Anatomy of the Nervous System 1 Flashcards
Which parts of the body focus on the CNS?
- Brain and spinal cord
Which parts of the body focus on the PNS?
cranial & spinal nerves- communication between CNS & all parts of body
What are the motor divisions of the nervous system? How are they differentiated?
Somatic ns: voluntary; from CNS to skeletal muscle
Autonomic ns: involuntary; (visceral motor); from CNS to cardiac muscle, smooth muscle, glands
Sympathetic division: “fight or flight”
Parasympathetic division: conserve energy at rest
What is a neuroglia? Provide examples
supporting cells - small cells that surround and wrap delicate neurons
§ Astrocytes (CNS)
§ Microglial cells (CNS)
§ Ependymal cells (CNS)
§ Oligodendrocytes (CNS)
§ Satellite cells (PNS)
§ Schwann cells (PNS)
What are the characteristics and roles of astrocytes?
star-shaped, most abundant; anchor neurons close to capillaries
- nutrient exchange, guide migration of young neurons, clean up environment (excess NT, K+ ions), even shown to release NT!
What are the characteristics and roles of microglia?
protective; touch neurons to monitor well-being; can transform into macrophages to engulf micro-organisms and/or cellular debris
What are the characteristics and roles of ependymal cells?
line cavities of brain & spinal cord
- Form permeable barrier between cerebrospinal fluid (CSF) in cavities and tissue fluid bathing CNS cells
What are the characteristics and roles of oligodendrocytes?
“few branches”
- they have processes that form myelin sheaths around CNS nerve fibres
What are the characteristics and roles of satellite cells?
§ surround neuron cell bodies in ganglia – thought to do many of the same things that astrocytes do in the CNS
What are the characteristics and roles of schwann cells?
form myelin sheaths around larger neurons in PNS; vital to peripheral nerve cell regeneration
What are special characteristics of neurons?
§ Extreme longevity (lasts a person’s lifetime); amitotic, with few exceptions
§ High metabolic rate: requires continuous supply of oxygen and glucose
How are neurons classified?
according to the # of processes extending from the body
What are the characteristics and roles of sensory neurons?
carry impulses toward CNS; primary, secondary and tertiary
o Except for bipolar neurons in some special organs; almost all primary sensory neurons are unipolar
o Higher order sensory neurons are all multipolar and reside entirely in the CNS
What are the characteristics and roles of motor neurons
carry impulses away from CNS to effectors
o Multipolar with most cell bodies in CNS (except some autonomic neurons)
What are the characteristics and roles of interneurons (Association neurons)?
between motor and sensory neurons
o integration of info; multipolar; most entirely within CNS; 99% of neurons of the body
What are the subdivisions of the CNS?
§ Cerebral hemispheres
§ Diencephalon
- thalamus
- hypothalamus
- epithalamus
§ Brain stem
- midbrain
- Pons
- medulla
§ Cerebellum
The Ventricles of the Brain are filled and lined with what?
continuous with one another and with central cavity of spinal cord / filled with CSF & lined by ependymal cells
Paired lateral ventricles separated by narrow ___ ___
septum pellucidum
Each ventricle communicates with narrow ____ in diencephalon via ___ ___
3rd ventricle; interventricular foramen
3rd ventricle to 4th ventricle (dorsal to pons) via ___ ___
cerebral aqueduct
What are the 3 apertures of the ventricles of the brain?
- paired (1)lateral apertures & (2)median aperture that connect ventricles to (3)subarachnoid space (surrounds brain)
The ___ (ridges) is separated by ___ (shallow groves), & ___ (deep grooves)
gyri; sulci; fissures
What are the 2 types of fissures?
o Longitudinal fissure
o Transverse cerebral fissure
What are the Lobes of The Cerebral Hemispheres
frontal, parietal, occipital, temporal, insular
Each hemisphere has which 3 basic regions
- Cerebral cortex of gray matter superficially
- White matter internally
- Basal nuclei deep within white matter
What is the function of the Cerebral Cortex
allows us to perceive, communicate, remember, understand, appreciate, initiate voluntary movements – conscious behaviour
What are brodmann areas?
numbered according to subtle differences in thickness, structure of contained neurons; some areas link with particular functions; other functions (memory & language) have overlapping domains; more diffusely organized
What are the 3 functional areas of the cerebral cortex?
§ Motor
§ Sensory
§ Association
Describe the Primary motor cortex
= precentral gyrus of frontal lobe of each hemisphere
- pyramidal cells allow control of skeletal muscles; axons project to spinal cord as pyramidal/corticospinal tracts
- entire body represented spatially in primary motor cortex of each hemisphere (called somatotopy)
Describe the Premotor cortex
- anterior to precentral gyrus
- helps plan movements by selecting and sequencing basic motor movements into more complex tasks (e.g. playing a musical instrument, keyboarding)
- coordinates movement of several muscle groups simultaneously/sequentially by activating motor cortex
- can control voluntary actions that depend on sensory feedback
Describe broca’s area?
