anatomy final
posterior column medial lemniscus pathway
-the nerve impulses for conscious proprioception and most tactile sensations ascend to the cortex along a common pathway formed by three-neuron sets -these neurons are a part of the posterior columns which consist of the gracile fasciculus and cuneate fasciculus -impulses conducted along this pathway are concerned with fine touch, proprioception, and vibratory sensations
myelinated fiber tracts in white matter
* association fibers: connect one part of the cortex to another in the same hemisphere * commissural fibers - corpus callosum - largest white matter tract * projection fibers - connect the cortex to lower parts of the CNS
cerebellum functions
1. error control in body movements (executes the movement intended by cerebral cortex and makes adjustments in muscle contraction) 2. predictive function (detects speed and progress of body movements and will slow down and even stop them in order to smoothly accomplish a movement) 3. efficient body movement (influences antagonistic muscles for most efficient body movement) 4. maintains muscle tone (to maintain posture and equilibrium
cerebellum
10% of brain volume, but over 50% of neurons in CNS
merkel's discs
They provide for 25% of all mechano-receptors are Merkel's disc. They are densely populated in the lips, fingertips, genitalia. they are found in association to hair follicles. since they are slowly adapting, they detect continuous touch of objects against the skin. they are important in determining the texture
action potential
a brief fluctuation in membrane potential caused by the rapid opening and closing of voltage-gated ion channels; they sweep like a wave along axons to transfer information from one place to another in the nervous system
corpus callosum
a bundle of transverse white fibers that connect right hemisphere to left hemisphere
reticular formation
a column of gray matter interspersed among fibers of white matter that extends from the medulla to the thalamus
tectospinal
a contralateral tract that is responsible for postural muscle tone associated with auditory and visual stimuli
transduction
a conversion of the stimulus. the sensory receptor or sense organ must receive the stimulus and transducer the stimulus into an electrical response (generator potential), it will eventually lead to a nerve impulses. each type of sensory receptor can only transducer one type of stimulus.
integration of the sensory input
a region of the CNS must receive and integrate the information that is carried by the action potential and converted to a sensation, this is the final pathway
first order neuron
a sensory neuron that conducts impulses from somatic receptors (periphery) to the spinal cord and the brainstem
transduction (conversion) of the stimulus
a sensory receptor or sense organ must receive the stimulus and transduce the stimulus into an electrical response (generator potential); it will eventually lead to a nerve impulse. each type of sensory receptor can only transduce one type of stimulus
ruffini corpuscles
a single encapsulated myelinated nerve ending with multi- branched or sprayed axonal endings. large receptor fields, slowly adapting
receptor potential
a stimulus-induced change in the membrane potential of a sensory receptor
separate cells
a synapse with first order neurons located in sense organs; hair cells in the ears, rods and cones in the retina (eyes) and gustatory receptor cells on taste buds
graded potential
a wave of electrical excitation that corresponds to the size of the stimulus; they are in ligand/mechanically graded ion channels, are localized and the amplitude depends on the stimulus strength. they are used by dendrites for returning signals from sensory organs. they also get weaker as they travel along nerve fibers and last for several milliseconds to several minutes
gyri
act as specific land marks
major indirect tracts such as rubrospinal, tectospinal, and vestibulospinal
additional sensory pathways
receptive field of a sensory neuron
an area with in which a stimulus of appropriate quality and strength will cause a sensory neuron to initiate a nerve impulse
generator potential
an electrical response, when this generated potential reaches threshold (if it's large enough) will then generate and action potential in a sensory neuron. it elicits a nerve impulse that will be generated and conducted along a sensory pathway from the CNS to the PNS. it is not propagated like an action potential.
