Brain Basics Flashcards
anterior
in front
posterior
behind
superior
top
inferior
below
dorsal
back
ventral
front
caudal
tail
rostral
beak
number of neurons in brain
86 billion
number of neurons in entire NS
100 billion
structure of an axon
every neuron has an input area with multiple branches called dendrites
the cell body contains the nucleus
there is an axon (long projection) in which neural impulses travel down
synapses are where neurons form junctions with each other
2 broad categories of neurons
sensory (afferent)
motor (efferent)
afferent
sensory
efferent
motor
what are sensory neurons connected to and where do they travel?
connected to sensory cell or organ and travel towards the CNS
what are motor neurons connected to and where do they travel?
innervate and synapse with muscles and travel away from CNS
2 major branches of the NS
peripheral and central nervous system
what is the CNS?
neural tissue in the brain, brainstem and spinal cord
what is the PNS
outside the brain and spinal cord including the spinal and cranial nerves
bundles of neurons in the PNS
nerves
definition of nerve
bundles of neurons in the PNS
definition of tracts
bundles of neurons in CNS
bundles of neurons in CNS
tracts
grey matter
neuronal cell bodies and neurones nuclei
white matter
myelinated axons
what is myelin and its function?
lipid rich tissue with a pale appearance that insulates the axon to allow electrical signals to travel larger distances without diminishing
where is white matter often found?
connecting areas of grey matter to target tissue or organ, or connecting areas of the brain
how is myelin produced in the PNS?
by Schwann cells
how is myelin produced in the CNS
by oligodendrocytes
white and grey matter areas in the brain
outer cortex is grey matter with central areas containing large amounts of connecting white matter tracts
white and grey matter areas in the spinal cord
central grey matter areas where synapses and connections take place on a horizontal plane
white matter tracts in outer parts of the cord
role of white matter tracts in the spinal cord
info travels up and down spinal cord in white mater tracts
collection of neuronal cell bodies in the CNS
ganglion
collection of neuronal cell bodies outside the CNS
nuclei
definition of nuclei
collection of neuronal cell bodies outside the CNS
definition of ganglion
collection of neuronal cell bodies in the CNS
what is the basal ganglia? what does it include?
several interconnected parts located deep in the brain
includes: caudate nucleus, putamen, globus pallidus, substantia nigra, nucleus accumbent, subthalamic nucleus
what do the parts of the basal ganglia rely on to function correctly to create coordinated smooth movements?
dopamine from the substantia nigra
role of basal ganglia
to create coordinated smooth movements
putamen and globus pallidus make up the…
lenticular nucleus (lentiform)
lenticular nucleus (lentiform)
putamen and globus pallidus
caudate nucleus and putamen make up the…
dorsal striatum
what makes up the dorsal striatum?
caudate nucleus and putamen
nucleus accumbens and olfactory tubicle make up the…
ventral stiatum
what makes up the ventral striatum?
nucleus accumbens and olfactory tubicle
why is the substantia nigra dark?
melanin
damage to the basal ganglia results in what?
○ Problems with initiating and control of movements
○ Tremors, posture difficulties, etc
○ Parkinson’s (reduction in number of neurons of substantia nigra in midbrain - dopamine) and Huntingdon’s (loss of neurons in caudate nucleus)
divisions of the autonomic NS
sympathetic and parasympathetic
role of ANS
self-regulates without conscious thought with its own autonomy
sympathetic NS actions
fight or flight
increase HR, breathing rate
parasympathetic NS actions
rest and digest
pupils constrict to accomodate near vision
where is the sympathetic NS?
exits the spinal cord at the thoracolumbar region using a chain of paravertebral ganglia to transverse the full length of the body - sympathetic chains
where is the parasympathetic NS?
either hitchhike along cranial nerves or exit the CNS at the sacral region to innervate the viscera of the pelvis - craniosacral
divisions of the brain
cerebrum - forebrain
cerebellum - little brain (hindbrain)
brainstem - (hindbrain)
cerebrum - explain the make up/divisions
2 hemispheres separated by longitudinal fissure
outer region is the neocortex for higher order functioning
internal white matter of forebrain.
