Exam 4 Study Guide Flashcards
cylinder of nervous tissue that arises from the brainstem at the foramen magnum of the skull
spinal cord
the spinal cord passes through what?
vertebral canal
the spinal cord occupies how much of the vertebral canal?
2/3
the spinal cord gives rise to how many pairs of spinal nerves?
-first pair passes between the skull and C1
-the rest passes through intervertebral foramina
31 pairs
part of the spinal cord supplied by each pair of spinal nerves
segment
what are some longitudinal grooves on anterior and posterior sides?
anterior median fissure and posterior median sulcus
what are the four regions that the spinal cord is divided into?
-cervical
-thoracic
-lumbar
-sacral
what are the two areas of the spinal cord that are thicker than elsewhere?
cervical enlargement and lumbar enlargement
spinal enlargement: nerves to upper limb
cervical enlargement
spinal enlargement: nerve to pelvic region and lower limbs
lumbar enlargement
cord tapers to a point inferior to lumbar enlargement
conus medullaris (medullary cone)
bundle of nerve roots that occupy the vertebral canal from L2 to S5
cauda equina
three fibrous connective tissue membranes that enclose the brain and spinal cord
-separate soft tissue of central nervous system from bones of cranium and vertebral canal
meninges
what is the order of the meninges from superficial to deep?
dura mater (outside), arachnoid mater (middle), pia mater (inside)
the spinal cord has a central core of what that looks butterfly shaped in cross section
gray matter
this is visible from T2 through L1
- contains neurons of sympathetic nervous system
lateral horn
this surrounds gray matter in the spinal cord
white matter
three pairs of these white matter bundles are called what?
columns or funiculi
subdivisions of each column of white matter
tracts or fasciculi
carry sensory information up the spinal cord
ascending tracts
carry motor information down the spinal cord
-all nerve fibers in a given tract have a similar origin, destination and function
descending tracts
as the fibers pass up or down the brainstem and spinal cord they cross over from the left to the right side and vice versa
decussation
when the origin and destination of a tract are on opposite sides of the body
contralateral
when the origin and destination of a tract are on the same side of the body; does not decussate
ipsilateral
what do ascending tracts do?
carry sensory signals up the spinal cord
What are the three neurons that sensory signals travel across from origin in receptors to the destination in the sensory areas of the brain?
- first-order neurons
- second-order neurons
- third-order neurons
type of neuron that detects stimulus and transmits signals to spinal cord or brainstem
first-order neurons
type of neuron that continues to the thalamus at the upper end of the brainstem
second-order neurons
type of neuron that carries the signal the rest of the way to the sensory region of the cerebral cortex
third-order neurons
carries signals from midthoracic and lower parts of the body
-composes the entire posterior column below T6
-consists of first-order nerve fibers that travel up the ipsilateral side of the spinal cord
-terminates at the gracile nucleus of the medulla oblongata
-carries signals for vibration, visceral pain, deep and discriminative touch, and proprioception from lower limbs and lower trunk
gracile fasciculus
nonvisual sense of the position and movements of the body
proprioception
joins gracile fasciculus at T6
-occupies lateral portion of the posterior column
-carries the same type of sensory signals
-originates from the level of T6 and up
-fibers end in the cuneate nucleus on the ipsilateral side of the medulla oblongata
-carry signals to contralateral cerebral hemisphere
cuneate fasciculus
formed from the second-order neurons of gracile and cuneate systems that decussate in the medulla
medial lemniscus
one of the smaller tracts of the anterolateral system
-carry signals for pain, pressure, temperature, light touch, tickle, and itch
-first-order neurons end in posterior horn of spinal cord
-synapse with second-order neurons which decussate to other side of spinal cord and form this
-third-order neurons continue to form there to cerebral cortex
-send signals to the contralateral cerebral hemisphere
spinothalamic tract
a specific area of the skin that receives sensory input from a pair of spinal nerves
dermatome
a diagram of the cutaneous regions innervated by each spinal nerve
dermatome map
these overlap their edges as much as 50%
-necessary to sever or anesthetize three successive spinal nerves to produce a total loss of sensation in one dermatome
dermatomes
carry motor signals down the brainstem and spinal cord
-involve two neurons
descending tracts
What are the two neurons that are involved in the descending tracts?
upper motor neuron and lower motor neuron
motor neuron that originates in cerebral cortex or brainstem and terminates on a lower motor neuron
upper motor neuron
motor neuron in brainstem or spinal cord
-axon of lower motor neuron leads the rest of the way to the muscle or other target organ
lower motor neuron
from cerebral cortex for precise, finely coordinated limb movements
-decussate in lower medulla
-two neuron pathways
corticospinal tracts
ridges on anterior surface of the medulla oblongata formed from fibers of this system
pyramids
what are the two neuron pathways of the corticospinal tracts?
