Med Term - The Nervous System

Brain stem

comprising the forebrain, midbrain, and hindbrain

cerebrum

main (largest) portion of the brain, occupying the upper part of the cranial cavity; its two hemispheres, united by the corpus callosum, form the largest part of the CNS in humans

cerebellum

situated on the back of the brain stem; consisting of a median lobe (vermis) and two lateral lobes (the hemispheres)

diencephalon

region of the brain that includes the thalamus, hypothalamus, and the central core of the forebrain

encaphalon

brain

hypothalamus

region of the forebrain below the thalamus that coordinate both autonomic NS and the endocrine system. Regulates body temperature, thirst, hunger, the sleep-wake cycle, and physical expression of emotions

tha;amus

part of the brain that processes and relays all sensory and motor signals between the cerebral cortex and the spinal cord, and mediates motor activities, sensation, learning, and memory

spinal cord

That part of the CNS lodged in the spinal column

meninges

the three membranes covering the brain and spinal cord: dura mater, arachnoid, and pia mater

the three membranes covering the brain and spinal cord: dura mater, arachnoid, and pia mater

the outermost, toughest of the three meninges (membranes) of the brain and spinal cord

arachnoid

the delicate membrane interposed between the dura mater and the pia mater

pia mater

the innermost of the three meninges covering the brain and spinal cord

cerebrospinal fluid

fluid within the ventricles of the brain, the subarachnoid space in the brain and spinal cord, and the central canal

Cranial Nerves

the 12 pairs of nerves emerging from the cranial cavity through various openings in the skull, as follows

abducens

muscles of the eye turning the eye outward

accessory

neck and back muscles

facial

muscles of the face, ears, and scalp

glossopharyngeal

pertaining to the tongue, pharynx, and salivary glands

hypoglossal

beneath the tongue; associated with chewing, swallowing, and speech

oculomotor

movements of the eye, eyelid, lens and pupils

olfactory

sense of smell

optic

vision

trigeminal

movements of the upper and lower jaw needed for chewing

trochlear

eye movement

vagus

muscles needed for speech and swallowing

vestibulocochlear

located in the ear; balance and hearing

Spinal Accessory Nerves

the 31 pairs of nerves without special names that are connected to the spinal cord

parasympathetic

he part of the ANS bringing body functions back to normal after a stressful situation has ended

sympathetic

the part of the ANS assisting the body in emergencies, defense, and survival

cauda equina

the collection of spinal roots descending from the lower spinal cord and supplying the rectal area

encephalon

the brain

fissure

deep furrow in the brain

foramen magnum

a large opening in the occipital bone through which the spinal cord passes

ganglion

a knot; a group of nerve cell bodies located outside the CNS

gyrus (plural: gyri)

convolutions of the cerebrum

hemisphere

either half of the brain; the cerebrum is divided into the left and the right hemispheres that control different functions

limbic system

the part of the brain associated with attitudes and emotional behavior

nerve cells (neurons)

conducting cells of the NS consisting of a cell body containing the nucleus and its surrounding cytoplasm, the axon, and dendrites; specialized cells for transmitting impulses

neurilemma (sheath of Schwann)

the membrane surrounding the peripheral nerves

neurotransmitter

a chemical substance released at the end of a nerve fiber in response to a nerve impulse; neurotransmitters affect sleep, hunger, thinking, memory, movement, and emotions, for example, acetylcholine

plexus

a network of nerves or blood vessels

sulcus (plural: sulci

a groove, trench, or furrow on the brain surface

ventricle (brain)

interconnected cavities in the brain

amyotrophic lateral sclerosis (ALS)

progressive degeneration of the upper and lower motor neurons; usually fatal

anencephaly

congenital absence of the brain; death occurs

Bell's palsy

unilateral facial paralysis of sudden onset caused by lesion of the facial nerve

carpal tunnel syndrome

caused by repetitive overuse of the fingers, hands, or wrists, and inflammation of the median nerve in the tunnel. Symptoms are pain, especially at night; treatment involves anti-inflammatory drugs, splints, physical therapy, and ceasing overuse

