Nervous system pt 1 (brain, spinal cord, and ANS) Flashcards
structures in a spinal cord model
spinal nerve, dorsal root ganglion, anterior root, lateral, posterior, and anterior white columns, posterior and anterior grey horns, anterior median fissure, grey commissure, central canal, and posterior median sulcus
spinal nerve
mixed nerves that interact directly with the spinal cord to modulate motor and sensory information from the body’s periphery; there are 31 spinal nerves
mixed nerve
contains both sensory and motor neuron axons
dorsal root ganglion
contain cell bodies of sensory neurons; connects with the dorsal root which sends sensory information into the spinal cord
ganglion vs nerve
ganglion are bundles of cell bodies while nerves are bundles of axons (both are located within the PNS)
nerve vs tract
nerves are bundles of axons in the PNS while tracts are bundles of axons in the CNS
ganglion vs nuclei
ganglion are clusters of cell bodies in the PNS and nuclei are cell bodies in the CNS
roots vs horns in spinal cord
the neurons of the dorsal horn receive sensory information from the dorsal roots; vise versa, anterior horn will send motor information out via the anterior root
anterior root of a spinal nerve
aka motor root; receives motor output from the anterior horn of the spinal cord
lateral white column
white matter of spinal cord located on the lateral side; contains both descending and ascending tracts of axons
anterior white column
white matter located on anterior side (where anterior median fissure is); contains both descending and ascending tracts of axons
posterior white column
white matter on posterior side (where posterior median sulcus is); contains both descending and ascending tracts of axons
grey vs white matter
grey matter is neuron cell bodies and dendrites; while white matter is axons (think myelin sheath is white)
posterior grey horn
grey matter on posterior side that receives sensory input from posterior root
anterior grey horn
grey matter of anterior side that relays motor output to the anterior root
grey comminsure
the bridge that connects the left side of the grey matter in the spinal cord to the right side
anterior median fissure
deep groove on anterior side of spinal cord
central canal
canal in the middle of grey matter of the spinal cord; this carries CSF and helps to transport nutrients to the spinal cord, while also serving protection; is a remnant of the neural tube
posterior median sulcus
shallow groove on posterior side
sensory tracts
bring sensory input (ex. touch, pain, temperature) from the spinal cord to the brain via the brainstem; enter the spinal cord on the posterior side
motor tracts
sends motor information (voluntary and involuntary muscle control) from the spinal cord; located anterior in the spinal cord
what is a basic reflex arc?
the simplest neural pathway that allows for an automatic, rapid response to stimulus without brain involvement
basic reflex arc simple steps
a stimulus produces a response via a sensory receptor which sends a message to the sensory neuron, then to interneuron in integrating centre, then out of spinal cord via a motor neuron which elicits an effector that is either a muscle or a gland
sensory receptor
responds to a stimulus by producing a generator or receptor potential
integrating centre
one or more regions within the CNS that relay impulses from sensory to motor neurons
what is neurulation?
the folding process in vertebrate embryos in which the neural plate transforms into the neural tubule
first step of neurulation
the notochord induces the formation of the CNS by signaling the ectoderm germ layer to form the thick and flat neural plate
notochord
a cartilage skeletal rod supporting the body in embryos
ectoderm germ layer
outermost germ layer of the embryo
second step of neurulation
the neural groove; forming of the neural plate will change shape, becoming longer and narrowers, causing the lateral edges of the plate to rise and form the neural folds, while the central part remains depressed
third step of neurulation
the neural tubule forms; the neural folds move toward each other, forming a tube where the spinal cord and brain will be; after this further specialisation will occur
what is cerebrospinal fluid composed of?
mostly water and small amounts of Na, K, Ca, Mg, lactic acid, urea, glucose, proteins like albumin, and WBC’s
functions of cerebrospinal fluid
circulates around the brain and spinal cord to provide protection, buoyancy, nourishment, waste removal, and the maintenance of homeostasis
order of ventricles (and connectors)
lateral ventricles; connect to third ventricle via the interventricular foramen; third ventricle will connect to the fourth ventricle via the cerebral aqueduct
what separates the lateral ventricles?
