Chapter 15 Brain and Cranial Nerves Anterior Central

Chapter 15 Brain and Cranial Nerves

Anterior Central sulcus Posterior Fig. 15. 1 a (left) Parietal lobe Frontal lobe Gyrus Sulcus Parieto-occipital Cerebrum sulcus Lateral sulcus Occipital lobe Temporal lobe Brainstem Pons Cerebellum Medulla oblongata Spinal cord (a) Left lateral view

Cerebral hemispheres Fig. 15. 1 b Anterior Frontal lobe Cerebrum Temporal lobe Occipital lobe Posterior Eye Olfactory bulb Optic nerve Olfactory tracts Optic chiasm Pituitary gland Optic tract Mammillary bodies Midbrain Pons Brainstem Medulla oblongata Cranial nerves Cerebellum

Anterior Fig. 15. 1 c Frontal lobe Central sulcus Parietal lobe Corpus callosum Diencephalon Posterior Parieto-occipital sulcus Occipital lobe Interthalamic adhesion Thalamus Hypothalamus Pineal gland Tectal plate Pituitary gland Temporal lobe Midbrain Brainstem Pons Medulla oblongata Spinal cord Cerebral aqueduct Fourth ventricle Cerebellum

Copyright © Mc. Graw-Hill Education. Permission required for reproduction or display. Fig. 15. 2 (left) Rhombencephalon Prosencephalon Mesencephalon Prosencephalon Rhombencephalon Spinal cord (a) 4 weeks Myelencephalon Telencephalon Optic vesicle Diencephalon Mesencephalon Metencephalon Mesencephalon Optic vesicle Diencephalon Telencephalon Metencephalon Spinal cord Myelencephalon Spinal cord (b) 5 weeks

Copyright © Mc. Graw-Hill Education. Permission required for reproduction or display. Fig. 15. 2 (right) Central sulcus Cerebrum Outline of diencephalon Midbrain Cerebellum Lateral sulcus Midbrain Cerebellum Pons Medulla oblongata Spinal cord (c) 13 weeks (d) 26 weeks Cerebrum Midbrain Pons Medulla oblongata Thalamus Pituitary gland Cerebellum Spinal cord (e) Birth Brainstem

Fig. 15. 3 (a) Gray matter White matter Cortex Inner white matter Corpus callosum Internal capsule Cerebral nuclei Lateral ventricle (a) Coronal section of cerebrum

Cortex (gray matter) (a) Inner gray matter Cerebrum Cerebellum Medulla oblongata Fig. 15. 3 Cerebellum (b) (c) Inner gray matter Gray matter Fourth ventricle Brainstem Outer white matter (b) Cerebellum and brainstem

Fig. 15. 3 Fourth ventricle Inner gray matter Cerebrum Cerebellum Medulla oblongata (b) (c) Outer white matter

Fig. 15. 3 (d) Spinal cord Cerebrum (b) (c) Cerebellum Medulla oblongata Central canal Outer white matter Spinal cord (d) Inner gray matter

Fig. 15. 4 Cranial meninges Skin of scalp Periosteum Bone of skull Arachnoid granulation Periosteal layer Dura mater Meningeal layer Subdural space (potential space) Arachnoid mater Subarachnoid space Arachnoid trabeculae Pia mater Dural venous sinus (superior sagittal sinus) Cerebral cortex • Connective tissue layers that separate soft brain tissue from bones of cranium • protects blood vessels that supply brain • contain and circulate cerebrospinal fluid White matter Falx cerebri

Fig. 15. 4 Cranial meninges • Dura mater dura = tough • dense, irregular connective tissue • meningeal layer deep to periosteal layer (layers usually fused together) • where not fused, dural venous sinuses form; large veins that drain blood from brain Skin of scalp Periosteum Bone of skull Periosteal layer Dura Meningeal layer mater Subdural space Arachnoid mater Subarachnoid space Arachnoid trabeculae Pia mater Cerebral cortex White matter

Fig. 15. 4 Cranial meninges • epidural space is potential space between dura mater and bones • subdural space is potential space under dura mater Skin of scalp Periosteum Bone of skull Periosteal layer Dura Meningeal layer mater Subdural space Arachnoid mater Subarachnoid space Arachnoid trabeculae Pia mater Cerebral cortex White matter

Fig. 15. 4 Cranial meninges • Arachnoid mater (AKA arachnoid membrane) • external to pia mater • resembles spider web • composed of collagen and elastic fibers called arachnoid trebeculae • subarachnoid space filled with trebeculae Skin of scalp Periosteum Bone of skull Periosteal layer Dura Meningeal layer mater Subdural space Arachnoid mater Subarachnoid space Arachnoid trabeculae Pia mater Cerebral cortex White matter

