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Neurology basic science, anatomy and physiology 3, anatomy and physiology…
Neurology basic science
anatomy and physiology 3
cerebral perfusion
hyperventilation→↓Pco₂→constriction→↓cerebrel blood flow→↓ICP
CPP=MAP-ICP, if CPP=0, there is no cerebral perfusion
cerebral perfusion relies on a pressure gradient between mean arterial pressure(MAP) and intracranial pressure(ICP)
primarily driven by Pco₂
cerebral artery
middle cerebral artery(MCA): 外側
posterior cerebral artery(PCA): 後、下側
anterior cerebral artery(ACA): 前,内側
watershed zones: internal border zone stroke→proximal upper and lower extrimity weakness, posterior cerebral/middle cerebral cortical border zone stroke→high order visual dysfunction
circle of Willis
VA (PICA and AICA branch)
BA (SCA branch)
PCA
Pcom
MCA
ACA (Acom)
ICA
dural venous sinuses(硬膜静脈洞)
drain blood from cerebral vein and receive CSF from arachnoid granulation, empty into internal juglar vein
venous sinus thrombosis: ↑ICP, msy lead to venous hemorrhage
components
superior/inferior sagittal sinus(上矢状静脈)
great cerebral vein of Galen
straight sinus
confluence of the sinus(静脈洞交会)
occipital sinus
transverse sinus
sigmoid sinus
juglar foramen
superior ophthalamic vein(上眼静脈)
sphenoparietal sinus(蝶形頭頂静脈洞)
cavernous sinus(海綿静脈洞)
ventricular system
3rd ventricle→4th ventricle via cerebral aqueduct of Sylvius
4thventricle→subarachnoid space via foramen of Luschka(lateral) or Magendie(medial)
lateral ventricles→3rd ventricle via foramina of Monro
CSF from ependymal cells of choroid plexus(脈絡叢)
brain stem
5,6,7,8 exit the pon
9,10,11,12 are in medulla
1,2,3,4 are above pons
3,4,6,7 nuclei are medial
pineal gland: melatonin secretion, circadian rhythm
superior colliculi(上丘): direct eye movement to stimuli or objects of interest
inferior colliculi(下丘): auditory
cranial nerve nuclei
medulla: 9,10,12
spinal cord: 11
pons: 5,6,7,8
lateral nuclei: sensory
midbrain: 3,4
medial nuclei: motor
cranial nerve and vessel pathway
foramen ovale(卵円孔): CN5₃
foramen spinosum(棘孔): middle meningeal artery(中硬膜動脈)
foramen rotundum(正円孔): CN5₂
internal auditory meatus(内耳道): CN7,8
superior orbital fissure(上眼窩): CN3,4,6,5₁
juglar foramen: CN9,10,11, juglar vein
optic canal: CNⅡ, ophthalmic artery
hypoglossal canal(舌下神経管): CN12
cribriform plate(篩版): CN1
foramen magnum: brainstem, spinal root of CN11, vertebral artery
cranial nerves
Ⅲ; oculomotor; eye movement(SR,IR,MR,IO), pupillary constriction(sphincter pupillae; Edinger-Westphal nucleus), accomodation, eyelid opening; motor
Ⅳ; trochlear; eye movement(SO); motor
Ⅱ; sight; sensory
Ⅴ; trigeminal; mastication(咀嚼), facial sensation(ophthalmic, maxillary, mandibular), somatosensation from anterior 2/3 of tongue; both
Ⅰ; olfactory; smell; sensory
Ⅵ; abducens; eye movement(LR); motor
Ⅶ; facial; facial movement, taste, lacrimation, salivation, eyelid closing, auditory volume modulation; both
Ⅷ; vestibulocochlear(内耳神経);hearing, balance; sensory
Ⅸ; glossopharyngeal(舌咽神経); taste and sensation of tongue, swallowing, salivation, monitoring carotid chemo- and basoreceptor, elevation of pharynx/larynx; both
Ⅹ; vagus; taste, swallowing, soft palate elevation, midline uvula(正中口蓋), talking, cough reflex, parasympathetic, aortic baso- and chemoreceptor; both
Ⅺ; accesory; SCM, trapezius; motor
Ⅻ; hypoglossal; tongue movement; motor
vagal nuclei
nucleus ambiguus(疑核): motor innervation of pharynx, larynx, upper esophagus (Ⅸ,Ⅹ,Ⅺ)