hemispheres connected by corpus callous and anterior and posterior commissures
anterior commisure
nub at front of fornix
nub at front of fornix
anterior commisure
posterior commisure
nub in front of pineal gland
nub in front of pineal gland
posterior commisure
parts of the corpus callosum
- Genu is the knee (front bend)
- Body (middle part)
- Splendium/bandage (back bulb)
septum pellucidum
Between corpus callosum and fornix is the septum pellucidum
- Thin membrane separating lateral ventricles from each other and midbrain
what is between the fornix and corpus callosum?
septum pellucidum
Thalamus role
- Sensory filter in diencephalon
sensory info and the thalamus
- Sensory info through eyes to lateral geniculate nucleus through thalamus
- Inferior colliculi
○ Auditory info pass through medial geniculate nucleus of thalamus - Not olfactory info
- Trigeminal nerve, cranial nerve go to thalamus
- Also connected to cerebellum, basal ganglia, limbic system, etc
- Inferior colliculi
diencephalon
made up of the thalamus, hypothalamus and epithalamus (inc. pineal gland)
part of the forebrain
relay station for sensory info towards brain (not olfactory)
role of brainstem
links spinal cord to cerebellum and cerebrum
all motor and sensory signals pass through the brainstem to reach their destinations
divisions of the brainstem
midbrain
pons
medulla oblongata
role of midbrain
reflexive or involuntary movements of the eyes, head, and body towards the direction of visual and auditory stimuli.
reticular formation
role of pons
filled with tracts passing up and down the CNS
nuclei for cranial nerves 5 6 and 7 are in dorsal part of pons
role of medulla oblongata
ventral part contains tracts (corticospinal tracts on ventral surface form the longitudinal ridges of the medullary pyramids)
tracts cross in the pyramids from one side of the body to the other
nuclei for cranial nerves 8, 9, 10, 11, and 12 are found in the dorsal parts
role of cerebellum
balance, proprioception, coordination
where is the cerebellum?
posterior cranial fossa of the skull
Corpora quadrigemina
2 nubs in front of each hemisphere of cerebellum (in the midbrain)
- 2 superior colliculi (visual system and movements) - 2 inferior colliculi (auditory system and vestibular system)
how is the cerebellum connected to the brainstem?
- 3 pairs of peduncles (white matter) connect cerebellum to brainstem
○ Superior - midbrain
○ Middle - pons
○ Inferior - medulla oblongata
what surrounds the cerebellum?
dura mater
what separates the cereberum and cerebellum?
- Tentorium cerebelli
○ 2 sheets of dura mater separating from cerebrum
divisions of the cerebellum
- From mid to outside: vermis, medial and lateral zones
- Anterior, posterior and folloculo lobes
○ Anterior and posterior separated by primary fissure
○ Postero-lateral fissure separates body (A and P) and folloculo lobe
- Anterior, posterior and folloculo lobes
blood supply to the cerebellum
- 3 pairs of arteries supplying blood to cerebellum
○ Posterior, inferior cerebellar arteries - branch from vertebral arteries. Before basilar artery
○ Anterior, inferior cerebellar arteries - from basilar artery (labyrinthe artery branches from internal auditory)
○ Superior cerebellar arteries - from basilar artery just before the end - right next to posterior cerebral arteries
olive
medulla oblongata
Olive –> olivary nuclei (movement, auditory)
central sulcus
- Central sulcus separates frontal and parietal lobes
lateral sulcus
- Lateral sulcus separates parietal and temporal and temporal and frontal lobes
Pareto-occipital sulcus
- Parieto-occipital sulcus separates the parietal and occipital lobes
sulcus between frontal and parietal
central
sulcus between parietal and occipital
parieto-occipital
sulcu between parietal and temporal and temporal and frontal lobes
lateral
cortex anterior of central sulcus
premotor cortex
premotor cortex location
cortex anterior of central sulcus
cortex posterior of central sulcus
somatosensory cortex
somatosensory cortex location
cortex posterior of central sulcus
lobes of the brain
frontal
parietal
occipital
temporal
limbic lobe - central lobe where limbic system is
gyri
ridges
sulci
depressions
role of frontal lobe
movement
decision making
emotions
role of parietal lobe
sensation
role of occipital lobe
vision
role of temporal lobe
memory
language
hearing
spinal cord length and location
continuation of the medulla oblongata through the foramen magnum in the occipital bone to the L1 or L2 vertebra ending in the conus medullaris
42-45cm long
spinal cord forms what after the L1/L2 region?