the septum pellucidum
where is the third ventricle located?
in the diencephalon
where is the fourth ventricle located?
in the hindbrain and posterior to the pons
what lines ventricles?
ependymal cells
three openings in the fourth ventricle
the two lateral apertures in the side walls and the median aperture in the roof
three parts of the brainstem
midbrain, pons, and medulla oblongata
olives
located within the medulla oblongata and are a pair of prominent oval structures on either side of the medullary pyramids
pyramids
two ventral longitudinal ridges formed by the pyramid tracts
decussation of pyramids
crossover of the corticospinal tracts
structures of the pons
autonomic respiratory centre which has the pneumotaxic centre and the apneustic centre
pneumotaxic centre of the pons
upper part of the pons and will switch off inspiration
apneustic centre of the pons
located in the lower part of the pons and stimulates inspiratory neurons
function of the pons
helps to regulate breathing through the respiratory centre and helps to coordinate and maximize efficency of motor output via the pontine nucelus
diencephalon
contains the thalamus and the hypothalamus
where is the thalamus located?
in the walls of the third ventricle
how are the structures of the thalamus connected?
by interthalamic adhesion
where is the hypothalamus located?
in a small area between the thalamus and the midbrain
cerebral peduncle
is medial to the pons and is a pair of large nerve fibre bundles; these connect the cerebral cortex to various other parts of the CNS, including the brainstem and the spinal cord
inferior colliculus
inferior to the superior colliculus; is associated with auditory processing; projects neurons from here to the thalamus and then the cerebral cortex
RAS
reticular activating system
reticular activating system functions
mainly for behavioural arousal and consciousness, but also for sleep when inactive and preventing sensory overload; 2 broad types of functioning
2 types of RAS functioning
modulatory and premotor
how does the RAS work?
through interconnected nuclei that has ascending pathways in the cortex and descending pathways to the spinal cord via the reticulospinal tract
oldest portion of the brain
the reticular activating system
where is the cerebellum located?
posterior to the brainstem
functions of the cerebellum
main function is to help direct motor controls through coordinating movement and balance; also plays a small role in language and vision
functions of the thalamus
main function is the sort, edit, and relay information from the body, hypothalamus, and cerebellum; also has some functions to mediate sensation, motor activities, cortical arousal, learning and memory
function of the hypothalamus
main function is to regulate the ANS and maintain homeostasis; also functions to regulate emotions such as anger, fear, and rage, and sleep
how does the hypothalamus play a role in homeostasis
regulates blood pressure, body temperature, hunger levels,water balance, and endocrine functions
biological clock located in the hypothalamus
suprachiasmatic nucleus
pineal gland
small endocrine gland located just above the third ventricle; plays a role in regulating circadian rhythms by producing and secreting melatonin; also referred to as the third eye
where is the cerebrum located?
the outside of the brain
outer covering of cerebrum
cerebral cortex
function of the cerebrum
main understanding and higher cognitive functions like reading, writing, speaking, math, science, music, and memory
gyrus
a raised ridge or fold
sulcus
shallow groove or furrow between two gyri
fissure
a deeper sulcus
frontal lobe
front of brain; functions in problem solving, language, judgement, inhibition, personality, and motor planning
parietal lobe
on top of brain; functions in sense of touch, taste, and smell
occipital lobe
back of brain; functions in visual perception
temporal lobe
on side of brain near temples; functions in memory, understanding. and processing auditory information
longitudinal fissure
divides the cerebral hemispheres; is a sagittal plane
central sulcus
frontal plane that divides the brain into front and back or into frontal and parietal lobes
precentral gyrus
ridges anterior to central sulcus
postcentral syrus
ridges posterior to central sulcus
parieto-occipital sulcus
sagittal plane that divides parietal and occipital lobes
insula
a small region deep in the cerebral cortex within the lateral sulcus
lateral cerebral sulcus
divides frontal and temporal lobes from the parietal lobe
transverse fissure
divides the cerebrum from the cerebellum
projection tracts
connect the cerebral cortex to the brainstem and spinal cord or vise versa; they carry information between the brain and the rest of the body
commissural tracts
connect corresponding regions of the two hemispheres; allow for communication and coordination of these two regions
association tracts
connect different regions within the same hemisphere of the brain; links areas of the cerebral cortex that have different functions
primary motor area
located in the precentral gyrus and is responsible to initiating and controlling voluntary movements through sending motor commands to skeletal muscles via the corticospinal tract
primary somatosensory area
located in the postcentral gyrus and is responsible for processing sensory information from the body such as touch, pain, and temperature; it receives input from the skin, muscles, and joints via sensory pathways
sensory homonculus
a somatotopic map where different parts are represented proportionally to the amount of sensory input they provide
motor homunculus
shows where different regions of the cortex correspond to voluntary movements of specific body parts
where and what is the primary gustatory cortex?
