Lab 19

1. Lab 19 Cranial Nerves & Brain dissection

2. Today • Intro to the brain • The cranial nerves • Human and sheep brain anatomy • Get to work • CLEAN UP

3. Practical 4 • Thurs 12/6 • 50 points: about half brainmodels and half book figures (with a few fresh brains too) • Know: • List of brain parts on objectives (names and locations only; you will need to know functions on the exam though) • The 12 cranial nerves: names, locations, & functions (shown in blue in this lecture)

4. Externalstructures cerebral hemispheres cerebrum midbrain cerebellum pons medulla central sulcus precentral gyrus postcentral gyrus lateral sulcus longitudinal fissure frontal lobe parietal lobe occipital lobe temporal lobe Internal structures: corpus callosum basal ganglia (nucleus) Caudate Putamen internal capsule thalamus hypothalamus hippocampus amygdala pineal gland pituitary gland reticular formation fornix substantia nigra cingulate gyrus optic chiasm lateral ventricles mammilary bodies corpora quadrigemina inferior colliculus superior colliculus Brief intro to the brain

5. Major Regions and Landmarks Figure 14–1

6. Regions of the Adult Brain • Telencephalon (cerebrum) – cortex, white matter, and basal nuclei • Diencephalon – thalamus, hypothalamus, and epithalamus • Mesencephalon –midbrain (brain stem) • Metencephalon – pons (brain stem), cerebellum • Myelencephalon – medulla oblongata (brain stem)

7. Some terms • nucleus: collection of neuron cell bodies in the CNS • tract: collection of axons in the CNS • ganglia: collection of neuron cell bodies in the PNS • nerve: collection of axons in the PNS • Cranial nerves • Spinal nerves

8. Tour through the brain • From caudal/inferior to rostral/superior

9. The Brain Stem • Includes: • mesencephalon (midbrain) • pons • medulla oblongata • Note: some consider the diencephalon part of the brain stem as well

10. Anatomy:Brain stem Most cranial nerves are located in the brain stem

11. Posterior view

12. Medulla Oblongata

13. Cerebellum

14. Cerebellum – side view

15. Mesencephalon

16. Mesencephalon

17. The Diencephalon • Thalamus • Hypothalamus • Pineal gland • Pituitary gland Figure 14–5a

18. Telencephalon • Cerebrum • Largest part of brain, includes huge wrinkly cerebral hemispheres • Basal nuclei

19. The Basal Nuclei (Ganglia) Figure 14–14b, c

20. Lateral Ventricles

21. The Limbic System Figure 14–11a

22. The Cerebral Cortex • 4 Lobes: • frontal • parietal • temporal • occipital Figure 14–12b

23. Cerebral Cortex landmarks • Lateral sulcus • Longitudinal fissure • Central sulcus • Precentral gyrus (primary motor) • Postcentral gyrus (primary sensory) • Association areas are for integrating information

24. Motor and Sensory Areas of the Cortex • Central sulcus separates motor and sensory areas Figure 14–15a

25. Cranial Nerves

26. Cranial Nerves • 12 pairs connected to brain Figure 14–18

27. Cranial Nerves Figure 13.5a

28. Cranial Nerves • Twelve pairs of cranial nerves arise from the brain • They have sensory, motor, or both sensory and motor functions (mixed) • Each nerve is identified by a number (I through XII) and a name • Four cranial nerves carry parasympathetic fibers that serve muscles and glands

29. 3 main types of Cranial Nerves Sensory nerves: • carry somatic (touch) or special sensory information Motor nerves: • axons of somatic motor neurons Mixed nerves: • mixture of motor and sensory fibers

30. I – Olfactory II – Optic III – Occulomotor IV – Trochlear V – Trigeminal VI – Abducens VII – Facial VIII – Vestibulococlear IX – Glossopharyngeal X – Vagus XI – Accessory XII – Hypoglossal Cranial Nerves On Occasion, Our Trusty Truck Acts Funny; Very Good Vehicle Anyhow

31. Summary of Function of Cranial Nerves Figure 13.5b

32. You need to learn: • Names • Numbers • Locations • Main functions (in blue)

33. Anterior View Lateral view

34. The Olfactory Nerves (I) Figure 14–19

35. Olfactory Nerves (I) • Don’t originate or enter brainstem • Primary function: • special sensory (smell) • Arises from the olfactory epithelium • Passes through the cribriform plate of the ethmoid bone • Fibers run through the olfactory bulb and terminate in the primary olfactory cortex • Functions solely by carrying afferent impulses for the sense of smell

36. The Optic Nerves (II) Figure 14–20

37. Optic Nerves (II) • Enter diencephalon • Primary function: • special sensory (vision) • Arises from the retina of the eye • Optic nerves pass through the optic canals and converge at the optic chiasm • They continue to the thalamus (diencephalon) where they synapse

38. CNs III,IV,VI • All motor only • All innervate eye muscles

39. The Oculomotor Nerves (III) Figure 14–21

40. Oculomotor Nerves (III) • Primary function: • motor (many eyeball movements, pupil constriction, controlling lens shape) • Origin: • mesencephalon • Destination: • somatic motor: 4 extrinsic eye muscles: • visceral motor: parasympathetic NS cell bodies in the ciliary ganglion, got to intrinsic eye muscles

41. The Trochlear Nerves (IV) Figure 14–21

42. Trochlear Nerves (IV) • Smallest CN • Primary function: • motor (eye movement: looking down) • Origin: • mesencephalon • Destination: • superior oblique muscle (that’s it!)

43. The Abducens Nerves (VI) Figure 14–21

44. The Abducens Nerves (VI) • Primary function: • motor (eye movement: looking to the side) • Origin: • pons • Destination: • lateral rectus muscle (just one eye muscle)

45. The Trigeminal Nerves (V) Figure 14–22

46. Trigeminal Nerves (V) • Largest CN – it’s huge! • Primary function: • mixed (sensory and motor) to face All sensory from face; motor for chewing • Three branches • ophthalmic branch (sensory) • maxillary branch (sensory) • mandibular branch (sensory and motor) • Destinations • sensory: sensory nuclei in pons • motor: muscles of mastication

47. The Facial Nerves (VII) Figure 14–23

48. Facial Nerves (VII) • Primary function: • mixed (sensory and motor) to face Motor to facial muscles; taste • sensory: • taste receptors on anterior 2/3 of tongue • motor: • Facial muscles, parasympathetic to lacrimal and salivary glands **Bell’s Palsy

49. The Vestibulocochlear Nerves (VIII) Figure 14–24

50. Vestibulocochlear Nerves (VIII) • Primary function: special sensory • vestibular branch: • balance and equilibrium • cochlear branch: • hearing • Origin: receptors of inner ear • Destination: nuclei in both pons and medulla