Chapter 24: NEURO Flashcards
What does the PNS include?
nerve fibers outside the brain and spinal cord
What is the outer layer of the nerve cell bodies?
cerebral cortex aka gray matter that lacks myelin
What is myelin?
white insulation on the axon that increases the conduction velocity of nerve impulses
What is the functions of the cerebral cortex?
- center for humans highest functions
- governing thought
- memory
- reasoning
- sensation
- voluntary movements
Which hemisphere is most dominant in the cerebrum?
left hemisphere (including those who are left handed)
What are the 4 lobes of each hemisphere?
- frontal (personality, behavior, emotions and intellect)
- parietal (center for sensation)
- temporal (hearing, taste and smell)
- occipital (visual receptor center)
What initiates voluntary movement?
the precentral gyrus of the frontal lobe
What area of the brain is associated with language comprehension?
wernickes area (when damaged in the dominant hemisphere, receptive aphasia results)
What area of the brain mediates motor speech?
brocas area (when damaged in dominant hemisphere expressive aphasia results and the person cant talk)
What is the basal ganglia?
large bands of gray matter within the 2 cerebral hemispheres that help to initiate/coordinate movement and control automatic associated movements of the body
What is the thalamus?
main relay station where the synapses is formed that is crucial to human emotion and creativity
What is the hypothalamus?
major respiratory center with basic vital functions (temp, HR, sex drive, appetite, BP, etc) and coordinator of ANS activity and response
What is the cerebellum?
located under the occipital lobe; concerned with motor coordination of voluntary movements, equilibrium and muscle tone (coordinates and smooths movement)
What is the brainstem?
central core of the brain consisting of mostly nerve fibers (CN 3-12 originate here) with the following 3 area:
1. midbrain: most anterior part with basic tubular structure of the spinal cord; merges into thalamus and hypothalamus & contains many motor neurons/tracts
- pons: contains ascending/descending motor tracts and 2 respiratory centers that coordinate with main respiratory center in the medulla
- medulla: continuation of spinal cord with vital autonomic centers and nuclei for CN 8-12
What is the spinal cord?
connects the brain to the spinal nerves and mediates reflexes of posture control, urination, and pain response; the lumbar cistern is inside this space and is the favored spot to withdraw samples of cerebrospinal fluid (CSF)
What is crossed representation?
a notable feature of the nerve tracts with the left cerebral cortex receiving sensory info. from and controls motor function to the right side of the body and the right cerebral cortex interacts with the left side of the body
How does sensation travel?
afferent fibers in the peripheral nerve > posterior (dorsal) root > spinal cord (where it takes 1 of 2 routes: anterolateral (spinothalamic tract) or the posterior (dorsal) columns
What tract transmits the sensations of pain, temperature, itch and crude touch?
anterolateral tract (spinothalamic tract)
What does the posterior (dorsal) columns conduct?
sensations of position (proprioception: w/o looking you know where your body parts are in space/relation to one another), vibration and finely localized touch (sterognosis: w/o looking you can identify familiar objects by touch)?
What organs are absent from the brain map?
- heart
- liver
- spleen
- no felt image: organs experience referred pain and pain is felt by proxy by other body parts with a felt image *
Where is pain in the heart felt?
- chest
- shoulder
- left arm
Where is pain in the spleen felt?
- top of the left shoulder
What do corticospinal fibers mediate?
voluntary movement, particularly very skilled, discrete and purposeful movement such as writing
What is the extrapyramidal tracts?
include all motor nerve fibers from the motor cortex, basal ganglia, brainstem, and spinal cord that are outside the pyramidal tract; it maintains muscles tone and controls body movements (ex: walking)
What are the upper motor neurons?
complex; can influence/modify the lower motor neurons and are located within the CNS. They convey impulses from motor area of the cerebral cortex to the lower motor neurons in the anterior horn cells of the spine (ex: cospinal, corticobulbar, extrapyramidal tracts)
What are some examples of UMN diseases?
- stroke
- cerebral palsy
- MS
What are lower motor neurons?
located in the PNS; last pathways that funnels neural signals and provides the last direct contact with the muscles (ex: CN and spinal nerves of the PNS)
What are some examples of LMN diseases?
- bell palsy (CN 7)
- spinal cord lesions
- poliomyelitis
How does the PNS carry nerve input?
to the CNS via sensory afferent fibers and deliver output from the CNS via the efferent fibers (nerves = bundle of fibers outside the CNS)
What are reflexes?
defense mechanisms of the NS that are involuntary, operate below LOC control and permit a quick reaction to painful/damaging situations. reflexes also help body maintain balance and muscle tone