cerebral palsy (CP

permanent brain damage that occurs during pregnancy, birth, or immediately after birth; those with CP lack muscle control, coordination, and tone as well as posture and balance. It can also impact fine motor skills

cerebrovascular accident (CVA)

a decrease in blood flow supply to the brain and death to that specific portion of the brain; three types of CVA are hemorrhagic stroke, a rupture of cerebral blood vessels; thrombotic stroke, a blood clot in the arteries leading to the brain; and embolic stroke, which occurs when an embolus (fragment of blood clot) lodges in a cerebral vessel and causes occlusion

concussion, also closed head injury (CHI)

a violent blow to the head; there may or may not be a loss of consciousness

convulsion (seizure)

an involuntary contraction or series of contractions of the voluntary muscles; sudden disturbances in mental functions and body movements, some with loss of consciousnes

encephalitis

inflammation of the brain, usually caused by an infection

epilepsy

seizure disorder; cause usually unknown; symptoms managed with medication

fracture (skull)

a break in the bones of the skull; cause can be accidents, falls, gunshot wounds

hematoma

blood (clot) outside of blood vessels because of trauma or stroke; if located in the brain, the clot must be dissolved or removed if large enough to cause pressure on the brain

herpes zoster

"shingles"; an acute inflammatory disease of the spinal nerve (sensory root ganglion) caused by a reactivation of the varicella-zoster virus in someone who has previously had chicken pox. Symptoms are a painful skin rash with blisters

huntington's chorea

chorea is ceaseless rapid, jerky, involuntary movements; Huntington's chorea is a hereditary disease marked by chronic progressive chorea and mental deterioration

hydrocephalus

"water on the brain"; a congenital or acquired condition marked by dilation of the cerebral ventricles and accumulation of cerebrospinal fluid within the skull; typically, there is enlargement of the head, prominence of the forehead, mental deterioration, and convulsions

meningitis

inflammation of the meninges of the brain and spinal cord caused by bacterial, viral, or fungal infection

meningocele (myelomeningocele)

hernial protrusion of the meninges through a bone defect in the cranium or vertebral column; a severe form of spina bifida

migraine (headache)

moderate to severe headache, usually one sided and accompanied by nausea, vomiting, and extreme sensitivity to light and sound

multiple sclerosis (MS)

brain and spinal cord contain areas of degenerated myelin. Symptoms include weakness, incoordination, speech disturbances, and visual complaints

myasthenia gravis (MG)

a progressive neuromuscular disorder characterized by chronic fatigue and muscle weakness. Onset is gradual, with difficulty speaking and swallowing and weakness of the facial muscles; the weakness may then extend to other muscles enervated by cranial nerves, especially the respiratory muscles

narcolepsy

chronic sleep disorder with daytime drowsiness and sudden attacks of sleep which can occur at any time during daytime activities such as talking or working

neuropathy

disease or dysfunction of one or more peripheral nerves, typically causing numbness or weakness. Present in various medical conditions

organic brain syndrome (chronic brain syndrome)

a general term used to describe decreased mental function due to a medical disease such as Alzheimer's disease or Parkinson's disease; symptoms include changes in memory, behavior, language skills, and ability to carry out activities of daily living

parkinson's disease (PD)

a slowly progressive, degenerative, neurologic disorder characterized by resting tremor

petit mal seizures

a minor seizure lasting only a few seconds with momentary clouding of consciousness; the individual may not be aware of the episode. It is more frequent in children

poliomyelitis (polio)

an acute viral disease with fever, sore throat, headache, vomiting, and often stiffness of the neck and back; may be minor or major—causing permanent paralysis; prevented by vaccination since the late 1950s

sciatica

severe pain in the leg along the course of the sciatic nerve; also pain radiating into the buttock and lower limb, most commonly caused by herniation of a lumbar disk

spina bifida

birth defect of the neural tube (brain and spinal cord) during embryonic development; incomplete closing of the vertebral column and meninges of the spinal column. Results in neurological defects similar to spinal cord injury

spinal cord injuries

a traumatic disruption of the spinal cord that can cause paraplegia and quadriplegia; spinal fractures and dislocations are common in car accidents, falls, and gunshot wounds

subdural hematoma

venous bleeding beneath the dura mater, usually a result of a closed head injury. Symptoms include drowsiness, headache, confusion, seizures, and signs of intracranial pressure and paralysis. Treatment involves surgical evacuation of the blood through burr holes in the skull or a craniotomy if the blood has solidified and cannot be aspirated through burr holes