- upper motor neuron in cerebral cortex
- lower motor neuron in spinal cord
What are the 31 pairs of spinal nerves?
-8 cervical
-12 thoracic
-5 lumbar
-5 sacral
-1 coccygeal
spinal nerves: thoracic
T1-T12
spinal nerves: cervical
C1-C8
spinal nerves: lumbar
L1-L5
spinal nerves: sacral
S1-S5
spinal nerves: coccygeal
Co
what form spinal nerves?
proximal branches
sensory input to spinal cord
posterior (dorsal) root
contains the somas of sensory neurons carrying signals to the spinal cord
posterior (dorsal) root ganglion
motor output out of spinal cord
anterior (ventral) root
formed from roots arising from L2 to Co
cauda equina
quick, involuntary, stereotyped reactions of glands or muscle to stimulation
-automatic responses to sensory input that occur without our intent or often even our awareness
somatic reflexes
what are the four important properties of a reflex?
- require stimulation
- are quick
- are involuntary
- are stereotyped
properties of a reflex: not spontaneous actions, but responses to sensory input
reflexes require stimulation
properties of a reflex: involve few, if any, interneurons and minimum synaptic delay
reflexes are quick
properties of a reflex: occur without intent and difficult to suppress; automatic response
reflexes are involuntary
properties of a reflex: occur essentially the same way every time
reflexes are stereotyped
What is the pathway of reflex arc?
-somatic receptors
-afferent nerve fibers
-integrating center
-efferent nerve fibers
-effectors
pathway of reflex arc: in skin, muscles, or tendons
somatic receptors
pathway of reflex arc: carry information from receptors to posterior horn of spinal cord or the brainstem
afferent nerve fibers
pathway of reflex arc: a point of synaptic contact between neurons in gray matter of spinal cord or brainstem
-determines whether efferent neurons issue signal to muscles
integrating center
pathway of reflex arc: carry motor impulses to skeletal muscle
efferent nerve fibers
pathway of reflex arc: the somatic effectors carry out the response
effectors
Look over the last couple slides of Chapter 13
:)
toward the forehead (front)
rostral
toward the spinal cord (back)
caudal
What are the three major portions of the brain?
-cerebrum
-cerebellum
-brainstem
-83% of brain volume
-cerebral hemispheres, gyri, and sulci, longitudinal fissure, corpus callosum
cerebrum
-contains 50% of the neurons
-second largest brain region, located in posterior cranial fossa
cerebellum
-the portion of the brain that remains if the cerebrum and cerebellum are removed
-diencephalon, midbrain, pons, and medulla oblongata
brainstem
deep groove that separates cerebral hemispheres
longitudinal fissure
thick folds on the brain
gyri or gyrus
shallow grooves on the brain
sulci or sulcus
thick nerve bundle at bottom of longitudinal fissure that connects hemispheres (white matter)
corpus callosum
the seat of neuron cell bodies, dendrites, and synapses
-dull white color when fresh, due to little myelin
-forms surface layer (cortex) over cerebrum and cerebellum
-forms nuclei deep within brain
gray matter
bundles of axons
-lies deep to cortical gray matter, opposite relationship in the spinal cord
-pearly white color from myelin around nerve fibers
-composed of tracts, or bundles of axons, that connect one part of the brain to another, and to the spinal cord
white matter
three connective tissue membranes that envelop the brain (continuation of the spinal cord)
-lies between the nervous tissue and bone
-as in spinal cord, they are the dura mater, arachnoid mater, and the pia mater
-protect the brain and provide structural framework for its arteries and veins
meninges
folds inward to extend between parts of the brain
-falx cerebri
-tentorium cerebelli
-falx cerebelli
meninges
separates the two cerebral hemispheres
falx cerebri
separates cerebrum from cerebellum
tentorium cerebelli
separates the right and left halves of the cerebellum
falx cerebelli
inflammation of the meninges; caused by bacterial and virus invasion of the CNS by way of the nose and throat; signs include high fever, stiff neck, drowsiness, and intense headache; may progress to coma then death within hours of onset; diagnosed by examining the CSF for bacteria
-serious disease of infancy and childhood
-especially between 3 months and 2 years of age
meningitis
what meninges are most affected by meningitis?
