Chapter 12- The Central Nervous System

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Central Nervous System

the portion of the vertebrate nervous system consisting of the brain and spinal cord 429


the concentration of nerve tissue and sensory organs at the anterior end of an organism –rostral *toward the snout 430


On the head, towards the nose 430


that part of the central nervous system that includes all the higher nervous centers –pinkish gray tissue -wrinkled –male mass 1600 g. / 3.5 lbs –female mass 1450 g. / 3.2 lbs –both are equal in size 430

Embryonic Development of neural tube

–embryonic ectoderm 1 neurall plate froms form surface ectoderm 2 neural plate iaginates, forming the neural groove, flanked by neural folds 3 neural fold cells migrate to form neural crest, which will form musch of the PNS and many other sturctures 4 neural groove becomes the neural turbe which will form CNS structures –3 weeks ectoderm thickens to form neural plate –4th week, neural tube formed / differentiates rapidly into the CNS –5th week, primary vesciles give rise to secondary brain vesicles –26th week,continued growth causes surfaces to crease and fold 430

Neural plate

Thickened region of ectoderm formed by the third to fourth week of embryonic development, which develops into the neural tube. –ivaginates forming a groove flanked by neural folds 430

Neural Folds

Raised ridges in the neural plate that surround the deepening 430neural groove.

Neural groove

Groove resulting from further growth and thickening of the neural plate. — 430

Neural tube

a tube of ectodermal tissue in the embryo from which the brain and spinal cord develop 430


The outermost of the three primary germ layers in animal embryos; gives rise to the outer covering and, in some phyla, the nervous system, inner ear, and lens of the eye. 430


constituting or relating to a tail 430

Neural Crest

A band of cells along the border where the neural tube pinches off from the ectoderm; the cells migrate to various parts of the embryo and form the pigment cells in the skin, bones of the skull, the teeth, the adrenal glands, and parts of the peripheral nervous system. –some neurons destined to reside in ganglia 430

Primary Brain Vesicles

expansion of the neural tube into forebrain (prosencephalon), midbrain (mesencephalon) and hindbrain (rhombencephalon) 430


Developing forebrain that will become the diencephalon and telencephalon. 430


AKA; prosencephalon top of the brain which includes the thalamus, hypothalamus, and cerebral cortex; responsible for emotional regulation, complex thought, memory aspect of personality 430


the middle part of the brain between the diencephalon and the pons; also called the midbrain –remains undivided 430


AKA; mesencephalon 430


–hind brain –divides into metencephalon and myelencephalon 430


AKA; rhombencephalon 430

Secondary brain vesicles

subdivision of the primary brain vesicles into –telencephalon, diencephalon,-forebrain — metencephalon, and myelencephalon–hindbrain –week 5 430


a subdivision of the brain that, along with the diencephalon, makes up the prosencephalon (forebrain); cerebral hemispheres –endbrain 430


This part/lobe of the brain is responsible for Body temperature regulation, pituitary hormone control, autonomic nervous system responses. Includes: –thalamus, –epithalamus, –Hypothalamus –retina of eye –interbrain 430


the part of the hindbrain that develops into the –pons and the –cerebellum –medulla oblongata –afterbrain 431


The most posterior region of the brain; the area of the brain stem between the metencephalon and the spinal cord, one of the two divisions of the hindbrain (the other is the metencephalon). –spinal brain 431

Cerebral hemispheres

the right and left halves of the cerebrum 431


anterior portion of the brain consisting of two hemispheres 431


a neural structure lying below the thalamus; directs eating, drinking, body temperature; helps govern the endocrine system via the pituitary gland, and is linked to emotion 431


the brain’s sensory switchboard, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla 431


contains the hormone-secreting pineal gland; forms the roof of the diencephalons 431


a band of nerve fibers linking the medulla oblongata and the cerebellum with the midbrain 431


the "little brain" attached to the rear of the brainstem; it helps coordinate voluntary movement and balance 431

