Neuro Flashcards
CNS is made of
brain and spinal cord
PNS is made of
all nerve fibers outside of brain/spinal cord.
- 12 pairs CNs
- 31 pairs spinal nerves and branches: sensory and motor
afferent nerve fx
sensory afferent nerves carry messages to CNS from sensory receptors
efferent nerve fx
motor efferent nerves carry messages from CNS to muscles/glands
PNS fx
carries sensory, motor, and autonomic messages that govern internal organs and blood vessels
cerebral cortex is made of?
- outer cerebrum layer of nerve cells
- 2 hemispheres that each have 4 lobes
cerebral cortex fx
governs thought, memory, reasoning, sensation, voluntary movement
what are the 4 lobes of each cerebral hemisphere and their functions
- frontal: personality, behavior, emotion, intellectual function. precentral gyrus initiates voluntary movement
- parietal lobe: postcentral gyrus primary center for sensation
- occipital lobe: primary visual receptor center
- temporal lobe: primary auditory reception center, taste/smell
wernicke’s area location, function?
damage to it results in?
in temporal lobe. associated with language comprehension.
damage to wernicke’s in patient’s dominant hemisphere causes receptive aphasia: person can hear sound but it has no meaning, like a foreign language
broca’s area location, function?
damage to it results in?
in frontal lobe. mediates motor speech.
damage in the dominant hemisphere causes expressive aphasia: person cannot talk. can understand language and knows what they want to say but when they speak there is only garbled sound.
when does damage to cortical areas occur? what can the damage cause?
occurs when the highly specialized neurologic cells are deprived of blood supply like when a cerebral artery becomes occluded (ischemic stroke) or when vascular bleeding occurs (hemorrhagic stroke) or vasospasms.
damage can cause motor weakness, paralysis, loss of sensation, impaired ability to understand/process language.
basal ganglia are what? where? function?
large bands of gray matter buried deep in the 2 cerebral hemispheres. they form the subcortical-associated motor system (extrapyramidal system) and help to initiate and coordinate movement and control automatic associated movements of the body (ie arm swing alternating with legs when walking)
what’re some pathologic disorders involving basal ganglia?
i dont know lol
thalamus function
main relay station. sensory pathways of spinal cord, cerebellum, basal ganglia, and brainstem form synapses on their way to cerebral cortex.
integrating center with connections crucial to human emotion and creativity
pathologic disorders of thalamus?
iono
hypothalamus size, location, function
size of almond. inferior to thalamus, above midbrain, resting in sella turcica.
links CNS to endocrine system via pituitary.
control center for many PNS autonomic functions:
-sex drive
-temp
-HR/BP
-sleep
-anterior/posterior pituitary gland regulation and coordination of ANS
-stress response
-major respiratory center
pathology of hypothalamus
- gliomas
- hamartomas
what’s cerebellum, where, function
it is a coiled structure under occipital lobe.
concerned with motor coordination of voluntary movements, equilibrium (postural balance of the body), and muscle tone.
does not initiate movement: coordinates and smooths it. (playing the piano, swimming, or juggling).
Like autopilot: corrects the voluntary movements but operates entirely below the conscious level.
relays info btwn muscles and areas of cerebral cortex involved in muscle control
whats brain stem? function? where’s brain stem? what it made of?
- central core (lower section) of the brain consisting of mostly nerve fibers
- continuous with spinal cord
- Cranial nerves III through XII originate from nuclei in the brainstem
- fx: Connects motor and sensory tracts from brain to body
- made of 3 areas: midbrain, pons, medulla
midbrain location and what is it
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.
what is the pons
enlarged area containing ascending sensory and descending motor tracts.
has two respiratory centers (pneumotaxic and apneustic) that coordinate with the main respiratory center in the medulla.
what’s the medulla
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
spinal cord
- long, cylindric structure of nervous tissue
- about as big around as your little finger.
- occupies the upper two thirds of the vertebral canal from the medulla to lumbar vertebrae L1-L2.
- white matter, bundles of myelinated axons that form the main highway for ascending and descending fiber tracts that connect the brain to the spinal nerves.
- mediates reflexes of posture control, urination, and pain response.
- nerve cell bodies, or gray matter, are arranged in a butterfly shape with anterior and posterior “horns.”
- vertebral canal 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).
crossed representation
CNS pathway. 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.
where are sensory receptors? function?
Millions of sensory receptors are embroidered into the skin, mucous membranes, muscles, tendons, and viscera. They monitor conscious sensation,
internal organ functions, body position, and reflexes.
sensory pathway
Sensation travels in the afferent fibers in the peripheral nerve, through the posterior (dorsal) root,
and into the spinal cord. There it may take one of two routes: the anterolateral or spinothalamic tract, or the posterior (dorsal) columns
spinothalamic tract function, pathway
contains sensory fibers that transmit the sensations of pain, temperature, and crude or light touch.
pathway:
The fibers enter the dorsal root of the spinal cord and synapse with a second sensory neuron. The second-order neuron fibers cross to the opposite side
and ascend up the spinothalamic tract to the thalamus.
-Fibers carrying pain and temperature sensations ascend the lateral spinothalamic tract
-crude touch ascend anterior spinothalamic tract.
