ACCORDING TO THE CLASSICAL IDEA FUNCTIONS OF MUSCULOSKELETAL SYSTEM, VISCERAL AND WAYS, CONDUCTING FLUID, CONTROLLED BY SYSTEMS THAT CONDUCTS

Transcription

1 ACCORDING TO THE CLASSICAL IDEA FUNCTIONS OF MUSCULOSKELETAL SYSTEM, VISCERAL AND WAYS, CONDUCTING FLUID, CONTROLLED BY SYSTEMS THAT CONDUCTS IRRITATION; LATEST COMBINED INTO SEPARATE DEPARTMENTS - THE NERVOUS SYSTEM (SYSTEMA NERVOSUM).

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3 NERVOUS SYSTEM CARRIES: THE UNION OF THE BODY INTO A COHERENT WHOLE; PROVIDES REGULATION OF VARIOUS PROCESSES; COORDINATING THE FUNCTIONS OF VARIOUS ORGANS AND TISSUES; INTERACTION WITH THE ENVIRONMENT.

4 CENTRAL NERVOUS SYSTEM (CNS) BRAIN AND SPINAL CORD COMMAND CENTRAL PNS (PERIPHERAL NERVOUS SYSTEM) INCLUDE NERVES THAT GO OUT TO TARGETS IN THE BODY

5 Skull and Vertebrae PROTECTIONS 3 protective layers called meninges 1. Dura Mater (outer layer): consists of connective tissue, blood vessels, and nerves. 2. Arachnoid Mater (middle layer): elastic and weblike membrane. 3. Pia Mater (inner layer): contains nerves and blood vessels. 4. Cerebrospinal fluid a clear watery liquid separates the middle and inner layers acts as a shock absorber exchange of nutrients between blood and nervous system

6 Cerebrum Thalamus Pineal gland Hypothalamus Pituitary gland Cerebellum Pons Medulla oblongata Spinal cord

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8 THE BRAIN THE BRAIN IS THE CONTROL CENTER OF THE BODY IT IS ABOUT 2% OF YOUR BODY WEIGHT AND USES 20% OF YOUR BODY S OXYGEN

9 PARTS OF THE BRAIN DIVIDED INTO THREE PARTS CEREBRUM CEREBELLUM BRAIN STEM

10 Cerebrum 1. Largest part of the brain The main structures: 2 hemispheres - Right and Left Connected by the Corpus Callosum Right side controls - left side of the body Left side controls right side of the body Six LOBES 1. Frontal Lobe 4. Temporal Lobe 2. Parietal Lobe 5. Insular Lobe 3. Occipital Lobe 6. Limbic Lobe

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14 Gray Matter vs. White Matter Gray Matter Absence of myelin in masses of neurons accounts for gray matter of the brain Cerebral Cortex White Matter - Myelinated neurons gives neurons a white appearance inner layer of cerebrum

15 Cerebellum The second largest part of the brain Located below the cerebrum at back of the skull This part is responsible for the balance and muscle coordination

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17 Brain Stem Connects the brain to spinal cord The Two Regions act as switchboard Medulla Oblongata Controls heart rate, breathing rate, and flow of blood through the blood vessels. Pons Relays signals between the cerebrum and the cerebellum

18 Other Structures inside the Brain Thalamus receives messages from sensory receptors; relays information to proper regions of cerebrum Hypothalamus - regulates hunger, thirst, fatigue, anger, etc. Controls the pituitary gland for endocrine function

19 Section 35-3 Cerebrum Thalamus Pineal gland Hypothalamus Pituitary gland Cerebellum Pons Medulla oblongata Spinal cord

20 Cross Section of the Spinal Cord Gray matter Central canal Spinal nerve White matter Meninges

21 Spinal nerves Part of the peripheral nervous system 31 pairs attach through dorsal and ventral nerve roots Lie in intervertebral foramina

22 Spinal nerves continued Division based on vertebral locations 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal Cauda equina ( horse s tail ): collection of nerve roots at inferior end of vertebral canal

23 Spinal nerves continued Note: cervical spinal nerves exit from above the respective vertebra The root of 1 spinal nerve - from above C1 The root of 2 spinal nerve from between C1 and C2, etc. Clinically, for example when referring to disc impingement, both levels of vertebra mentioned, e.g. C6-C7 disc impinging on root 7 Symptoms usually indicate which level is damaged More about spinal nerves in the peripheral nervous system lecture

