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Motor, Sensory, Visual and Olfactory Areas of Medial Surface of the Brain
In this specimen we can identify the following functional areas (labelled) and structures in the medial surface of the cerebrum.
- Primary Motor area
- Primary Sensory area
- Visual area
- Olfactory area
- Corpus callosum
Primary motor area
The primary motor area is located in the precentral gyrus and anterior part of paracentral lobule. It produces isolated movements on the opposite side of the body
The somatotopical representation of the body in the medial surface is foot, lower leg and anal and genital region
Primary sensory area
The primary sensory area occupies the postcentral gyrus and posterior part of paracentral lobule. It receives fibers from ventral posterior lateral and ventral posterior medial nuclei of thalamus. This area is concerned with perception of exteroceptive (pain, touch and temperature) and proprioceptive (vibration, muscle and joint sense) sensations from the opposite half of the body.
The somatotopical representation of the body in the medial surface is foot, lower leg and anal and genital region
Visual areas
The primary visual area is situated in the walls and floor of the posterior part of the calcarine sulcus. It receives fibers from lateral geniculate body. The area is concerned with reception and perception of isolated visual impressions such as color, size, form, motion, illumination and transparency.
The secondary visual area surrounds the primary visual area. The area interprets and relates the visual information received by primary visual area. Thus the area is responsible for recognition of the objects seen.
Olfactory areas
The olfactory area is the portion of the cerebral cortex that is concerned with the sense of smell. The connections of the olfactory system also involve the limbic cortex, called the secondary olfactory areas. These include the cortex in the anterior portion of the parahippocampal gyrus, an area that has been referred to as the entorhinal cortex.
Corpus callosum
The corpus callosum is the largest commissure of the brain connecting the cerebral cortex of the two cerebral hemispheres. The parts of the corpus callosum are rostrum, genu, trunk/body and splenium. The genu and the splenium can be appreciated in the midline in the horizontal section of the cerebrum. The genu is located anteriorly and medial to the frontal lobes while the splenium is located posteriorly and medial to the occipital lobes.
The corpus callosum is mainly responsible for the transfer of interhemispheric information that is essential for bilateral responses and in learning processes.
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