Ch 24 Neurologic sys Jarvis Flashcards
carries sensory (afferent) messages to the CNS from sensory receptors, motor (efferent) messages from the CNS out to muscles and glands, and autonomic messages that govern the internal organs and blood vessels.
peripheral nervous system
has areas responsible for personality, behavior, emotions, and intellectual function
frontal lobe
has areas responsible for sensation
parietal lobe
lobe is responsible for visual reception
occipital
lobe is responsible for hearing, taste, and smell
-behind the ear has the primary auditory reception center
temporal
is the outer layer of nerve cell bodies; it looks like “gray matter” because it lacks myelin
cerebral cortex
is the white insulation on the axon that increases the conduction velocity of nerve impulses.
Myelin
is the center for a human’s highest functions, governing thought, memory, reasoning, sensation, and voluntary movement
cerebral cortex
Each half of the cerebrum is a ?;
-the left hemisphere is dominant in most (95%) people, including those who are left-handed
hemisphere
Each hemisphere is divided into four lobes:
frontal, parietal, temporal, and occipital
precentral gyrus of the frontal lobe initiates
voluntary movement
parietal lobe’s postcentral gyrus is the primary center for
sensation
in the temporal lobe is associated with language comprehension. When damaged in the person’s dominant hemisphere, receptive aphasia results. The person hears sound, but it has no meaning, like hearing a foreign language
Wernicke’s area
in the frontal lobe mediates motor speech. When injured in the dominant hemisphere, expressive aphasia results; the person cannot talk. The person can understand language and knows what he or she wants to say but can produce only a garbled sound.
Broca’s area
cerebral artery becomes occluded
(ischemic stroke)
vascular bleeding
(hemorrhagic stroke)
are large bands of gray matter buried deep within the two cerebral hemispheres that form the subcortical-associated motor system (the extrapyramidal system)
basal ganglia
help to initiate and coordinate movement and control automatic associated movements of the body (e.g., the arm swing alternating with the legs during walking).
basal ganglia
is the main relay station where the sensory pathways of the spinal cord, cerebellum, basal ganglia, and brainstem form synapses (sites of contact between two neurons) on their way to the cerebral cortex. It is an integrating center with connections that are crucial to human emotion and creativity.
thalamus
(sites of contact between two neurons)
synapses
is a major respiratory center with basic vital functions: temperature, appetite, sex drive, heart rate, and blood pressure (BP) control; sleep center; anterior and posterior pituitary gland regulator; and coordinator of autonomic nervous system activity and stress response.
hypothalamus
is a coiled structure located under the occipital lobe that is concerned with motor coordination of voluntary movements, equilibrium (i.e., the postural balance of the body), and muscle tone
- “automatic pilot” on an airplane in that it adjusts and corrects
- corrects the voluntary movements but operates entirely below the conscious level.
cerebellum
is the central core of the brain consisting of mostly nerve fibers
-Cranial nerves III through XII originate from nuclei in the brainstem
brainstem
Brainstem has 3 areas:
- Midbrain
- Pons
- Medulla
The most anterior part of the brainstem that still has the basic tubular structure of the spinal cord. It merges into the thalamus and hypothalamus. It contains many motor neurons and tracts.
Midbrain
—The enlarged area containing ascending sensory and descending motor tracts. It has two respiratory centers (pneumotaxic and apneustic) that coordinate with the main respiratory center in the medulla.
Pons
—The continuation of the spinal cord in the brain that contains all ascending and descending fiber tracts. It has vital autonomic centers (respiration, heart, gastrointestinal function) and nuclei for cranial nerves VIII through XII. Pyramidal decussation (crossing of the motor fibers) occurs here
Medulla
is the long, cylindric structure of nervous tissue about as big around as your little finger. It occupies the upper 2/3 of the vertebral canal from the medulla to lumbar vertebrae L1-L2
spinal cord
its white matter is bundles of myelinated axons that form the main highway for ascending and descending fiber tracts that connect the brain to the spinal nerves. It mediates reflexes of posture control, urination, and pain response. Its nerve cell bodies, or gray matter, are arranged in a butterfly shape with anterior and posterior “horns.”
spinal cord
continues down beyond the spinal cord for several inches. The lumbar cistern is inside this space and is the favored spot to withdraw samples of cerebrospinal fluid (CSF).
vertebral canal
is a notable feature of the nerve tracts; the left cerebral cortex receives sensory information from and controls motor function to the right side of the body, whereas the right cerebral cortex likewise interacts with the left side of the body
Crossed representation (pathway of CNS)
(formerly spinothalamic) contains sensory fibers that transmit the sensations of pain, temperature, itch, and crude touch
-(i.e., not precisely localized).
anterolateral tract
fibers conduct the sensations of position, vibration, and finely localized touch.