24 Protection: Bone Meninges CSF (cerebrospinal fluid) 3 meninges: dura mater (outer) arachnoid mater (middle) pia mater (inner) 3 potential spaces epidural: outside dura subdural: between dura & arachnoid subarachnoid: deep to arachnoid

25 Spinal cord coverings and spaces eneral_esi_epidural_space.jpg

26 LP (lumbar puncure) = spinal tap (needle introduced into subdural space to collect CSF) Lumbar spine has to be flexed so the needle can pass between spinous processes Originally thought to be a narrow fluid-filled interval between the dural and arachnoid; now known to be an artificial space created by the separation of the arachnoid from the dura as the result of trauma or some ongoing pathologic process; in the healthy state, the arachnoid is attached to the dura and a naturally occurring subdural space is not present. Epidural space is external to dura Anesthestics are often injected into epidural space Injection into correct space is vital; mistakes can be lethal

27 Spinal cord anatomy Posterior median sulcus ( p ) Anterior median fissure ( a ) White matter (yellow here) Gray matter (brown here) p a

28 Gray/White in the spinal cord Hollow central cavity ( central canal ) Gray matter surrounds cavity White matter surrounds gray matter (white: ascending and descending tracts of axons) H shaped on cross section Dorsal half of H : cell bodies of interneurons Ventral half of H : cell bodies of motor neurons No cortex (as in the brain) Dorsal (posterior) white gray Central canal Ventral (anterior)

29 Spinal cord anatomy Gray commissure with central canal Columns of gray running the length of the spinal cord Posterior (dorsal) horns (cell bodies of interneurons) Anterior (ventral) horns (cell bodies of motor neurons) Lateral horns in thoracic and superior lumbar cord * * *

30 Spinal Cord Connects the brain and rest of the body (PNS) 31 pairs of spinal nerves Reflexes processed directly by spinal cord Reflex quick, automatic, unconscious responses Result of reflex arcs shortest nerve pathways

31 White matter of the spinal cord (myelinated and unmyelinated axons) Ascending fibers: sensory information from sensory neurons of the body up to the brain Descending fibers: motor instructions from the brain to spinal cord Stimulates contraction of body s muscles Stimulates secretion from body s glands Commissural fibers: white-matter fibers crossing from one side of cord to the other Most pathways cross (or decussate) at some point Most synapse switch two or three times along the way, e.g. in the brain stem, thalamus or other

32 The Brain: embryonic development Develops from neural tube The brain subdivides into Forebrain Midbrain Hindbrain These further divide, each with a fluid filled region: ventricle, aqueduct or canal Spinal cord also has a canal Two major bends, or flexures, occur (midbrain and cervical)

33 Brain development Learn forebrain, midbrain and hindbrain in (b) See next color coded pics in reference to (d) Learn (e) Encephalon means brain (otherwise you do not need to learn c )

34 Space restrictions force cerebral hemispheres to grow posteriorly over the rest of the brain, enveloping it Cerebral hemispheres grow into horseshoe shape (b and c) Continued growth causes creases, folds and wrinkles

35 Cerebral hemispheres Diencephalon Thalamus Hypothalamus Brain stem Midbrain Pons Medulla Cerebellum Spinal cord Anatomical classification

36 Cerebrum Diencephalon Brainstem Cerebellum Parts of Brain

37 Usual pattern of gray/white in CNS White exterior to gray Gray surrounds hollow central cavity Two regions with additional gray called cortex Cerebrum: cerebral cortex Cerebellum: cerebellar cortex

38 Gray and White Matter Like spinal cord but with another layer of gray outside the white Called cortex Cerebrum and cerebellum have Inner gray: brain nuclei (not cell nuclei) Clusters of cell bodies Remember, in PNS clusters of cell bodies called ganglia More words: brains stem is caudal (toward tail) to the more rostral (noseward) cerebrum

39 Ventricles Central cavities expanded Filled with CSF (cerebrospinal fluid) Lined by ependymal cells (these cells lining the choroid plexus make the CSF: see later slides) Continuous with each other and central canal of the spinal cord In the following slides, the ventricles are the parts colored in blue

40 Lateral ventricles Pair, horseshoe shape In cerebral hemispheres Anterior are close, separated only by thin Septum pellucidum