vestibulospinal
an ipsilateral tract that is responsible for gross postural adjustments in response to head movements
motor areas
are regions in the frontal lobe that manage muscular movement
receptive field
area within which a stimulus of appropriate quality and strength will cause a sensory neuron to initiate a nerve impulse
inferior cerebellar peduncle
ascending afferent fibers from cord and medulla
hair cell receptors
auditory receptors, they generate receptor potentials because they convert mechanical energy into electrical energy. there are outer and inner hair cell receptors that make up the cranial nerve and contract upon electrical stimulation
inferior colliculi
auditory reflex center (bottom)
cerebral nuclei
basal ganglia; only found in gray matter
primary gustatory cortex
base of the post central gyrus, interprets sensations related to the sense of taste
cranial bones and meninges
brain is protected by
major parts of the brain
brain stem, diencephalon, cerebrum, cerebellum
middle tract
carries fibers from cortex
anorexia
causes damage to the feeding center
CSF
clear, colorless fluid with a total volume in the adults of 100-200 ml
nucleus
collection or cluster of neuronal cell bodies in the gray matter
cerebral cortex
composed of gray matter
sensory
concerned with reception and interpretation of sensory impulses
midbrain
connects the pons and diencephalon
vermis
connects two cerebellar hemispheres
sensory cranial nerves
contain only sensory fibers "sensory nerves" - 1,2,8
tuberal
contains the infundibulum - connects hypothalamus to pituitary gland
medulla oblongata
continuous with upper part of the spinal cord
homeostatic functions of the hypothalamus
controls and integrates the ANS, connects with reflex center in the medulla, integrates the activity of the nervous system with the endocrine system (produces hormones), regulates emotional and behavioral patterns, regulates eating and drinking through the feeding, satiety, and thirst centers, regulates body temp through heat gain and heat loss centers
gray matter
convoluted outer surface called the cerebellar cortex
obesity
damage to the satiety center
white matter
deep to the cortex
white matter
deep to the cortex and arranged into three cerebellar tracts: superior, middle, inferior cerebellar peduncles
insula
deep within brain - covered by frontal, temporal, and parietal bone (aka Island of Reil)
diencephalon
develops from forebrain
-lower motor neurons extend from the brain stem and spinal cord to skeletal muscles; these lower motor neurons are called the final common pathway -upper motor neurons (UMN) extend from the cerebral cortex (frontal lobe) to the anterior horn of the spinal cord as well as the pons and the medulla
difference between damage to the upper and lower motor neurons
longitudinal fissure
divides the cerebrum into right and left halves
third ventricle
drains the lateral ventricles
fourth ventricle
drains the third ventricles
lobes
each hemisphere is subdivided into 5 lobes by sulci and fissures - named according to cranial bone above it
these two systems generally have opposing actions one stimulates the other one inhibits
effector organs
no innervation
effects of parasympathetic divisions on adipose tissue
promote voiding
effects of parasympathetic divisions on bladder/urethra
little or no effect
effects of parasympathetic divisions on blood vessels
increase motility and secretion, relax sphincters
effects of parasympathetic divisions on digestive tract organs
stimulate muscle
effects of parasympathetic divisions on eye (ciliary muscle)
constrict eye pupils
effects of parasympathetic divisions on eye (iris)
stimulate release of bile
effects of parasympathetic divisions on gallbladder
stimulate secretion
effects of parasympathetic divisions on glands: nasal, gastric, salivary, pancreas, lacrimal
decrease rate
effects of parasympathetic divisions on heart muscle
no innervation
effects of parasympathetic divisions on kidney
stimulate glucose storage
effects of parasympathetic divisions on liver
constrict bronchioles
effects of parasympathetic divisions on lungs
no innervation
effects of parasympathetic divisions on sweat glands
stimulate lipolysis
effects of sympathetic divisions on adipose tissue
inhibit voiding
effects of sympathetic divisions on bladder/urethra
vasoconstriction, increase blood pressure
effects of sympathetic divisions on blood vessels
decrease motility and secretion, constrict sphincters
effects of sympathetic divisions on digestive tract organs
no innervation
effects of sympathetic divisions on eye (ciliary muscle)
dilate eye pupils
effects of sympathetic divisions on eye (iris)
inhibit release of bile
effects of sympathetic divisions on gallbladder