dorsal motor nucleus(背側運動核): send autonomic fibers to heart, lung, upper GI (Ⅹ)
nucleus solitarius(孤束核): visceral sensory information (Ⅶ,Ⅸ,Ⅹ)
cranial nerve reflex
lacrimation: Ⅴ₁ to Ⅶ
jaw jerk: Ⅴ₂ to Ⅴ₃
corneal: Ⅴ₁ to Ⅱ
pupillary: Ⅱ to Ⅲ
gag: Ⅸ to Ⅹ
spinal nerves
C1-C7 above vertebra, C8 below C7, others below
vertebral disc herniation: nucleus pulposus herniate through annulus fibrosus(線維輪), common at L4-L5 or L5-S1, affected below the level of herniation, compression of S1 cause absense of ankle reflex
C=8, T=12, L=5, S=5, C=1
spinal cord
subarachnoid space extend to lower border of S2 vertebra
lumbar puncture is usually performed between L3-L4 or L4-L5
end at lower border of L1-L2 vertebrae
mastication muscles(咀嚼筋): masseter(咬筋), temporalis(側頭筋), medial pterygoid(内側翼突筋), innervated by Ⅴ₃
muscles involved in eye movement
SR:上直筋
IO: 下斜筋
MR: 内直筋
LR: 外直筋
IR: 下直筋
SO: 上斜筋
anatomy and physiology 1
ependymal cell
ciliated simple columnar form that line the ventricles and central canal of spinal cord
cilia and microvili
sensory receptor
Ruffini corpuscle
dendritic endings, adapt slowly
finger tip, joint
pressure, slippage, joint angle change
Merkel disc
large, myelinated, adapt slowly
finger tips, superficial skin
pressure, deep static touch, position sense
free nerve ending
C=slow, unmyelinated ; Aδ=fast, myelinated
allskin, epidermis, some viscera
pain, temperature
Meissner corpuscle
large, myelinated, adapt quickly
glabrous skin (hair less)
dynamic, fine/light touch, position sense
Pacinian corpuscle
large, myelinated, adapt quickly
deep skin, ligament, joint
vibration, pressure
Schwann cells
myelinate 1 PNS axon, promote axonal regeneration
from neural crest
injured in Guillain-Barre syndrome
neuron
dendrite, cell bodies, axon
signal transmitting cell of the nervous system, do not devide in adulthood
Nissl staining (RER)
Wallerian degeneration: degeneration distal to site of injury
astrocyte
most common glial cell in CNS
physical support, repair, extracellular K⁺buffer, removal of excess neurotransmitter, component of BBB, glycogen fuel reserve buffer
myelin
↑conduction velocity→saltatory conduction(跳躍伝導) at node of Ranvier
oligodendrocyte in CNS and Schwann cells in PNS
microglia: phagocytic cell in CNS
Oligodendrocytes
from neuro ectderm
injured in multiple sclerosis, progressive multifocal leukoencephalopathy, leukodystrophies
myelinate many(~30) axons in CNS
peripheral nerve
epineurium(神経上膜)>perineurium(神経周膜)>endoneurium(神経内膜)
in Guillain-Barre syndrome, inflammatory infiltrate to endoneurium
chromatolysis(中心性色質融解)
round cellular swelling, displacement of the nucleus to peripheral, dispersion of Nissl body
concurrent with Wallerian degeneration
reaction of neuronal cell body to axonal injury
neurotransmitter change with disease
GABA(nucleus accumbens(側坐核)): ↓anxiety, ↓Huntington disease
norepinephrine (locus ceuleus(青斑核)): ↑anxiety, ↓depression
dopamine (SNc(黒質緻密部), ventral tegmentum): ↓depression/Parkinson, ↑schizophrenia/huntington
serotonin (raphe nucleus(縫線核)): ↓anxiety/depression/parkinson
acetylcholine(basal nucleus of Meynert): ↓Alzheimer/Huntington, ↑parkinson
meninges
arachnoid mater(くも膜): from neural crest
pia mater(軟膜): from neural crest
dura mater(硬膜): from mesoderm
CSF flows in the subarachnoid space, located between arachnoid and pia mater
epidural space: between dura mater and skull, containing blood and vessels
blood brain barrier
formed by: tight junction between nonfenestrated capillary endothelial cells, basement membrane, astrocyte foot process
