diencephalon: position & division (5parts) it lies between cerebrum & midbrain. the narrow...
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Diencephalon: position & division (5parts) It lies between cerebrum & midbrain. The narrow space between the left & right diencephalons is the 3rd ventricle.
Dorsal thalamus is used as a center for judging the positions of the rest components of diencephalon.
The part anteroinferior to it is hypothalamus;the portion behind it is metathalamus; the anterio---posteriorly going & continuous structure superior to it is epithalamus,and the structure inferior to it (its base connecting midbrain) is subthalamus.
Guo Ling, MD, PhDDepartment of Anatomy
Internal Structure of ThalamusVentroposteriolateral nucleus(VPLN) is
to relay the superficial and deep sensation informations from neck, trunk & limbs to the superior 2/3 part of the
first sensory area(FSA) in crebrum.
Ventroposteriomedial nucleus(VPMN) is to transmit facial sensation informations (including
taste ) to the inferior 1/3part of FSASmell information is not sent to the center
through diencephophalon, but it is directly delivered to the gustatory area in cerebrum.
Ventral posteromedial N
Ventral posterolateral N
(Dorsal) Thalamus (right)
Mediodorsal N
Ant.nucleus group
Medial geniculate body
Lateral geniculate body
Thalamic Nuclei of Specific Afferents
Epithalamus
thalamic medullary stria habenular trigone(nucleus)
habenular commissurepineal body
medial geniculate body lateral geniculate body
Metathalamus
Both contain the two nuclei relaying informations of sound and light(&color), respectively.
Subthalamus(subthalamic nucleus connecting the
tegmentum of midbrain ) Hypothalamus
External features (front to back) optic chiasma cinereous tuber mamillary body
Internal Structure of Hypothalamus
supraoptic nucleus
paraventricular nucleus
infundibular(arcuate)
nucleus
supraopticochiasmatic
nucleus
Internal
4 nuclei& 3 tracts
Infundibular nucleus
Target tissue
Telencephalon (rhinencephalon & 2 cerebral
hemispheres) sulcus-----downfolds on the surface of cerebra
gyrus----- upfolds (appearance in 7-month-old fetus )
CEREBRUM
Front pole
Occipital poleTemporal pole
Dorsolateral surface
Inf.surface
Medial surface
DIVISION
2 surfaces, 3 sulci 3 poles & 5 lobes
Cerebral Hemisphere :five lobes
frontal lobe
parietal lobe
occipital lobe
insula
temporal lobeinsula
in
Four Gyri in Frontal Lobe precentral gyrus superior frontal gyrus middle frontal gyrus inferior frontal gyrus
Three Gyri &Two Lobules in Parietal Lobe postcentral gyrus, superior parietal lobule, inferior parietal lobule, supramarginal gyrus angular gyrus
superior temporal gyrus, middle temporal gyrus, inferior temporal gyrus, trasverse temporal gyrus.
Four Gyri in Temporal Lobe
2 Gyri,2 Lobules,3 Sulci ,1 Fornix,1 Septum & 1 Callosum in Medial Surface
corpus callosum, fornix, cingulate gyrus, parahippocampal gyrus, transparent septum, cingulate sulcus, parietooccipital sulcus, calcarine sulcus, anterior part oparacentral lobule, posterior part of paracentral lobule.
olfactory bulb
olfactory tract
olfactory trigone
anterior perforated substance
Inferior Surface
cingulate gyrus parahippocampal gyrus
uncus
hippocampus
dentate gyrus
Limbic Lobe
dentate gyrus
Hippocampus
UncusParahippocampal gyrus
Cingulate gyrus
Functional Localization of Cerebral Cortex ( Brodmann`s map--- 55 areas )
Primary motor area(areas 4, 6 ): precentral gyrus & anterior part of paracentral lobule
Functional Features of Primary Motor Area
1) Cross control
2) “upsidedown” control 3) paralysis following injury ( Skeletal muscles lose the ability to move voluntarily )
General sensory area: postcentral gyrus & posterior part of paracentral lobule
Functional Features
of General Sensory Area
1) cross projection
2)“upsidedown” projection
3) lack of sensation after injury
Auditory area (41, 42 ): transverse temporal gyrus deafness after injury
Visual area(17): cortex on both sides of calcarine sulcus, blidness after injury
Language areas lie in the dominant (left) hemisphereand are 5 unique anatomical units for manipulating
human languages . The animal cortex has no such areas .
(Broca area)
Motor speech area
Writing area
Visual language area
Auditorylanguage area
Internal Structures of Cerebral Hemispheres Cortex(surface pallium):6 layers of nerve cells(neocortex),3 layers ( paleocortex / archicortex ) .26 billion neurons , no new neuron increase after birth.
52 areas of Brodmann(1909):dorsolateral surface
52 areas of Brodmann (1909):medial surface
Internal Structure : imbedded deep in cerebrumbasal nucleus & medulla
Corpus striatum
Basal nucleus (ganglia)
(1)caudate nu
(2)lentiform nu
putamen
globus pallidus
(3)amygdaloid body
(4)claustrum
a.Association fibers connect one cortex area with another only in one hemisphere(R/L). b.Commissural fibers
connect the left hemispheric cortex with the right one.
c.Projection fibres work as a connecting bridge between the cerebral cortex and subcortic structures
Medulla--White matter consists of 3 kinds of nervous fibers.
Association Fibers (4 tracts )superior longitudinal fasciculus arcuate fibers
cingulumuncinate fasculus,
Commissural Fibres (4 tracts ) corpus callosum ant. & post. commissures fornix
Internal capsule is a gate to the passaage of projection fibers andis imbedded among dorsal thalamus,caudate & lentiform nuclei .
headface
upperlimb
Low limb
acoustic radiation optic radiation
Precentral gyrus
1.Composition & Position of Internal Capsule
2.DIVISIONanterior limb
genu
posterior limb
ant. thalamic radiation
frontopontine tract
corticonuclear tract
corticospinal tract
central thalamic radiation
optic radiationparieto-occipito-tempora-pontine tract
acoustic radiation
3.Fiber Tracts Passing Internal Capsule
Internal Capsule (lateral view)
1)Muscular paralysis on the opposite half side of body
2)Impairment of general sensation on opposite half side of body
3)Blindness on opposite half side of visual field
4.Typical Signs Following Injury
3 Opposite Symptoms
Ventricular System & Its Communication Left and right
lateral ventricles
(interventricular
foramen)
Third ventricle
(mesencephalic
aqueduct)
Fourth ventricle
(median and lateral
apertures of
fourth ventricle)
Subarachnoid space