Brain image used, with permission, from the Yakovlev-Haleem collection from the National Museum of Health and Medicine.
Cerebrum: Midsagittal Anatomy
Key Points of Interest
Diencephalon
- The diencephalon comprises numerous thalamic regions, most notably the thalamus and the hypothalamus
- We can remember its central location by the clinical syndrome of central herniation, which typically first involves the diencephalon.
- And we can remember its autonomic function (from the hypothalamus) by the clinical syndrome of diencephalic autonomic storm (or dysautonomia).
Corpus callosum
- The corpus callosum
- C-shaped, prominent white matter pathway, connects the bilateral cerebral hemispheres.
- We can remember its function by corpus callosotomy (aka "split brain" surgery), which involves transection of the corpus callosum (and commissures), usually to stop the spread of seizures.
- Clinical correlation, see callosal dysgenesis
Key Midsagittal Sulci
- The central sulcus distinguishes the frontal lobe from the parietal lobe.
- The parieto-occipital sulcus distinguishes the parietal and occipital lobes.
- The calcarine sulcus lies along mid-section of the occipital lobe.
- The primary visual cortex lies along the banks of the calcarine sulcus.
Key Midsagittal Gyri
- The cingulate gyrus lies within the superior limbic lobe.
- The uncus is the antero-inferior gyral thumb.
Other Prominent Midsagittal Structures:
- The fornix, which wraps around the thalamus, which underlies it.
- The interthalamic adhesion, which is the medial thalamic bump.
- The hypothalamus, beneath the thalamus (it surrounds the 3rd ventricle) and comprises numerous nuclei, including:
- The mammillary bodies, just anterior to the brainstem.
- A portion of the pituitary gland (anteriorly).
- The pineal gland (of the epithalamus) lies along the posterior diencephalon.
- The tectum lies along the upper posterior surface of the brainstem.
- To help remember the position of the pineal gland above the tectum consider that pineal tumors can compress the tectum, which causes vertical gaze palsy, called Parinaud's syndrome.
- CSF funnels through the cerebral aqueduct (of Sylvius) in the upper brainstem.
- The fourth ventricle is the collection of CSF in the mid-brainstem level.