Nervous System(Chapter 14) Flashcards
Brain
- major organizing and processing center of the NS
- site of consciousness, sensations,memory,intellect, coordination and control of complex muscle movements
- outer layer gray matter(cortex)=consist of nuclei of neurons,
- inner layer white matter (tracts)=consist of myelinated axons of neurons
developmental patter of the brain
-brain and spinal cord arise from embryological tissue(ectoderm) beginning as a hollow, neural tube
4 main parts of the brain
1) Cerebrum: largest anterior portion of brain, divided into R & L cerebral hemispheres
2) Diencephalon: (interbrain) consists of the hypothalamus, thalamus, epithalamus and the pineal gland.
3) Cerebellum: (little brain) 2nd largest part of the brain, also divided into R&L cerebellar hemispheres
4) Brainstem: (lower brain) consists of the midbrain, pons, and medulla oblongata
Meninges(3 protective membranes that surround the brain)
-Dura Mater
- Dura Mater
- 2 fused layers:
- outer periosteal(endosteal) layer: adherent to cranial bone
- inner meningeal layer: 2 layers separated by space containing interstitial fluid and cerebral blood vessels, including a few large dural venous sinuses
Dural sinuses
- venous channels found between layers of dura mater in the brain.
- they receive blood from the internal and external veins of the brain
- receive CSF from the subarachnoid space
- then empty into the internal jugular vein
- dural venous sinuses have no tunica media
- no valves
- csf found in subarachnoid space
Dural folds
-inward extensions of dura mater that hold the brain in position and contain dural venous sinuses
3 major dural folds
Falx cerebri: lies btw the 2 cerebral hemispheres(IN the longitudinal fissure)
Falx cerebelli: lies btw the 2 cerebellar hemispheres
Tentorium Cerebelli: located btw cerebrum and cerebellum(in the transverse fissure)
Arachnoid mater
- Subarachnoid space- contains CSF around brain and spinal cord
- arachnoid granulations(villi)- knoblike projections of the arachnoid.
- Function: absorb CSF from subarachnoid space and empty it into sagittal sinus
Pia mater
- a thin, vascular membrane that adheres to the convolutions of the brain via astrocyte processes
- supplies nutrients 02 to the surface of brain
Cerebrum
-largest and most anterior portion of the brain
-consist of outer gray matter(cortex nuclei and inner white matter)
Function: site of conscious perception of somatic sensations, voluntary muscle movements, memory, intellect and personality
-somatic sensation: perssure, temp, pain, conscious memory
-R/L cerebral hemispheres
-olfactory bulbs- inferior aspect- contain sensory fibers from nose
-optic chiasma(anterior to pituitary)-optic nerves from retaina of eye cross over at optic chiasma
gyri(gyrus)
- ridges or convolutions of gray matter(cortex)
- ex: precentral and post cendtral gyrus
fissures/sulci
- deep/shallow grooves btw gyro of gray matter
- increase surface area of he cortex and separate each hemisphere into 4 lobes
central sulcus
-btw frontal and parietal lobes
precentral gyrus
- anterior to centeral sulcus
- CONTAINS PRIMARY MOTOR AREA of cerebral cortex
lateral cerebral sulcus
- separates the frontal lobe from the temporal lobe
- 5th lobe lies within this sulcus
- insula-part of limbic system
parietal-occipital sulcus
-separates parietal from the occipital lobe
longitudinal fissure
-separates the cerebrum into r and left hemisphere, falx cerebri dura fold lies here
postcentral gyrus
- posterior to the central sulcus
- contains primary somatosensory area of cerebral cortex
transverse fissure
- along with tenorium cerebelli
- supports the posterior part of cerebrum
- separates the cerebellum from the cerebrum
cerebrum(4 lobes)
- frontal lobe-btw central suclus and lateral cerebral fissure
- occipital lobe-posterior to parieto-occipital fissure
- partietal lobe-posterior to central sulcus(anterior to parieto-occipital lobe)
- temporal lobe- inferior to the lateral cerebral fissures
- insula-5th lobe of the brain and part of the limbic system, located beneath parts of the frontal, parietal, and temporal lobes
Cerebral white matter tracts(3)
formed by myelinated axons
1) Association: transmit impulses btw gyri of same cerebral hemisphere
2) Commissural- horizontal tracts: transmit impulses btw gyri of right and left hemispheres
Ex: corpus callousum(largest), anterior and posterior commissures
3) Projection- transmit impulses from cerebrum to lower CNS(thalamus, brainstem, spinal cord)
ex: internal capsule: thick band that contains ascending and descending axons
Function org of cerebral cortex
-sensory areas
-sensory areas involved in perception(conscious awareness of sensation)
primary somatosensory area(post central gyrus, areas 1,2,3)
-sensory area
- receives sensory information from receptors in skin to localize points of body for light touch, pressure, pain or temp, and proprioception(join.muscle position).
