1. Anatomy hippocampus

2. introduction
• Hippocampus is a
curved structure on the
medial aspect of
temporal lobe that
bulges into floor of
temporal horn.
• Hippocampus – seahorse
• Curved shape which
resembles a shape of a
seahorse.

3. • Consists of two
interlocking U shaped
gray matter structures
– Hippocampus proper
( Ammon horn)
Superolateral, upsidedown U.
– Dentate gyrus
Inferomedial U

4. Anatomic divisions
Head ( Pes hippocampus )
• most anterior part, oriented transversely
• 3 – 4 digitations on superior surface.
Body
• Cylindrical, oriented parasagittally.
Tail
• Most posterior, narrows then curves around
splenium to form indusium griseum above cc.

6. Hippocampus sulcus
• The hippocampal
sulcus, also known as
the hippocampal
fissure, is a sulcus that
separates the dentate
gyrus from
the subiculum.

7. Based of histology
– Cornu Ammonis (CA)
•
•
•
•
CA1
CA2
CA3
CA4
– Dentate Gyrus
• Fascia Dentata
• Hilus (region CA4)

9. relationship
• Medially, the ambient cistern which
separates the hippocampus from
brainstem.
• Choriodal fissure and temporal horn
superiorly.
• Parahippocampal gyrus inferiorly.
• temporal horn of lateral ventricle
laterally.

12. amygdala / hippocampal
head
• The best landmark for separating amygdala
from hippocampus is the anterior temporal
horn, known as the uncal recess.
• The amygdala is always superior to the
temporal horn.

14. hippocampal head
• morphology: hippocampal
digitations, (pes hippocampus)
• landmarks
– basilar artery to interpeduncular cistern.

16. hippocampal body
– Morphology: Swiss roll appearance, of two
interlocking U-shaped structures (cornu
ammonis and dentate gyrus)
– landmark:
• The hippocampal body is oval
and found adjacent to the brainstem
• The white matter tracts of the alveus and
fimbria are superior to the hippocampus.

18. hippocampal tail
• morphology: smaller and harder to
describe internal structure.
• landmarks
– The hippocampal tail is
demonstrated as it ascends posterior to
the brainstem.
– from the point at which the fornix can be
seen in full profile.

20. Best choice of imaging
• MR in a slightly oblique plane,
perpendicular to long axis of
hippocampus.
– Coronal T1 weighted
– Coronal T2 high resolution
– Coronal FLAIR.

21. MRI imaging

22. Amygdala lies anterior &superior to hippocampus, at
medial aspect of temporal lobe.
Tail of caudate nucleus ends in amygdala.
Pes hippocampus (hippocampal head) lies just posterior
to amygdala.

23. Digitations of the hippocampal head (pes hippocampus).
The hippocampus is separated from amygdala by uncal
recess of temporal horn. The uncinate gyrus connects
medial hippocampus with amygdala.

24. Hippocampal body is bordered medially by ambient
cistern & laterally by temporal horn of lateral ventricle.

25. Hippocampal fissural cyst is normal variant ( incomplete
fusion of hippocampal sulcus )

26. Image at posterior thalamus shows tail of hippocampus.
Tail is narrowest portion of hippocampus as it extends
posteriorly.

27. Image through splenium of corpus callosum shows
fimbria as it becomes crus of fornix.
Two crus of fornix unite to form commissure of fornix
(hippocampal commissure).

28. Zoomed image of coronal view

31. Uncus the medial most structure, lateral to it is the
amygdala which is superior to temporal horn

32. The uncal recess separates the amygdala from
hippocampal head

33. Tail is narrowest portion of hippocampus as it extends
posteriorly.

34. Sagittal section the whole of hippocampus is seen
posterior to temporal horn