Fig. 15. 4 Cranial meninges • Pia mater pia = tender; mater = mother • deepest meningeal layer • areolar connective tissue • highly vascularized • sticks to brain Skin of scalp Periosteum Bone of skull Periosteal layer Dura mater Meningeal layer Subdural space Arachnoid mater Subarachnoid space Arachnoid trabeculae Pia mater Cerebral cortex White matter

Fig. 15. 5 Cranial Dura Septa • • Dural venous sinus (superior sagittal sinus) Dura mater Falx cerebri Inferior sagittal sinus folds of dura mater 4 partitions of cranial cavity stabilize brain falx cerebri • largest dura septa • midsaggital plane; separates right and left cerebral hemispheres • anterior inferior attachment to crista galli of ethmoid • posterior inferior attachment to internal occipital crest • contains two dural venous sinuses: superior saggital sinus and inferior saggital sinus Dural venous sinus (superior sagittal sinus)

Cranium Fig. 15. 5 Cranial Dura Septa • falx cerebelli • separates right and left cerebellaral hemispheres • contains occipital sinus in posterior vertical border Dura mater Dural venous sinus (superior sagittal sinus) Falx cerebri Inferior sagittal sinus Tentorium cerebelli Straight sinus Transverse sinus Diaphragma sellae Confluence of sinuses Pituitary gland Sigmoid sinus Falx cerebelli Occipital sinus

Cranium Fig. 15. 5 Cranial Dura Septa • tentorium cerebelli Dura mater Dural venous sinus (superior sagittal sinus) Falx cerebri Inferior sagittal sinus • horizontal fold of dura mater Tentorium • separates occipital and cerebelli Diaphragma temporal lobes from sellae cerebellum Pituitary • contains transverse sinuses gland in posterior border • anterior border has tentorial notch; brain stem passes through Straight sinus Transverse sinus Sigmoid sinus Falx cerebelli Occipital sinus Transverse sinus

Cranium Fig. 15. 5 Cranial Dura Septa • diaphragma sellae Dura mater Dural venous sinus (superior sagittal sinus) Falx cerebri Inferior sagittal sinus • smallest dura septa • form roof over sella turica of Tentorium cerebelli sphenoid bone • infundibulum passes through; Diaphragma pituitary gland hangs fromsellae infundibulum Straight sinus Transverse sinus Confluence of sinuses Sigmoid sinus Falx cerebelli Occipital sinus Pituitary gland

Fig. 15. 5 Copyright © Mc. Graw-Hill Education. Permission required for reproduction or display. Cranium Dura mater Dural venous sinus (superior sagittal sinus) Falx cerebri Inferior sagittal sinus Tentorium cerebelli Straight sinus Transverse sinus Diaphragma sellae Confluence of sinuses Pituitary gland Sigmoid sinus Falx cerebelli Occipital sinus Cranium Dura mater Falx cerebri Dural venous sinus (superior sagittal sinus) Inferior sagittal sinus Diaphragma sellae Pituitary gland Straight sinus Tentorium cerebelli Tentorial notch Transverse sinus Confluence of sinuses Falx cerebelli Occipital sinus Brainstem Midsagittal section © The Mc. Graw-Hill Companies, Inc. /Photos and Dissections by Christine Eckel Posterior view

Fig. 15. 6 Brain Ventricles • 4 cavities in brain, connected to each other and central canal of spinal cord • Make and contain cerebrospinal fluid Posterior Third ventricle Anterior Interventricular foramen Lateral ventricles Cerebral aqueduct Fourth ventricle Lateral aperture Median aperture Central canal of spinal cord (a) Lateral view

Posterior Third ventricle Anterior Interventricular foramen Lateral ventricles Cerebrum Lateral ventricle Interventricular foramen Third ventricle Cerebral aqueduct Fourth ventricle Lateral aperture Median aperture Central canal of spinal cord (a) Lateral view Central canal of spinal cord (b) Anterior view

Cerebrospinal Fluid • clear, colorless liquid • bathes surfaces of CNS • brain floats in CSF, preventing it from being crushed under its own weight • cushions brain during sudden movements • transports nutrients and chemicals to brain; removes waste from brain • formed by choroid plexus in each ventricle

Fig. 15. 7 Corpus callosum Ependymal Longitudinal fissure cells Choroid plexus in lateral ventricles Capillary Pia mater Cavity of ventricle (a) Coronal section of the brain, close-up (b) Choroid plexus • Blood plasma secreted through ependymal cells • ependymal cells secrete CSF • CSF circulates through ventricles, enters subarachnoid space, removed from subarachnoid space