inhibit secretion by vasoconstriction of vessels
effects of sympathetic divisions on glands: nasal, gastric, salivary, pancreas, lacrimal
increase rate
effects of sympathetic divisions on heart muscle
decrease urine output
effects of sympathetic divisions on kidney
stimulate glucose release
effects of sympathetic divisions on liver
dilate bronchioles
effects of sympathetic divisions on lungs
stimulate copious sweating
effects of sympathetic divisions on sweat glands
meissner's corpuscles
encapsulated nerve endings that elicit large myelinated sensory nerve fibers, they have small receptive fields and they rapidly adapt
stimulation, transduction, generator potential, impulse generation and conduction, integration of sensory input
events of perception of a sensation in order
pressure sensitive receptors found in large muscular arteries that regulate blood pressure are baroreceptors, they are located in the aorta, carotid
example of general somatic senses
CSF is formed by
filtration of blood water through a network of capillaries produced at the rate of about 1 liter per day and ependymal cells called the choroid plexus
impulse generation and conduction
first order neuron, second order neuron, third order neuron
merkel's discs
flattened portions of dendrites of sensory neurons. they contact the stratum basale. small receptor fields, slowly adapting
falx cerebelli
found between right and left halves of cerebellum
free nerve endings
found everywhere in the skin and they detect pain (nociception), temperature, itch, tickle, touch, pressure and stretch
age 20, 3 lbs
full growth and weight of the brain
confusion, dizziness, convulsions, unconsciousness
glucose deficiency in the brain may cause
taste buds
gustation, taste
cortex contains
gyri, deep grooves called fissures, and shallower grooves called sulci - gives the cerebellum a convoluted appearance - pattern is similar in every brain
hearing
hair cells
raise temp - shiver
heat gain
sweating
heat loss
microscopically, by location and by the type of stimulus detected
how are receptors classified?
from receptors located in the skin as well as proprioception
how do the general somatic senses arise
feeding center
hunger and desire for food ; damage = anorexia
primary motor cortex
immediately anterior to the central sulcus (pre central gyrus)
motor association cortex
immediately anterior to the pre-central gyrus - learned complex and sequential nature motor skills - generates nerve impulses that causes muscles to contract in a specific sequences that has been practiced and learned (muscle memory)
hypothalamus
inferior to thalamus; receives sensory impulses from sound, taste, smell, and somatic and visceral receptors, 3 major regions possessing important nuclei ( mammillary, tuberal, supraoptic)
satiety center
inhibits appetite
pons white matter
interconnects different levels of the brain by way of tracts and relays nerve impulses related to voluntary skeletal movements from the cerebral cortex to the cerebellum
hydrocephalus
is CSF can't circulate or drain properly due to an obstruction in the ventricles or subarachnoid space, a buildup will occur causing increased pressure on the brain - headache, nauseous, coma
cerebrum
largest part of the brain
brain
largest/most complex; center for registering sensations, correlating them with one another and with stored info, making decisions, and taking action; center for intellect, emotions, behavior, and memory
pathway of CSF flow
lateral ventricles -- foramen of Monro --third ventricle -- 4th ventricle -- aqueduct of Sylvius (cerebral aqueduct) -- central canal of spinal cord
pacinian corpuscles
lie in the dermis, hypodermis (subcutaneous level), and in deep fascial tissues; only stimulated by very rapid movements of the tissues; they adapt at a few hundredths of a second, rapid adapting
Broca's motor speech cortex
located in frontal cortex - translates thought into speech and coordinates voluntary muscle activity
limbic systems
located in the cerebral hemispheres and diencephalon
motor pathway of the spinal cord
lower motor neurons -> right anterior corticospinal tract -> spinal cord and left lateral corticospinal tract -> pyramid and decussation in the medulla -> upper motor neurons -> through the midbrain to the right side of the body
primary olfactory cortex
medial aspect of the temporal lobe - smell
posterior column medial lemniscus pathway
medial lemniscus extends from the medulla to the thalamus to the somatosensory cortex. this pathway carries discrete signals of the posterior columns of the spinal cord decussates to the medulla, it will ascend into the thalamus
other cranial nerves
mixed - both sensory and motor fibers.
