Neuroanatomy Flashcards
what are afferent signals?
signals that move from the body to the brain (sensory)
what are efferent signals?
signals that move from brain to body (motor)
what is the central nervous system (CNS)?
the brain and the spinal cord
what is the peripheral nervous system (PNS)? what other systems does it contain?
- nervous tissue outside the brain and spinal cord
- somatic and autonomic nervous system
what is the somatic nervous system? what do it’s afferent and efferent signals do?
- conscious sensation and movement in relation to the outside world
- afferent - sensation of the outside world, touch
- efferent - movement in relation to the outside world
what is the autonomic nervous system? what do it’s afferent and efferent signals do?
- unconscious afferent and efferent signals
- afferent - sensation of internal environment (blood acidity, how much stomach is stretched)
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efferent - movement of internal environment without our conscious involvement
- sympathetic NS
- parasympathetic NS
what are the efferent systems of the autonomic nervous system? do they work bilaterally?
- sympathetic and parasympathetic nervous systems
- there is a unilateral sympathetic response across the body and extreme lateralization of response
what does the sympathetic nervous system do?
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mobilizes energy, fight or flight, main goal is to be ready for some action, maximize and mobilize energy/resources on hand
- heart pounds more to bring more O2 to the brain
- body starts creating more energy, ATP to use
- blood constricts to the core and the brain to prevent bleeding in limbs
what does the parasympathetic nervous system do?
- conserves energy, rest and digest, main goal is to store energy for later, digest faster
- not always mutually exclusive or in opposition to one another
- ex. healthy sexual activity
what are cell clusters?
cell clusters - grey matter regions
- nucleus, nuclei (CNS) vs. ganglion/ganglia (PNS)
what are bundles?
bundle of axons - white matter regions
- tract (CNS) vs. nerve (PNS) vs. fibres (all)
what are the anatomical directions when referring to quadrapedal animals?
- anterior (rostral) - head of the animal, posterior (caudal) - end of spinal cord of the animal
- dorsal/superior - spine side, ventral/inferior - stomach side
- lateral - towards the outside of the body, medial - towards the line of symmetry
what are the anatomical directions when referring to the bipedal neuroaxis of humans?
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anterior - head (including the midbrain), posterior - end of spinal cord
- after the midbrain, it switches
- anterior - front of our face,
- posterior - back of our head
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dorsal- spine side, ventral - stomach side
- we don’t use the terms superior/inferior for the midbrain to botton of spine
- after the midbrain, it switches
- dorsal/superior - top of the head, ventral/inferior - bottom of the brain
- lateral - towards the outside of the body, medial - towards the line of symmetry
what is a coronal section?
cutting to separate front half of brain from the back half
what is a horizontal section?
cutting to separate the top of the brain from the bottom half
what is a mid-sagittal section?
cutting to separate sides of the brain down the middle
what is a sagittal section?
any cut separating the sides of the brain
what is the composition of the spinal cord from anterior to posterior?
- cervical, thoracic, lumbar, and sacral vertebrae protect the spinal cord
- intermittent projections form spinal cord because the spinal cord is protected by bones and the axons bundle together to squeeze through between bones
why does the spinal cord narrow as you go down the spine?
- narrows as you go down since the efferent neurons on the lower end leave to control parts of the body
- barely any sensory information coming in at the bottom of the spinal cord
- sensory axons increase as you move up the spinal cord
what is the cauda equina?
sack of nerve roots at the lower end of the spinal cord that leave the spinal cord to connect to other parts of the body
what does the composition of grey and white matter look like in the spine? what are the different parts responsible for?
- grey matter is on the inside and shaped like an H, white matter surrounding
- opposite of how white matter and grey matter are organized in the brain
- dorsal side of spinal cord is responsible for sensory information and ventral side is responsible for motor information
- motor cell bodies - cell bodies are in the grey matter of the spinal cord
- sensory cell bodies - cell bodies are in the ganglia outside the spinal cord (dorsal root ganglia)
why is the segment of damage of the spinal cord important?
- spinal cord damage is related to segment of damage
- closer to brain → worse damage
- affects all the motor and sensory axons/cell bodies below it
what are the 3 major divisions in the brain?
- forebrain, midbrain, hindbrain
- all appear in early development
what are the 5 major divisions in the brain?
- forebrain - telencephalon, diencephalon
- midbrain - mesencephalon
- hindbrain - metencephalon, myelencephalon
what are the functions of the myelencephalon? what directional terms are we using?
dorsal is along our back, posterior is towards our feet, anterior is towards the top of our head
- medulla - is the junction between spinal cord and brain, has lots of tracts and myelinated axons
- responsible for involuntary control of life-sustaining functions
- reticular formation - runs from myelencephalon to mesencephalon (midbrain to hindbrain)
- responsible for arousal, wakefulness, arousal and sleep
what are the functions of the metencephalon? where are the different regions?