pia mater and arachnoid mater
this type of meningitis can cause swelling of the brain, enlargement of the ventricles, and hemorrhage
bacterial meningitis
four internal chambers within the brain
ventricles
ventricles: one on each cerebral hemisphere
two lateral ventricles
tiny pore that connects to third ventricle
interventricular foramen
single narrow medial space beneath corpus callosum
-cerebral aqueduct runs through midbrain and connects third to fourth ventricle
third ventricle
small triangular chamber between pons and cerebellum
-connects to central canal, runs down through spinal cord
fourth ventricle
this continuously flows through and around the CNS
-driven by its own pressure, beating of ependymal cilia, and pulsations of the brain produced by each heartbeat
cerebrospinal fluid
describe how CSF flows
-CSF secreted in lateral ventricles flows through intervertebral foramina into third ventricle
-then down the cerebral aqueduct into the fourth ventricle
-third and fourth ventricles add more CSF along the way
what are the functions of CSF?
- buoyancy
- protection
- chemical stability
functions of CSF: allows brain and spinal cord to float
-allows brain to attain considerable size without being impaired by its own weight
buoyancy
functions of CSF: protects the brain from striking the cranium when the head is jolted
-shaken child syndrome and concussions do occur from severe jolting
protection
functions of CSF: flow of CSF rinses away metabolic wastes from nervous tissue and homeostatically regulates its chemical environment
chemical stability
this part of the brain controls the endocrine system
-major control center of autonomic nervous system and endocrine systems
hypothalamus
a stalk that attaches the pituitary gland to the hypothalamus
infundiblulum
what are the functions of hypothalamic nuclei?
- hormone secretion
- autonomic effects
- thermoregulation
- food and water intake
- rhythm of sleep and waking
- memory
- emotional behavior
functions of the hypothalamus: controls anterior pituitary
-regulates growth, metabolism, reproduction, and stress responses
hormone secretion
functions of the hypothalamus: major integrating center for autonomic nervous system
-influences heart rate, blood pressure, gastrointestinal secretions, etc.
autonomic effects
functions of the hypothalamus: hypothalamic thermostat monitors body temperature
-activates heat-loss center when temp is too high
-activates heat-promoting center when temp is too low
thermoregulation
functions of the hypothalamus: hunger and satiety centers monitor blood glucose and amino acid levels
-thirst center monitors osmolarity of the blood
food and water intake
functions of the hypothalamus: controls 24-hour (circadian) rhythm of activity
rhythm of sleep and waking
functions of the hypothalamus: mammillary nuclei receive signals from hippocampus
memory
functions of the hypothalamus: anger, aggression, fear, pleasure, and contentment
emotional behavior
largest and most conspicuous part of the human brain
-seat of sensory perception, memory, thought, judgement, and voluntary motor actions
cerebrum
increase amount of cortex in the cranial cavity
gyri and sulci
What are the parts of the cerebrum?
- frontal lobe
- parietal lobe
- occipital lobe
- temporal lobe
- insula
part of cerebrum: voluntary motor functions
-motivation, foresight, planning, memory, mood, emotions, social judgement, and aggression
frontal lobe
part of cerebrum: receives and integrates general sensory information, taste, and some visual processing
parietal lobe
part of cerebrum: primary visual center of brain
occipital lobe
part of cerebrum: areas for hearing, smell, learning, memory, and some aspects of vision and emotion
temporal lobe
part of cerebrum: understanding spoken language, taste and sensory information from visceral receptors
insula
what are the three types of tracts of the cerebral white matter?
- projection tracts
- commissural tracts
- association tracts
cerebral white matter tract: extend from the brain out to the rest of the body
-extends vertically between higher and lower brain and spinal cord centers
-carries information between cerebrum and rest of the body
projection tracts
cerebral white matter tract: cross from one cerebral hemisphere through bridges called commissures
-most pass through corpus callosum
-anterior and posterior commissures
-enables the two sides of the cerebrum to communicate with each other
commissural tracts
cerebral white matter tract: shortest fibers because they stay within hemisphere; do not cross
-connect different regions within the same cerebral hemisphere
-long association fibers
-short association fibers
association tracts
association tracts: fibers that connect different lobes of a hemisphere to each other
long association fibers
association tracts: fibers that connect different gyri within a single lobe
short association fibers
masses of cerebral gray matter buried deep in the white matter, lateral to the thalamus
-involved in motor control, related to Parkinson’s disease
basal nuclei
important center of emotion and learning
limbic system
monitors surface electrical activity of the brain waves
-useful for studying normal brain functions as sleep and consciousness
-in diagnosis of degenerative brain diseases, metabolic abnormalities, brain tumors, etc.