Posterior (Dorsal) Columns.
—Without looking you know where your body parts are in space and in relation to one another
Position (proprioception)//Posterior (Dorsal) Columns.
—You can feel vibrating objects
Vibration//Posterior (Dorsal) Columns.
—Without looking you can identify familiar objects by touch
Finely localized touch (stereognosis)//Posterior (Dorsal) Columns.
Pain originating in the spleen is felt on the
top of the left shoulder.
mediate voluntary movement, particularly very skilled, discrete, purposeful movements such as writing.
Corticospinal fibers (in motor cortex)
origin of the tract in the motor cortex is arranged in a specific pattern called
somatotopic organization.
are a complex of all the descending motor fibers that can influence or modify the lower motor neurons. They are located completely within the CNS.
Upper motor neurons (UMNs)
Examples of UMN diseases are
stroke, cerebral palsy, and multiple sclerosis.
maintains muscle tone for gross automatic movements, such as walking
extrapyramidal tract
form the subcortical-associated motor system (the extrapyramidal system) They help to initiate and coordinate movement and control automatic associated movements of the body (e.g., the arm swing alternating with the legs during walking).
Basal Ganglia.
are located mostly in the peripheral nervous system
Lower motor neurons (LMNs)
is the “final common pathway” because it funnels many neural signals here and provides the final direct contact with the muscles. Any movement must be translated into action by LMN fibers.
LMN
Examples of LMNs are cranial nerves and spinal nerves of the peripheral nervous system. Examples of LMN diseases are
Bell palsy in the face (cranial nerve VII), spinal cord lesions, and poliomyelitis.
is a bundle of fibers outside the CNS
nerve
(1) Stretch or/deep tendon reflexes (myotatic), e.g., patellar (or knee jerk)
(2) superficial (cutaneous), e.g., plantar reflex;
(3) visceral (organic), e.g., pupillary response to light and accommodation.
3 types of Reflex Arc
(myotatic, or stretch) reflex has 5 components: (1) an intact sensory nerve (afferent), (2) a functional synapse in the cord, (3) an intact motor nerve fiber (efferent), (4) the neuromuscular junction, and (5) a competent muscle
deep tendon
are LMNs that enter and exit the brain rather than the spinal cord
Cranial nerves
Cranial nerves I and II extend from the
cerebrum
cranial nerves III through XII extend from the
midbrain and brainstem.
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal
Spinal Nerves
is the cutaneous distribution of the various spinal nerves.
Dermal segmentation
is a circumscribed skin area that is supplied mainly from one spinal cord segment through a particular spinal nerve . The dermatomes overlap, which is a form of biologic insurance, i.e., if one nerve is severed, most of the sensations can be transmitted by the one above and the one below
dermatome
thumb, middle finger, and fifth finger are each in the dermatomes of
C6, C7, and C8
axilla is at the level of
T1
nipple is at the level of
T4.
umbilicus is at the level of
T10
groin is in the region of
L1
knee is at the level of
L4.
peripheral nervous system divided 2
somatic and autonomic
innervate the skeletal (voluntary) muscles
somatic fibers
innervate smooth (involuntary) muscles, cardiac muscle, and glands
autonomic fibers (unconscious activity)
Motor activity in the newborn is under the control of the
spinal cord and medulla
(infants) Movements are directed primarily by
primitive reflexes
(infants)cerebral cortex develops during the
first year
(infants)process of myelinization follows a
cephalocaudal and proximodistal order (head, then neck, trunk, and out to extremities)
order in which we observe the infant gaining motor control
(lifts head, lifts head and shoulders, rolls over, moves whole arm, uses hands, walks)
causes a general atrophy with a steady loss of neuron structure in the brain and spinal cord
-touch and pain sensation, taste, and smell may be diminished.
aging process
Reductions in brain volume are normal in healthy aging, but more increased atrophy occurs with AD
- accompanied by a progressive decrease in cerebral blood flow and oxygen consumption= dizziness
aging process
comes from a direct blow that causes rotation of the brain inside the skull and shear injury
Concussion
is a sudden loss of strength, a temporary loss of consciousness (a faint) caused by lack of cerebral blood flow, e.g., low BP.
