Chapter 17: The Nervous System Flashcards
Central nervous system
brain and spinal cord
peripheral nervous system
12 pairs of cranial nerves, spinal and peripheral nerves
frontal lobe
The frontal lobes are considered our emotional control center and home to our personality. There is no other part of the brain where lesions can cause such a wide variety of symptoms (Kolb & Wishaw, 1990). The frontal lobes are involved in motor function, problem solving, spontaneity, memory, language, initiation, judgement, impulse control, and social and sexual behavior. The frontal lobes are extremely vulnerable to injury due to their location at the front of the cranium, proximity to the sphenoid wing and their large size.
parietal lobe
The parietal lobes can be divided into two functional regions. One involves sensation and perception and the other is concerned with integrating sensory input, primarily with the visual system. The first function integrates sensory information to form a single perception (cognition). The second function constructs a spatial coordinate system to represent the world around us. Individuals with damage to the parietal lobes often show striking deficits, such as abnormalities in body image and spatial relations (Kandel, Schwartz & Jessel, 1991).
occipital lobe
The occipital lobes are the center of our visual perception system. They are not particularly vulnerable to injury because of their location at the back of the brain, although any significant trauma to the brain could produce subtle changes to our visual-perceptual system, such as visual field defects and scotomas.
cerebellum
The cerebellum is involved in the coordination of voluntary motor movement, balance and equilibrium and muscle tone. It is located just above the brain stem and toward the back of the brain
brainstem
The brain stem plays a vital role in basic attention, arousal, and consciousness. All information to and from our body passes through the brain stem on the way to or from the brain. Like the frontal and temporal lobes, the brain stem is located in an area near bony protrusions making it vulnerable to damage during trauma.
midbrain
The midbrain or mesencephalon (from the Greek mesos - middle, and enkephalos - brain[1]) is a portion of the central nervous system associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation
pons
The pons is a structure located on the brain stem, named after the Latin word for “bridge” or the 16th-century Italian anatomist and surgeon Costanzo Varolio (pons Varolii).[1] It is cranial to the medulla oblongata, caudal to the midbrain, and ventral to the cerebellum. In humans and other bipeds, this means it is above the medulla, below the midbrain, and anterior to the cerebellum. This white matter includes tracts that conduct signals from the cerebrum down to the cerebellum and medulla, and tracts that carry the sensory signals up into the thalamus.[2]
The pons in humans measures about 2.5 cm in length. Most of it appears as a broad anterior bulge rostral to the medulla. Posteriorly, it consists mainly of two pairs of thick stalks called cerebellar peduncles[disambiguation needed]. They connect the cerebellum to the pons and midbrain.[3]
The pons contains nuclei that relay signals from the forebrain to the cerebellum, along with nuclei that deal primarily with sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture
medulla
The medulla oblongata is a portion of the hindbrain that controls autonomic functions such as breathing, digestion, heart and blood vessel function, swallowing and sneezing.