electroencephalogram (EEG)
the range of mental processes by which we acquire and use knowledge
-such as memory perception, thought, reasoning, judgement, memory, imagination, and intuition
cognition
cognition: parietal lobe association area
perceiving stimuli
unaware of objects on opposite side of the body
contralateral neglect syndrome
cognition: temporal lobe association area
identifying stimuli
inability to recognize, identify, and name familiar objects
agnosia
person cannot remember familiar faces
prosopagnosia
cognition: association area planning our responses and personality
-inability to execute appropriate behavior
frontal lobe association area
information management entitles learning, memory, forgetting
memory
acquiring new information
learning
information storage and retrieval
memory
eliminating trivial information; as important as remembering
forgetting
defects in declarative memory
-inability to describe past events
amnesia
ability to tie one’s shoes
procedural memory
unable to store new information
-can’t learn anything new
anterograde amnesia
person cannot recall things known before injury
-forget what happened before
retrograde amnesia
diagram of the primary somesthetic cortex which resembles an upside-down sensory map of the contralateral side of the body
sensory homunculus
point-to-point correspondence between an area of the body an an area of the CNS
somatotopy
this includes several abilities: reading, writing, speaking, and understanding words assigned to different regions of the cerebral cortex
-there are two of these areas
language
what are the two language areas?
- Wernicke area
- Broca area
language area: permits recognition of spoken and written language and creates plan of speech
-when we intend to speak, this area formulates phrases according to learned rules of grammar
-transmits plan of speech to Broca area
Wernicke area
language area: motor control of language (pronunciation)
-generates motor program for the muscles of the larynx, tongue, cheeks, and lips
-transmits program to primary motor cortex for commands to the lower motor neurons that supply relevant muscles
Broca area
these language area lesions produce aprosody- flat emotionless speech
affective language area
any language deficit from lesions in same hemisphere (usually left) containing the Wernicke and Broca areas (language defect)
aphasia
lesion in Broca area
-slow speech, difficulty in choosing words, using words that only approximate the correct word
nonfluent (Broca) aphasia
lesion in Wernicke area
-talking in nonsense
-speech normal and excessive, but uses senseless jargon
-cannot comprehend written and spoken words
fluent (Wernicke) aphasia
can speak normally and understand speech, but cannot identify written words or pictures
anomic aphasia
Which cranial nerves are sensory nerves?
one, two, and eight
which cranial nerves are motor nerves?
three, four, six, eleven, and twelve
which cranial nerves are mixed (both sensory and motor)?
five, seven, nine, ten
study the muscles of the eye
6 muscles
-rectus: straight
-oblique: slanted
everything runs automatically without voluntary control
-heart rate, blood pressure, body temperature
autonomic nervous system
unconscious, automatic, stereotyped responses to stimulation involving visceral receptors and effectors and somewhat slower responses
visceral reflexes
visceral reflex arc order
-receptors
-afferent neurons
-interneurons
-efferent neurons
-effectors
visceral reflex arc: nerve endings that detect stretch, tissue damage, blood chemicals, body temperature, and other internal stimuli
receptors
visceral reflex arc: leading to the CNS
afferent neurons
visceral reflex arc: in the CNS
interneurons
visceral reflex arc: carry motor signals away from the CNS
efferent neurons
visceral reflex arc: that make adjustments
effectors
What are the two divisions of the ANS?
- sympathetic division
- parasympathetic division
division of the ANS: prepare body for fight-or-flight
-excites the hearts but inhibits digestive and urinary function
-prepares body for physical activity: exercise, trauma, arousal, competition, anger, or fear
-increases heart rate, BP, airflow, blood glucose levels, etc
-reduces blood flow to the skin and digestive tract
sympathetic division
division of the ANS: rest and digest
-calms many body functions reducing energy expenditure and assists in bodily maintenance
-digestion and waste elimination
-“resting and digesting” state
parasympathetic division
signal must travel across two neurons to get to the target organ
-must cross a synapse where these two neurons meet in an autonomic ganglion
-presynaptic neuron
-synapses with a postganglionic neuron whose axon extends the rest of the way to the target cell
autonomic pathway
the first neuron has a soma in the brainstem or spinal cord
presynaptic neuron
skeletal muscles
-one synapse neuromuscular juncture
somatic efferent innervation
cardiac muscle, smooth muscle, glands
-2 synapses
-2 neurotransmitters
autonomic efferent innervation
also called the thoracolumbar division because it arises from the thoracic and lumbar regions of the spinal cord
-relatively short preganglionic and long postganglionic fibers
-preganglionic neurosomas in lateral horns and nearby regions of the gray matter of spinal cord
sympathetic division
what is the origin of sympathetic nervous system?
