Brain of Fetus 5 Months Old
The fetal nervous system, i.e., baby's brain and spinal cord - is one of the first systems to develop.
The specimen reveals a sagittal section of the cranial cavity. The lateral surface of the cerebrum and the cerebellum are identified. Part of the duramater enveloping the brain is also seen. The inferior surface of the cerebrum is separated from the cerebellum by the tentorium cerebelli. The falx cerebelli is also visualized here. The major sulci and gyri are also identified in the developing brain. The sulci seen in the superolateral surface of the cerebrum are the central, precentral, lateral and intraparietal sulci. The gyri seen are the precentral, and superior and inferior parietal lobules. The sulci and gyri in the frontal, temporal and occipital lobes are not well defined.
The cerebrum is the uppermost part of the brain. It contains two hemispheres seperated by a central fissure. The cerebrum contains the major lobes of the brain and is responsible for receiving and giving meaning to information from the sense organs, as well as controlling the body.
The cerebellum is a major structure of the hindbrain that is located near the brainstem. It is responsible for coordinating voluntary movements. It is also responsible for a number of functions including motor skills such as balance, coordination, and posture.
The dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. The duramater covering the brain is made up of two layers: outer endosteal and inner meningeal. The dural venous sinuses are present between these layers.
The tentorium cerebelli is a horizontal projection of the meningeal dura mater that covers and separates the cerebellum in the posterior cranial fossa from the posterior parts of the cerebral hemispheres. It is attached posteriorly to the occipital bone along the grooves for the transverse sinuses. Laterally, it is attached to the superior border of the petrous part of the temporal bone, ending anteriorly at the anterior and posterior clinoid processes.
The anterior and medial borders of the tentorium cerebelli are free, forming an oval opening in the midline (the tentorial notch), through which the midbrain passes. The venous sinuses related to it are: straight sinus, transverse sinus and superior petrosal sinus.
The falx cerebelli is a small midline projection of meningeal dura mater in the posterior cranial fossa. It is attached posteriorly to the internal occipital crest of the occipital bone and superiorly to the tentorium cerebelli. Its anterior edge is free and is between the two cerebellar hemispheres. The venous sinus related to it is the occipital sinus.
Sulci and Gyri on the superolateral surface of cerebrum:
The superolateral surface of the right cerebral hemisphere is visualized in this specimen. The superolateral surface is arbitrarily divided into four lobes: frontal, parietal, temporal and occipital with the help of three main sulci, i.. e., central, lateral, and parieto-occipital and two imaginary lines. The first imaginary line is a vertical line joining the parieto-occipital sulcus to the preoccipital notch. The second line is a backward continuation of the horizontal part of the posterior ramus of the lateral sulcus till it joins the first line. The grey matter of the cerebrum is arranged in the form of sulci and gyri.