombosis: Blood clot in a vessel of the brain (ischemic stroke).

• Duritis: Inflammation of the dura mater.

• Encephalitis: Inflammation of the brain.

• Meningioma: Tumor of the meninges.

• Meningitis: Inflammation of the meninges.

• Neuralgia: Pain in a nerve.

• Neuropathy: Disease of the nerves.

• Subdural hematoma: Bleeding below the dura mater.

Not Built from Word Parts

• Alzheimer disease: Type of dementia; brain shrinks, tissue dies.

• Bell palsy: Temporary paralysis of one side of the face due to inflammation.

• Cerebral aneurysm: Weak vessel in the brain, risk of rupture.

• Cerebral embolism: Blood clot in the brain, causing stroke.

• Cerebral palsy: Brain defect causing uncontrolled muscle control.

• Dementia: Cognitive decline.

• Epilepsy: Recurrent seizures.

• Multiple sclerosis (MS): Degenerative disease with demyelination of brain and spinal cord, loss of muscle control.

Surgical Terms

Built from Word Parts

• Neurectomy: Excision of a nerve.

• Neuroplasty: Surgical repair of a nerve.

• Neurotomy: Incision into a nerve.

• Radicotomy/Rhizotomy: Incision into a nerve root.

Diagnostic Terms

Built from Word Parts

• Cerebral angiography: Recording of the vessels of the cerebrum.

• CT myelography: Process of recording the spinal cord using CT imaging.

• Electroencephalogram (EEG): Record of the electrical activity of the brain.

Not Built from Word Parts

• Computed tomography (CT): Computerized radiographic process producing sectional images.

• Magnetic resonance imaging (MRI): High-strength, computer-controlled magnetic fields producing sectional images.

• Positron emission tomography (PET): Nuclear medicine procedure combined with CT imaging.

• Evoked potential studies (EP studies): Group of tests measuring brain activity in response to stimuli.

• Lumbar puncture (LP): Diagnostic test involving aspiration of CSF from the spinal canal.

Complementary Terms

Built from Word Parts

• Anesthesia: Without feeling.

• Aphasia: Loss of speech.

• Cephalgia: Pain in the head (headache).

• Encephalopathy: Disease of the brain.

• Hemiplegia: Paralysis of one side of the body.

• Mental: Pertaining to the mind.

• Neurology: Study of nerves.

• Quadriplegia: Paralysis of all four limbs.

• Subdural: Pertaining to below the dura mater.

Not Built from Word Parts

• Coma: State of profound unconsciousness.

• Concussion: Injury to the brain, often from trauma.

• Conscious: Alert and aware of surroundings.

• Disorientation: State of confusion regarding time, place, or identity.

• Dysarthria: Inability to use speech muscles properly.

• Ataxia: Lack of muscle coordination.

• Incoherent: Unable to express oneself clearly.

• Seizure: Sudden, involuntary body movements due to abnormal brain activity.

• Syncope: Dizziness or fainting.

Types of Cognitive Impairments

• Mild cognitive impairment (MCI): Significant memory difficulty, often a precursor to dementia.

• Age-related memory impairment: Normal memory changes associated with aging.

• Delirium: Acute disturbance of consciousness and cognition, often due to metabolic disturbances, drugs, alcohol, trauma, infection, or hypoglycemia.

• Pseudodementia: Cognitive impairment not caused by brain tissue damage, but by mental illness such as major depression.

Behavioral Health Terms

Built from Word Parts

• Psychiatrist: Physician specializing in the study and treatment of mental disorders.

• Psychology: Study of the mind.

• Psychopathy: Disease of the mind.

• Psychosis: Abnormal condition of the mind, including derangement, delusions, and hallucinations.

Not Built from Word Parts

• Anorexia nervosa: Eating disorder characterized by disturbed body image and self-starvation.

• Anxiety disorder: Disorder marked by feelings of apprehension, tension, real or imagined threats.

• Attention deficit/hyperactivity disorder (ADHD): Disorder involving learning and behavioral problems.

• Autism: Mental disorder with impairment in socialization and communication.

• Bipolar disorder: Major psychological disorder with mood disturbances, including manic and depressive episodes.

Abbreviations

Summary Table: Key Structures and Functions

Example: A patient with meningitis (inflammation of the meninges) may present with headache, fever, and neck stiffness. Diagnosis may involve a lumbar puncture to analyze CSF.

Additional info: The nervous system is essential for integrating sensory input, coordinating voluntary and involuntary actions, and maintaining homeostasis. Disorders can affect cognition, movement, sensation, and behavior.