Neuro Flashcards
CNS is composed of
brain and spinal cord
PNS is composed of
12 pairs of cranial nerves
31 pairs of spinal nerves and all of their branches
Cerebral cortex is the center for
our highest functions - governs thought, memory, reasoning, sensation, voluntary movement
The left hemisphere of the Cerebral cortex dominant in __ percent of people
95%
each hemisphere is divided into how many lobes?
4
what are the 4 lobes of each hemisphere of the cerebral cortex?
- frontal
- occipital
- parietal
- temporal
Brokus area of the frontal lobe mediates ___. When it is damaged in the dominant hemisphere, ___ occurs.
motor speech; expressive aphasia (the person cannot talk (they understand language and know what they want to say but when they try to talk it comes out garbled)
precentral gyrus initiates
voluntary movement
postcentral gyrus in the parietal lobe is the primary center for
sensation
Werneke’s area in the temporal lobe is associated with ___. When this is damaged in the dominant hemisphere, the person gets ___.
language comprehension; receptive aphasia - the person hears sound but it has no meaning, like hearing a foreign language
the occipital lobe is the primary
visual receptor center
Basal ganglia controls
automatic associated movements of the body (i.e. when walking arm swing alternates with legs)
subcortical motor system which we call the
extrapyramidal system
Thalamus is the main relay station for the
CNS; sensory pathways of spinal cord and brainstem form synapses here on the way to the cortex
Hypothalamus is a major control center that regulates
vital functions: temperature, heart rate, blood pressure control, sleep center, anterior and posterior pituitary gland regulator, coordinator of autonomic nervous system activity and emotional status
Cerebellum is the coiled structure under the occipital lobe which is concerned with
motor coordination of voluntary moments, and equilibrium and muscle tone
Cerebellum does NOT initiative movement but it
coordinates and smooths movements - ex. playing piano, swimming, juggling — it adjust and corrects our voluntary movements but it operates entirely below conscious level
brainstem, 3 parts
central core of the brain that consists mostly of neural fibers, 3 parts: midbrain, ponds, medulla
midbrain
most anterior part, still has a basic tubular structure resembling spinal cord; merges into thalamus and hypothalamus, contains many motor neurons and tracts
ponds
enlarged area that contains ascending and descending fiber tracts
medulla
continuation of the spinal cord in the brain that contains all of our ascending and descending fiber tracts that connect brain and the spinal cord; has vital autonomic centers such as respiration, heart and GI function as well as some of nuclei for CN 8-12; this is where pyramidal decussation occurs (crossing over of motor fibers — i.e. stroke in right side of brain affects left side of body)
pyramidal decussation
crossing over of motor fibers — i.e. stroke in right side of brain affects left side of body
motor nerve fibers originate in the motor cortex, travel to the brainstem where they cross to the opposite side then pass down in the lateral column of the spinal cord
spinal cord is the long cylindrical structure about as round as your little finger that occupies the upper 2/3 of the vertebral canal. it’s the main highway for
all fiber tracts that connect brain to spinal nerves; it mediates our reflexes; its nerve cell bodies/gray matter are arranged in butterfly/H-shape with anterior and posterior horns
left cerebral cortex controls motor function to
right side of body and vice versa
2 particular pathways of CNS
corticospinal tract (pyramidal tract) extrapyramidal tract
10% of cortiospinal fibers do not cross - these descend in the
anterior column of the spinal cord
corticospinal fibers mediate our
voluntary movement (skilled, discreet, purposeful - like writing)
extrapyramidal tract includes
all the motor fibers originating in the motor cortex, or the ganglia, or the brainstem and spinal cord that are outside the pyramidal tract
extrapyramidal tract is a much more ___ motor system
primitive:
these subcortical fibers maintain muscle tone and gross body movements (like walking)
cerebellar system: coordinates our
movement, maintains equilibrium and helps maintain posture
sensation travels in the ___ fibers in the ___ nerve, then through the posterior or dorsal route, then into the spinal cord
afferent; peripheral
once at the spinal cord, sensation takes one of two tracts:
(1) spinalthalamic tract
(2) posterior or dorsal columns tract
spinalthalamic tract contains sensory fibers that transmit the sensation of
pain, temperature, and crude or light touch
posterior or dorsal columns tract conducts the sensation of
position sense, vibration, and localized touch
propioception
position sense–means that without looking you know where your body parts are in space and in relation to each other
stereognosis
without looking you can identify a familiar object by touch
some organs are absent from the brain map: heart, liver, spleen — you know you have one, but you have no felt image about it — pain originating in these organs is ___ because no felt images exist in which to have pain, so pain is felt by ___
referred; proxy
Upper motor neurons:
a complex of all the descending motor fibers that can influence/modify the lower motor neurons
they are located completely within the CNS
convey impulses for motor areas of the cerebral cortex to the lower motor neurons in the anterior horn cells of the spinal cord
upper motor neuron diseases
CVA, cerebral palsy, MS
Lower motor neurons are located mostly in the
PNS
examples: cranial nerves, spinal nerves of the PNS
lower motor neuron diseases:
spinal cord lesions, polio, ALS (lou gherigs)
in order for reflex arc to work, you have to have 5 components:
- intact sensory nerve (afferent)
- functional synapse in the cord
- intact motor nerve fiber (efferent)
- neuromuscular junction must be intact
- muscle has to be competent/working