Anatomia - generalities of the encephalon

The neurocranium contain the encephalon, the meningis, the intracranial portion of the cranial nerves (are twelve pairs of

nerves that emerge mainly from the brain stem, with the exception of the first two, and converge information principally to

head and neck...they posses a real and apparent origin), vessels and the cerebrospinal fluid associate with the ventricles

(are in direct communication with the central canal of the spinal cord and they are the 4* ventricle (between the brain

stem and cerebellum) continuous with the 3* via the acqueductus of Silvio (the ventricle is found in the diencephalon) it is

then continous with the two lateral ventricles found in the two cerebral hemisphere thanks to the two foramens of

Monro)...The neurocranial fossa present a base and a volt. The volt is formed by the frontal, parietal and occipital bone.

The base is subdivided into 3 main cavities...

Cavities in the neurocranium:

• Anterior cranial fossa (frontal bone, ethmoid bone and lesser wing of the sphenoid bone) present the lamina cribosa

and the crista galli

• Middle cranial fossa (lesser wings of the sphenoid bone until the petrous part of the temporal bone) it contains the sella

turcica that host the hypophysis and many fissures and foraminae for the passage of neurovascular structures

• Posterior cranial fossa (mainly formed by the occipital bone) characterize by the presence of the foramen magnum

The encephalon is invested by the meningis...the most external layer is the dura mater that adheres with the periosteum of

the different bones that compose the neurocranium and with the sutures and sagittal sulcus, it also forms the septi that

will partially subdivide the cavities into lodges...the septi are:

• The cerebral falx: (large semilunar sagittal septum) extend from the crista galli until the tentorio cerebelli running inside

the interemispheral scissure, dividing the two cerebral emisphere

• The cerebellar falx: (sagittal septum)placed in the posterior cranial fossa under the tentorium cerebelli, attached to the

internal occipital crest, it runs in between the two cerebellar emisphere

• The tentorio cerebelli: starts from the internal occipital protuberance and continue katerally in the transverse occipital

sulcus to terminate at the level of the posterior clinoid process...the anterior free margin delimits together with the sella

turgica the oval foramen of Pacchioni...the tentorio cerebelli subdivide the cranial cavity into a supratentorial lodge

(where the brain or forebrain is found) and a subtentorial lodge (where the brain stem and the cerebellum are localized)

• The diaphragm of the sella turgica: is a small septum that extend over the sella turgica.

Supratentorial lodge:

The brain or forebrain is composed by the telencephalon and diencephalon...

• The telencephalon is composed by two cerebral hemisphere that almost completely encircle the diencephalon...it

occupies the anterior and middle cranial fossa and the volt...the two hemisphere are divided by the interemispheric

sulcus and at the base of the sulcus a lamina of white matter that join the two hemisphere called the corpus callosum,

can be recognize...each hemisphere present some sulcus and gyri that subdivide the hemisphere into cerebral lobes:

frontal, parietal, temporal, occipital, limbic and insula of Reil...the major sulcus are:

Lateral sulcus of Silvio

◦ Central sulcus of Rolando

◦ Parieto-occipital sulcus

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