Spinal cord
C1-7
T1-12
L1-5
S1-5
CN1
(S)olfactory-smell
CN2
(S)optic: vision
CN3
(M)occulomotor: pupil constriction, opening eye(lid elevation), most EOM
CN4
(M)Trochlear: downward, inward rotation of eye
CN5
(B)Trigeminal: motor: jaw clenching; lateral jaw movement
sensory: facial. nerve has 3 divisions-opthalmic, maxillary, mandibular
CN6
(M)Abducens:lateral deviation of eye
CN7
(B)-facial:
motor: facial movements, expression, closing eye, closing mouth
sensory: taste for salty, sweet, sour, bitter (anterior 2/3 tongue)
CN8
(S)-acoustic: hearing-cochlear division; balance-vestibular division
CN9
(B) Glossopharyngeal
motor: pharynx
sensory: posterior portions of eardrum, ear canal, posterior tongue taste
CN10
(B) Vagus
motor: palate, pharynx, larynx
sensory: pharynx, larynx
CN11
(M): spinal accessory-sternomastoid and upper portion of trapezius
CN12
(M)-hypoglossal-tongue
DTR physiology
over both CNS and PNS. Involuntary stereotypical response that may involve as little as 2 neurons (1 afferent sensory, 1 efferent motor) across a single synapse. tapping the tendon activates special sensory fibers in the partially stretched muscle, triggering a sensory impulse that travels to the spinal cord via a peripheral nerve. the stimulated sensory fiber synapses directly with the anterior horn cell innervating the same muscle. when the impulse crosses the neuromuscular junction, the muscle suddenly contracts, completing reflex arc
grading muscle strength
0-no muscular strength
1-a barely detectable flicker or trace of contraction
2-active movement of body part with gravity eliminated
3-active movement against gravity
4- active movement against gravity with some resistance
5-active movement against full resistance without evident fatigue-normal
coordination requirements
4 areas: muscle strength/system; cerebellar system (rhythmic movement and steady posture; vestibular system (balance and coordinating eye, head, body movements); sensory system for position sense
Rapid Alternating Movements (RAM)-arms
- Hand to thigh-palmar/dorsum
- Thumb tapping to index finger fast
cerebellar disease will impair movements
Rapid Alternating Movements (RAM)-legs
patient taps ball of foot to your hand
Point-to-point movements:arms
finger-to nose
In cerebellar disease movements are clumsy, unsteady, inappropriately varying of speed, force, and direction. finger may overshoot its mark and finally reach it-dysmetria
Point-to-point movements:legs
heel-to-shin. place heel to opposite knee and run down shin
gait
walk across room, her-to-toe, walk on toes then heels
stance: romberg
romberg: position sense-patient stand feet together and with eyes open and then close both eyes for 30-60 seconds w/o support. . In ataxia from dorsal column disease and loss of position sense, vision compensates for the sensory loss. the patient stands fairly well with eyes open but loses balance when they are closed=positive romberg.
cerebellar ataxia: difficulty standing with feet together eyes open or closed
stance pronator drift
patient stands for 20-30 seconds with both arms straight forward palms up, and with eyes closed. normal-person holds arms well. now instruct patient to maintain arm position and tap arms briskly downward-arms normally return to horizontal position. pronation of one forearm=corticospinal tract lesion in contralateral hemisphere
Sensory system: pain
spinothalmic tracts:
sharp or dull: cotton swab versus paperclip tip
sensory system: temp
spinothalmic: hot versus cold (test tubes w hot and cold water)
sensory system: light touch
spinothalmic and posterior
wisp of cotton-ask when pt feels something
sensory system: vibration
tuning fork to joint locations-ask what patient feels
sensory system:proprioception (position)
start with big toe and pt eyes closed. ask when up or down then move proximal with ankle, fingers, wrist, elbow
discriminative sensations:for?
test ability of the sensory cortex to correlate, analyze, and interpret sensations. They depend on touch and position sense. If diminished-disease of sensory cortex
stereognosis
ability to identify an object by feeling. familiar object in hand: coin, paperclip, key, pencil. Distinguishing heads from tails is a sensitive test
**astereognosis: inability to recognize objects in hand
number identification
if patient unable to handle objects in hand draw a number using blunt object in the patients palm
Graphesthesia
2-point discrimination
using the 2 ends of a paperclip touch a finger pad in 2 places simultaneously. alternate with one point touch. Record the minimal distance at which the patient can discriminate one from 2 points, normally less than 5mm in finger pads. lesions of the sensory cortex will increase the distance between recognizable points
point localization
briefly touch a point on the patients skin with eyes closed. have patient open eyes and point to place touched
extinction
touch corresponding areas on both sides of the body. normally patient can feel both at same time
dermatomes
areas of skin innervated by single nerve root
Grading reflexes
0-none 1+ somewhat diminished low normal 2+ average normal 3+ brisker than average; possibly indicative of disease 4+very brisk hyper reactive; clonic
anal reflex
last reflex to die
meningeal signs
neck mobility: normally neck is supple and pt able to flex chin to chest w/o difficulty
brudzinski’s sign
as flexing neck watch the hips and knees in response-normally relaxed; flexion of hips and knees=positive sugest irritation
Kernig’s sign
flex pt leg at both the hip and knee and then straighten the knee. normally should not produce pain (discomfort upon full extension behind knee may be normal)
=pain and increased resistance to extending the knee =positive sign (bilateral)
asterixis
helps identify metabolic encephalopathy. ask patient to “stop traffic” by extending both arms with hands cocked up and fingers spread. watch for 1-2 minutes. sudden brief nonrhythmic flexion of the hands and fingers indicative of liver disease, uremia, and hypercapnia
resting (static) tremors
most present at rest-decrease or disappear with voluntary movement-pill-rolling tremors of parkinsons
postural (action) tremors
during maintenance of posture; hyperthyroid, anxiety, fatigue
intention tremors
absent at rest and appear with activity worse as gets near target-disorders of cerebellar pathways such as MS
oral-facial dyskinesias
rhythmic, repetitive, bizarre movements that invlove the face, mouth, jaw, and tongue-tardive dyskinesia.