nonpolar/lipid-soluble substance cross rapidly via diffusion
prevent substance from reaching CSF/CNS
few region without BBB: area postrema(嘔吐中枢), organum vasculosum lamina terminalis; OVLT(終板器官)or neurosecretory products to enter circulation
anatomy and physiology 2
hypothalamus
anterior nucleus(前核): cooling, parasympathetic
posterior nucleus: heating, sympathetic
ventromedial nucleus(腹内側核): satiety
suprachiasmatic nucleus(視交叉上核): circadian rhythm
lateral nucleus(外側核): hunger
supraoptic and paraventricular nucleus(視索上核,室傍核): ADH and oxytocin
maintain homeostasis: thirst, water balance, controlling adenohypophysis and neurohypophysis release, regulating hunger, autonomic nervous system, temperature, and sexual urge
preoptic nucleus(視索前核): thermoregulation, sexual behavior
vomiting center
CTZ and vomiting center recieve from: M₁, D ₂, H₁, 5-HT₃, neurokinin-receptor
coordinated by nucleus tractus solitarius(孤束核), which recieve information from chemoreceptor trigger zone (in 4th ventricle), GI tract, vestibular system(前庭系), CNS
sleep physiology
ACTH, prolactin, melatonin, norepinephrine; SCN→norepinephrine release→pineal gland→melatonin
REM or non-REM
regulated by circadian rhythm (SCN)
stage
awake(eye-open)
awale(eye-closed)
REM sleep(25%)
depression increases total REM sleep but decrease REM latency
extraocular movement
dreaming, nightmare, penile/clitoral tumescene(陰茎/陰核腫脹)
non-REM sleep
N1(5%): light sleep
N2(45%): deeper sleep
N3(25%): deepest, sleepwalking, night terror, bedwetting occur
thalamus
llateral geniculate nucleus(外側膝状体): vision (from CNⅡ, optic chiasm, optic tract to calcarine sulcus(鳥距溝)
medial geniculate nucleus: hearing (from superior olive and inferior colliculus of tectum to auditory cortex of temporal lobe)
ventral postero-medial nucleus: face sensation, taste(from trigeminal(三叉神経) and gustatory(味覚) pathway to 1° somatosensory cortex)
ventral lateral nucleus: motor (from basal ganglia, cerebellum to motor cortex)
ventral postero-lateral nucleus: vibration, pain, pressure, proprioception(固有受容), light touch, temperature(from spinothalamic and dorsal columns/medial leminiscus to 1° somatosensory cortex
limbic system(大脳辺縁系)
hippocampus(海馬), amygdalae(扁桃体), mammillary body, anterior thalamic nuclei(視床前核), cingulate gyrus(帯状回), entorhinal cortex(嗅内野)
feeding, fleeing, fighting, feeling, sex
emotion, long-term memory, olfaction, behavior modulation, ANS function
dopaminergic pathway
mesolimbic: if altered, ↑activity
nigrostriatal(黒質線条体): if altered, ↓activity (extrapyramidal symptoms(錐体外路症状))
mesocortical: if altered, ↓activity
tuberoinfundibular(漏斗隆起): if altered, ↓activity→↑prolactin→↓libido, sexual dysfunction, galactorrhea, gynecomastia
cerebellum
input
contralateral cortex via middle cerebellar peduncle
ipsilateral proprioceptive information(固有受容器) via inferior cerebellar penduncle from spinal cord
output
Purkinje cells→deep nuclei of cerebellu,→contralateral coretex via superior cerebellar penduncle
modulate movement
deep nuclei: dentate, emboliform(栓状核), globose(球状核), fastigial(室頂核)
lateral: voluntary movement of extremities; when injured, ipsilateral fall
medial: truncal ataxia, nystagmus, head tilting; bilateral
basal ganglia
important in voluntary movement and making postural adjustment
receive cortical input, provide negative feedback to cortex
striatum(線条体)=putamen(被殻)+caudate(尾状核)
lentiform(レンズ核)=putamen+globus pallidus(淡蒼球)
pathway
cortex
+
striatum D1
+
GPi
-
thalamus
1 more item...