Medulla Oblongata

lower or hindmost part of the brain 431

Brain Stem

the part of the brain continuous with the spinal cord and comprising the medulla oblongata and pons and midbrain and parts of the hypothalamus 431

Midbrain Flexures

result from restricted space for brain development 431

Cervical Flexures

When the neural tube bends at the junction of the hindbrain and spinal cord –brain grows more rapidly than membranous skull that contains it 431


the folds in the cerebral cortex that increase the surface area of the brain 431

Embryonic Scheme

Embryonic development 431 12.2

Medical Scheme

effect of space restriction on brain development 431-432


the layer of unmyelinated neurons (the gray matter) forming the cortex of the cerebrum 431

Ventricles, brain

–arise from expansions of lumen cavity of embryonic neural tube –ventricular chambers filled with cerebrospinal fluid –lined by ependymal cells / type of neuroglia 431

Ependymal Cells

type of neuroglial cell found in the ventricles, circulate cerebrospinal fluid 431

Lateral Ventricles

–paried –deep in each cerebral hemisphere –large C shaped chambers, reflect pattern of cerebral growth –Anteriorly / lie close together / separated by thin median membrane called septum pellucidum –communicates with third ventricle in diencephalon 431

Brain Development, space restriction, effect of

–5th week, formation of two major flexures causes the telecephalon and diencephalon to angle toward the brain stem –13th week, development of cerebral hemispheres, also 26th week and birth –initially cerebral surface is smooth –6th month, folding begins, convolutions become more obvious as development continues Figure 12.3 432

Septum Pellucidum

A structure that lies immediately ventral to the corpus callosum, is most prominent anteriorly, and consists of two thin-walled membranes separated by a narrow cleft, forming a small cavity (cavum of septum pellucidum). –transparent wall 432

Third Ventricle

a narrow ventricle in the midplane below the corpus callosum 432

Interventricular foramen

the small opening (on both the right and left sides) that connects the third ventricle in the diencephalon with the lateral ventricle in the cerebral hemisphere –foramen of Monro 432

Forth Ventricle

ventricle located between the brain stem and the cerebellum 432

Cerebral aqueduct

a canal connecting the third and fourth ventricles 432

Lateral Apertures

the side walls of the fourth ventricle that assists in connecting the ventricles to the fluid filled space surrounding the brain 433

Median Aperture

One of the three openings in the roof of the fourth ventricle through which cerebrospinal fluid enters the subarachnoid space of the brain and cord. Also called the foramen of Magendie. 433

Subarachnoid Space

contains cerebrospinal fluid –surrounds brain 433

Cerebral Hemispheres

the right and left halves of the cerebrum –83% of brain mass –elevated ridges of tissue called gyri –shallow grooves / sulci –deeper grooves / fissures 433


elevated ridges on cortical surface of the cerebral hemisphere, which increase the surface area and provide space for additional cortical neurons 433


shallow grooves that seperate gyri 433


deep grooves in the brain –separate large regions of the brain 433

Longitudinal Fissure

divides the cerebrum into right and left cerebral hemispheres 433

Transverse Cerebral Fissure

separates the cerebrum and the cerebellum 433

Central Sulcus

a brain fissure extending upward on the lateral surface of both hemispheres 433

Frontal Lobe

that part of the cerebral cortex in either hemisphere of the brain lying directly behind the forehead 433

Parietal Lobe

that part of the cerebral cortex in either hemisphere of the brain lying below the crown of the head 433

Precentral Gyrus

the convolution of the frontal lobe that is bounded in back by the central sulcus and that contains the motor area , frontal lobe; primary motor cortex; controls somatic motor neurons 433

Postcentral gyrus

the convolution of parietal lobe that is bounded in front by the central sulcus 433

Occipital Lobe

that part of the cerebral cortex in either hemisphere of the brain lying in the back of the head 433

