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