Fig. 15. 8 Dural venous sinus (superior sagittal sinus) Pia mater Choroid plexus 1. CSF is produced by the choroid plexus in the ventricles. 5 4 Interventricular foramen CSF flow Lateral aperture Arachnoid villi Venous fluid flow 1 2 3 Choroid plexus of fourth ventricle Median aperture Cerebral aqueduct Dura mater Subarachnoid space Central canal of spinal cord (a) Midsagittal section

Fig. 15. 8 Dural venous sinus (superior sagittal sinus) Pia mater Choroid plexus 2. CSF flows from the third ventricle through the cerebral aqueduct into the fourth ventricle. 5 4 Interventricular foramen CSF flow Lateral aperture Arachnoid villi Venous fluid flow 1 2 3 Choroid plexus of fourth ventricle Median aperture Cerebral aqueduct Dura mater Subarachnoid space Central canal of spinal cord (a) Midsagittal section

Fig. 15. 8 Dural venous sinus (superior sagittal sinus) Pia mater Choroid plexus 3. CSF in the fourth ventricle flows into the subarachnoid space by passing through the paired lateral apertures or the single median aperture, and into the central canal of the spinal cord. 5 4 Interventricular foramen CSF flow Lateral aperture Arachnoid villi Venous fluid flow 1 2 3 Choroid plexus of fourth ventricle Median aperture Cerebral aqueduct Dura mater Subarachnoid space Central canal of spinal cord (a) Midsagittal section

Fig. 15. 8 Dural venous sinus (superior sagittal sinus) Pia mater Choroid plexus 4 Interventricular foramen 4. As the CSF flows CSF flow through the subarachnoid Lateral aperture space, it removes waste products and provides buoyancy to support the brain. 5 Arachnoid villi Venous fluid flow 1 2 3 Choroid plexus of fourth ventricle Median aperture Cerebral aqueduct Dura mater Subarachnoid space Central canal of spinal cord (a) Midsagittal section

Fig. 15. 8 Dural venous sinus (superior sagittal sinus) Pia mater Choroid plexus 4 Interventricular foramen CSF flow Lateral aperture 5. Excess CSF flows into arachnoid villi, then drains into the dural venous sinuses. The greater pressure on the CSF in the subarachnoid space ensures that CSF moves into the venous sinuses without permitting venous blood to enter the subarachnoid space. 5 Arachnoid villi Venous fluid flow 1 2 3 Choroid plexus of fourth ventricle Median aperture Cerebral aqueduct Dura mater Subarachnoid space Central canal of spinal cord (a) Midsagittal section

Fig. 15. 8 Arachnoid Superior villus sagittal sinus Dura mater (meningeal layer) Arachnoid mater Subarachnoid space Pia mater CSF flow Pia mater Dura Choroid plexus mater (periosteal layer) Interventricular foramen Arachnoid villi 5 Dural venous sinus (superior sagittal sinus) 4 Venous fluid flow 1 (b) Arachnoid villus 1. CSF is produced by the choroid plexus in the ventricles. 2. CSF flows from the third ventricle through the cerebral aqueduct into the fourth ventricle. 3. CSF in the fourth ventricle flows into the subarachnoid space by passing through the paired lateral apertures or the single median aperture, and into the central canal of the spinal cord. 4. As the CSF flows through the subarachnoid space, it removes waste products and provides buoyancy to support the brain. 5. Excess CSF flows into arachnoid villi, then drains into the dural venous sinuses. The greater pressure on the CSF in the subarachnoid space ensures that CSF moves into the venous sinuses without permitting venous blood to enter the subarachnoid space. CSF flow Cerebral aqueduct Lateral aperture Choroid plexus of fourth ventricle Median aperture 2 3 Dura mater Subarachnoid space Central canal of spinal cord (a) Midsagittal section

Blood-Brain Barrier Astrocyte • perivascular feet of astrocytes are external layer Nucleus Perivascular feet • tight junctions between cells of capillaries prevent movement of unwanted materials Erythrocyte inside • continuous basement membrane capillary is 3 rd layer • lipid-soluble compounds can diffuse through plasma membrane and enter brain (nicotine, alcohol, some anesthetics, etc. ) Fig. 15. 9 Capillary Continuous basement membrane Tight junction between endothelial cells Nucleus of endothelial cell

Cerebral Hemispheres Left cerebral Right cerebral hemisphere Anterior Frontal lobes Parietal lobes Occipital lobes • Left and right hemispheres separated by longitudinal fissure along midsaggital plane Gyrus Sulcus • hemispheres almost completely separate • communication between hemispheres through tracts, bundles of axons Precentral gyrus Central sulcus • corpus callosum is largest Postcentral gyrus Longitudinal fissure Superior view Fig. 15. 10 Posterior