Parietooccipital Sulcus

located on the medial surface of the hemisphere 433

Lateral Sulcus

separates temporal lobe from parietal and frontal lobes 433

Temporal lobe

that part of the cerebral cortex in either hemisphere of the brain lying inside the temples of the head 433


cerebral lobe located deep within lateral sulcus forms part of its floor 433

Basal Nuclei

masses of cerebral gray matter buried deep in the white matter- 3 brain centers: caudate nucleus, putamen, and globus pallidus- receive input from substantia nigra of the midbrain and motor areas of the cerebral cortex, and send signals back to both of these locations- involved in motor control 433

Cerbral Cortex

the intricate fabric of interconnected neural cells that covers the cerebral hemispheres; the body’s ultimate control and information-processing center –gray matter –neuron cell bodies –dendrites –associated glia –blood vessels –NO fiber tracts –Billions of neurons arranged in six layers –2-4mm thick 1/8 in. –40% of brain mass –convolutions triple its surface area –K. Brodmann / 1906 numbered mosiac of 52 cortical areas called Brodmann areas 435

Brodmann Areas

A classification of cortical regions based on subtle variations in the relative appearance of the six layers of neocortex. –52 areas –K. Brodmann / 1906 435

Cerebral Cortex, functions

Functional areas –motor areas –sensory –association –Each hemisphere controls sensory and motor functions of opposite side 2 hemispheres no entirely equal in function / lateralization ( specialization) of cortical functions no functional area of cortex acts alone and conciuos behavior involves the entire cortex in one way or another 435

Motor Areas

functional area of the cerebral cortex that controls voluntary motor functions –posterior part of frontal lobes 1 Primary motor cortex 2 Premotor cortex 3 Broca’s Area 4 Frontal Eye Field 437

Primary Motor Cortex

The region of the cerebral cortex that directly controls the movements of the body; located posterior to the frontal lobes –precentral gyrus of frontal lobe of each hemisphere 435

Pyramidal Cells

a neuron characterized by a pyramid-shaped cell body and elongated dentric tree; found in the cerebral cortex –in gyri –allow concious control –precise or skilled voluntary movements of skeletal muscles –project to spinal cord 435

Pyramidal tracts

massive voluntary motor tracts formed by long axons of pyramidal cells whichh project to the spinal cord 435

Corticospinal Tracts

arise from primary motor cortex, crosses in medulla, descends via lateral corticospinal tract to ventral gray matter (anterior horn cells). 10% of fibers do not cross. Voluntary motor control 435


mapping the body in CNS structures 435

Motor Homunculi

upside – down caricatures representing the motor innervation of body regions 435

Premotor Cortex

anterior to the precentral gyrus in the frontal lobe; controls learned motor skills of a repetitious or patterened nature; coordinates movement of several muscle groups simultaneously or sequentially; involved in planning of movements that deepend on sensory feedback –15% of pyramidal tract fivers –memory bank for skilled motor activities 437

Broca’s Area

controls language expression-an aread of the frontal, usually in the left hemisphere, that directs the muscle movements involved in speech –lies anterior to inferior region of premotor area –becomes active as we prepare to speak and even think about voluntary motor activities other than speech 437

Motor Speech Area

a part of the left frontal lobe responsible for coordinating the muscles used in producing speech. it is often called broca’s area, after its discoverer. is one of the exceptions to the rule that the left side controls the right side of your body. 437

Frontal Eye Field

located partially in and anterior to the permotor cortex and superior to Broca’s area; controls voluntary movement of the eyes; wont control eye reflexes 437

Sensory Areas

–occur in the …… –parietal –insular –temporal –occipital lobes 1 Primary somatosensory Cortex 2 Somatosensory Association Cortex 3 Visual Areas 4 Auditory Areas 5 Olfactory Cortex 6 Gustatory Cortex 7 Visceral sensory Area 8 vetibular -equilibrium Cortex 437-439

Primary Somatosensory Cortex

resides in the postcentral gyrus of the parietal lobe, just posterior to the primary motor cortex; receive information from the general (somatic) sensory receptors in the skin and from proprioceptors (position sense receptors) in skeletal muscles, joints, and tendons; capable of spatial discrimination (identification of body region being stimulated) 437

