Lateral fissure (sulcus)
Runs between temporal lobe and frontal/parietal lobes
Separates frontal lobe from parietal lobe
Generally separates primary motor cortex (precentral gyrus) from primary somatosensory cortex (postcentral gyrus)
Continuation of primary motor and primary somatosensory cortex onto medial surface of hemisphere
Primary visual cortex is on either side of calcarine fissure
Separates parietal and occipital lobes
What can be seen on ventral aspect of hemisphere?
Medial and lateral olfactory striae
Anterior perforated substance (between medial and lateral olfactory striae)
Uncus of temporal lobe
Uncus on medial aspect of temporal lobe herniates through tentorial notch and compresses structures of the brainstem
Proximal regions of middle cerebral artery give off branches (lenticulostriate arteries) that penetrate brain in the region of anterior perforated substance
Supply basal ganglia and middle part of internal capsule (including genu)
Rupture or occlusion of these terminal arteries is a common cause of stroke
What artery supplies small anteromedioventral territory of head of caudate and putamen in many cases?
Anterior cerebral artery
Deep within lateral fissure
Covered by frontal operculum, parietal operculum and temporal operculum
Branches of middle cerebral artery are in this region
Basal ganglia is deep to insular cortex
Transverse temporal gyri
On upper surface of temporal operculum (near lower part of postcentral gyrus)
Primary auditory cortex
Optic (visual) radiations
Lateral geniculate nucleus of the thalamus (near posterior region of thalamus) sends out tough fibers that loop forward then outward then backward to fan out in occipital lobe and terminate in calcarine cortex
Most anterior group of fibers is called Meyer's loop (responsible for upper visual field); note Meyer's loop is in temporal lobe!
Lateral structure of the temporal lobe
C-shaped region of cortex made up of cingulate gyrus and parahippocampal gyrus
Info from cingulate cortex reaches parahippocampal gyrus through cingulum
Collateral sulcus (fissure)
Under (ventral) parahippocampal gyrus??
What is at the rostral end of the parahippocampal gyrus?
On surface of uncus and on rostral region of parahippocampal gyrus
Sometimes can see small elevations on surface created by clusters of cells within outer layers of entorhinal cortex
C-shaped pathway that interconnects medial regions of forebrain (septal nuclei and hypothalamus) to laterally located temporal lobe (hippocampus)
Floor of lateral ventricle and roof of 3rd ventricle??
Curves downward caudal to anterior commissure and continues to mammillary body
Small part passes further rostrally (pre-commissural part of fornix) to connect with septal region
C-shaped structure that interconnects amygdala and septal region of forebrain
Small diameter, between caudate and thalamus
Major efferent pathway of the amygdala
Pes (foot) of the hippocampus
Largest part of hippocampus at rostral end
Marked by several indentations that resemble toes
Thin layer of white matter than covers hippocampus
Formed by axons of neurons in subiculum and some hippocampal pyramidal cells
As axons leave pyramidal cells they bend abruptly to become parallel to the surface formin alveus, and then continue longitudinally in the fimbria
Axons leave pyramidal cells and form alveus then form fimbria
Fimbria grows as hippocampus progressively diminishes in size posteriorly and becomes fornix
Where does the parahippocampal gyrus end?
What can you see if you open the hippocampal fissure?
Teeth of the dentate gyrus
Maybe the fornix
Where is the amygdala?
Complex of nuclei within the uncus
What is located on the medial surface of the uncus?
Primary olfactory cortex
What does the anterior commissure connect?
Some oflactory nuclei
Connections/direction of mammillary --> fornix --> hippocampus
Info goes both ways!
Mammillary bodies --> fornix --> hippocampus
Hippocampus --> fornix --> mammillary bodies
ALSO: septal region (in front of anterior commissure) --> fornix --> hippocampus (this would be using ACh)
AND: hippocampus --> fornix --> septal region
Fornix is bidirectional!
What does the uncus cover?
Amygdala and most anterior part of hippocampus
Rostral to caudal, what we see
Most rostrally we see amygdala
More caudal see most anterior part of hippocampus (pes!)
Most caudal see normal hippocampus (where we see our normal circuitry)