Syncope
is rotational spinning caused by neurologic disease in the vestibular apparatus in the ear or the vestibular nuclei in the brainstem.
vertigo
occur with epilepsy, a paroxysmal disease characterized by altered or loss of consciousness, involuntary muscle movements, and sensory disturbances.
Seizures
is a subjective sensation that precedes a seizure; it could be auditory, visual, or motor
Aura
is a partial or incomplete paralysis.
Paresis
is a total loss of motor function caused by a lesion in the neurologic or muscular system or loss of sensory innervation.
Paralysis
is the inability to control the distance, power, and speed of a muscular action
Dysmetria
is an abnormal sensation (e.g., burning, tingling).
Paresthesia
is difficulty forming words
Dysarthria
is difficulty with language comprehension or expression
dysphasia
may occur with high fever in infants and toddlers. Or they may be a sign of neurologic disease.
Seizures
Tested at 1 year. Chronically elevated lead levels cause
developmental delay or loss of a newly acquired skill or may be asymptomatic.
Decreased blood to brain (orthostatic hypotension) increases the risk for falls. Major risks for falls: balance and gait disorder, polypharmacy, history of recent falls. Other risks: older age, female, poor vision, cognitive decline, environmental clutter, and alcohol use
Aging Adult
get up at night and then feel faint while standing to urinate
Micturition syncope
—Decrease or loss of smell occurs bilaterally with tobacco smoking, allergic rhinitis, and cocaine use.
Anosmia
Unilateral loss of smell in the absence of nasal disease is
neurogenic anosmia
is the normal degree of tension (contraction) in voluntarily relaxed muscles
Tone
occurs with myasthenia gravis, dysfunction of cranial nerve III, or Horner syndrome
Ptosis (drooping)
with increased intracranial pressure
Papilledema
causes a sudden, unilateral, dilated, and nonreactive pupil.
Increasing intracranial pressure
occurs with disease of the vestibular system, cerebellum, or brainstem.
Nystagmus
Slow, clumsy, and sloppy response is termed
- occurs with cerebellar disease.
dysdiadochokinesia
is clumsy movement with overshooting the mark and occurs with cerebellar disorders, alcohol intoxicatio
Dysmetria
is a loss of balance that is increased by the closing of the eyes.
-occurs with cerebellar ataxia (multiple sclerosis, alcohol intoxication), loss of proprioception, and loss of vestibular function
positive Romberg sign
is an uncoordinated or unsteady gait
Ataxia
is used to test the legs for deep-vein thrombosis.
Homans sign
—Decreased pain sensation.
Hypoalgesia
—Absent pain sensation.
Analgesia
Loss of vibration sense occurs with ? (e.g., diabetes and alcoholism). Often this is the first sensation lost.
-worse at the feet and gradually improves as you move up the leg,
peripheral neuropathy
, which has a clear zone of deficit for its dermatome
specific nerve lesion
—Inability to identify object correctly. Occurs in sensory cortex lesions (e.g., stroke).
Astereognosis
is the ability to “read” a number by having it traced on the skin
-inability to do it = sensory cortex lesion
Graphesthesia
4+ Very brisk, hyperactive with clonus, indicative of disease
3+ Brisker than average, may indicate disease, probably normal
2+ Average, normal
1+ Diminished, low normal, or occurs only with reinforcement
0 No response
Test the Reflexes
is a set of rapid, rhythmic contractions of the same muscle
Clonus
, frequent consecutive stimuli are perceived as one strong stimulus.
summation
normal response of the triceps reflex is
extension of the forearm
normal response of the biceps reflex causes
flexion of the forearm
3 months of age, the infant raises the head and arches the back as if in a swan dive. This response is the
Landau reflex