Spatial Discrimination

identifying the site or pattern of the stimulus (studied by the two-point discrimination test) 437

Somatosensory Homunculus

the "little man" representation of the somatosensory cortex, more sensitive to physical stimuli have more space on homunculus (face, hands, lips) BODY MAP 437

Somatosensory Association Cortex

lies posterior to primary somatosensory cortex and has many connections with it; function is to integrate sensory inputs (temperature, pressure, and so forth) relayed to it via the primary somatosensory cortex to produce an understanding of an object being felt; determines size, texture, and relationships of parts of objects being felt 437

Visual Areas

extreme posterior aspect of occipital lobe- impulses from the eyes by way of the optic nerves and tracts, area 18 is association are for the interpretation of what we see 437

Primary Visual Cortex

on the extreme posterior tip of occipital lobe, but most of it is buried in the calcarine sulcus in medial aspect of occipital lobe; recieves visual information that originates on retina of the eye 437

Primary Visual Striate Cortex

what the Posterior pole of the Occipital lobe is known as because of its striped appearance 437

Visual Association Area

Located next to the primary visual cortex, transforms basic sensations, such as lights, lines, colors, and textures, into complete, meaningful visual perceptions, such as persons, objects, or animals. 438

Auditory Areas

superior margin of themporal lobe abutting lateral sulcus –sound energy excites hearing receptors of inner ear –impulses transmitted to primary auditory cortex –interpreted as pitch loudness and location 438

Auditory Association Area

interpretation of sounds as speech, music, or noise. 438

Olfactory Cortex

lies on medial aspect of the temporal lobe in a small region called piriform lobe which is dominated by hooklike uncus; part of the primitive rhinecephalon which includes all parts of cerebrum that recieves olfactory signals (olfactory tracts and bulbs that extend to the nose); region of conscious awarness of oders 438

Piriform Lobe

olfactory portion of the brain that’s seperated from the rest of the cerebrum by a sulcus at the anterior part 438


Medial surface of the olfactory area deep within the temporal lobe 438


Includes all parts of the creebrum that receive olfactory signals–the orbitofrontal cortex, the uncus and associated regions located on or in the medial aspects of the temporal lobes, and the protruding olfactory tracts and bulbs that extend to the nose. –limbic system 439

Limbic System

a system of functionally related neural structures in the brain that are involved in emotional behavior 439

Gustatory Cortex

region involved in perception of taste stimuli; located in insula deep to temporal lobe 439

Visceral Sensory Area

posterior to gustatory cortex; involved in conscious perception of visceral sensations (ex: upset stomach, full bladder) 439

Vestibular equilibrium cortex

Posterior of the insula and adjacent parietal cortex that is responsible for conscious awareness of balance 439

Multimodal Association Areas

receive inputs from multiple sensory areas; send outputs to multiple areas, including the premotor cortex; allow us to give meaning to information received, store it as memory, compare it to pervious experience, and decide on action to take; each individiual perception come together (hear, see, touch, feel, and smell); can be divided into 3 parts (anterior association area, posterior association area, limbic association area) 439

Anterior Association Area

in frontal lobe, also called prefrontal cortex; the most complicated cortical region of all; involved with intellect, complex learning abilities, recall, and personality; contains working memory needed for judgment, reasoning, persistence, and conscience; development depends on feedback from social enviornment 439

Posterior Association Area

large region encompassing parts of temporal, parietal, and occipital lobes; play role in recognizing patterns and faces, localizing us and our surroundings in space, and binding different sensory inputs into a coherent whole; involved in understanding written and spoken language 439

Limbic Association Area

includes cingulate gyrus, the parahippocampal gyrus, and hippocampus; part of limbic system; provides emotional impact that makes a scene important to us; hippocampus establishes memories that allow us to remember incidents 439