At the thalamus the fibers synapse with a third sensory neuron, which carries the message to the sensory cortex for full interpretation.
posterior dorsal columns function, pathway
These fibers conduct the sensations of:
• Position (proprioception)—Without looking you know where your body parts are in space and in relation to one another.
• Vibration
• Finely localized touch (stereognosis)—Without looking you can identify familiar objects by touch
pathway:
These fibers enter the dorsal root and proceed immediately up the same side of the spinal cord to the brainstem. At the medulla they synapse with a
second sensory neuron and then cross. They travel to the thalamus, synapse again, and proceed to the sensory cortex, which localizes the sensation and
makes full discrimination.
organs absent from sensory cortex
heart, liver, or spleen.
You know you have them but you have no “felt image” of it. Pain originating in these organs is referred because no felt image exists in which to have pain. Pain is felt
“by proxy” by another body part that does have a felt image. For example, pain in the heart is referred to the chest, shoulder, and left arm, which were its
neighbors in fetal development. Pain originating in the spleen is felt on the top of the left shoulder.
extrapyramidal tracts are what, do what
- include all the motor nerve fibers originating in the motor cortex, basal ganglia, brainstem, and spinal cord that are outside the pyramidal tract.
- more primitive motor system.
- subcortical motor fibers maintain muscle tone and control body movements, especially gross automatic movements such as walking.
upper motor neurons are what, where, function, examples, and diseases
-a complex of all the descending motor fibers that can influence or modify the lower motor neurons.
-located completely within the CNS
-convey impulses from motor areas of the cerebral cortex to the lower motor neurons in the anterior horn cells of
the spinal cord
-Examples are corticospinal, corticobulbar, and extrapyramidal tracts
-UMN diseases are stroke, cerebral palsy, and multiple sclerosis.
lower motor neurons where, what, examples, diseases
- located mostly in the peripheral nervous system
- cell body of the LMN is located in the anterior gray column of the spinal cord, but the nerve fiber extends from here to the muscle
- LMN 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
- Examples of LMNs are cranial nerves and spinal nerves of the peripheral nervous system.
- Examples of LMN diseases are spinal cord lesions, poliomyelitis, and amyotrophic lateral sclerosis.
nerve
-peripheral nerve function
A nerve is a bundle of fibers outside the CNS.
-The peripheral nerves carry input to the CNS via their sensory afferent fibers and deliver output from the
CNS via the efferent fibers.
reflex definition? types/examples?
basic defense mechanisms of the nervous system.
- involuntary
- operate below the level of conscious control
- permit a quick reaction to potentially painful or damaging situations.
- help the body maintain balance and appropriate muscle tone
4 types:
- Deep tendon reflexes (myotatic), e.g., patellar (or knee jerk)
- superficial, e.g., corneal reflex, abdominal reflex
- visceral (organic), e.g., pupillary response to light and accommodation
- pathologic (abnormal), e.g., Babinski (or extensor plantar) reflex.
reflex pathway
The fibers that mediate the reflex are carried by a specific spinal nerve. In the simplest reflex tapping the tendon stretches the muscle spindles in the
muscle, which activates the sensory afferent nerve. The sensory afferent fibers carry the message from the receptor and travel through the dorsal root into
the spinal cord. They synapse directly in the cord with the motor neuron in the anterior horn. Motor efferent fibers leave via the ventral root and travel to the muscle, stimulating a sudden contraction.
deep tendon reflex components
The deep tendon (myotatic, or stretch) reflex has five 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.
cranial nerves are what?
Cranial nerves are LMNs that enter and exit the brain rather than the spinal cord.
where to CN 1 AND 2 extend from?
3 thru 12?
Cranial nerves I and II extend from the cerebrum; cranial
nerves III through XII extend from the lower diencephalon and brainstem.
what do the 12 pairs of CN supply primarily? except?
The 12 pairs of cranial nerves supply primarily the head and neck, except the vagus nerve which travels to the heart, respiratory muscles, stomach, and gallbladder.
spinal nerves where? supply what? names? what type of nerve?
The 31 pairs of spinal nerves arise from the length of the spinal cord and supply the rest of the body.
They are named for the region of the spine from
which they exit: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
-“mixed” nerves because they contain both sensory and motor fibers.
-Each nerve innervates a particular segment of the body. -Dermal segmentation is the cutaneous distribution of the various spinal nerves.
dermatome
A dermatome is a circumscribed skin area that is supplied mainly from one spinal cord segment through a particular spinal nerve.
-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 landmarks
• The thumb C6 1st/2nd fingers C7 4th/5th fingers C8 • The axilla is at the level of T1. • The nipple is at the level of T4. • The umbilicus is at the level of T10. • The groin is in the region of L1. • The knee is at the level of L4.
autonomic nervous system: somatic vs autonomic fibers
The peripheral nervous system is composed of cranial nerves and spinal nerves. These nerves carry fibers that can be divided functionally into two parts:
somatic and autonomic. The somatic fibers innervate the skeletal (voluntary) muscles; the autonomic fibers innervate smooth (involuntary) muscles,
cardiac muscle, and glands.
The autonomic system mediates unconscious activity. its overall function is to maintain homeostasis of the body.
aging and neurologic
aging > gradual atrophy > steady loss of neuron structure in the brain and spinal cord > decrease in weight and
volume with a thinning of the cerebral cortex, reduced subcortical brain structures, and expansion of the ventricles
