anatomy final

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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


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