responsible for the perception of taste and is located in the middle of the brain within the insular lobe just above the auditory area and at the bottom of the postcentral gyrus
where and what is the primary auditory cortex?
responsible for sound processing and is located in each hemisphere within the sylvian fissure, just beneath the gustatory area
where and what is the primary visual cortex?
responsible for visual processing and is located within the occipital lobe
somatic nervous system
includes voluntary skeletal movement
autonomic nervous system
involuntary system and includes both parasympathetic and sympathetic systems
enteric nervous system
facilities the motor, sensory, absorptive, and secretory functions of the GI tract
three layer of meninges
dura mater, arachnoid mater, and pia mater
function of the meninges
to cover and protect the CNS, while containing CSF; as well as to enclose the venous systems
dura mater
is superficial layer and the strongest layer; composed of cartilage and has two layer of fibrous CT that separate to form dural sinuses
2 layers of dura mater
periosteal (superfical) and meningeal (deep)
how does the neural plate form?
neuroectoderm tissues differeniate into the ectoderm and this thickens to form the neural plate
how does the neural crest form?
the neural plate will bend dorsally, with the two ends joining at the neural plate border, forming the neural crest
how does the neural crest disconnect from the epidermis?
when the neural tubule is closed
what do neural crest cells differniate into?
the peripheral nervous system
what does the notochord persist as after embroyonic development?
the nucelus pulposus of the intervertebral discs
arachnoid mater
middle layer with web-like extensions; it is seperated from the dura mater by the subdural space; arachnoid villi will protrude into the superior sagittal sinus and permit CSF reabsorption
pia mater
deepest layer of meninges; layer of vascularised CT that clings tightly to the brain
epidural space
the area between the dura mater and the spinal cord; contains fat and CT
subarachnoid space
seperates the pia mater from the arachnoid mater; contains CSF and blood vessels
periosteal layer
dense, fiborous layer of the dura mater; closely adhered to the skull; acts as protection, forms the calvaria, and ends at the foramen magnum
meningeal layer
fibrous layer of the dura mater; is in direct contact with the arachnoid mater and helps to form the dural sinuses
superior sagittal sinus
one of the major venous sinuses in the brain and is part of the dural venous system which collects and drains blood from the brain; located within the dura matter within the sagittal fissure
falx cerebri
in the longitudinal fissure and seperates the hemisphers; is attatched to the crista galli
straight sinus
runs along the line where the falx cerebri meets the tentorium cerebeli
tentorium
horizontal dural fold that seperates the occpital lobe and cerebellum
falx cerebelli
along the vermis of the cerebellum
different extensions of dural mater in the brain
falx cerebri, falx cerebeeli, straight sinus, superior sagittal sinus, and tentorium
ascending tract
CNS fibres carrying sensory information from the spinal cord or periphery to the brain; ex. gracile and cuneate fasciculus and spinothalamic tracts
descending tract
CNS fibres carrying motor information from the brain to the spinal cord or periphery; ex. lateral and anterior corticospinal tracts and rubrospinal, tectospinal, etc.
foramen magnum
opening in the occipital bone of the skull through which the spinal cord emerges and arteries enter
calvaria
the outermost part of the skull; formed by the periosteal layer
dorsal horn
located in grey matter and contains interneurons that receive sensory and visceral information
where are lateral horns only found?
only in thoracic and lumbar regions
two types of integration centres
either monosynaptic or polysynaptic
neural plate border
separates the ectoderm from the neural plate
what do the apertures do?
connect the fourth ventricle (and the others) to the subarachnoid space
how do ependymal cells control CSF composition?
through ion pumps; this also helps waste removal
what is the normal volume of CSF?