Cerebral Lobes Left cerebral Right cerebral hemisphere Anterior Frontal lobes Parietal lobes Occipital lobes • five lobes per hemisphere • frontal lobe ends at central sulcus and lateral sulcus on inferior side • concerned with voluntary motor functions, concentration, verbal communication, decision making, planning, personality • precentral gyrus is mass of nervous tissue anterior to central sulcus • parietal • temporal • occipital • insula (not visible at surface) Gyrus Sulcus Precentral gyrus Central sulcus Postcentral gyrus Longitudinal fissure Superior view Posterior

Cerebral Lobes Left cerebral Right cerebral hemisphere Anterior Frontal lobes Parietal lobes Occipital lobes • five lobes per hemisphere • parietal lobe bordered by central sulcus, longitudinal fissure, and parieto-occipital sulcus • involved with general sensory functions (ex. evaluating shape and texture of objects being touched) • temporal lobe is inferior to lateral sulcus • involved with hearing and smell Gyrus Sulcus Precentral gyrus Central sulcus Postcentral gyrus Longitudinal fissure Superior view Posterior Copyright © Mc. Graw-Hill Education. Permission required for reproduction or display.

Cerebral Lobes Left cerebral Right cerebral hemisphere Anterior Frontal lobes Parietal lobes Occipital lobes • five lobes per hemisphere • occipital lobe • resonsible for processing incoming visual information and storing visual memories • insula (not visible at surface) • deep to lateral sulcus • probably involved in interoceptive awareness, emotional responses, empathy, and interpretation of taste Gyrus Sulcus Precentral gyrus Central sulcus Postcentral gyrus Longitudinal fissure Superior view Posterior

Fig. 15. 11 Frontal lobe (retracted) Primary motor cortex (in precentral gyrus) Central sulcus Premotor cortex Parietal lobe Primary somatosensory cortex (in postcentral gyrus) Somatosensory association area Frontal eye field Motor speech area (Broca area) Parieto-occipital sulcus Wernicke area Insula Primary gustatory cortex Gnostic area Lateral sulcus Temporal lobe (retracted) Primary auditory cortex Auditory association area Primary olfactory cortex Occipital lobe Primary visual cortex Visual association area

Primary motor cortex (within precentral gyrus) Lip s a ja w Knee Trunk Neck Toes Ankle Genitals Toes e Ey No ey nd Hip Leg Foot Hip Should er Arm E For lbow ear m W Lit r tle Hanist R f i mi ing ng d dd f er Ind le fininger g ex fin er Th ger um b Ey el Fa id an ce d Trunk ck lder b Shou um Ne Arm w Elbo rm Forea t Wris d er Han fing ger r tle fin e Lit ng fing er Ri dle fing id x M de In Th Primary somatosensory cortex (within postcentral gyrus) se ce Fa , th tee d jaw , s Lip s, an gum e Tongu eb all Tong ue nx Phary Intra-abdominal Pharynx Lateral Medial Primary somatosensory cortex Medial Lateral Primary motor cortex Fig. 15. 12

How do we learn what different parts of the brain do? • Study people who have had brain injuries • Ex. Phineas Gage • railroad construction worker • injured Sept. 1848: tamping rod (13 pounds, 3. 5 feet long) went through his head

Page 457 Copyright © Mc. Graw-Hill Education. Permission required for reproduction or display. Computer reconstructions of Phineas Gage’s skull injury. Dornsife Neuroscience Imaging Center and Brain and Creativity Institute, University of Southern California. H. Damasio et al. , “The return of Phineas Gage: Clues about the brain from the skull of a famous patient, ” Science, 264(5162): 1102 -1105 © 1994 American Association for the Advancement of Science

• Gage’s personality changed after he recuperated • became irreverent and profane, incapable of making decisions • Research into his case led to understanding of working of frontal lobe

Other cases • Rep. Gabrielle Giffords • Shot while talking to constituents • Bullet entered left side of forehead, exited at back of left side of head • After recovery, can understand language, but has difficulty speaking clearly

• Dr. John Hamdi, retired professor of chemistry • suffered a skull fracture during a skiing accident, then a stroke • paralysis on the right side of the body • inability to speak properly • took great effort to say “I want water. ” • “Dr. Hamdi could convey the general sense of what he was trying to say, but his speech was slow and effortful, conveyed in a flat monotone, filled with pauses, and almost completely devoid of [grammatical structure]. ” • Writing also had bad grammatical structure • Could sing perfectly well, without missing any words From The Tell-Tale Brain by V. S. Ramachandran