- map of entire body is present here
- a larger regions of it receives impulses from lips.fingers than from the thorax or hip(sensory homunculus)
Primary visual area( occiputal lobe, area 17)
-sensory area
- receieves impulses along fibers from retina via thalamus, perceives current visual image
- destruction of this area results in blindness
Primary Auditory area(superior temporal grus)
-sensory area
- superior part of the temporal lobe
- receives impulses from cochlea(inner ear)
- via thalamus for hearing sounds(pitch and rhythm)
- association area recognizes sounds such as speech, music or noise
Primary Olfactory Area(medial surface of temporal lobe)
-sensory area
- receives impulses from olfactory receptors in nasal cavity for recognition of various odors
- tumors in the area causes client to experience pleasant or unpleasant ordors
Primary gustatory area(postcentral gyrus in parital cortex)
-sensory area
-receives impulses from taste buds and is involves in gustatory perception and taste discrimination
Function org of cerebral cortex
-motor area
-control execution of voluntary movements
primary motor area(AREA 4- precentral gyrus of frontal lobe)
-motor area
- has map of entire body
- controls voluntary movement of skeletal muscle groups
- more cortical area devoted to fingers than toes(motor homunculus)
Motor (Brocas) speech area(AREA 44.45)
-motor area
- plannining and production of speech
- control muscles of larynx,pharynx,mouth and breathing muscles
- CVA or damage in this area results in confluent aphasia or expressive aphasia(inability to tom or articulate words
- nonfluent aphasia
- expressive aphasia
- motor aphasia
- broca=brooken speech(way to remember)
Function org of cerebral cortex
-association area
- large areas pf all 4 lobes anterior to motor area
- connected with one another by association tracts.
- deal with integrative functions such as memory, emotions, reasoning, will, judgement, personality traits, and intelligence
Somatosensory association area
-association area
- posterior to the somatosensory area
- determine shape and texture of objects by feeling it
- determine orientation of one object to another
- relationship of one body part to another
- enables compare current sensation with past experiences
Premotor area
-association area
- association area anterior to primary motor area
- controls learned motor skills of complex and sequential nature and causes contraction of specific groups of muscles in a specific sequence
- typing, playing piano, writing or reading
wernicke area(left temporal/parietal lobes) -association area
- left temporal and parietal lobes
- interprets the meaning of speech
- understanding
- verbal communication by adding emotions, such as joy or anger, to spoken words
- CVA or damage in this area results in fluent aphasia or receptive aphasia, inability to understand spoken or written words
- word salad: string of words with no meaning
- person can speak but cannot arrange words in coherent fashion
Prefrontal cortex(frontal association area)
- anterior to frontal lobe
- involve reasoning, intelligence, judgement, planning for the future
- conscience, recall of information
- complex learning, foresight, intuition, mood, development of abstract ideas and personality
Common integrative area
-functions by integrating information to form thoughts and dictate an appropriate response
Hemispheric lateralization(LEFT)
- receives somatic sensory signals from and controls muscles on right side of body
- controls muscles on right side of body
- reasoning
- numerical and scientific skills
- ability to use and understand sign language
- spoken and written language
Hemispheric lateralization(RIGHT)
- Receives somatic sensory signals from and controls muscles on left side of body
- musical and artistic awareness
- space and pattern perception
- recognition of faces and emotional content of facial expressions
- generating emotional content of language
- generating mental images to compare spatial relationships
- identifying and discriminating among odors
Basal Nuclei
- paired masses of gray matter in each cerebral hemisphere
- globus pallidus, putamen, caudate nucleus
- inititate and terminate movements, suppress unwanted movements and regulate muscle tone
- produce the inhibitory neurotransmitter dopamine
Limbic system(emotional brain)
- ring of structures on the inner border of the cerebrum and floor of the diencephalon