psychoses
tics
brief repetitive stereotyped coordinated movements occuring at irregular interval. tourettes and drugs such as phenothiazines and amphetamines
nystagmus
defined by its fast phase: example if the eyes jerk quickly to the patients left and drift back slowly to the right, the patient is said to have left-beating nystagmus
discriminative sensations:for?
test ability of the sensory cortex to correlate, analyze, and interpret sensations. They depend on touch and position sense. If diminished-disease of sensory cortex
stereognosis
ability to identify an object by feeling. familiar object in hand: coin, paperclip, key, pencil. Distinguishing heads from tails is a sensitive test
**astereognosis: inability to recognize objects in hand
number identification
if patient unable to handle objects in hand draw a number using blunt object in the patients palm
2-point discrimination
using the 2 ends of a paperclip touch a finger pad in 2 places simultaneously. alternate with one point touch. find the minimal distance at which the patient can discriminate one from 2 points, normally less than 5mm in finger pads. lesions of the sensory cortex will increase the distance between recognizable points
point localization
briefly touch a point on the patients skin with eyes closed. have patient open eyes and point to place touched
extinction
touch corresponding areas on both sides of the body. normally patient can feel both at same time
dermatomes
areas of skin innervated by single nerve root
Grading reflexes
0-none 1+ somewhat diminished low normal 2+ average normal 3+ brisker than average; possibly indicative of disease 4+very brisk hyper reactive; clonic
anal reflex
last reflex to die
meningeal signs
neck mobility: normally neck is supple and pt able to flex chin to chest w/o difficulty
brudzinski’s sign
as flexing neck watch the hips and knees in response-normally relaxed; flexion of hips and knees=positive sugest irritation
Kernig’s sign
flex pt leg at both the hip and knee and then straighten the knee. normally should not produce pain (discomfort upon full extension behind knee may be normal)
=pain and increased resistance to extending the knee =positive sign (bilateral)
asterixis
helps identify metabolic encephalopathy. ask patient to “stop traffic” by extending both arms with hands cocked up and fingers spread. watch for 1-2 minutes. sudden brief nonrhythmic flexion of the hands and fingers indicative of liver disease, uremia, and hypercapnia
resting (static) tremors
most present at rest-decrease or disappear with voluntary movement-pill-rolling tremors of parkinsons
postural (action) tremors
during maintenance of posture; hyperthyroid, anxiety, fatigue
intention tremors
absent at rest and appear with activity worse as gets near target-disorders of cerebellar pathways such as MS
oral-facial dyskinesias
rhythmic, repetitive, bizarre movements that invlove the face, mouth, jaw, and tongue-tardive dyskinesia.
psychoses
tics
brief repetitive stereotyped coordinated movements occuring at irregular interval. tourettes and drugs such as phenothiazines and amphetamines
nystagmus
defined by its fast phase: example if the eyes jerk quickly to the patients left and drift back slowly to the right, the patient is said to have left-beating nystagmus
Cranial nerves sensory/motor acronym
Some Say Marilyn Monroe, But My Brother Says Bridgette Bardot Mmmmmm Mmmmm
