1. Human Anatomy CentralNervous System Part I The Brain

2. CNS • Consists of 2 anatomical components Brain Spinal cord

3. The Brain • 3 subdivisions A. Cerebrum B. Cerebellum • Brainstem • Additional Structures

4. Subdivisions of the Brain • A. Cerebrum • B. Cerebellum • Brainstem

5. Sagittal Section of Brain • A. Cerebrum • B. Cerebellum • Brainstem • Additional • structures

6. A. The Cerebrum • Surface forms a series of elevated ridges – gyri (gyrus, sng.) • Surface also has shallow depressions – sulci (sulcus, sng.)

7. Gyri of Cerebrum

8. Sulci of Cerebrum

9. Central Sulcus

10. Lateral Sulcus

11. Longitudinal Fissure

12. Cerebral Hemispheres • Cerebrum consists of two cerebral hemispheres Left Right

13. Lobes of the Cerebrum

14. Lobes of the Cerebrum • Four lobes from the surface

15. Four Lobes of Cerebrum(that can be seen on the lateral surface) • Frontal • Parietal • Occipital • Temporal

16. Cerebral Lobes

17. 1. Frontal Lobe • Forms the anterior portion of the cerebral hemispheres • Posterior boundary is central sulcus • Inferior boundary is lateral sulcus • Most posterior gyrus is the precentral gyrus • Precentral gyrus is primarily concerned with voluntary motor (skeletal muscles) function. It is also known as the primary motor cortex of the brain.

18. Frontal Lobe

19. Precentral Gyrus Precentral Gyrus Central Sulcus

20. Organization of precentral gyrus(primary motor cortex)

21. Precentral Gyrus

22. Broca’s Speech Area(motor speech area) Controls muscles neccesary for vocalization (words) Usually found in left frontal lobe

23. Frontal Lobe Frontal eye field Cognitive activities – judgement, reasoning, planning See Clinical Views on pp. 459 & 461

24. 2. Parietal Lobe • Posterior to the central sulcus • Anterior to the occipital lobe • Most anterior gyrus is the postcentral gyrus • Postcentral gyrus receives information from the body such as touch, pressure, pain and temperature. It is also known as the primary somatosensory cortex.

25. Parietal Lobe

26. Postcentral gyrus Central sulcus Postcentral gyrus

27. Organization of postcentral gyrus(primary somatosensory cortex)

28. Postcentral gyrus

29. Parietal Lobe Wernicke’s area – understanding speech and formulating words to express thoughts and emotions

30. 3. Occipital Lobe • Forms the posterior region of each cerebral hemisphere • Responsible for processing incoming visual information and storing visual memories • Known as the visual cortex

31. Occipital Lobe

32. Occipital Lobe Occipital lobe

33. 4. Temporal Lobe • Inferior to lateral sulcus • Involved with hearing, interpreting speech and language and smell • Known as the auditory cortex

34. Temporal Lobe

35. Brodmann Areas (1 century ago)

36. B. The Cerebellum • 2 cerebellar hemispheres • Coordinates and “fine-tunes” skeletal muscle movements • Ensures the pattern of skeletal muscle contractions leads to smooth, coordinated movements • Stores memories of previously learned patterns of movement (writing, piano playing, ping pong, Gameboy) • Cerebrum sends “rough draft” of which movement it wants and cerebellum coordinates and “fine-tunes” the command. • Adjusts skeletal muscle activity to maintain equilibrium and posture

37. Effects of alcohol and drugson the cerebellum • Disturbance of gait • Loss of balance and posture • Inability to touch your finger to your nose with your eyes closed….lack of proper proprioceptive information

38. B. The Cerebellum

39. C. Brainstem • Consists of the following regions: • Mesencephalon • Pons • Medulla oblongata • Brainstem is the most primitive part of the brain.

40. Brainstem

41. 1. Mesencephalon

42. Mesencephalon • Roof is made up of 4 “bumps” called the corpora quadrigemina (4) • Superior colliculi (2) – visual reflex centers, help track objects within a visual field and coordinates skeletal muscles in order to keep object in visual field • Inferior colliculi (2) – audio reflex centers, involve reflex turning of head in the direction of a sound….BANG!

43. Corpora quadrigemina

44. 2. Pons • Anterior surface of brainstem • Contains nerve pathways Brain Spinal cord

45. 3. Medulla oblongata • Most inferior part of the brainstem and is continuous with the spinal cord • Medulla ends and spinal cord begins at the foramen magnum • Contains several autonomic centers that control the following functions: • Cardiac center – controls heart rate and strength of contraction • Vasomotor center – controls blood pressure by regulating constriction or relaxation of arteriole walls • Respiratory center –controls rate of respiration

46. Medulla oblongata

47. Medulla oblongata

48. Medulla oblongata • Descending axons (motor) cross over to the other side in the medulla oblongata • Ascending axons (sensory) cross over to the other side in the medulla oblongata • Therefore, a stroke (CVA) on one side of the brain will affect the body on the opposite side

49. D. Additional Structures in the Brain • Corpus callosum • Thalamus • Hypothalamus

50. 1. Corpus callosum • A physical connection between the 2 cerebral hemispheres • A pathway of communication between the 2 cerebral hemispheres • Comprised mainly of myelinated axons traveling from one hemisphere to the other hemisphere