The midbrain (mesencephalon) connects the pons and cerebellum to the forebrain. It is the shortest segment of the brainstem at around 2 cm long, located in the posterior cranial fossa. The midbrain contains the crus cerebri, mesencephalic nucleus of the trigeminal nerve, and decussation of the superior cerebellar peduncles. Its lateral relations include the parahippocampal gyri and interpeduncular fossa. The midbrain is divided into the dorsal tectum and cerebral peduncles.

1. MIDBRAI
NDr. Komal Parmar

4. Introduction
• Traverses the hiatus in the
tentorium cerebelli, and connects
the pons and cerebellum with the
forebrain.
• Shortest brain stem segment, not
more than 2 cm in length,
• lies in the posterior cranial fossa.
• Crus Cerebri
• Mesencephalic Nucleus of the
Trigeminal Nerve
• Decussation of the Superior
Cerebellar Peduncles

5. Relations
• Lateral- Parahippocampal Gyri

6. Interpeduncular Fossa

8. Divisions-
• Dorsal tectum- dorsal to the cerebral
aqueduct, and consists of the
pretectal area and the paired
superior and inferior colliculi (corpora
quadrigemina).
• Cerebral Peduncles- right and left,
each of which is further divided into a
ventral crus cerebri and a dorsal
tegmentum by a pigmented lamina,
the substantia nigra.

9. Structure

19. White Matter-
Tracts

20. Tracts

29. Grey Matter-
Nuclei

30. Nuclei

44. Other Features

48. Organization-
Transverse
Sections

51. Blood Supply
and Clinical
Correlates