Brain Anatomy Part I
Section IV. Cingulate Sulcus and Gyrus Overview
The first concept in this section is recognition that the midline sagittal image is a key image in neuroradiology. There is a wealth of anatomic information on the midline sagittal image, including key gyri, key sulci, the corpus callosum, pineal region, pituitary region, posterior fossa structures, and much more. Many radiologists begin interpretation of a head MRI with inspection of this image.
For now, we will focus on the cingulate sulcus, cingulate gyrus, and the medial extent of the central sulcus.
The cingulate gyrus/sulcus has key relationships to the corpus callosum, frontal lobe, and parietal lobe. It is seen in-profile in the sagittal plane.
Cingulate Gyrus and Sulcus
The cingulate sulcus (yellow) is in profile and encircles the anterior portion of the cingulate gyrus (pink), which in turn encircles the corpus callosum (red). Posteriorly, there is an oblique upsweep called the pars marginalis of the cingulate sulcus. Notice that the pars marginalis is immediately posterior to the medial extent of the central sulcus (dark blue). The continuation of the sulcus overlying the posterior cingulate gyrus is the subparietal sulcus.
Cingulate Gyrus and Sulcus
The mid-portion of the cingulate sulcus is well-visualized on coronal images, separating the cingulate gyrus from the superior frontal gyrus (light blue).
The central portion of the cingulate sulcus lies within the axial plane and is only seen as two paralell convoluted sheets (tire-track sign). The pars maginalis and the anterior segments are well seen in the axial plane.
Add Images of Tire-Track Sign.........
Signs of the pars marginalis of the cingulate sulcus will be key ways to identify the central sulcus, the most important surface landmark to master first.
Signs of the Pars Marginalis
Near the vertex, the cingulate sulcus pars marginalis often has upturned edges, resulting in a Salvador Dali type upturned mustache (although this can vary or can be unilateral). The medial extent of the central sulcus extends medial to the bracket of the cingulate sulcus.
Sign of the Pars Marginalis
The cingulate sulcus has many important features on axial images. Identification of the cingulate sulcus is one of the best ways to identify the central sulcus on axial images. First, notice how it consistently shifts anteriorly while scrolling superior-to-inferior (anterior shift sign). In addition to the shift, the mustache 'flattens out' to a Tom Selleck type mustache.
The cingulate sulcus develops in close concert with the corpus callosum. Disordered development of the corpus callosum is associated with abnormalities of the cingulate sulcus.
Agenesis of the Corpus Callosum
The development of the corpus callosum and cingulate sulcus are related. Where there is agenesis of the corpus callosum, the cingulate sulcus does not evert and is not seen. On sagittal images, sulci extend inferiorly to the border of the ventricles.
Partial Absence of the Corpus Callosum
Partial absence of the corpus callosum. Where the corpus callosum is absent, the sulci extend inferiorly to the ventricular surface. Note that the corpus callosum forms front to back (and rostrum last), hence absence of the posterior portions (posterior body, isthmus, splenium) and rostrum.
The cingulate gyrus contains limbic cortex and is often involved with pathology affecting limbic regions.
Infectious Limbic Encephalitis
Middle aged patient with Kluver-Bucy syndrome and ultimate diagnosis of herpes encephalitis (coronal T2 FLAIR, coronal T1 with gad). Herpes encephalitis is a form of infectious limbic encephalitis. Areas of limbic cortex were involved including the cingulate gyrus (and also insula, medial temporal lobe, temporal pole, and portions of the posterior/medial basal frontal lobes).
Summary of Key Clinical Correlate Concepts of the Cingulate Gyrus/Sulcus
Develops in concert with the corpus callosum
Contains limbic cortex and may be involved with limbic encephalitis
The posterior cingulate gyrus is affected early with several forms of dementia or even MCI