- pons - on the ventral side (belly)
piece of big white matter with afferent and efferent axons, info continuing from spinal cord and medulla - responsible for ability to feel and ability to move
- cerebellum - on the dorsal side (back)
- 10% of brain volume and more than 50% of - neurons needed for sensory and motor coordination
what are the functions of the mesencephalon? where are the different regions?
- tectum - dorsal (back) side, has the superior colliculi (eye movement in response to visual stimuli) and inferior colliculi (head movement in response to sound)
- responsible for how we move our eyes and bodies in relation to sights and sounds
- parinaud’s syndrome - inability to move eyes, especially upwards
- tegmentum - ventral (belly) side, related to movement in relation to motivation
- contains reticular formation, periaqueductal grey (behaviour linked to fear/emotions), dopamine-producing regions, and red nucleus
- dopamine-producing regions = substantial nigra (damage=parkinsons), and ventral tegmental area
- red nucleus has key role in movement related to species-specific behaviour
- drug addiction is related to strong activation of tegmentum
what are the functions of the diencephalon? where are the different regions?
- now switched to dorsal as top of the head and ventral as chin
- thalamus - dorsal, receives all sensory info except olfaction
- projection neurons stop and create a synapse so there is an opportunity to modify signal
- corticothalamic loops responsible for consciousness (receives from and sends to the cortex)
- responsible for sensation, movement, and consciousness
- hypothalamus - ventral, controls the pituitary gland
- other diverse functions such as sex, aggression, feeding, sleep, etc
what are the functions of the telencephalon? where are the different regions?
- is the cerebral cortex and underlying structures
- damage here is wide-ranging in it’s symptoms
- outer layer = cerebral cortex, cortex, neocortex
what are the different types of convolutions?
- gyrus/gyri - folds outward
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sulcus/sulci - folds inwards
- if sulci are very prominent or important, they are also called fissures
- they are not functionally meaningful but damage may show up in one and not the other
how are the two hemispheres separated?
- the hemispheres are separated by the longitudinal fissure
- connected by a few tracts (commissures)
- corpus callosum - largest commissure of white matter connecting the hemispheres of the brain
what fissures separate the lobes of the brain? what are some important areas around these fissures?
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central fissure separates frontal and parietal lobes
- precentral gyrus - gyrus in front of central fissure (motor)
- postcentral gyrus - gyrus behind the central fissure (somatosensation)
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lateral fissure separates temporal lobe from frontal/parietal
- the insula - deep inside the lateral fissure under the first layer of cortex (older piece of cortex)
- involved in taste and emotions of disgust
what is the limbic system?
- mainly the amygdala, hippocampus, and cingulate cortex
- is between the cortex and the brain stem
- amygdala is important in emotion and learning and behaviour
- hippocampus is important for long term memory, spatial navigation
-
cingulate cortex is a long piece of grey matter surrounding the corpus collosum
- is an older cortex, has less layers
- symptoms from damage can vary from region to region
what is the basal ganglia?
- deeper gray matter structures
- includes striatum (caudate + putamen) and globus pallidus
- sometimes others (subthalamic nucleus)
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nucleus accumbens is a subregion of striatum/caudate, sometimes called ventral striatum
- involved in motivation, movement, reward-seeking
- critical in movement, skills, habits, decision making
- muscle memory
what is the anatomy of the cortical layers of the telencephalon?
- neocortex has 6 layers, outermost is layer 1 and innermost is layer 6
- motor cortex and somatosensory cortex each have 6 layers
- same number of layers, but layers differ in thickness
- layer 4 - major input layer, somatosensory cortex has a thicker layer 4
- layer 5 - major output layer, motor cortex has a thicker layer 5
- there are different types of neurons (projection or interneurons) at different layers
what are the main support structures of the brain?
blood, meninges, cerebrospinal fluid
how does blood flow into and through the brain?
- right/left internal and vertebral carotid arteries are the only blood supply to the brain
- relatively limited supply, damage to the arteries has devastating results
- neurons in the brain die if they don’t get blood for 4 minutes
- blood supply cut off = no reserves, no oxygen, no ATP, brain failure
- parts of the brain get blood from a single artery
what is the blood brain barrier
- in the rest of our body, gaps in capillary walls (pores) allow entrance and exits
- in the brain, we have no pores, we have tight junctions in the capillaries
- we also have astrocytes wrapped around capillaries to protect the brain
- mediate entrance into the brain
what are the layers of the meninges?
- three main layers: duramater, arachnoid mater, pia mater
- from outside to inside, thickest to thinnest
- between arachnoid mater and pia mater, there is a thin layer of fluid (CSF)
what is cerebrospinal fluid? where is it produced and where does it go?
- constantly produced by the brain in the lateral ventricles
- lateral ventricles → third ventricle → fourth ventricle through aqueducts
- some goes into brain and some down into central canal (spinal cord)
- passage occasionally gets blocked
- can be used to transport nutrients or get rid of waste
- primarily for protection, works like an air bag
- stops the brain from being compressed and slows down impact