150 mL
how are the brainstem and spinal cord different?
they have similar structures but the brainstem contains embedded nucleus
difference between anterior and lateral columns vs posterior columns?
anterior and lateral columns have both ascending and descending tracts, whereas posterior columns only have ascending tracts
2 different types of reflexes and subtypes
intrinsic (inborn) and learned (acquired); can be broken down into either somatic or visceral reflexes
ventricles
the central lumen of the neural tube that have branched off to carry CSF and act as a cushion
what hangs from the roof of each ventricle?
the choroid plexus
what is located inside the choroid plexus?
capillary and pia mater
where does the spinal cord join the medulla obloganta?
at the foreman magnum
functions of the medulla obloganta
functions overlap with the hypothalamus; cardiovascular (heart rate and blood pressure) and respiratory functions, as well as vomiting, hiccuping, sneezing, and coughing
what reabsorbs CSF into the dural venous system?
the arachnoid villi
what makes up the majority of the dicheaphlon?
the thalamus, 80%
is the thalamus more involved in sensory or motor information?
sensory
how does the hypothalamus support endocrine functions?
it controls secretions of the anterior pituitary gland and produces hormones of the posterior pituitary gland
main components of the cerebrum
outer cerebral cortex, inner white matter, and grey matter nuclei within the white matter
function of the dural septa
to limit excessive movement of the brain
what are found within lateral grey horns?
autonomic motor neurons
difference between regular motor neurons and autonomic motor neurons in the spinal cord
autonomic motor neurons are located more laterally and do not synapse with anything
ascending sensory tracts located in the posterior white column of the spinal cord
gracile fasciculus and cuneate fasciculus; gracile is located medial and cuneate is located laterally
main descending motor tracts
the anterior and lateral corticospinal tracts
how many cranial nerves are there?
12
what allows the medulla oblongata to connect to the spinal cord?
the foramen magnum
what side of the medulla are the pyramids located on?
the anterior side
what are pyramids associated with?
lateral corticospinal tracts
what do the pyramids contain?
most motor output for the brain; except what passes through the anterior corticospinal tract
what are located within each olive?
inferior olivary nucleus
function of the inferior olivary nuclei
these take input from the CNS system and send them to the cerebellum; associated with fine motor coordination
other nuclei in the medulla
cardiovascular system, respiratory system, vomiting system, deglutition system, sneezing system, coughing system, and gustatory centre
pontine nuclei
found in the pons and function in coordination of voluntary motor output
where are the cerebral peduncles located?
above the pons and the midbrain
where are the colliculus found?
in the midbrain
tectum
region on the posterior side of the midbrain and is made of the superior and inferior colliculus
what makes the startle reflex?
the tectum
why are structures in the brain folded lots?
increases surface area to increase the amount of neurons
where are half of the neurons in your brain located?
the cerebellum
what is the cerebellum mostly made of?
grey matter and neuron cell bodies
vermis
medial bridge of the cerebellum
folia
infoldings of the cerebellum, these function to increase surface area to have more neurons
arbor vitae
the tree like structure that attaches the cerebellum to the brainstem
superior cerebellar peduncle
axons extend to red nuclei and the thalamus
middle cerebellar peduncle
carries impulses for voluntary nucleus from pontine nuclei
inferior cerebellar peduncle
axons carrying information related to balance and equilibrium
what does the diencephalon contain?
the thalamus, hypothalamus, epithalamus, and the pineal gland
what does the diencephalon surround?
the third ventricle
how many nuclei are in the thalamus?