+
striatum D2
-
GPe
-
STN
2 more items...
SNc
+
-
direct pathway: SNc input stimulate striatum,,, disinhibiting the thelamus via GPi(↑motion)
indirect pathway: SNc input stimulate the striatum,,, inhibiting the thalamus(↓motion)
dopamin stimulate directpathway and inhibit indirect pathway(↑motion)
cerebral cortex region
prefrontal association area(前頭連合野)
Broca area
frontal eye field
Sylvian fissure(シルヴィウス溝)
limbic association area
primary auditory cortex
primary visual cortex
Wernicke area
somatosensory association area
primary somatosensory
primary motor
central sulcus
arcurate fasciculus
homunculus
topographic representation of motor and sensory areas
(medial to lateral) foot>hand>head
neural tube defect
meningomyelocele: meninges and neural tissue herniate theough body defect
anecephaly(無脳症): failure of rostal neuropore to close→no forebrain, open calvarium, polyhydraminos(羊水過多()
myeloschisis(脊髄裂): rachischisis(二分脊椎), exposed unfused neural tissue
neuropores fail to fuse(4th week)→persistent connectiopn between amniotic cavity and spinal canal
associated with low folic acid intake
↑AFP, AChE
spina bifida occulta(潜在性二分脊椎): failure of caudal neuropore to close, but no herniation
meningocele(髄膜瘤): meninges herniate through body defect, associated with spina bifida cystica
neural development
notochord become nucleus pulposus(髄核)
basal plate(基板); ventral, motor
alar plate(翼板); dorsal, sensory
notochord induce overlying ectderm to differentiate into neuroectoderm and form neural plate
naural plate→neural tube and neural crest cell
holoproencephaly
failure of hemisphere to separate
usually occur during weeks 5-6
mutation in shh pathwayt
cleft lip/palate, cyclopia(単眼症)
13 trisomy and fetal alcohol syndrome
tongue development
1st and 2nd branchial arch form anterior 2/3 (sansation Ⅴ₃, taste Ⅶ)
3rd and 4th branchial arch from posterior 1/3 (sansation and taste Ⅸ, extreme posterior Ⅹ)
Ⅻ innervate hypoglossus(舌骨舌筋), genioglossus(オトガイ舌筋), styloglossus(茎突舌筋)
Ⅹ innervate palatoglossus(口蓋舌筋)
anatomy and physiology 4
spinal cord and associated tract
ascending
dorsal column
pressure, vibration, fine touch, proprioception
fasciculus gracilis (薄束): lower body
fasciculus cuneatus (楔状束): upper body
lateral spinothalamic tract
pain, temperature
anterior spinothalamic tract
descending
lateral corticospinal tract: voluntary motor
anterior corticospinal tract: voluntary motor
components
anterior white commissure
anterior horn
posterior horn
anterior spinothalamic tract
central canal(中心管)
lateral corticospinal tract
dorsal column
arm outside, leg inside
function
lateral corticospinal tract
voluntary movement of contralateral limbs
1° motor cortex→descends ipsilaterally, decussate at caudal medulla→descend contralaterally
leaves spinal cord
spinothalamic tract
sensory nerve ending→enter pinal cord
decussates in spinal cord as anterior white commisure→ascend contralaterally
pain, temperature, crude touch, pressure
dorsal column
sensory nerve ending→enter spinal cord→ascend ipsilaterally in dorsal column
decussates(交差する) in medulla→ascend contralaterally as the medial lemniscus(内側毛帯)
pressure, vibration, fine touch, proprioception
clinical reflex
biceps and brachioradialis reflex(上腕二頭筋/腕橈骨筋反射)=C5,C6
triceps reflex=C7,C8
patellar reflex(膝蓋腱反射)=L3,L4
cremasteric reflex(挙睾反射)=L1,L2
achilles reflex=S1,S2
anal wink reflex=S3,S4
primitive reflex
sucking reflex(吸啜反射): sucking response when roof of mouth is touched
palmar reflex: curling of fingers if palm is stroked
