Neuroanatomy Lab (Week 5)

Question 1

Lateral fissure (sulcus)

Answer 1

Runs between temporal lobe and frontal/parietal lobes

Question 2

Central sulcus

Answer 2

Separates frontal lobe from parietal lobe

Generally separates primary motor cortex (precentral gyrus) from primary somatosensory cortex (postcentral gyrus)

Question 3

Paracentral lobule

Answer 3

Continuation of primary motor and primary somatosensory cortex onto medial surface of hemisphere

(lower limbs)

Question 4

Calcarine fissure

Answer 4

Primary visual cortex is on either side of calcarine fissure

Question 5

Parieto-occipital sulcus

Answer 5

Separates parietal and occipital lobes

Question 6

What can be seen on ventral aspect of hemisphere?

Answer 6

Olfactory bulb

Olfactory tract

Medial and lateral olfactory striae

Anterior perforated substance (between medial and lateral olfactory striae)

Orbital gyri

Uncus of temporal lobe

Question 7

Uncal herniation

Answer 7

Uncus on medial aspect of temporal lobe herniates through tentorial notch and compresses structures of the brainstem

Question 8

Lenticulostriate arteries

Answer 8

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

Question 9

What artery supplies small anteromedioventral territory of head of caudate and putamen in many cases?

Answer 9

Anterior cerebral artery

Question 10

Insular cortex

Answer 10

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

Question 11

Transverse temporal gyri

Answer 11

On upper surface of temporal operculum (near lower part of postcentral gyrus)

Primary auditory cortex

Question 12

Optic (visual) radiations

Answer 12

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!

Question 13

Lateral structure of the temporal lobe

Answer 13

Entorhinal cortex

Hippocampus

Amygdala

Question 14

Limbic cortex

Answer 14

C-shaped region of cortex made up of cingulate gyrus and parahippocampal gyrus

Info from cingulate cortex reaches parahippocampal gyrus through cingulum

Question 15

Collateral sulcus (fissure)

Answer 15

Under (ventral) parahippocampal gyrus??

Question 16

What is at the rostral end of the parahippocampal gyrus?

Answer 16

Uncus

Question 17

Entorhinal cortex

Answer 17

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

Question 18

Fornix

Answer 18

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

Question 19

Stria terminalis

Answer 19

C-shaped structure that interconnects amygdala and septal region of forebrain

Small diameter, between caudate and thalamus

Major efferent pathway of the amygdala

Question 20

Pes (foot) of the hippocampus

Answer 20

Largest part of hippocampus at rostral end

Marked by several indentations that resemble toes

Question 21

Alveus

Answer 21

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

Question 22

Fimbria

Answer 22

Axons leave pyramidal cells and form alveus then form fimbria

Fimbria grows as hippocampus progressively diminishes in size posteriorly and becomes fornix

Question 23

Where does the parahippocampal gyrus end?

Answer 23

Hippocampal fissure?

Question 24

What can you see if you open the hippocampal fissure?

Answer 24

Teeth of the dentate gyrus

Maybe the fornix

Question 25

Where is the amygdala?

Answer 25

Complex of nuclei within the uncus

Question 26

What is located on the medial surface of the uncus?

Answer 26

Primary olfactory cortex

Question 27

What does the anterior commissure connect?

Answer 27

Temporal lobes

Some oflactory nuclei

Question 28

Connections/direction of mammillary –> fornix –> hippocampus

Answer 28

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!

Question 29

What does the uncus cover?

Answer 29

Amygdala and most anterior part of hippocampus

Question 30

Rostral to caudal, what we see

Answer 30

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)