Lateralization of Cortical Functioning

Right or left dominance is based on which hemisphere is dominant for language. 90% of people are left dominate and most are also right-handed. Left hemisphere controls: reasoning, language, math ability, logic. Right hemisphere controls: creativity, intuition, emotion, visual. 439


localization of function on either the right or left sides of the brain 440

Cerebral Dominance

the tendency of each brain hemisphere to exert control over different functions, such as language or perception of spatial relationships –90% of people have left hemisphere dominance over language, math, logic 440

Cerebral White matter

second of three basic regions of each cerebral hemisphere; responsible for communication between cerebral areas and between cerebral cortex and lower CNS centers; consists mainly of myelinated fibers bundled into large tracts 440


Connections of nerve fibers which allow the two hemispheres of the brain to communicate with one another 441

Commissural Fibers

Connect 2 hemispheres and allow communication between them. 441

Corpus Callosum

–largest commissure –lies superior to lateral ventricles –deep within longitudinal fissure 441

Posterior commissures

joining of axons from one side of spinal cord to the other. 441

Anterior Commissures

allows communication between olfactory nerves and oculomotor nerves 441

Projection fibers

type of fiber tract; enter cerebral cortex from lower brain or spinal cord centers or descend from cortex to lower area; motor output leaves through these fibers from cerebral cortex; tie the cortex to rest of nervous system and to body’s receptors and effectors; run vertically 441

Internal Capsule

a compact band formed by projection fibers at the top of the brain stem on each side; pass between the thalamus and some of basal nuclei 441

corona Radiata

–radiating crown –distinctive arrangement of projection tract fibers 441

Basal Nuclei

AKA; Basal Ganglia –deep within cerebral white matter –third basic region of each himisphere –subcortical nuclei 441

Basal Ganglia

–AKA; basal nuclei –deep within cerebral white matter –third basic region of each himisphere –subcortical nuclei –a set of subcortical structures that directs intentional movements 441

Caudate Nucleus

learning, memory, comprehension of language, part of basal ganglia –most of mass of each grop of basal nuclei 441

Caudate Nucleus Putamen

2 components of the basal ganglia that receive input from the cerebral cortex and substantia nigra, send output to the globus pallidus –& globus pallidus constitiute most of the mass of each group of vasal nuclei 441

Globus Pallidus

large subcortical structure, one part of the basal ganglia –most of mass of each group of basal nuclei 441

Lentiform Nucleus

a basal ganglion shaped like a lens and including the outer reddish putamen and the inner pale yellow pallidum –flanks internal capsule laterally 441

Corpus Striatum

the name for lentiform and caudate nuclei because the fibers of the internal capsule that course past and through them give them a striped appearance 441

Subthalamic Nuclei

Located in subthalamus, all subthalamic nuclei are interconnected with ascending +descending nerve tracts, and work together with the basal nuclei cerebellum+ cerebrum. In control of body movement –functionally associated with basal nuclei 441

Substantia Nigra

a layer of deeply pigmented gray matter in the midbrain 441


Forming central core of forebrain and surrounded by cerebral heimspheres the ____________consists largly of three paired stuctures………… Thalamus, Hypothalamus, Epithalamus –these gray matter areas collectively enclose third ventricle 441


large egg-shaped structures of gray matter that form the dorsal subdivision of the diencephalon –bilateral egg shaped nuclei –form superolateral walls of third ventricle –"inner room" 441

Interthalamic Adhesion

AKA; intermediate mass A small, midline mass of gray matter that connects the right and left thalamic bodies –80% of diencephalon 441

Intermediate Mass

Another name for interthalamic adhesion? 441

Ventral posterolateral Nuclei

recieve impulses form general somatic sensory receptors –touch, pressure, pain, ect. 442

Lateral Geniculate Bodies

can be found by following the optic tracts under the pyriform lobes of the brain. these are lateral bulges of the thalamus and are relay centers for vision. many of the fibers within the optic tracts terminate here. 442

Medial Geniculate Bodies

relays centers for sound 442


–below thalamus –caps brain stem –forms inferolateral walls of third ventricle –merging into midbrain inferiorly, hypothalamus extends from optic chisma(cross over point of the optic nerves) to posterior margin of mammillary bodies 443