Fig. 15. 11 Frontal lobe (retracted) Primary motor cortex (in precentral gyrus) Central sulcus Premotor cortex Parietal lobe Primary somatosensory cortex (in postcentral gyrus) Somatosensory association area Frontal eye field Motor speech area (Broca area) Parieto-occipital sulcus Wernicke area Insula Primary gustatory cortex Gnostic area Lateral sulcus Temporal lobe (retracted) Primary auditory cortex Auditory association area Primary olfactory cortex Occipital lobe Primary visual cortex Visual association area

Functional areas of the cerebrum • Primary motor cortex (AKA somatic motor area) • controls voluntary skeletal muscle activity • neurons cross to the opposite side of brainstem and spinal cord • left primary motor cortex controls right side of body • information processed in premotor cortex (AKA somatic motor association area) anterior to primary motor cortex • coordinates learned, skilled motor activities (moving eyes while reading) • Frontal eye field • superior surface of middle frontal gyrus • control and regulate eye movement for reading, and coordinating binocular vision • Sometimes considered part of motor cortex

Page 469 Frontal Lobotomy • Introduced as “cure” for mental disturbances, especially violence • 1936 by Portuguese neurologist Egas Moniz Copyright © Mc. Graw-Hill Education. Permission required for reproduction or display. Prefrontal cortex • no existing treatments except heavy sedation, physical restraint • Destroyed connections between prefrontal areas and rest of brain • Moniz earned Nobel prize in 1949 • Procedure became overused, had serious side effects; was not effective on many patients Needle probe Orbit

Functional areas of the cerebrum • Motor speech area (AKA Broca area) • interolateral portion of left frontal lobe • responsible for controlling muscular movements for speaking • Wernicke area • overlaps parietal and occipital lobes on left hemisphere • association area involved in recognizing, understanding and comprehending spoken or written language

Functional areas of the cerebrum • Primary somatosensory cortex • located in postcentral gyrus of parietal lobes • receives somatic sensory information (touch, pressure, pain, temperature) somatosensory association area • Somatosensory association area located posterior to somatosensory cortex • interprets sensory information • integrates sensations to determine texture, temperature, pressure, shape

Functional areas of the cerebrum • Primary visual cortex • receives and processes incoming visual information • Primary auditory cortex • receives and processes incoming auditory information • Primary gustatory cortex • located in insula • processes taste information • Primary olfactory cortex • provides conscious awareness of smells somatosensory association area

Functional areas of the cerebrum • Visual association area • located in occipital lobe • surrounds primary visual area • enables processing of visual information • analyze color, movement, and form to identify what it is we are seeing • integrates disparate shapes and colors into a single things (such as a face) visual cortex visual association area

Functional areas of the cerebrum • Gnostic area • covers regions of parietal occipital, and temporal lobes • integrates sensory, visual, and auditory information • provides comprehensive understanding of complex sets of stimuli

Fig. 15. 11 Frontal lobe (retracted) Primary motor cortex (in precentral gyrus) Central sulcus Premotor cortex Parietal lobe Primary somatosensory cortex (in postcentral gyrus) Somatosensory association area Frontal eye field Motor speech area (Broca area) Parieto-occipital sulcus Wernicke area Insula Primary gustatory cortex Gnostic area Lateral sulcus Temporal lobe (retracted) Primary auditory cortex Auditory association area Primary olfactory cortex Occipital lobe Primary visual cortex Visual association area

What does that tell us? • If someone can understand language but not speak properly (Gabby Giffords and Dr. Hamdi) where is the damage? • What areas are not damaged?

Fig. 15. 13 Arcuate fibers (a) Sagittal view Association Tracts Corpus callosum Longitudinal fasciculi Parietal lobe Longitudinal fissure Cortex Frontal lobe Temporal lobe Occipital lobe • groups of axons with similar function • connect different regions of same hemisphere Commissural tracts (in corpus callosum) Cerebral nuclei Lateral ventricle Thalamus Lateral sulcus Third ventricle Projection tracts Pons Decussation in pyramids Medulla oblongata (b) Coronal section

Fig. 15. 13 Arcuate fibers Longitudinal fasciculi (a) Sagittal view Corpus callosum • Arcuate fibers are short and connect neighboring gyri in same hemisphere • ex. tract connects primary motor cortex to motor association area Frontal lobe Temporal lobe • Longer association tracts are composed of longitudinal fasciculi; connect gyri in different lobes of same hemisphere • ex. tract connects Wernicke area to motor speech (Broca) area

