Internal structures of hemispheres

Make it easy

Fibers

white matter fibers White matter is composed of

myelinated axons (nerve fibers) + neuroglial cells + blood capillaries.

actively affects how the brain learns and functions. While grey matter is primarily associated with processing and cognition, white matter modulates the distribution of action potentials, acting as a relay and coordinating communication between different brain regions

Typescommissural

fibers

projection fibers

Association fibers

Types connects region of the 2 hemispheres. example:1-corpus callosum (largest bundle).2- anterior commissure .3- posterior commissure .

commissural fibers

Typescommissural

fibers

projection fibers

Association fibers

Types Links different cortical area of the same

hemisphere. 2 types: 1- short association fibers:small bundle of fibers that connect adjacent gyri 2- long association fibers :For distant gyri, bundled together to make named structures.Example: Cingulum within cingulate gyrus Connects frontal and parietal lobes with temporal lobe .

Association fibers

Typescommissural

fibers

projection fibers

Association fibers

Types fibers that pass from the brainstem reaching

various regions. Exampels :Cut the braincut in the middle of the hemispherefibers will look like a fan and these projection fibers

projection fibers

http://www.google.jo/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwiC-6L6_4PLAhUGQBoKHWLdCoYQjRwIBw&url=http://slideplayer.com/slide/4280841/&psig=AFQjCNHM-mZrrIXdaHYbviu-H77oVKNRoA&ust=1455977219601792

Exampels : 1- corona radiata :Fibers which are dorsal (above ,superior)to the basal ganglia and close to the cortex .divided into (radiations)-Eg. optic radiation, auditory radiation.

2- A.internal capsule B. external capsule C.extreme capsule

projection fibers

Fibers travelling between “around” basal ganglia

http://www.google.com.bh/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwjZio2VvP7KAhXI6RQKHZiUCG4QjRwIBw&url=http://www.slideshare.net/eduerden/anat-321-lab4-presentation&psig=AFQjCNELLxRKYgCfcOLBjyCa8Px4pG8HIg&ust=1455786988254127

Basal nuclei masses of grey matter embedded in white

matter.

Cotrex ???

Basal nuclei

Pale globe

lens

Basal nuclei

thin line of grey matter its function isn't well known

Basal nucleiClaustrum barrier

Thalamus sensory station of the body not a part of basal nuclei used as a landmark to define different

projection fibers .

The fibers travelling between lentiform nucleus and caudate and between lentiform and thalamus is called

Between 2 limbs there is a structure like a knee»» the genu of internal capsule .

projection fibers

internal capsule

projection fibers The fibers travelling between lentiform

nucleus and claustrum is called

external capsule

The bundle between the claustrum and insula is called

projection fibers

extreme capsule

http://www.google.com.bh/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwjZio2VvP7KAhXI6RQKHZiUCG4QjRwIBw&url=http://www.slideshare.net/eduerden/anat-321-lab4-presentation&psig=AFQjCNELLxRKYgCfcOLBjyCa8Px4pG8HIg&ust=1455786988254127

Insula

Fibers

Other internal structures of cerebral hemisphere :❶septum pellucidum : double membrane) delicate membrane “part of anterior horn of

lateral ventricle”. bounded by corpus callosum superiorly and

fornix inferiorly.

Fornix(bundles of fibers that originate from hippocampus.

Other internal structures of cerebral hemisphere :❶septum pellucidum : double membrane) delicate membrane “part of anterior horn of

lateral ventricle”. bounded by corpus callosum superiorly and

fornix inferiorly. Inner surface of septum pellucidum composed of

ependymal cell, because this surface considered as part of the wall of the lateral ventricle.

we have 2 septum pellucidum (cavumpellucidum separate between them).

composed of both gray and white matter . (although it appears white in fresh specimen of brain ) .

http://www.google.com.bh/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwi8ruqvsITLAhVGRBQKHS0RD54QjRwIBw&url=http://www.slideshare.net/dr_ansari2000/csf-productioncirculation-absorption&psig=AFQjCNEDl46cgJ37kbd30YRq2R12iJ3ROA&ust=1455990141131261

fresh specimen of brain

❷corpus callosum : the largest bundle of commissural fibers . Covered with:-1.rostrum (the smallest) 2.genu(most anterior)3.body( the largest) 4.splenium(most posterior) .

Other internal structures of cerebral hemisphere :

Ventricles Four CSF-filled cavities located within the

brain . Lined by ependymal cells . Contain specialized vascular structures

called :choroid plexuses »» synthesis of CSF .

3rd ventricle in diencephalon 4th in hindbrain cerebral aqueduct in midbrain .

❶Lateral ventricles C-shaped of lateral ventricle to allow it to

extend to all lobes of brain. Each lateral ventricle is connected to 3rd

ventricle by foramen of monro . 2 in number

3rd ventricle connected to 4th by cerebral aqueduct then continue as centralcanal of spinal cord .

Does not contain choroidplexus .

Body » in parietal lobe . Ant.horn » in frontal lobe . Post. Horn » in occipital lobe . Inf. Horn » in temporal lobe .

Interthalamic connection : Bridge of tissue running through the 3rd ventricle connecting the 2 thalami .

❶Lateral ventricles

4th ventricle Tent shaped cavity Anterior to cerebellum, Posterior to pons and

medulla oblongata Communicates with subarachnoid space

through:-foramen of magendie(1 in number) » central .-foramen of luschka (2 in number ) » lateral .

MRI

Choroid plexuses Invagination of pia matter with blood

capillaries inside it, found through ventricles Components :-Endothelial layer(fenestrated)-Pial membrane.-Choroidal epithelial cells :form the blood -CSF barrier and responsible of active transport of the substances in and out of CSF

CSF

We have 150 ml of CSF in our body due to high turnover. “subarachnoid space”

Only 20 ml of CSF in ventricles (less than 50%).