1. Parts of the Brain Dr Ajith Sominanda Department of Anatomy

2. Nervous System Environmental stimuli Information Processing Effects

3. Nervous system and Brain Few facts from your A/Levels or high school biology Nervous system consists of nerve tissues: neurons and glia Brain and spinal cord belongs to CNS In CNS, macroscopically white and gray matter are identifiable These white and gray matter are arranged into different areas of the brain and spinal cord

4. In a Fresh brain or Spinal cord., – White is due to myelinated (protein +l ipid); nerve fibers or Axons – Gay is due to cells; neurons & glia But in imaging techniques gray and white may look different Nervous system and Brain Few facts from your A/Levels or high school biology

6. Brain in the cranial cavity video

7. Terms in Neuroanatomy encountered in your A/Ls Cerebrum Cerebellum Brain Stem (mid brain, pons, medulla) Meningies (Dura mater, arachnoid mater & pia mater) Ventricles CSF Nervous System CNS (Brain & Spinal cord) PNS (Cranial nerves, Spinal nerves, peripheral ganglia) Nerve tissue Neuron Glial cell Neurits (Axons & Dendrits) Synapse Nerve fiber, ganglia & peripheral nerve Gray matter & White matter Development Neuroectoderm, neural tube, neural crest cells

8. Is the key to understand its structure

9. Neural Tube Neural crests

10. Development - Major points Nervous system develops from an area of ectoderm called neuroectoderm or neural plate of the embryo Neuroectoderm give rise to neural tube and the peripheral nerves develop from neural crests

11. Forebrain Midbrain Hindbrain Naming different areas of the developing neural tube

12. neural tube bends and grow EmbryoSwollen & Folded neural tube Cervical flexure Pontine flexure Cephalic flexure

13. Areas of developing neural tube

14. Areas of developing neural tube and their future components Forebrain Midbrain Hindbrain

15. Thus, brain is the modified cephalic (front) part of neural tube by growth (swelling) and folding

17. Main parts of the adult brain Revision 1.Forebrain I.Cerebral hemispheres or cerebrum II.Diencephalon Thalamus, Epithalamus, Hypothalamus & Subthalamus 2.Midbrain 3.Hindbrain I.Pons and Cerebellum II.Medulla

19. Forebrain Cerebrum or Cerebral hemispheres Represent the largest part of the brain Has extensively convoluted cerebral cortex Has internal white matter fiber bundles Has internal masses of gray matter Also contains cavities; lateral ventricles Two hemispheres are connected by a bundle of white matter called corpus callosum

20. Forebrain Cerebrum or Cerebral hemispheres

21. Cerebral Cortex (gray matter) Contains cells (neurons & glia) Extensive folding forms sulci and gyri Large sulci / fissures divides cerebral hemispheres into different lobes

22. Sulci- Lateral, Central, parieto-occipital Frontal lobe, Parietal lobe, Occipital lobe & Temporal lobe Topography of cerebral hemispheres Supero-lateral surface of the brain

23. Main Sulci and Gyri Draw

24. Cingulate gyrus, cuneus, lingular gyrus Cingulate sulcus, calcarine sulcus Topography of cerebral hemispheres medial surface of the brain

25. Insular lobe

26. Functional localization

27. Cerebral White matter 1.Consists of Axons that connect different parts of the nervous system 2.These axons are arranged in bundles which can be displayed by dissection

28. Cerebral White matter Three types of axon bundles (fasciculi) are present in cerebral white matter: A.Association fibers Confined to a hemisphere and connects cortical areas within the hemisphere B.Transverse or Commissural fibers Connects 2 hemispheres Axons runs in corpus callosum and anterior commissure, C.Projection fibers Connect cerebral cortex with subcortical structures, brain stem and spinal cord

29. Cerebral White matter

32. Corpus Callosum (Transverse or Commissural fibers) Cerebral White matter

33. Corpus Callosum

34. Corona radiata & Internal capsule (Contains projection fibers) Cerebral White matter

35. More details during the practical sessions

36. Other internal structures of cerebral hemispheres Diencephalic structures (Thalamus, hypothalamus, epi thalamus and sub thalamus)

37. Other internal structures of cerebral hemispheres Telencephalic gray matter – Corpus striatum (telencephalic gray matter associated with lateral ventricles) Striatum (caudate nucleus, nucleus accumbens & putamen) Pallidium (globus pallidus)

38. Other internal structures of cerebral hemispheres

39. Histology of cerebral cortex Cerebral gray and white matter is (histologically) arranged in layers Three Histologically different areas can be identified: 1.Paleocortex (olfactory system) 2.Archicortex (hipocampal formation) 3.Neocortex (rest of cerebral cortex) - 3 layers 6 layers

40. Neocortical Histology Histology of cerebral cortex

41. There are two types of neurons : 1.Principal neurons a.Typical principal cells are pyramidal cells b.Atypical principal cells are fusifom cells 2.Inter neurons Histology of cerebral cortex

42. Principal neurons connect with other neurons in CNS in 3 ways I.Projection neurons/fibers (subcortical areas such as thalamus, corpus striatum, brain stem & spinal cord) II.Association neurons/fibers (connects cortical neurons in same hemisphere) III.Comissural neurons/fibers (connects cortical neurons in opposite hemisphere ) Histology of cerebral cortex