rooting reflex(探索反射): movement of head toward one side if cheek or mouth is stroked
plantar reflex(Babinski sign): dorsiflexion of large toe and fanning of other toe with plantar stimulation
Moro reflex: abduct/extend arms when startled and then draw together
Galant reflex: stroking along one side of the spine while newborn is in ventral suspension cause lateral flexion of lower body toward stimulated site
landmark
T4=nipple
T7=xiphoid process(剣状突起)
C6=include thumb
T10=umbilicus, referred pain in early appendicitis
C4=low-collar shirt
L1=inguinal ligament
C3=high turtleneck shirt, diaphragm and gallbladder pain referred to the right shoulder via phrenic nerve
L4=kneecap
C2=posterior half of skull
S2,S3,S4=sensation of penile and anal zone
ophthalmology
normal eye components
choroid(脈絡膜)
retina
sclera
fovea(中心窩)
posterior chamber
vitreous chamber(硝子体腔)
anterior chamber(前眼房)
macula
lens
optic disk
pupil
iris
cornea
zonular fibers(小帯線維)
ciliary body
aqueous humor(房水) pathway
produced by nonpigmented epithelium on ciliary body
uveoscleral outflow(ブドウ膜強膜)
drainage into uvea and sclera
trabecular outflow (経線維柱帯房水流出): 90%
trabecular meshwork→canal of Schlemn→episcleral vasculature(胸膜上血管)
pupillary control
pupillary light reflex
light in retina sends a signal via CN2 to pretectal nuclei(被蓋前核) in midbrain that activate bilateral Edinger-Westphal nuclei; pupil constrict bilaterally
illumination of 1 eye results in bilateral pupillary constriction
mydriasis
dilation, sympathetic
hypothalamus→ciliospinal center of Budge→exit at T1 to superior cervical ganglion→plexus along internal carotid, through cavernous sinus; enters orbit as long ciliary nerve to pupillary dilator muscle
sympathetic fibers also innervate smooth muscle of eyelids and sweat glands of forehead and face
miosis
Edinger-Westphal nucleus→ciliary ganglion (via CN3)
→short ciliary nerve→sphincter pupillae muscle
constriction, parasympathetic
ocular motility
CNⅣ
superior oblique muscle
CNⅢ
medial rectus muscle
inferior oblique muscle
superior rectus muscle
inferior rectus muscle
CNⅥ
lateral rectus muscle
regional specification
midbrain
mesencephalon
midbrain, cerebral aqueduct(中脳水道)
hindbrain(菱脳)
metencephalon(後脳)
pona, cerebellum, upper part of fourth ventricle
myelencephalon(髄脳)
medulla, lower part of fourth ventricle
forebrain
telencephalon(終脳)
cerebral hemisphere, lateral ventricle
diencephalon(間脳)
thalamus, hypothalamus, third ventricles
neuron origin
neuroepithelia: CNS neuron, ependymal cell(上衣細胞), oligodendrocyte, astrocyte
mesoderm: microglia
neural crest: PNS neuron, Schwann cell
posterior fossa malformation
Chiari 1 malformation
ectopia of cerebellar tonsils(小脳扁桃), usually asymptomatic
Dandy-Walker syndrome
agenesis cerebellar vermis lead to cystic enlargement of 4th ventricle that fills enlarged posterior fossa
associated with noncommunicating hydrocephalus, spina bifida
Chiari 2 malformation
herniation of cerebellar vermis(虫部) and tonsil through foramen magnum with aqueductal stenosis→hydrocephalus(水頭症)
associaed with lumbrosacral(腰仙) meningomyelocele
syringomyelia(脊髄空洞症)
associated with Hiari malformation
cystic cavity within central canal of spinal cord
bilateral symmetrical loss of pain and temperature sensation in upper extremities
otology
outer ear
pinna(耳介), auditory canal, tympanic membrane
inner ear
cochlea; low frequency heard at apex, high at base
middle ear
ossicles(malleus, incus, stapes): conduct and amplify sound