Cingulate gyrus, mammillary bodies and subthalamic nucleus

Show numbers

1. Amygdala

In Image 5 both amygdalae are seen located at the anterior end of the medial temporal lobes. However, in Image 6, because the coronal section of the brain is slightly uneven, only one amygdala is visible (labelled 1). On the other side of the brain the amygdala has been replaced by the more posteriorly located hippocampus. The amygdalae are part of the limbic system and important centres for emotion. Each amygdala is at the core of one of the two major limbic circuits – the hippocampus is at the core of the other.

Show list

1.
Amygdala
2.
Hippocampus
3.
Mammillary bodies
4.
Thalamus
5.
Internal capsule
6.
Corpus callosum
7.
Corona radiata
8.
Cingulate gyrus
9.
Fornix (plural fornices)
10.
Lateral ventricle
11.
Third ventricle
12.
Insula
13.
Subthalamic nucleus
14.
Substantia nigra

In this view we see:

A coronal section of the brain showing the cingulate gyrus above the corpus callosum. The cingulate gyrus partially encircles the corpus callosum and has a role in the limbic system, which includes the amygdala (seen in Images 5 and 6), hippocampus and parahippocampal gyrus (seen in Image 7).
The roughly spherical mammillary bodies underneath the third ventricle in the centre of the image. The mammillary bodies are two small structures, each receiving input from its respective hippocampus via the left and right fornices (see fornix in Images 4 and 5).
The subthalamic nucleus located below the thalamus. It is one of the five major components of the basal ganglia, and has motor, limbic and cognitive functions.

Location

Each cingulate gyrus on the left and right side of the brain is a component of the limbic system. The anterior cingulate cortex is linked to the amygdala, and the posterior cingulate is linked to the hippocampus. The cingulate gyrus partially encircles the corpus callosum.

Images 5, 6 and 7 show the cingulate gyrus in cross-section (coronal section) sitting above the corpus callosum. However, in the side (mid-sagittal) view shown in Image 2, we can see the curve of the cingulate gyrus following the curve of the corpus callosum immediately below the cingulate gyrus.

Structure

While the cingulate cortex was previously divided into an anterior and a posterior division by Brodmann, Korbinian in 1909, more recently three regions have been recognised:

anterior cingulate cortex (ACC),
midcingulate cortex (MCC),
retrosplenial cortex (RSC) located behind the most posterior part of the corpus callosum – the splenium.

Function

The anterior cingulate cortex (ACC) – is concerned with functions of the autonomic nervous system (autonomic regulation) such as innervation of glands, heart muscle and the smooth muscle of the viscera and blood vessels. These autonomic functions also include a role in emotion.

The midcingulate cortex (MCC) – is concerned with movement of the muscles of our trunk, arms and legs (skeletomotor functions), where electrical stimulation of the MCC causes touching, kneading, rubbing and pressing the fingers or hands together, and lip puckering or sucking. The MCC is also involved with cognitive functions such as anticipation of cognitive processing, working memory and the pleasure we feel after receiving a reward.

The posterior cingulate cortex (PCC) – is involved in the ability to recall objects that make up our environment (topographic memory) and the way we remember the routes we take to walk, drive or move through our environment (topokinetic memory).

The retrosplenial cortex (RSC) – is part of a network that mediates finding our way through our environment (topokinetic navigation) and memory. The RSC is also involved in our visual orientation to our environment (visuospatial orientation).