Nervous System Medical Terminology

Word Parts brain = encephal/o examples: encephalitis, encephalography spinal cord = myel/o examples: myelosis, myelitis nerves = neur/o, neur/i examples: neurology, neurosis

walk = ambul/o examples: ambulate, ambulation head = cephal/o examples: cephalgia shaken; violent agitation = concuss/o example: concussion bruise = contus/o example: contusion

sound = ech/o example: echoencephalography sensation, feeling = -esthesia example: anesthesia, anesthetic membranes = mening/o examples: meningitis, meningocele abnormal fear = -phobia example: necrophobia, claustrophobia

mind = psych/o example: psychosis, psychology sleep = somn/o example: somnambulism brain, cerebrum = cerebr/o example: cerebral cerebellum = cerebell/o

Structures central nervous system = brain and spinal cord peripheral nervous system = 12 pairs of cranial nerves extending from the brain and the 31 pairs of spinal nerves extending from the spinal cord.

Meninges Meninges - three layers of connective tissue membrane that enclose the brain and spinal cord. These are the dura mater, arachnoid membrane, and pia mater.

The dura mater is the thick, tough outermost membrane. epidural – above the dura mater, but within the surrounding bone walls. subdural – below the dura membrane, but above the arachnoid membrane.

The arachnoid membrane, which resembles a spider web, is the second layer surrounding the brain and spinal cord. The subarachnoid space, located below the arachnoid membrane, and above the pia mater, contains cerebrospinal fluid.

The pia mater, the third layer of the meninges, is located nearest to the brain and spinal cord. It consists of delicate connective tissue and a rich supply of blood vessels.

Cerebrospinal Fluid Cerebrospinal Fluid, also known as CSF, is a clear, colorless, watery fluid produced by special capillaries within the ventricles of the brain. It flows throughout the brain and spinal cord, and it nourishes, cools, and cushions these organs from shock or injury.

The Brain The structures of the brain are protected by the cranium and spinal column. The functions vital to life support are located in the most protected portion of the brain.

Cerebrum – largest and uppermost portion of the brain. Responsible for all thought, judgment, memory, association. Cerebral cortex – made up of gray matter; outer layer of the cerebrum, arranged in folds. Two halves – left and right hemisphere.

Each hemisphere is divided into four lobes: (not on note sheet): frontal lobe – controls motor functions. parietal lobe – receives and interprets nerve impulses. occipital lobe – controls eyesight temporal lobe – controls the senses of hearing and smell.

The Lobes of the Brain

Major parts of the brain Label internal brain structures according to the overhead transparency.

cerebellum – second largest part of the brain. Located at back of head, below the posterior part of cerebrum. Receives incoming messages regarding movement within joints, muscle tone, positions of the body.

Brainstem – stalk-like portion of the brain; connects the cerebral hemispheres with the spinal cord. It is made up of the: midbrain – provides conduction pathways. pons – where the nerves cross (right side vs. left side) medulla oblongata – controls basic life functions: respirations, heart rate, blood pressure.

The pons, which means bridge, is where nerve cells cross from one side of the brain to control the opposite side of the body. The medulla oblongata controls basic life functions including the muscles of respiration, heart rate, and blood pressure.

The thalamus is located below the cerebrum The thalamus is located below the cerebrum. It monitors sensory stimuli by suppressing some and magnifying others. It relays impulses to and from the cerebral cortex and the sense organs of the body. The hypothalamus is located below the thalamus, and regulates vital body functions, such as heart rate, blood pressure, body temperature, hunger, water balance, thirst, sleep-wakefulness, endocrine system.

The Nerves A nerve is one or more bundles of neuron cells. A tract is a bundle or group of nerve fibers. Ascending tracts carry nerve impulses toward the brain. Descending = away from the brain.

A neuron is the basic cell of the nervous system. Types: sensory or afferent carry impulses toward the brain or spinal cord. Motor or efferent carry impulses away from the brain and spinal cord.

innervation – the supply of nerves to a body part. stimulus – anything that excites or activates a nerve and causes an impulse. impulse – a wave of excitation transmitted through nerve fibers and neurons. reflex – automatic, involuntary, response to some change

Synapse – the space between two neurons. A neurotransmitter is a chemical messenger that transmits messages between nerve cells by making it possible for the nerve impulse to “jump” across the synapse to the next neuron.

Some axons are protected by a white fatty tissue protective covering called myelin sheath. It gives nerve fibers a white color, so the myelinated axons of nerves are known as “white matter.” The term myelinated means having a myelin sheath.

In multiple sclerosis, demyelination occurs, which is the loss of this protective covering. The portions of nerves that do not have a myelin sheath are gray, and make up the gray matter of the brain and spinal cord.

Cross section of spinal cord

Levels of Consciousness conscious – alert, awake, responding appropriately. syncope – fainting, brief loss of consciousness. Sometimes referred to as a “syncopal episode”. lethargy – lowered level of consciousness; listless; drowsiness. Lethargic.

stupor – a state of impaired consciousness, marked by a lack of responsiveness to environmental stimuli. coma – a profound, deep state of unconsciousness, marked by the absence of spontaneous eye movements, no response to painful stimuli, and no vocalization (speech).

comatose – refers to a person who is in a coma. delirium – potentially reversible condition often associated with a high fever that comes on suddenly. dementia – a slowly progressive decline in mental abilities.

Peripheral Nervous System Consists of cranial nerves and spinal nerves. The autonomic nervous system controls the involuntary actions of the body. It is divided into: Sympathetic – fight or flight. Parasympathetic – rest and digest.