41 Third ventricle In diencephalon Connections Interventricular foramen Cerebral aqueduct

42 Fourth ventricle In the brainstem Dorsal to pons and top of medulla Holes connect it with subarachnoid space

43 Subarachnoid space Aqua is blue on this pic Under thick cover of the brain Filled with CSF also Red: choroid plexus (more later)

44 Anatomy of Surface Gyri (plural of gyrus) Elevated ridges Entire surface Grooves separate gyri A sulcus is a shallow groove (plural, sulci) Deeper grooves are fissures

45 Gyri (plural of gyrus) Elevated ridges Entire surface Grooves separate gyri A sulcus is a shallow groove (plural, sulci) Deeper grooves are fissures

46 Parts of Brain Cerebrum Diencephalon Brainstem Cerebellum

47 simplified Back of the brain: perception Top of the brain: movement Front of the brain: thinking

48 Drugs and the Nervous System Drug any substance, other than food that changes the structure or function of the body Legal Illegal

49 Neuron: Nerve Cell Basic structural unit of the nervous system Consists of: nucleus nerve fibers/dentrites axon

50 Nerves Sensory Nerves: carry messages to the brain and spinal cord from the body Motor Nerves: carry messages from the brain and spinal cord to the body

51 Connecting or Mixed Nerves: Carry both sensory and motor messages

52 Divisions of CNS CNS - central nervous system: consists of the brain and spinal cord

53 Peripheral Nervous System a. any nerves outside the brain and spinal cord b. Autonomic nervous system: controls involuntary body functions

54 Central Nervous System 1. Brain: a. Mass of nerve tissue b. Protected by membranes & the cranium or skull

55 C. Cerebrum Largest section of the brain Responsible for: reasoning, thought, memory, speaking, sensation, sight, hearing, voluntary body movement

56 D. Cerebellum Responsible for: coordination of muscles, balance, posture, & muscle tone

57 Responsible for: E. Midbrain conducting impulses between brain parts certain eye reflexes

58 Pons Responsible for: conducting messages to other parts of the brain Reflex actions such as chewing, production of saliva

59 G. Medulla Oblongata Lowest part of the brain stem Connects to the spinal cord Responsible for: regulating heart beat, respirations, swallowing, coughing, b/p

60 2. Spinal Cord Goes down back of the body from Medulla Oblongata Surrounded and protected by vertebrae Responsible for reflex actions Carries sensory and motor messages

61 3. Meninges Consists of 3 membranes Covers and protects the brain and spinal cord

62 C. Dura mater Three Membranes thick, tough outer layer D. Arachnoid mater middle delicate weblike layer E. Pia mater inner most layer with blood vessels to nourish the nerves

63 4. Ventricles Four hallow spaces located in the middle of the brain. Connected to each other Filled with fluid called cerebrospinal fluid

64 Cerebrospinal Fluid Circulates continuously Serves as shock absorber to protect the brain and spinal cord

65 carries nurients to parts of the brain and spinal cord helps to remove metabolic products & wastes after circulation, absorbed into the blood vessels of the dura mater.

66 Peripheral Nervous System Made of all nerves outside the brain and spinal cord Consists of cranial and spinal nerves

67 A. Cranial Nerves 12 pairs & their branches Some responsible for special senses: sight, hearing, taste, smell Others receive sensations: touch, pressure, pain, temperature

68 B. Spinal Nerves 31 pairs & their branches Carries messages to & from the spinal cord Both sensory and motor nerves

69 31 spinal nerves: 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal

70 3. Autonomic Nervous System Helps maintain a balance in involuntary functions of the body. But allows the body to react in times of emergency.

71 2 divisions of ANS Sympathetic nervous system acts in emergency cases Parasympathetic counter acts the sympathetic NS after the emergency

72 SNS increase heart rate increase resp. rate increase b/p decrease digestive system activity PNS decrease heart rate decrease resp. rate decrease b/p increase digestive system activity

73 Cerebral hemispheres: note lobes Divided by longitudinal fissure into right & left sides Central sulcus divides frontal from parietal lobes

74 Lateral sulcus separates temporal lobe from parietal lobe Parieto-occipital sulcus divides occipital and parietal lobes (not seen from outside) Transverse cerebral fissure separates cerebral hemispheres from cerebellum

75 Coronal section Note: longitudinal fissure, lateral sulcus, insula Note: cerebral cortex (external sheet of gray matter), cerebral white, deep gray matter (basal ganglia)