- overlaps Brodmann areas 44 & 45
- Present in one hemisphere (usually the left)
- Motor speech area that directs muscles of speech production
- originally thought to be only a motor speech area
Describe the frontal eye field.
Brodmann area 8;
* controls voluntary movements of the eyes
What are the Sensory Areas of the brain?
Occur in parietal, insular, temporal, and occipital lobes
Describe the Primary Somatosensory Cortex
- in postcentral gyri of parietal lobe (Brodmann areas 1-3)
- receives general sensory information from skin and proprioceptors of skeletal muscle, joints, and tendons
- capable of spatial discrimination: identification of body region being stimulated
Describe the Somatosensory Association Area
- posterior to Primary Somatosensory Cortex (Brodmann areas 5-7)
- integrate/analyze somatic inputs (temp, pressure, ..) – interpret wrt size, texture, relationship of parts based on prior experience – think of feeling in your pocket for a particular item
___ ___ ___ surrounds primary visual cortex
Visual association area
What is visual agnosia?
the inability to recognize/understand things that you see
What is the function of the primary auditory cortex?
Interprets information from inner ear as pitch, loudness, and rhythm
What is the function of the auditory association area?
interpretation based on memory – speech, words, music, thunder, etc.
What is the function of the vestibular cortex?
- Responsible for conscious awareness of balance (position of head in space)
- posterior part of insula & adjacent parietal cortex
- not visible at surface
- deep in lateral sulcus
What is are the characteristics and the function of the olfactory cortex
- Medial aspect of temporal lobes = uncus
- small in humans; most of surrounding tissue now forms limbic system (emotions, memory)
- Involved in conscious awareness of odors
What is are the characteristics and the function of the gustatory cortex
- in the insula, just deep to the temporal lobe
- Involved in perception of taste
What are the characteristics and the function of the visceral sensory area?
- Posterior to gustatory cortex
- Conscious perception of visceral sensations,
e.g., upset stomach or full bladder
What are Multimodal Association Areas
any cortical area that is not “primary”
* Receive inputs from multiple sensory areas
* Send outputs to multiple areas
* Broadly divided into three parts:
Anterior association area, Posterior association area & Limbic association area
What is the most complicated cortical region and what is it involved with?
Prefrontal cortex - involved with intellect, cognition, recall, and personality (working memory)
Which part of the brains development depends on feedback from social environment
Prefrontal cortex
Tumors or lesions can result in what for the prefrontal cortex?
mood swings, loss of attentiveness, inhibitions
Which lobes are involved with the posterior association area?
temporal, parietal & occipital lobes
What is an example of contralateral neglect?
localization of self & surroundings in space – e.g. someone with damage to this area may not dress or wash one side of the body
Which Multimodal Association Areas receives input from all sensory association areas
Posterior association area
Describe the limbic association area
Provides emotional impact that makes scene important and helps establish memories (part of limbic system)
e.g. be aware of the danger associated with a particular situation & to remember it
What is lateralization
division of labor between hemispheres
what is cerebral dominance
hemisphere that is dominant for language
left hemisphere dominant for what in 90% of people
language, math, logic
e.g. compose a sentence, add numbers, memorize a list
The right hemisphere dominates what
dominates for visual-spatial skills, intuition, emotion, artistic and musical skills – our creative & insightful side
most individuals with left cerebral dominance are ___-handed
most individuals with right cerebral dominance are___-handed or ____
right: left; ambidextrous
Commissural fibers
connect corresponding areas between the 2 hemispheres – largest is corpus callosum
Association fibers
connections within a hemisphere (connect gyri, lobes)
Projection fibers
cortex to rest of the nervous system; these ones run vertically
What is the function of the basal nuclei?
- project to premotor & prefrontal cortices to influence muscle movements directed by primary motor cortex
- roles in starting, stopping, monitoring intensity of movements executed by cortex, especially if sustained like arm swinging while walking; also inhibit antagonistic and/or unnecessary actions by filtering them out and sending only best response to cortex
- also associated with cognition and emotions
The thalamus - Bilateral nuclei that makes up 80 % of the diencephalon & is connected by commissure called …
interthalamic adhesion - means intermediate mass
The Diencephalon includes what?
Thalamus, Hypothalamus, Epithalamus
What is the thalamic function?