asymmetry (unevenness of the cerebral hemisphere)
more pronounced in men; women have larger connections between the two hemispheres
face, hands, lips
most sensory receptors
superior tract
mostly efferent fibers that carry impulses from cerebellum to midbrain, thalamus, and cortex
Parkinson's disease
neurons from the corpus striatum that produce dopamine degenerate ( excessive muscle tone leads to rigidity, decreased mobility, tremors, involuntary muscle contraction, foot shuffling, expressionless face
detect damage to the tissues whether physical or chemical
nociceptors
generated potential
not the same as an action potential, each type of sensory receptor can only transduce one kind of stimulus
gray matter of cerebral aqueduct
nuclei for origin for CN 3,4 and the corpora quadrigemina (two pairs of rounded nuclei) on roof of midbrain
gray matter of medulla oblongata
nuclei for origin for CN VIII through XII and autonomic reflex centers - neurons receive sensory messages from fibers in ascending tracts. The axons of these cell bodies will cross over to opposite side through pyramids and go onto higher brain centers
pons gray matter
nuclei for origin of CN 5,6,7,8 and the pneumotaxic and apneustic centers - regulate rate and rhythm of breathing along with medulla
2 functions of limb systems
one is memory
optic nerves meet and cross at the
optic chiasm - later vision doesn't cross, medial does
twelve pairs of cranial nerves
originate from the brain; named on the basis of distribution and are numbered by order of attachment from anterior to posterior
basal ganglia
paired masses of gray matter deep within each cerebral hemisphere
basal ganglia
paired masses of gray matter deep within each cerebral hemisphere; serve as relay station for control of skeletal muscle movements that originate in cerebral cortex. Also serve as extensive interconnections between cerebral cortex , thalamus, hypothalamus, and some fibers descend into cord
primary somatosensory cortex (areas 1,2,3)
parietal lobe immediately posterior to the central sulcus (post central gyrus) receives sensory impulses from cutaneous muscle and visceral receptors. (extends from longitudinal fissure to lateral fissure) -- each area on the body is represented by a specific area on the gyrus - sensory body image
pineal gland
part of the epithalamus that secretes the hormone melatonin that helps regulate the body's natural cycle of sleeping and waking hours (circadian rhythm) in conjunction with hypothalamus
the primary motor area of the cerebral cortex is the pre-central gyrus in the frontal lobe. the neurons in the frontal lobe are quite large; they allow conscious control over voluntary movements of skeletal muscle. these neurons have very long axons and they form massive voluntary motor tracts. most of these neurons are involved with conscious motor control (skeletal muscle) of the face, the tongue, the hands, as well as posture, reflexes and muscle tone. motor innovations are contralateral (opposite side). the left frontal lobe controls muscles on the right side of the body and vice versa
patient experience of the difference between damage to the upper and lower motor neurons
reticular activating system
performs three functions: 1. regulation of muscle tone 2. arousal from sleep with stimulation from eyes ears skin 3. maintains consciousness and alertness
auditory association cortex
permits 3 aspects of hearing - auditory memory, recognition of meaning of speech, distinguish between speech noise and music
rods and cones
photoreceptors in the eyes (located in the retina)
white matter of the medulla oblongata
portions of myelinated motor (descending) and sensory (ascending) tracts - these tracts connect to the higher brain centers) ; pyramids ; largest motor tracts (descending), triangular in shape; decussation - neurons in left cerebral cortex control skeletal muscles on the right side of the body
occipital lobe
primary visual cortex
lateral ventricles (1 and 2)
principle site of CSF production
lateral ventricles (1 and 2)
produce CSF
supraoptic
produces two hormones - ADH and oxytocin
meissner's corpuscles
provide for 40% of the sensory innovation to your hands, they are sensitive to weak stimuli and are actually myelinated axon terminals that are formed by flattened schwann cells
somatosensory association cortex (areas 5,7)
receives sensory impulses directly from the thalamus; primary and association sensory areas permit aspects of sensory perception - 1. memory of sensory experiences 2. pain, temp, touch 3. allows you to distinguish one sense from another as well as shape and texture
mammillary
relay station for sense of smell
ruffini corpuscles
represent 20% of the mechano-receptors in the hand. they are found in the skin, ligaments and tendons. they are important in signaling heavy, continuous touch and pressure. they are important in regulating the degree of joint rotation