- governs emotional aspect of the brain
- functions in emotional aspects of behavior and memory and is associate with pleasure and pain
- involved in olfaction
- includes:
- cingulate gyrus
- hippocampus
- dentate gryus
- amygdala
- mammillary bodies
- thalamus
- olfactory bulb
*(hippo mammal) has teeth(dent) w/friensds (amy, thala,olga) all are (cingul)
Diencephalon
-it surrounds the 3rd ventricle and consist of thalamus, hypothalamus, circumventricular organs and epithalamus
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Diencephalon(thalamus/relay station)
- relay station for all sensory impulses
- located superior to the midbrain and contains nuclei
Diencephalon(hypothalamus)
- found inferior to the thalamus, had four major regions(mammillary, tuberal, supraoptic, and pre optic)
- major regulators of homeostasis
- regulation of emotional and behavioral patterns
- eating and drinking through the feeding center, satiety center, and thirst center
- thermostat of body- it aids in controlling body temp
- it controls ANS
- produces releasing and inhibiting hormones, oxytocin, and ADH
- regulates circadian rhythms and states of consciousness
Diencephalon(epithalamus)
- lies superior and posterior to the thalamus and contains the pineal gland and the habenular nuclei
- pineal gland secrets melatonin
- habenular nuclei are involved in olfaction, especially emotional responses to odors
Diencephalon(circumventricular organs)
- monitor chemical changes in the blood because they lack a blood-brain barrier
- cvo includes parts of the hypothalamus, the pineal gland, and pituitary gland
- function to coordinate homeostatic activities of the endocrine and nervous system
- site of entry into the brain of HIV
Cerebellum
- coordination of skeletal muscle contractions-
- may have role in cognition and language processing
Brain stem and reticular formation
- parts btw spinal cord and diencephalon
- midbrain, pons, medulla oblongata
- extending throughout the brainstem is reticular formation; netlike region of gray and white matter
medulla oblongata
- continuous with upper portion of spinal cord
- contain both sensory and motor tracts
structural region of medulla
- bulges of white matter called pyramids on the anterior aspect formed by corticospinal tracts
- decussation of pyramids results in neurons in the left cerebral cortex controlling skeletal muscles on the right side of the body and vice versa
- olive lateral to each pyramid containing inferior olivary nucleus
- nucleus provides instructions for cerebellum to make adjustments to muscle activity as you learn new motor skills
- right and left gracile nucleus and cuneate nucleus
- posterior column tracts form synapses in these nuclei
- postsynaptic neurons then relay sensory information to the thalamus on the opposite side of the brain
- axons ascent to the thalamus in white matter called medial lemniscus
- posterior column pathway end in nuclei medial lemniscus pathway
- nuclei are components of sensory pathways for gustation, hearing, equilibrium
- contains cranial nerves 8-12
medulla oblongata(function)
- cardiovascular center
- regulate rate and force of heartbeat
- diameter of BV
- medullary rhythmic area of resp center
- adjusts basic rhythm of breathing
- reflex center for swallowing coughing, sneezing, hiccuping
pons(bridge)
- located superior to the medulla
- provides connection btw cerebral cortex and opposite hemisphere of cerebellum
- tracts and cranial nerves nuclei
- contain pneumotaxic and apneustic resp center
- contains cranial nerves 5-7 and vestibular branch of cranial8
Midbrain
-extends from the pons to the diencephalon
-contains nuclei and tracts
-parts of the ventricle found here
-cerebral peduncles: consist of axons of the corticospinal, corticobulbar tracts(cortex to medulla)]
-tectum-situated posteriorly and contains four rounded elevations: 2superior ones called superior colliculli(coordinates head,eyes,and trunk movements in response to visual stimuli)
2 inferior colliculli(coordinate head eyes and trunk movements in response to auditory stimuli
-contains left and right sustantia nigra(produces dopamine, controls subconscious motor activities), the left and right red nucleus(controls muscle movements)
-contain origins for cranial nerves 3 and 4
Reticular formation
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