Fig. 15. 13 • Commissural tracts connect two hemispheres Longitudinal fissure Cortex Commissural tracts (in corpus callosum) Cerebral • commissure = nuclei axonal bridge • ex. Corpus callosum Lateral ventricle Thalamus sulcus Third ventricle Projection tracts Decussation in pyramids Pons Medulla oblongata (b) Coronal section

Fig. 15. 13 • Projection tracts link cerebral cortex to inferior brain regions and spinal cord Longitudinal fissure Cortex Commissural tracts (in corpus callosum) Cerebral nuclei Lateral sulcus Lateral ventricle Thalamus Third ventricle Projection tracts Decussation in pyramids Pons Medulla oblongata (b) Coronal section

Fig. 15 Diencephalon Corpus callosum Fornix Septum pellucidum Choroid plexus in 3 rd ventricle Habenular nucleus Epithal. Pineal gland amus Posterior commissure Interthalamic adhesion Anterior commissure Tectal plate Midsagittal section

Diencephalon • Sandwiched between inferior regions of cerebral hemispheres

Diencephalon • Epithalamus • includes pineal gland (secretes melatonin, regulates circadian rhythm)

Diencephalon • Thalamus • made of 12 thalamic nuclei • axons from nuclei project into regions of cerebral cortex • impulses from all conscious senses except olfaction converge on thalamus, relayed to the primary somatosensory cortex

Diencephalon • Hypothalamus • Master control of autonomic nervous system and endocrine system (hormones) • Regulation of body temperature • Control of emotional behavior, and food and water intake • Regulation of circadian (sleep-wake) rhythms

Fig. 15. 18 Diencephalon Thalamus Pineal gland Thalamus Optic chiasm Diencephalon Infundibulum Mammillary bodies Superior colliculi Tectal Midbrain plate Inferior colliculi Optic tract Cerebral peduncle Superior cerebellar peduncle Midbrain Optic tract Middle cerebellar peduncle Pons Cranial nerves Pons Pyramids Olive Decussation of the pyramids Medulla oblongata Inferior cerebellar peduncle Brainstem Medulla oblongata Fourth ventricle Olive Nucleus cuneatus Nucleus gracilis (b) Posterolateral view (a) Anterior view

Fig. 15. 18 Midbrain Diencephalon Thalamus Pineal gland • somatic motor axons pass through from primary motor Superior cortex to spinal cord Midbrain colliculi Tectal • integrates information from Inferior plate cerebrum and cerebellum colliculi • controls involuntary Pons movement of erector spinae muscles • produce neurotransmitter dopamine Medulla oblongata Optic tract Cerebral peduncle Superior cerebellar peduncle Middle cerebellar peduncle Inferior cerebellar peduncle Fourth ventricle Olive Nucleus cuneatus Nucleus gracilis (b) Posterolateral view

Fig. 15. 19 Midbrain • substantia nigra houses clusters of Tectum neurons that • affects movement, Tegmentum emotional response, ability to experience pleasure and pain • degeneration causes Parkinson’s disease Posterior Superior colliculus Cerebral aqueduct Reticular formation Periaqueductal gray matter Nucleus for oculomotor nerv Medial lemniscus Red nucleus Substantia nigra Cerebral peduncle Oculomotor nerve (CN III) Anterior Midbrain, cross-sectional view

Page 470 Boxer Muhammad Ali and actor Michael J. Fox are two famous Parkinson disease patients. © Kenneth Lambert/AP Photo

Fig. 15. 18 Midbrain • Tectum = tectal plate • contains sensory nuclei • superior colliculi are visual reflex center; help visually track moving objects and control reflexes in response to visual stimulus • inferior colliculi are auditory reflex centers; control reflexive response to sound Diencephalon Thalamus Pineal gland Superior colliculi Midbrain Tectal Inferior plate colliculi Pons Medulla oblongata (b) Posterolateral view

Fig. 15. 18 Diencephalon Pons • Contains sensory and motor tracts that connect brain to spinal cord • helps regulate breathing Pineal gland Superior colliculi Midbrain Tectal plate Inferior colliculi Pons Medulla oblongata (b) Posterolateral view

Fig. 15. 21 Medulla oblongata • Continuous with spinal cord • All communication between brain and spinal cord goes through medulla • Pyramids hold corticospinal (pyramidal) tracts • some cross to opposite side of brain at decussation of the pyramids • Olives relay sensory impulses to cerebellum, especially proprioceptive information Posterior Fourth ventricle Olive Pyramid Inferior olivary nucleus Decussation of pyramids Spinal cord Anterior (a) Medulla oblongata, cross-sectional view