autonomic reflex centers
respiratory (breathing rhythm) cardiac control (force/rate of heart beat) vasomotor (vessel vasoconstriction) coughing, vomiting, sneezing, swallowing, hiccupping :: receive visceral, afferent fibers from spinal/cranial nerves and synapse in reflex centers - efferent fibers leave by way of spinal/cranial nerves
aphasia
result of injury to the association or motor speech areas - inability to use/comprehend words; can make sound, but not articulate speech
hemispheres
right and left halves of the cerebrum
cerebral cortex
sensory, motor and integrative signals are processed
tentorium cerebelli
separate cerebellum from occipital lobe
falx cerebri:
separate right from left cerebral hemisphere
pons
separates medulla from midbrain contains gray and white matter. 2 types of tracts - longitudinal (posterior ) and transverse (anterior)
cerebellar nuclei
several - gray matter
nucleus in the corpus striatum
substantia nigra
second order neuron
synapses with a first order neuron in the brainstem which will conduct impulses from the spinal cord and the brainstem up to the thalamus
third order neuron
synapses with a second order neuron in the thalamus. They relay impulses from the thalamus up to the somatosensory cortex (post-central gyrus) of the cerebrum where the conscious perception of the sensation is elicited
sensory receptor
takes the stimulus and converts it into a graded potential called a receptor potential (AKA generator potential)
primary auditory cortex
temporal lobe, recognized pitch and rhythm
the CSF is reabsorbed by
the arachnoid villi of the superior sagittal blood sinus
cognition
the awareness and acquisition of knowledge is credited to the thalamus
glucose
the brain has limited storage capacity for __________ and must be continually supplied
5
the brain has permanent damage with more than _____ min without oxygen
20
the brain requires ______ % of the total oxygen content
lateral grey horns, spinal cord
the cell bodies of Sympathetic preganglionic neurons are located in the ____________ of the T1 through L2 segments of the ______________
preganglionic neuron
the first of two autonomic motor neurons, the cell body is located in the brain or spinal cord and they are myelinated axons, which usually extends to an autonomic ganglion where it synapses with the postganglionic neuron
postganglionic neuron
the second neuron in the autonomic motor pathway, the cell body and dendrites are located in autonomic ganglia, where they synapse with one or more preganglionic fibers. They are non-myelinated Axon fibers of a postganglionic neuron terminates in a visceral effector organ
ascending sensory pathways are relayed to
the thalamus and then the cerebral cortex
either exciting or inhibiting ongoing activities of effector organs
the visceral motor neurons regulate visceral activities by either exciting or inhibiting ongoing activities of effector organs
formation of CSF
there are four CSF filled cavities within the brain called ventricles (also travels through central canal of spinal cord)
meissner's corpuscles
they are found in the thermos of the skin, mostly non-hairy parts of the skin (lips, fingertips, palms of the hands, and soles of the feet
pacinian corpuscles
they represent 15% of the mechano-receptors of the hand. they are important in detecting tissue vibrations. they are a myelinated afferent axon terminal surrounded by layers of lamella. they contain a lymph-like fluid inside
thirst center
thirst
falx cerebri, falx cerebelli, tentorium cerebelli
three extensions of the meningeal layer of the dura mater separate parts of the brain
white matter of cerebral aqueduct
tracts organized into cerebral peduncles that convey motor and sensory impulses
rubospinal
tracts that originate from the red nucleus and are responsible for motor input of gross postural tone
cerebral aqueduct
transports CSF
the sympathetic (thoracolumbar) and the parasympathetic (craniosacral)
two divisions that distribute visceral outflow from the CNS are
injury to cerebellum results in cerebellar ataxia
uncoordinated gait and movement as if you were drunk
frontal lobe
under frontal bone
occipital lobe of cerebrum
under occipital bone
parietal lobe
under parietal bone
temporal lobe
under temporal bone
visual association cortex
visual memory - recognition, evaluation, visual memory
superior colliculi
visual reflex center (top)
postganglionic neuron: the second neuron in the autonomic motor pathway, the cell body and dendrites are located in autonomic ganglia, where they synapse with one or more preganglionic fibers. They are non-myelinated Axon fibers of a postganglionic neuron terminates in a visceral effector organ
what are postganglionic axons in the parasympathetic and sympathetic systems?