Tay-Sach's disease

an inherited inborn error of metabolism caused by an enzyme deficiency causing altered lipid metabolism that results in accumulation of a specific lipid in the brain, leading to physical and mental retardation. It is a progressive disorder, marked by degeneration of brain tissue, dementia, convulsions, paralysis, blindness, and death

whiplash

a popular term for an acute cervical sprain; acceleration extension injury of the cervical spine

aphasia

partial or total loss of the ability to communicate verbally or using written words; caused by a traumatic brain injury, brain tumor, or stroke

ataxia

lack of muscle coordination which may affect voluntary movements such as speaking, swallowing, and walking. Caused by injury or disease of the CNS

Babinski's sign

reflex response; when sole of the foot is stroked, the big toe turns up instead of down (normal in newborn, but pathologic later on)

comatose

a state of deep unconsciousness for a prolonged period, usually as a result of trauma, stroke, cancer, or infection in the brain

deep tendon reflex

reflex response (muscle contraction) in response to a sharp tap on a tendon at the insertion of a muscle; used to evaluate the integrity of the spinal cord and peripheral NS

paralysis

loss of sensation or voluntary muscle function; usually caused by damage or disorder of the muscles or the nerves supplying the muscles

paresthesia

an abnormal sensation such as burning or prickling

paresis

slight or incomplete paralysis

Romberg test

a test of the sense of balance, e.g., the patient may lose balance when standing erect, feet together, and eyes closed

spasticity

disorder of the muscles resulting in tight or stiff muscles and the inability to control those muscles; caused by imbalance of signals from the brain and spinal cord to the muscles

stimulus

that which can cause a physiological response by an organ or tissue. For example, the ear, and sensory receptors in the skin are sensitive to external stimuli such as sound and touch

tremor

unintentional, rhythmic muscle movement with back and forth movements of one or more parts of the body, most commonly of the hands. Caused by disease or trauma to the brain

angiogram (arteriogram), cerebral

a radiopaque substance is injected into arteries in the neck, then X-ray films are taken; used to evaluate blood vessels in the brain for clots or bleeding

computerized tomography (CT) brain scan; also called CAT scan

three-dimensional view of brain tissue obtained as X-ray beams pass through layers of the brain. A CT scan will show areas of tumors, hemorrhage, blood clots, aneurysms

echoencephalogram

use of ultrasound to show displacement of brain structures

electroencephalogram (EEG)

record of electrical activity of the brain; often used to diagnose epilepsy

magnetic resonance imaging (MRI) of the brain

noninvasive technique using magnetic waves to create an image of the brain; it provides visualization of fluid, soft tissue, and bony structures, and is far more precise and accurate than most diagnostic tools

myelogram (myelography)

use of X-ray together with the injection of a special dye to make pictures of the vertebra (bones) and fluid of the spinal column to evaluate for tumors or a herniated disk

pneumoencephalogram (PEG)

the radiograph obtained by visualization of the fluid-containing structures of the brain after cerebrospinal fluid is intermittently withdrawn by lumbar puncture and replaced by air, oxygen, or helium

positron emission tomography (PET) scan

images of various structures show how the brain uses glucose and gives information about brain function; used to assess for Alzheimer's, stroke, epilepsy, brain tumors and schizophrenia

ventriculography

radiography of the cerebral ventricles after introduction of air or other contrast medium

burr hole

holes made into the skull with a drill creating openings in bone to permit access for biopsy, insertion of drains for relieving pressure, or for monitoring devices

cordotomy

cutting of nerve fibers of the spinal cord to relieve intractable pain

craniotomy

any operation on the cranium, e.g., puncture of the skull and removal of a hematoma to relieve pressure on the brain

laminectomy

excision of the posterior arch (back side) of a vertebra to view the spinal cord or to relieve pressure