Fig. 15. 22 Cerebellum (a) Midsagittal section Cerebral aqueduct • convoluted surface covered by cerebellar cortex Midbrain • folia = folds in cerebellum • arbor vitae = white matter Fourth ventricle • functions: Pons • fine-tunes and coordinates skeletal muscle movements • enables precise, smooth movements Medulla • maintains posture and equilibrium oblongata Tectal plate White matter (arbor vitae) Folia Gray matter

Fig. 15. 22 Cerebellum • two cerebellar hemispheres • anterior lobe and posterior lobe separated by primary fissure • vermis is narrow band of cortex • separates hemispheres • helps maintain balance Cerebellar hemisphere Primary fissure Anterior lobe Vermis Posterior lobe Folia Posterior (b) Cerebellum, superior view

Fig. 15. 23 Corpus callosum Anterior commissure Limbic System • Includes structures from cerebrum and diencephalon • Processes and experiences emotion • motivation • emotion Olfactory bulb Olfactory tract • emotional memory Midsagittal section Cingulate gyrus Fornix Ant. thalamic nucleus Septal nucleus Mammillary body Hippocampus Amygdaloid body Parahippocampal gyrus

Fig. 15. 23 Corpus callosum Anterior commissure Cingulate gyrus Fornix Ant. thalamic nucleus Septal nucleus Limbic System • Cingulate gyrus = cerebral cortex within longitudinal fissure • receives input from rest of limbic system, focuses attention Olfactory bulb Midsagittal section Mammillary body Hippocampus Amygdaloid body Olfactory tract Parahippocampal gyrus

Fig. 15. 23 Corpus callosum Anterior commissure Cingulate gyrus Fornix Ant. thalamic nucleus Septal nucleus Limbic System • Parahippocampal gyrus = cortical tissue in temporal lobe Mammillary body Hippocampus • works with hippocampus • Hippocampus stores memories, forms long-term memories • Fornix connects hippocampus with other limbic structures Olfactory bulb Midsagittal section Amygdaloid body Olfactory tract Parahippocampal gyrus

Fig. 15. 23 Corpus callosum Anterior commissure Limbic System • Amygdaloid body involved with emotion, especially fear • codes and stores memories based on emotion • olfactory bulbs, tracts, and cortex process odor sensation Olfactory bulb Olfactory tract Midsagittal section Cingulate gyrus Fornix Ant. thalamic nucleus Septal nucleus Mammillary body Hippocampus Amygdaloid body Parahippocampal gyrus

Fig. 15. 24 Cranial nerves Olfactory bulb, termination of olfactory nerve (CN I) Olfactory tract Optic chiasm Optic nerve (CN II) Infundibulum Optic tract Oculomotor nerve (CN III) Trochlear nerve (CN IV) Pons Trigeminal nerve (CN V) Abducens nerve (CN VI) Facial nerve (CN VII) Vestibulocochlear nerve (CN VIII) Medulla oblongata Glossopharyngeal nerve (CN IX) Vagus nerve (CN X) Hypoglossal nerve (CN XII) Accessory nerve (CN XI) Spinal cord Cranial Nerves • Originate on inferior surface of brain • Part of peripheral nervous system (PNS) • Numbered starting with most anterior

Fig. 15. 24 Cranial nerves Olfactory bulb, termination of olfactory nerve (CN I) Olfactory tract Optic chiasm Optic nerve (CN II) Infundibulum Optic tract Oculomotor nerve (CN III) Trochlear nerve (CN IV) Pons Trigeminal nerve (CN V) Abducens nerve (CN VI) Facial nerve (CN VII) Vestibulocochlear nerve (CN VIII) Medulla oblongata Glossopharyngeal nerve (CN IX) Vagus nerve (CN X) Hypoglossal nerve (CN XII) Accessory nerve (CN XI) Spinal cord Cranial Nerves • Some are motor only • • • oculomotor (CN III) trochlear (CN IV) abducens (CN VI) accessory (CN II) hypoglossal (CN XII) • Some are sensory only • olfactory (CN I) • optic (CN II) • vestibulocochlear (CN VIII) • Some carry both signals • • trigeminal (CN V) facial (CN VII) glossopharyngeal (CN IX) vagus (CN X)

Fig. 15. 24 Cranial nerves Olfactory bulb, termination of olfactory nerve (CN I) Cranial Nerves • Mnemonics Olfactory tract Optic chiasm Optic nerve (CN II) Infundibulum Optic tract Oculomotor nerve (CN III) Trochlear nerve (CN IV) Pons Trigeminal nerve (CN V) Abducens nerve (CN VI) Facial nerve (CN VII) Vestibulocochlear nerve (CN VIII) Medulla oblongata Glossopharyngeal nerve (CN IX) Vagus nerve (CN X) Accessory nerve (CN XI) Hypoglossal nerve (CN XII) Spinal cord • • • On Occasion Our Trusty Truck Acts Funny Very Good Vehicle Any How • for function: • • • Oh Once One Takes The Anatomy Final Very Good Vacations Are Heavenly • • • Some Say Marry Money But My Brother Says Big Brains Matter More