-preganglionic neuron: the first of two autonomic motor neurons, the cell body is located in the brain or spinal cord and they are myelinated axons, which usually extends to an autonomic ganglion where it synapses with the postganglionic neuron -the cell bodies of Sympathetic preganglionic neurons are located in the lateral gray horns of the T1 through L2 segments of the spinal cord
what are preganglionic axons in the parasympathetic and sympathetic systems?
touch, pressure, vibration, itch, tickle, warmth, cold and pain
what are the general somatic senses
-the autonomic ganglia, they are the rest and digest responses that conserve and restore body energy, digest and absorb nutrients, and eliminate waste products -located very close to or actually within the wall of a visceral organ -main type of parasympathetic ganglia is terminal ganglia
what are the parasympathetic ganglia, where are they located and what types are there?
meissner's corpuscles, hair cell receptors, separate cells, merkel's discs, pacinian corpuscles, ruffini corpuscles, free nerve endings
what are the types of receptors
they are organs that receive impulses from both sympathetic and parasympathetic fibers. examples are the heart, blood vessels, kidney and lungs; one system overrides the other
what do dual innervations indicate?
an unmyelinated postganglionic fiber that provides slow nerve impulse transmission
what is a C-fiber?
the balance between the parasympathetic and sympathetic activity
what is autonomic tone?
controls and integrates the autonomic nervous system
what is one main function of the hypothalamus?
input to the nervous system is provided by sensory receptors that detect such stimuli as touch, sound, light, pain, cold, and warmth. these receptors change sensory stimuli into nerve signals and the information conveyed in these signals is then processed by the nervous system. the components of the brain interact to receive sensory input, integrate and store the information, and transmit motor responses
what is the somatic sensory system, what are its functions and responsibilities
transmit nerve impulses to three effector organs, which are glands, smooth muscle and cardiac muscle
what is the visceral efferent pathway?
sensory memory
what parts of the brain make you aware of and able to remember the taste of coffee for example?
the parasympathetic rest and digest response
what region of the nervous system controls defecation and urination?
they provide information about body position, muscle tension, joint position and equilibrium and they transmit nerve impulses related to muscle tone, movement of body parts, body sensation and balance
what type of modalities do proprioceptors detect and what are their functions
they are stimulated and produce pain at temperatures below 10 degrees C and above 48 degrees C. they adapt very little or not at all because it allows the patient to keep being informed of the damaging stimulus and to seek treatment
what type of modality do nociceptors detect
action potential
when the graded potential is large enough to reach the threshold, it will generate an ___________
they are naked nerve endings located in the skin; there is a very high concentration of nociceptors in our bones. they are also located in anterior walls and joint surfaces. most other deep tissues are not extensively supplied with pain receptors
where are nociceptors located
in skeletal muscles, tendons, joints, ligaments, in CT coverings of bones and muscles, in and around joints, and in the internal ear and are stimulated by stretching or movement
where are proprioceptors located
synapses with a first order neuron in the brainstem which will conduct impulses from the spinal cord and the brainstem up to the thalamus
where are second order neurons located
-sympathetic ganglia is the flight or fight response in stress, fright or anger -located in a vertical row on either side of the vertebral column -two types of sympathetic ganglia: the paravertebral ganglia and the prevertebral ganglia -three possibilities for synapse are: it may synapse with postganglionic neuron in the ganglion it first reaches (this is the preferred mode of travel), it may ascend or descend to a higher or lower ganglion before synapsing with postganglionic neurons at a different level or it may continue, without synapsing, through the sympathetic trunk ganglion to a prevertebral ganglion where it synapses with the postganglionic neuron
where are sympathetic ganglia located, what types are there and what are 3 possibilities for synapse in these ganglia?
a sensory neuron that conducts impulses from somatic receptors (periphery) to the spinal cord and the brainstem
where are the first order neurons located
synapses with a second order neuron in the thalamus. they relay impulses from the thalamus up to the somatosensory cortex (post-central gyrus) of the cerebrum where the conscious perception of the sensation is elicited
where are third order neurons located