“Gateway” to cerebral cortex
Main thalamic function is to act as relay station for information coming into cortex
Sorts, edits, and relays ascending input such as:
- Impulses from hypothalamus for regulating emotion and visceral function
- Impulses from cerebellum and basal nuclei to help direct motor cortices
- Impulses for memory or sensory integration
Overall, it acts to mediate sensation, motor activities, cortical arousal, learning, and memory
Where is the hypothalamus located
Below the thalamus
Hypothalamus functions
- Autonomic control centre: centres for bp, heart, GI, respiration, etc
- Centre for emotional response & behavior: heart of limbic system
- Body temperature regulation:
- Regulation of food intake: hunger, satiety
- Regulation of water balance & thirst: release of ADH; thirst centre
- Regulation of sleep-awake cycles:
suprachiasmatic nucleus - Control of endocrine system: releasing factors plus 2 nuclei (supraoptic & paraventricular) produce ADH & oxytocin
What happens when a person has Hypothalamic disturbances
cause a number of disorders in the body homeostasis such as: severe body wasting, obesity, sleep disturbances, dehydration, emotional imbalances
What is the most dorsal portion of the diencephalon?
epithalamus
What is the role of the pineal gland?
extends from posterior border and secretes melatonin
* Melatonin—helps regulate sleep-wake cycle
The choroid plexus is part of which structure of the diencephalon?
Epithalamus
What are the regions of the brain stem?
midbrain
Pons
Medulla oblongata
What is the structure/functions of the brainstem?
- Similar structure to spinal cord but contains nuclei embedded in white matter
- rigidly programmed, automatic behaviors necessary to survival
- pathway between higher & lower neural centres
- associated with 10 pairs of cranial nerves
What is the Cerebral aqueduct
channel running through midbrain that connects 3rd & 4th ventricles
What is the Periaqueductal gray matter
nuclei that play a role in pain suppression and fight- or-flight response
- include nuclei that control cranial nerve III (oculomotor) and IV (trochlear)
What is the corpora quadrigemina?
superior colliculi are visual reflex centres when visually follow a moving object; inferior colliculi are part of auditory relay (also startle reflex)
In which part of the brain stem is the substantia nigra found? What is the function of the substantia nigra?
- Found in midbrain nuclei
- band-like nucleus;
- high melanin content (precursor of dopamine);
- linked to basal nuclei of cerebral hemispheres (its degeneration linked to Parkinson’s disease)
What is the red nucleus of the midbrain nuclei?
- have rich vascular supply,
- iron pigment in neuron cell bodies;
- relay nuclei for descending pathways influencing limb flexion
Where are the pons located and what are the names of its conduction tracts?
Located between midbrain & medulla oblongata; 4th ventricle separates pons from cerebellum.
– Longitudinal fibers connect higher brain centers and spinal cord
– Transversal/dorsal fibers relay impulses between motor cortex and cerebellum
What are the 3 parts of the medulla oblongata?
- Pyramids: two ventral longitudinal ridges formed by pyramidal tracts from motor cortex
- Decussation : point where pyramidal tracts cross over to opposite side of body
- Olives: swellings caused by underlying inferior olivary nuclei that relay stretch information from muscles and joints to cerebellum
What are the functions of the medulla oblongata?
- crucial role as autonomic reflex centre for homeostasis
- Cardiovascular centre: cardiac & vasomotor centers
- Respiratory centers: rate & depth of breathing
- Other centers: eg: vomiting, hiccupping, swallowing coughing, sneezing
What is the role of the cerebellum?
- Processes input from cerebral cortex, brain stem, & sensory receptors
- influences the timing & patterns of skeletal muscle contraction for smooth, daily movements – eg: driving, typing, playing a musical instrument, etc (not under conscious control)
- plays a major role in balance
What is the folia?
- Transversely oriented gyri
- contains thin cortex of gray matter with treelike pattern of white matter called arbor vitae
What are the lobes of the hemispheres of the cerebellum
anterior, posterior, & flocculonodular
virtually all fibers in cerebellum are____
ipsilateral
How does the limbic system work?
- emotional-visceral brain – esp: amygdala (anger, fear, assess danger), hippocampus (emotions & memory), anterior cingulate gyrus (gestures, resolve conflicts when frustrated)
- link between odors, memories & emotions
- close association with hypothalamus; provides a pathway for stress to have effects on blood pressure, GI tract, heart rate
Which Functional Brain System puts emotional responses to odors?
The Limbic System
What is the fuction of the reticular activating system (RAS)
o maintains arousal of brain;
o filter for incoming signals (RAS &
cerebral cortex disregard ~99% of all sensory stimuli)
Severe injury of which functional brain system results in permanent unconsciousness (coma)
Reticular formation