76 Cerebral cortex Executive functioning capability Gray matter: of neuron s bodies, dendrites, short unmyelinated axons 100 billion neurons with average of 10,000 contacts each No fiber tracts (would be white) 2-4 mm thick (about 1/8 inch) Brodmann areas (historical: 52 structurally different areas given #s) Neuroimaging: functional organization (example later)

77 Prenatal life: genes are responsible for creating the architecture of the brain Cortex is the last to develop and very immature at birth Birth: excess of neurons but not inter-connected 1 st month of life: a million synapses/sec are made; this is genetic 1 st 3 years of life: synaptic overgrowth (connections) After this the density remains constant though some grow, some die Preadolescence: another increase in synaptic formation Adolescence until 25: brain becomes a reconstruction site Connections important for self-regulation (in prefrontal cortex) are being remodeled: important for a sense of wholeness Causes personal turbulence Susceptible to stress and toxins (like alcohol and drugs) during these years; affects the rest of one s life The mind changes the brain (throughout life) Where brain activation occurs, synapses happen When pay attention & focus mind, neural firing occurs and brain structure changes (synapses are formed) Human connections impact neural connections (ongoing experiences and learning include the interpersonal ones)

78 Cerebral cortex All the neurons are interneurons By definition confined to the CNS They have to synapse somewhere before the info passes to the peripheral nerves Three kinds of functional areas Motor areas: movement Sensory areas: perception Association areas: integrate diverse information to enable purposeful action

79 Sensory areas Posterior to central sulcus Primary somatosensory cortex: postcentral gyrus of parietal lobe (allows conscious awareness of sensation and the ability to localize it: where the sensation is from) Somatosensory association area: behind it (understanding of what is being felt: the meaning of it)

80 From special sense organs Sight: occipital lobe Primary visual cortex (17) Handles info from contralateral retina (right ½ of visual field is on left side) Map of visual space If damaged: functionally blind because no conscious awareness of sight Visual association area (18 & 19) Face recognition is usually on the right side Hearing: temporal lobe Primary auditory area (41) Auditory association area (22)

81 Refer back to this labeled version as needed

82 fmri: functional magnetic resonance imaging Cerebral cortex of person speaking & hearing Activity (blood flow) in posterior frontal and superior temporal lobes respectively

83 Primary motor area continued Precentral gyrus of frontal lobe Precise, conscious or voluntary movement of skeletal muscles Large neurons called pyramidal cells Their axons: form massive pyramidal or corticospinal tracts Decend through the brain stem and spinal cord Cross to contralateral (the other) side in the brainstem Therefore: right side of the brain controls the left side of the body, and the left side of the brain controls the right side of the body

84 Motor areas continued Broca s area (44): specialized motor speech area Base of precentral gyrus just above lateral sulcus in only one hemisphere, usually left Word articulation: the movements necessary for speech Damage: can understand but can t speak; or if can still speak, words are right but difficult to understand

85 Motor areas continued Premotor cortex (6): complex movements asociated with highly processed sensory info; also planning of movements Frontal eye fields (inferior 8): voluntary movements of eyes

86 Homunculus little man Body map: human body spatially represented Where on cortex; upside down

87 Association Areas Remember Three kinds of functional areas (cerebrum) 1. Motor areas: movement 2. Sensory areas: perception 3. Association areas: everything else

88 Association Areas Tie together different kinds of sensory input Associate new input with memories Is to be renamed higher-order processing areas

89 Prefrontal cortex: cognition This area is remodeled during adolescence until the age of 25 and is very important for well-being; it coordinates the brain/body and inter-personal world as a whole Intellect Abstract ideas Judgment Personality Impulse control Persistence Complex Reasoning Long-term planning Social skills Appreciating humor Conscience Mood Mental flexibility Empathy Executive functioning e.g. multiple step problem solving requiring temporary storage of info (working memory)

90 Wernicke s area Region involved in recognizing and understanding spoken words Junction of parietal and temporal lobes One hemisphere only, usually left (Outlined by dashes) Pathology: comprehension impaired for written and spoken language: output fluent and voluminous but incoherent (words understandable but do not make sense; as opposed to the opposite with Broca s area)

91 Cerebral white matter Extensive communication Areas of cortex with each other Areas of cortex with brain stem and spinal cord Via (mostly) myelinated axon fibers bundled into tracts Commissures Association fibers Projection fibers

92 Commissures: interconnect right and left hemispheres so can act as a whole Corpus callosum is largest Association fibers: connect different parts of the same hemisphere; can be long or short