7
what connects the two lobes of the thalamus?
intermediate mass
what brain structures are part of the reticular activating system?
the brainstem and the thalamus
what occurs in the thalamus?
afferent synapses occur here
what system is also the brain of the ANS?
the hypothalamus
what system is associated with circadian rhythm?
the hypothalamus
what area grows the most during embryo development?
the cerebrum
another name for the postcentral gyrus
the primary somatic sensory centre
what sensory information is not processed in the postcentral gyrus
special senses
corpus callosum
connects the left and right central hemispheres; the largest bundle of axons in the brain
premotor area
sits anterior to precentral gyrus and functions to plan and organize movements
differences between meninges in cranium and spinal cord
there is only epidural space in the spinal cord and cranium has two layers of dura mater which form the venous systems
what is dura mater made of?
dense, irregular CT
what is contained in the epidural space?
fat and some CT
what meninges layer is very vascular and what is avascular?
pia mater is very vascular and arachnoid mater is avascular
what is arachnoid tissue made of?
loose collagen and some elastic fibres
what is contained in the subdural space?
interstital fluid
what is pia mater made of?
squamous to cuboidal epithelium with some collagen and elastic fibres
when do the dura mater layers split?
when they form venous sinuses
what are the sinuses lined with?
epithelium
function of venous systems
to drain venous blood from the brain and send it through the internal jugular veins
neurulation steps
formation of the neural plate, folding of the neural groove, elevation of the neural crest, convergence of the neural plate border ends, and closure of the neural tube
somites
form either side of the neural tubule
what do somites develop into?
the axial skeleton, skeletal muscle, and dermis
what vitamin is important to neurulation development?
folate a B vitamin
what develops into the neural crest?
the neural plate borders; which shift occurs when the ends join
what does the closure of the neural tubule do?
disconnects the neural crest from the epidermis
how does the CSF maintain homeostasis?
by carrying hormones produced in the hypothalamus
do the pyramids contain motor or sensory tracts?
motor
where are the inferior olivary nuclei located?
in the superior region of the medulla inside olives; these function in relaying motor output to and from the cerebellum
superior colliculus
part of the tectum and is involved in visual space, auditory space, and somatosensory space
reticular formation
region that runs through the brainstem and the superior spinal cord and is where white and grey matter are arranged like a net; contains both ascending and descending tracts
what is the ascending tract of the reticular formation?
the reticular activaiton system
what sense does the RAS not function in for sleep?
smell; hence no smells will wake you up
where do the axons of the RAS project to?
the hypothalamus and the thalamus
secondary functions of the thalamus
to mediate sensation, motor activities, cortical arousal, and memory
3 lobes in the cerebellum
anterior, posterior, and flocculonodular
function of the flocculonodular lobe
balance and equilibrium
function of the anterior and posterior lobes of the cerebellum
subconscious skeletal movement
2 fissures in the cerebellum
horizontal and primary
what are the ventricles a byproduct of?
the neural tubule
what ventricle connector has two openings?
the interventricular foramen
what cranial nerves are associated with inferior olivary nuclei
8, 9, 10 and 12
cerebral peduncle function
connect the cerebrum to the lower CNS
where are the cerebral peduncle found?
ventral midbrain and pons
what is the anatomy of the cerebral peduncle
white matter that make up motor tracts
descending pathway of the recticular formation
reticulosponal tracts
what is the transverse fissure filled by?
the tentorium cerebelli
what are examples of commissural tracts
anterior commissure and the corpus callosum
what is pia mater composed of?
collagen and elastic fibres, and is squamous to cubodial epithelium
arachnoid granulation
the process of CSF being reabsorbed through the archanoid villi
anatomy of ependymal cells
columnar with cilia
what nuclei is involved in coordinating muscle movements and is found in the midbrain?
red nuclei
what nuclei produces domanine?
substantia nigra nuclei
what is the diencephalon mostly made of?
grey matter
what is the pineal gland part of?
the epithalamus
what is the name for a visual representation map of the brain?
homunculus
posterior vs anterior parts of the pons
posterior part has the respiration centre and anterior part has the pontine nucleus
what are the cerebral peduncles continuation of?
the corticospinal tracts
nuclei groups contained in the reticular formation
lateral nuclei groups, medial nuclei groups, and raphe nucleus
what is the arachnoid mater made of?
elastic and collagen fibres and is avascular