lateral horn or T1 to L2
sympathetic chain ganglia chart
chapter 15 slide 12
each paravertebral ganglion is connected to a spinal nerve by two branches
communicating rami
small myelinated fibers that travel from spinal nerve to the ganglion by way of the white communicating ramus (myelinated)
-relatively short
preganglionic fibers
fibers that leave the ganglion by way of the gray communicating ramus (unmyelinated)
-relatively long
-forms a bridge back to the spinal nerve
postganglionic fibers
fibers that extend the rest of the way to the target organ
postganglionic fibers
after entering this, the postganglionic fibers may follow any of three courses
sympathetic chain
what are the three courses that postganglionic fibers may follow?
- some end up in ganglia which they enter and synapse immediately with a postganglionic neuron
- some travel up or down the chain and synapse in ganglia at other levels
- some pass through the chain without synapsing and continue as splanchnic nerves
parasympathetic division is also called what?
craniosacral division
this division arises from the brain and sacral regions of the spinal cord
-fibers travel in certain cranial and sacral nerves
parasympathetic division (craniosacral division)
what is the origin of long preganglionic neurons?
-midbrain, pons, and medulla
-sacral spinal cord segments S2 to S4
what are the two origins of the parasympathetic division?
- cranial origin
- sacral origin
origin from brain
cranial origin
origin from S2 to S4
sacral origin
pathways of these types of fibers
-fibers in cranial nerves 3, 7, 9, and 10
-fibers arising from sacral spinal cord
long preganglionic fibers
ganglia in or near target organs
-long preganglionic, short postganglionic fibers
terminal ganglia
this is less than sympathetic division
-one preganglionic fiber reaches the target organ and then stimulates fewer than five postganglionic cells
neuronal divergence
what are the parasympathetic cranial nerves?
-oculomotor nerve (3)
-facial nerve (7)
-glossopharyngeal nerve (9)
-vagus nerve (10)
cranial nerve: narrows pupil and focuses lens
oculomotor nerve (3)
cranial nerve: tear, nasal, and salivary glands
facial nerve (7)
cranial nerve: parotid salivary gland
glossopharyngeal nerve (9)
cranial nerve: carries majority of the components of parasympathetic nervous system
-viscera as far as proximal half of colon
-cardiac, pulmonary, and esophageal plexus
-provides majority of parasympathetic nervous system energy
vagus nerve (10)
remaining parasympathetic fibers arise from what levels of the spinal cord?
S2 to S4
this neurotransmitter is secreted by all preganglionic neurons in both divisions and the postganglionic parasympathetic neurons
-called cholinergic fibers
-any receptor that binds it is called cholinergic receptor
acetylcholine (ACh)
look over the neurotransmitters and their receptors slide
chapter 15 slide 23
most viscera receive nerve fibers from both parasympathetic and sympathetic divisions
-antagonistic effect
-cooperative effects
dual innervation
dual innervation: oppose each other (parasympathetic vs. sympathetic)
antagonistic effect
dual innervation: two divisions act on different effectors to produce a unified overall effect
cooperative effects
oppose each other; exerted through dual innervation of same effector cells
-heart rate decreases (parasympathetic)
-heart rate increases (sympathetic)
exerted because each division innervates different cells
-pupillary dilator muscle (sympathetic) dilates pupil
-constrictor pupillae (parasympathetic) constricts pupil
antagonistic effects
a baseline firing frequency of sympathetics
-keeps vessels in state of partial constriction
-increase firing frequency
-decrease in firing frequency
-can shift blood flow from one organ to another as needed
sympathetic vasomotor tone
increase in firing frequency
vasoconstriction
decrease in firing frequency
vasodilation
This division acting alone can exert opposite effects on the target organ through control of blood vessels. During stress…
-blood vessels to muscles and heart dilate
-blood vessels to skin constrict
sympathetic division
study of effects of drugs on the nervous system
neuropharmacology
this enhances sympathetic activity
-stimulate receptors or increase norepinephrine release
-cold medicines that dilate the bronchioles or constrict nasal blood vessels
sympathomimetics
this suppresses sympathetic activity
-block receptors or inhibit norepinephrine release
-beta blockers reduce high BP interfering with effects of epinephrine/norepinephrine on heart and blood vessels
sympatholytics
________ enhances activity while _________ suppresses activity
parasympathomimetics, parasympatholytics