93 Projection fibers: run vertically Cerebral cortex running down (with motor instructions) Or ascend to cerebral cortex from below (sensory info to the cortex)

94 Corona radiata: spray of projection fibers From precentral (motor) gyrus Combines with sensory fibers traveling to sensory cortex Form a band of fibers called internal capsule* Motor output from brain Sensory input to brain *

95 Projection fibers Corona radiata: fanning out of the fibers Internal capsule: bundled, pass down Commisure Corpus callosum: connects right and left hemispheres Decussation: crossing of pyramidal tracts

96 Cerebral hemisphere gray matter Cortex already reviewed Basal forebrain nuclei: near hypothalamus - related to arousal, learning, memory and motor control Islands of gray matter: nuclei (clusters of neuron cell bodies) Important group is basal ganglia (here ganglia doesn t refer to PNS cell bodies)

97 Basal ganglia Subcortical motor nuclei Part of extrapyramidal system Cooperate with cerebral cortex in controlling movements Most important ones: caudate nucleus, lentiform nucleus composed of putamen and globus pallidus Not part of basal forebrain nuclei (which are related to arousal, learning, memory and motor control) Transverse section

98 Internal capsule passes between diencephalon and basal ganglia and give them a striped appearance Caudate and lentiform sometimes called corpus striatum because of this

99 Basal ganglia Cooperate with cerebral cortex in controlling movements Communicate with cerebral cortex, receive input from cortical areas, send most of output back to motor cortex through thalamus Involved with stopping/starting & intensity of movements Dyskinesias bad movements Parkinson s disease: loss of inhibition from substantia nigra of midbrain everything slows down Huntington disease: overstimulation ( choreoathetosis ) degeneration of corpus striatum which inhibits; eventual degeneration of cerebral cortex (AD; genetic test available) Extrapyramidal drug side effects: tardive dyskinesia Can be irreversible; haloperidol, thorazine and similar drugs

100 Basal ganglia Note relationship of basal ganglia to thalamus and ventricles Transverse section again

101 Diencephalon (part of forebrain) Contains dozens of nuclei of gray matter Thalamus Hypothalamus Epithalamus (mainly pineal)

102 Thalamus (egg shaped; means inner room) Two large lobes of gray matter (over a dozen nuclei) Laterally enclose the 3 rd ventricle Gateway to cerebral cortex: every part of the brain that communicates with cerebral cortex relays signals through a nucleus in the thalamus (e.g. certain nucleus for info from retina, another from ears, etc.) Processing (editing) occurs also in thalamus Coronal section

103 Hypothalamus Forms inferolateral walls of 3 rd ventricle Many named nuclei Coronal section

104 Diencephalon surface anatomy Hypothalamus is between optic chiasma to and including mamillary bodies Olfactory bulbs Olfactory tracts Optic nerves Optic chiasma (partial cross over) Optic tracts Mammillary bodies (looking at brain from below)

105 Diencephalon surface anatomy Hypothalamus is between optic chiasma to and including mamillary bodies (from Ch 14: cranial nerve diagram)

106 Cranial Nerve names Identify as many as you can when looking at model and sheep brain (they will be more fully discussed in Chapter 14)

107 Below thalamus Hypothalamus Main visceral control center Autonomic nervous system (peripheral motor neurons controlling smooth and cardiac muscle and gland secretions): heart rate, blood pressure, gastrointestinal tract, sweat and salivary glands, etc. Emotional responses (pleasure, rage, sex drive, fear) Body temperature, hunger, thirst sensations Some behaviors Regulation of sleep-wake centers: circadian rhythm (receives info on light/dark cycles from optic nerve) Control of endocrine system through pituitary gland Involved, with other sites, in formation of memory

108 Hypothalamus (one example of its functioning) Control of endocrine system through the pituitary gland

109 Epithalamus Third and most dorsal part of diencephalon Part of roof of 3 rd ventricle Pineal gland or body (unpaired): produces melatonin signaling nighttime sleep Also a tiny group of nuclei Coronal section

110 Brain Stem Rigidly programmed automatic behavior necessary for survival Passageway for fiber tracts running between cerebrum and spinal cord Heavily involved with innvervation of face and head (10 of the12 cranial nerves attach to it) Midbrain Pons Medulla oblongata

