Neuroanatomy 1 — The Brain

Early development

formation of the neural tube:  neural groove and neural folds

cranial expansions [vesicles]

prosencephalon [forebrain]

mesencephalon [midbrain]

rhombencephalon [hindbrain]

flexures cephalic pontine cervical

ventricles

development of the vesicles

forebrain

olfactory bulbs [rhinencephalon]

cerebral hemispheres [telencephalon]

optic vesicles

diencephalon

pineal body

infundibulum

mesencephalon

tectum [forms optic lobes in lower vertebrates]

corpora quadrigemina

hindbrain

cerebellum

pons

medulla oblongata

[metencephalon + myelencephalon]

Development of the skull

formation of the cranial vault bones
    frontal
    parietal
    temporal
    occipital
    sphenoid
    ethmoid

craniosynostosis

neonatal skull development

The meninges

dura mater epidural space periosteal dura meningeal dura subdural space

arachnoid subarachnoid space

pia

The whole brain

Brain stem ¹

medulla oblongata fourth ventricle inferior velum forms its roof

ascending and descending tracts

inferior cerebellar peduncles (restiform bodies)

decussation of the pyramids

respiratory, vasomotor, cardiac centers

nuclei for cranial nn IX–XII

olivary nuclei [relay centers between cerebral cortex/basal nuclei and cerebellum]

reticular formation

pons

floor of the fourth ventricle

pontine nuclei

middle cerebellar peduncles

nuclei for cranial nn V–VIII

reticular formation

corticospinal, corticobulbar, and corticopontine tracts

Mesencephalon

midbrain [mesencephalon]

cerebral aqueduct (aqueduct of Sylvius) cerebral peduncles nuclei for cranial nn III–IV and anterior part of V red nucleus and rubrospinal tract superior cerebellar peduncle corpora quadrigemina superior colliculi [visual, auditory, tactile reflex centers] inferior colliculi [auditory reflex centers]

Cerebellum ^{2, 6}

anatomy

peduncles superior (brachia conjunctiva)... midbrain middle (brachia pontis)... pons inferior (restiform body)... medulla oblongata

cerebellar hemispheres

vermis

cerebellar cortex folia cerebelli fissures arbor vitae layers outer molecular layer [input] Purkinje cell layer [output] to deep cerebellar and lateral vestibular nuclei inner granular layer [input]

functional considerations

functions quickly with no storage

coordination of somatic motor activity

regulation of muscle tone

maintenance of equilibrium

lesions

do not result in paralysis

ataxia ³

hypotonia ⁴ and asthenia

tremors and nystagmus ⁵

ipsilateral representation

Forebrain

diencephalon

rostral limit is the interventricular foramina (foramina of Monro)

third ventricle lateral walls are the thalami intermediate mass [variable, ~60%] roof is the epithalamus floor is the hypothalamus

thalamus

major sensory center

crude, uncritical consciousness [the reptilian brain]

lateral geniculate, medial geniculate, and ventral posterior nuclei
    important relay stations in the visual, auditory, and
    somatosensory systems, respectively

epithalamus

choroid plexus and the production of cerebrospinal fluid (CFS)

pineal body

posterior commissure where it joins midbrain

hypothalamus optic chiasm infundibulum from tuber cinereum mammillary bodies

functions

regulation of body temperature, metabolism, sleep, emotions, sexual drive

integrated with endocrine system

Cerebrum

topology

hemispheres

longitudinal fissure

corpus callosum

surfaces dorsolateral inferior medial poles frontal occipital temporal

convolutions gyri sulci five lobes

cortex Brodmann 7 areas

lobes

frontal lobe

inferior frontal gyrus

speech center (Broca’s area):  Brodmann area 44

precentral gyrus primary motor cortex:  Brodmann area 4

central sulcus (fissure of Rolando) parietal lobe postcentral gyrus somatesthetic cortex:  Brodmann areas 1–3

lateral sulcus (Sylvian fissure)

temporal lobe

primary auditory center:  Brodmann ⁷  area 41 ^{8, 9}
secondary centers:  Brodmann areas 42, 22   [Wernicke’s area]

insula

occipital lobe

calcarine sulcus

visual area:  Brodmann area 17

parietooccipital sulcus

sulcus cinguli parallels corpus callosum gyrus cinguli:  smell association collateral sulcus inferiorly hippocampal gyrus lies medial uncus:  smell & taste appreciation

