The Central Nervous System Brain II Cranial Nerves

1. The Central Nervous System Brain II Cranial Nerves

2. Lecture Overview • Review/Questions from last lecture (Brain I) • Brain II (pp. 84-87) • Cerebrum • Myelinated tracts • Basal ganglia • Sensory areas • Motor areas • Brain coverings (meninges) • Cerebrospinal fluid (CSF) • Ventricular System • Cranial nerves

3. Review of Major Brain Areas 12 1 2 3 11 4 5 6 10 (White part) 7 8 9

4. Summary from Last Lecture

5. Brain - Cerebrum Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 • Over 85% of brain mass, with about 14 billion multipolar neurons in cortex • Lobes names for overlying bones. (See sulci above for divisions)

6. Brain - Cerebrum Upper figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 Lateral Sulcus Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013

7. Dural Folds Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 Falx Cerebri – within longitudinal fissure; separates cerebral hemispheres Tentorium Cerebelli – above cerebellum; separates occipital lobe from cerebellum

8. Myelinated Tracts of Cerebrum Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 • Three types of myelinated tracts form cerebral white matter: • 1. Association – same hemisphere • 2. Commisural – between corresponding gyri in opposite hemispheres (corpus callosum) • 3. Projection (Projector) – Ascending and descending tracts

9. Basal Nuclei (formerly basal ganglia) • nuclei are masses of gray matter in CNS • deep within cerebral hemispheres • three nuclei: caudate nucleus and putamen, (together called the striatum), and the globus pallidus • subconsciouscontrol certain muscular activities, e.g., learned movement patterns • Receive input from entire cerebral cortex. • Relay motor impulses originating in the substantia nigra (where is this?), along with their own output, through the thalamus to the motor cortex to influence muscle movement.

10. Basal Nuclei – Transparent View Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013

11. Brain – Sensory and Motor Areas * 4 6 1 5 8 7 2 3 9 40 (Gnostic) 44 39 22 10 42 18 43 41 19 17 Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 *Somatosensory (in figure) = Somesthetic (in your notes)

12. Meninges of the Brain - dura mater – outer, tough (anchoring dural folds) - arachnoid mater – web-like - pia mater – inner, delicate *Singular of meninges is meninx - Subdural space – like interstitial fluid - Subarachnoid space – CSF Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013

13. Cerebrospinal Fluid • ~500 ml/day secreted by choroid plexus of ventricles; only ~120 ml present in subarachnoid space at one time • circulates in all ventricles, cerebral aqueduct, central canal of spinal cord, and subarachnoid space • completely surrounds brain and spinal cord • clear liquid (more Na+ and Cl-, but less K+, Ca2+, glucose, and protein than plasma) • nutritive and protective (shock absorber)

14. Flow of CSF (Monro) (Luscka) (Magendie) Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013

15. Ventricles of the Brain • interconnected cavities • within cerebral hemispheres and brain stem • continuous with central canal of spinal cord • filled with cerebrospinal fluid (CSF) • lateral ventricles (2) • rt/lt cerebral hemispheres • under corpus callosum • third ventricle (1) • between thalamus • fourth ventricle (1) • between cerebellum and pons • cerebral aqueduct connect 3rd and 4th

16. Divisions of the Nervous System You are here CNS PNS

17. Peripheral Nervous System • Cranial nerves arising from the brain • Somatic fibers connecting to the skin and skeletal muscles • Autonomic fibers connecting to viscera • Spinal nerves arising from the spinal cord • Somatic fibers connecting to the skin and skeletal muscles • Autonomic fibers connecting to viscera

18. Cranial Nerves Paired. Numbered (roughly) in the order of their occurrence from anterior to posterior. Abbreviated using N or CN. Figure from: Hole’s Human A&P, 12th edition, 2010

19. The Cranial Nerves

20. Cranial Nerves I and II • Olfactory (I) • sensory • fibers transmit impulses associated with smell Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001 • Optic (II) • sensory • fibers transmit impulses associated with vision

21. Cranial Nerves III, IV, and VI • Abducens (VI) • primarily motor • origin in pons • motor impulses to the lateral rectus (LR) muscles that move the eyes • Oculomotor (III) • primarily motor • origin in midbrain • motor impulses to muscles that • raise eyelids • move the eyes • focus lens • adjust pupil size • Trochlear (IV) • primarily motor • origin in midbrain • motor impulses to the superior oblique (SO) muscles that move the eyes What’s a ganglion? Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

22. Cranial Nerve V • Trigeminal (V) • both sensory and motor • origin in pons • opthalmic division • sensory from surface of eyes (cornea), tear glands, scalp, forehead, and upper eyelids • maxillary division • sensory from upper teeth, upper gum, upper lip, palate, and skin of face • mandibular division • sensory from scalp, skin of jaw, lower teeth, lower gum, and lower lip • motor to muscles of mastication and muscles in floor of mouth Figure from: Hole’s Human A&P, 12th edition, 2010 Major sensory nerve of face

23. Cranial Nerve VII Figures From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson, 2013 • Facial (VII) • both sensory and motor • sensory from taste receptors (ant. 2/3 tongue) • motor to muscles of facial expression, orbicularis oculi, tear glands, and submandibular and sublingual salivary glands • Major MOTOR nerve of face

24. Cranial Nerves VIII and IX • Vestibulocochlear (VIII) • sensory • origin in pons • sensory from equilibrium receptors of ear • sensory from hearing receptors • Glossopharyngeal (IX) • both sensory and motor • origin in medulla • sensory from pharynx, tonsils, tongue (post. 1/3), and carotid arteries • motor to parotidsalivary gland and muscles of pharynx Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001

25. Cranial Nerve X • Vagus (X) • both sensory and motor • origin in medulla • somatic motor tomuscles of speech and swallowing • autonomic motor (parasympathetic) to viscera of thorax and abdomen • CVS and respiratory reflexes • sensory from pharynx, larynx, esophagus, and viscera of thorax and abdomen Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

26. Cranial Nerves XI and XII • Accessory (XI) • primarily motor • origin in medulla/spinal cord • motor to muscles of soft palate, pharynx, larynx, neck (sternocleidomastoid), and back (trapezius) • Hypoglossal (XII) • primarily motor • origin in medulla • motor to muscles of the tongue • impt in speech, mastication, and deglutition Figure from: Martini, Fundamentals ofAnatomy & Physiology, Pearson Education, 2004