Table 15. 8 a Olfactory Nerve (CN I) Olfactory tract (to cerebral cortex) Olfactory bulb Cribriform plate of ethmoid bone • Senses smell Axons of olfactory nerves (CN I)

Optic Nerve (CNII) • Vision from lateral side of eye travels to same side of visual cortex • Vision from medial side of eye crosses in optic chiasm, travels to opposite side of visual cortex Eye Table 15. 8 a-4 Optic nerve (CN II) Optic chiasm Optic tract Lateral geniculate nucleus of thalamus Optic projection axons Visual cortex (in occipital lobe)

Oculomotor Nerve (CNII) • Innervates upper eyelid muscleand 4 of 6 extrinsic eye muscles Medial rectus Inferior rectus Oculomotor Inferior oblique nerve (CN III) Levator Ciliary ganglion palpebrae Inferior rectus superioris Inferior oblique • Superior rectus • • Levator palpebrae superioris Optic nerve Superior rectus To ciliary muscles To sphincter pupillae

Trochlear CNIV • Controls movement of superior oblique eye muscle Optic nerve (CN II) Trochlear nerve (CN IV) Superior oblique

Table 15. 8 c CN V Trigeminal Nerve Ophthalmic branch (V 1) Trigeminal nerve Ophthalmic branch (V 1) Maxillary branch (V 2) Mandibular branch (V 3) Trigeminal ganglion Trigeminal nerve (CN V) Mandibular branch (V 3) Chorda tympani (from facial nerve) Maxillary branch (V 2) Superior alveolar nerves To muscles of mastication Lingual nerve Sensory distribution of trigeminal nerve Inferior alveolar nerve Submandibular ganglion To mylohyoid muscle Mental nerve Primary functions: • controls muscles of mastication • receives sensation from face

Abducens Nerve CN VI • Innervates lateral rectus eye muscle Lateral rectus (cut) Abducens nerve (CN VI) Optic nerve

Facial Nerve CN VII Geniculate ganglion Pons Facial nerve (CN VII) Posterior auricular branch Stylomastoid foramen Parotid gland Branch of lingual nerve of CN V Cervical branch • Innervates muscles of facial expression, lacrimal gland, salivary glands • Conducts taste from anterior 2/3 of tongue Temporal branch Lacrimal gland Greater petrosal nerve Pterygopalatine ganglion Zygomatic branch Chorda tympani nerve (traveling to mandibular branch of CN V) Buccal branch Submandibular ganglion Mandibular branch

Vestibulocochlear Nerve Vestibular branch Semicircular canals CN VIII Internal acoustic meatus Vestibulocochlear nerve (CN VIII) • Conducts equilibrium and auditory information from inner ear to brain • Originates in vestibular nerve and cochlear nerve within middle ear Pons Medulla oblongata Cochlear branch

Glossopharyngeal Nerve CN IX • Receives taste and touch sensation from posterior tongue • Innervates one pharynx muscle and parotid salivary gland Superior ganglion Otic ganglion To parotid gland Inferior ganglion Glossopharyngeal nerve (CN IX) To stylopharyngeus muscle To carotid body and carotid sinus To posterior 1/3 of tongue for taste and general sensation

Table 15. 8 f-2 CN X Vagus Nerve Superior ganglion Inferior ganglion Pharyngeal branch • Visceral sensory information from most internal organs Right vagus nerve (CN X) • Control of pharynx and larynx muscles • Control of smooth and cardiac muscle • Innervates glands, lungs, etc. Superior laryngeal nerve Internal laryngeal nerve External laryngeal nerve Left vagus nerve (CN X) Right recurrent laryngeal branch Left recurrent laryngeal branch Cardiac branch Lung Pulmonary plexus Heart Anterior vagal trunk (formed from left vagus) Kidney Spleen Liver Stomach Pancreas Small intestine Ascending colon Appendix

Accessory Nerve CN XI • Innervates trapezius, sternocleidomastoid, and other pharynx muscles Cervical region of spinal cord (C 1–C 5) Accessory nerve (CN XI) Sternocleidomastoid muscle Trapezius muscle

Hypoglossal Nerve CN XII Hypoglossal nerve (CN XII) • Innervates intrinsic and extrinsic tongue muscles C 1 C 2 C 3 Ansa cervicalis to infrahyoid muscles (cervical nerves running with hypoglossal) To tongue muscles To geniohyoid muscle