association areas

white matter

association tracts short association fibers long association fibers commissural tracts corpus callosum anterior and posterior commissural tracts

projection tracts

ascending [afferent] mostly from thalamus

descending [efferent]

corona radiata

basal nuclei ( basal ganglia ) 10 striatum putamen, caudate nucleus, nucleus accumbens claustrum, amygdaloid nucleus, substantia nigra, & globus pallidus [putamen + globus pallidus=lentiform nucleus] subthalamic nuclei internal capsule [between caudate and lentiform nuclei] external capsule [outside of lentiform nucleus] claustrum [lies lateral to external capsule] conditions linked with basal-nuclei dysfunction:    Parkinsonism    Huntington’s chorea    Tourette syndrome    athetosis    obsessive-compulsive disorder

conditioned reflexes

Pavlovian conditioning

milk let-down

Ventricles of the brain

fourth ventricle choroid plexus capillaries are part of pia, but covered with ependymal cells production of CSF median aperture (foramen of Magendie) lateral aperture (foramina of Luschka) hydrocephalus cerebral aqueduct (aqueduct of Sylvius) lies within mesencephalon

third ventricle choroid plexus interventricular foramina (foramina of Monro) lateral ventricles septum pellucidum central portion choroid plexus anterior, posterior, and inferior horns

arachnoid villi of the superior sagittal sinus

Meninges of the brain

dura mater

periosteal dura

meningeal dura

falx cerebri

superior and inferior sagittal sinuses

tentorium cerebelli

transverse and superior petrosal sinuses

straight sinus

falx cerebelli

occipital sinus

diaphragma sellae

arachnoid

subdural space

subarachnoid space

arachnoid trabeculae

over the gyri, pia + arachnoid=leptomeninx

cisterns

arachnoid villi

pia mater

Blood supply to the brain

common carotid a

external carotid a

internal carotid a

enters carotid canal

posterior communicating a

ophthalmic a

anterior cerebral a

middle cerebral a

subclavian a

internal thoracic a

thyrocervical trunk

costocervical trunk

vertebral a

through transverse processes of superior six cervical vertebrae

spinal branches

anterior spinal a

cerebellar branches

posterior inferior cerebellar a

anterior inferior cerebellar a

forms basilar a

posterior cerebral aa

circle of Willis (circulus arteriosus cerebri)

R posterior cerebral a -> R posterior communicating a -> R internal carotid a -> R anterior cerebral a -> anterior communicating a -> L anterior cerebral a -> L internal carotid a -> L posterior communicating a -> L posterior cerebral a -> basilar a bifurcation -> R posterior cerebral a ->...

ex DAVID, an Online Atlas of Human Anatomy for Clinical Imaging Diagnosis

Magnetic resonance angiogram ex Department of Radiology, Dartmouth-Hitchcock Medical Center

Go to beginning

Links

• Referenced sites
  
  
  • ¹  Surface views, dissections, and sections through the brainstem
    
    
  • ²  External features, nuclei, and fiber tracts of the cerebellum
    
    
  • ³  An overview of hereditary ataxias, from GeneClinics
    
    
  • ⁴  Benign congenital hypotonia
    
    
  • ⁵  A very comprehensive review of nystagmus and related ocular oscillations by B. Todd Troost, M.D.
    
    
  • ⁶ The University of Wisconsin—Madison has decided to make their Neuro611 pages unavailable to us outsiders, to which I say, “Bad show, Badgers”.
    Therefore, I searched for, and found, a better site presenting the cytoarchitecture of the cerebellum with its inputs and outputs.
    
    
  • ⁷  A nice biography of Korbinian Brodmann; although in German, it’s not like trying to read Kant, and there are lots of interesting photographs and scans of Brodmann’s sketches
    
    
  • ⁸  Cytoarchitectonic maps showing the Brodmann areas
    
    
  • ⁹  Locational descriptions of human Brodmann areas
    
    
  • ¹⁰  Connectivity within the basal nuclei
    
    
• Other sites
  
  
  • Split brain consciousness
    
    
  • Huntington’s chorea, from Northwestern University Medical School
    
    
  • Parkinson’s disease, an index of links from Wake Forest University School of Medicine
    
    
  • The Creutzfeldt-Jakob Disease Foundation site
    
    
  • Prion diseases, from Virtual Hospital^®
    
    
  • A neuroanatomy tutorial , with labelled images — University of Utah