111 Brain stem Midbrain Pons Medulla oblongata

112 Midbrain Corpora quadrigemina: Cerebral peduncles Contain pyramidal motor tracts XVisual reflexes XAuditory reflexes Periaqueductal gray (flight/flight; nausea with visceral pain; some cranial nerve nuclei) Substantia nigra (degeneration causes Parkingson s disease)

113 Dorsal view Pons Also contains several CN and other nuclei Middle cerebellar peduncles_ 3 cerebellar peduncles (one to each of the three parts of the brain stem)

114 Dorsal view Pons Also contains several CN and other nuclei Middle cerebellar peduncles_ 3 cerebellar peduncles (one to each of the three parts of the brain stem)

115 Medulla oblongata Relays sensory info to cerebral cortex and cerebellum Contains many CN and other nuclei Autonomic centers controlling heart rate, respiratory rhythm, blood pressure; involuntary centers of vomiting, swallowing, etc. Pyramids pyramidal decussation Pyramidal =corticospinal tracts; these are motor tracts which cross over in the decussation. They are named pyramids because they supposedly look like them, and also they originate from pyramidal neurons in the motor cortex. The tracts have the name of origin 1 st, therefore corticospinal tells you they go from the cortex ( cortico- ) to the spinal cord ( -spinal ) see later slides Dorsal view

116 With all labels.

117 Brain Stem in mid-sagittal plane Note cerebral aqueduct and fourth ventricle* * *

118 Cerebellum Two major hemispheres: three lobes each Anterior Posterior Floculonodular Separated from brain stem by 4th ventricle Vermis: midline lobe connecting hemispheres Outer cortex of gray Inner branching white matter, called arbor vitae

119 Functions of cerebellum Smooths, coordinates & fine tunes bodily movements Helps maintain body posture Helps maintain equilibrium How? Gets info from cerebrum re: movements being planned Gets info from inner ear re: equilibrium Gets info from proprioceptors (sensory receptors informing where the parts of the body actually are) Using feedback, adjustments are made Also some role in cognition Damage: ataxia, incoordination, wide-based gait, overshooting, proprioception problems

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122 Fig Copyright 2002 Pearson Education, Inc., publishing as Benjamin Cummings

123 cerebrum corpus callosum thalamus hypothalamus pituitary pons spinal cord Pineal gland cerebellum medulla oblongata

124 Research on neuron development and neural stem cells may lead to new approaches for treating CNS injuries and diseases The mammalian PNS has the ability to repair itself, the CNS does not. Research on nerve cell development and neural stem cells may be the future of treatment for damage to the CNS.

125 Neural Stem Cells. The adult human brain does produce new nerve cells. New nerve cells have been found in the hippocampus. Since mature human brain cells cannot undergo cell division the new cells must have arisen from stem cells.

126 Thalamus Relay center for sensory tracts from the spinal cord to the cerebrum. Contains centers for sensation of pain, temperature, and touch. Involved with emotions and alerting or arousal mechanisms.

127 The Reticular System, Arousal, and Sleep. The reticular activating system (RAS) of the reticular formation. Regulates sleep and arousal. Acts as a sensory filter. Fig

128 Sleep and wakefulness produces patterns of electrical activity in the brain that can be recorded as an electroencephalogram (EEG). Most dreaming occurs during REM (rapid eye movement) sleep.

129 Hypothalamus Regulates: autonomic control center- blood pressure, rate and force of heart contraction, center for emotional response and behavior body temperature water balance and thirst sleep/wake cycles appetite sexual arousal control of endocrine functioning: Acts on the pituitary gland through the release of neurosecretions.

130 Hypothalamus

131 Pituitary

132 thalamus Midbrain Cerebellar peduncles Tectum Superior colliculi Inferior colliculi Substantia nigra Red nuclei Posterior Red nucleus Substantia nigra Anterior

133 Midbrain Contains ascending and descending tracts to the cerebrum and thalamus. Reflex center for eye muscles. Also involved with processing visual and auditory information (connects head movements with visual and auditory stimuli).

134 Pons Connects the two halves of the cerebellum. Regulates breathing.

135 Medulla Oblongata Composed of nerve tracts to and from the brain (these tracts cross over left to right and right to left) May be regarded as an extension of the spinal cord Almost all of the cranial nerves arise from this region

136 Medulla Oblongata Contains control centers for many subconscious activities Respiratory rate Heart rate Arteriole constriction Swallowing Hiccupping Coughing Sneezing

137 Cerebellum Controls and coordinates muscular activity. Important in equilibrium, posture and movement.