cauda equina
ventral/anterior horns - role/what leaves here
give rise to motor neurons leaving spinal cord in ventral roots
dorsal horns - role
receive sensory info from afferent neurons arriving in through dorsal root ganglion
dorsal and ventral roots/horns merge to form what?
the spinal nerve
rootlets
leave the spinal cord to form roots (form bilateral pairs of spinal nerves in a designated spinal cord segment)
once the rootlets join to form roots, the nerve divides to make what?
anterior and posterior rami (contain sensory and motor fibres)
how many layers of meninges?
3
layers of meninges
dura mater
arachnoid mater
pia mater
pia mater
thin direct covering of gyri and sulk (inner layer)
arachnoid mater
web like middle layer
space between arachnoid and Pia mater layers
subarachnoid space
what is contained in the subarachnoid space?
arteries and veins
CSF
dura mater
tough outer layer lining the bones of the cranial cavity
how many layers in dura mater?
2
sagittal fold between the hemispheres
falx cerebri
falx cerebri
sagittal fold between the hemispheres
inferior part of the falx cerebra between the two parts of the cerebellum
falx cerebelli
inferior part of the falx cerebra between the two parts of the cerebellum
falx cerebelli
horizontal fold between the cerebrum and the cerebellum
tentorium cerebelli
tentorium cerebelli
horizontal fold between the cerebrum and the cerebellum
- Diphragma sella
covers sella turcica with pituitary gland inside
infoldings of the dura contain…
dural venous sinuses
where are the venous sinuses
between the two layers of dura mater
role of venous sinuses
drain blood from brain
how does the blood drains by the venous sinuses return to circulation
via internal jugular vein
main venous sinuses
- Superior sagittal
- Inferior sagittal
- Straight sinus
- Transverse sinus
- Sigmoid sinus
- Cavernous sinus
- Superior and inferior petrosal sinus
divisions of the blood supply to the brain
anterior and posterior circulation
anterior circulation is provided via the…
internal carotid arteries
the internal carotid arteries supply what part of the circulation
anterior
route of posterior circulation
initially formed from left and right vertebral arteries which merge to form the basilar artery as they pass through the foramen magnum
circle of willis is formed as the posterior communicating arteries branch from each cerebral artery off the basilar artery. these connect to the middle cerebral artery and then the anterior communicating artery
referred to as the vertebrobasilar system
fucntion of anterior circulation
anterior communicating artery (disinhibition, aphasia, apraxia, legs)
middle communicating artery (face, limbs, speech)
function of posterior circulation
posterior communicating artery
occipital lobe (vision)
cerebella signs
brainstem signs
brain is surrounded by what?
CSF
where is CSF found?
between pia mater and arachnoid mater is subarachnoid space
what produces CSF?
ependymal cells of the choroid plexus produce CSF
where is CSF made?
mainly lateral ventricles
how many ventricles are there?
4
ventricles of the brain
2 lateral ventricles
3rd
4th
role of interventricular foramen
allows CSF to flow from lateral ventricles into 3rd ventricle
cerebral aqueduct
links 3rd and 4th centricles
where can CSF leave?
4th ventricle to arachnoids layer (via lateral and medial aperture to the cisterns)
where does CSF return to and how?
returns to the dural venous sinuses through arachnoid granulations
disruption to flow of CSF causes what?
hydrocephalus
hydrocephalus
result of disruption to flow of CSF
role of CSF
shock absorber, buoyancy, immune function etc.
production of CSF
Produced by choroid plexus (20ml an hour - 150ml in CNS)
2 layers of the dura mater
periostial layer = outer layer
meningial layer = inner layer
space below the fornix
third ventricle (in midline of the brain) below pineal gland
cistern
CSF filled space