Mammillary bodies

paired pealike nuclei that bulge anteriorly from the hypothalamus; relay stations in the olfactory pathways 443


A stalk that attaches the pituitary gland to the hypothalamus. –between optic chiasma and mammillary bodies 443

Pituitary Gland

the master gland of the endocrine system –base of hypothalamus 443

Hypothalamus, Homeostatic Roles

1 Autonomic Control center 2 Center for emotional response 3 body temperature regulation 4 Regualtion of food intake 5 regulation of water balance and thirst 6 regualtion of sleep-wake cycles 7 control of endocrine system functioning 443-444

Autonomic control center

This regulates autonomic activity by controlling those areas in the brain and spinal cord involved with activity, thereby influencing blood pressure, heart rate and force of contraction of heart, digestive tract motility, pupillary size and other visceral function. 443

Center for emotional response

–hypothalamus lies at heart of limbic system (emotional part of brain) 444

Body temperature regulation

w/in the hypothalamus, measures temp of blood in the brain 444

Regulation of food intake

When energy inputs and outputs are balanced, the body remains constant. The hypothalamus plays a key role in regulating feeding behaviors. –response to changeing blood levels of certain nutrients or hormones 444

Regulation of water balance and thirst

–hypothalamus –body fluids become too concentrated osmoreceptors are activated- –release antidiuretic hormone ADH > causes kidney to retain water –same conditions also stimulate hypothalamic neurons in thirst cneter causing thirst 444

Regualtion of sleep wake cycles

–hypothalamus helps geuglate sleep through operation of suprachiasmatic nuclesu –daylight / dark cues from visual 444


detect changes in concentration of solutes in body fluids and resultant changes in osmotic activity 444

Suprachiasmatic Nucleus

a cluster of neurons in the hypothalamus that receives input from the retina regarding light and dark cycles and is involved in regulating the biological clock 444

Control of endocrine system functioning

–hypothalamus –helmsman of endocrine system in 2 ways ——releasing and inhibiting hormones —–supraoptic and paraventricular nuclei produce hormones ADH and oxytocin 444

Releasing and inhibiting hormones

produced by the hypothalamus, this controls the release of each of the hormones released by the anterior pituitary 444

Supraoptic Nuclei

One of the two pairs of hypothalamic nuclei that contain neurons whose axons terminate in the posterior pituitary; this pair is located above the optic chiasm, just posterior to the suprachiasmatic nuclei. 444

Paraventricular Nuclei

One of the two pairs of hypothalamic nuclei that contain neurons whose axons terminate in the posterior pituitary; this pair is located on the dorsal surface of the hypothalamus on each side of the third ventricle. 444


contains the hormone-secreting pineal gland; forms the roof of the diencephalons and most dorsal portion 444

Pineal Gland

a small endocrine gland in the brain 444

Pineal Body

a small endocrine gland in the brain 444

Brian Stem, Regions

Mid brain Pons Medulla Oblongata –each roughly an inch long / account for 2.5% of brain mass –nuclei of gray matter embedded in white matter –rigid automatic behaviors necessary for survival –between cerebrum and spinal cord –pathway for fiber tracts running between higher and lower neural centers –associated with 10 of 12 pairs of cranial nerves –innervation of head 445

Mid brain

Between diencephalon and pons –ventral aspect tow bulging cerebral peduncles from vertical pillars 445

Cerebral Peduncles

two bulging structures that contain descending pyramidal motor tracts –little feet of the cerebrum 445

Crus Cerebri

leg of the cerebrum; on each penduncle; contains a large pyramidal motor tract descending toward the spinal cord 445

Superior Cerebellar Peduncles

dorsally connects the cerebellum to the midbrain 445

Cerebral aqueduct

a canal connecting the third and fourth ventricles 446

Periaqueductal Gray matter

The____________surrounds the cerebral aqueduct and is part of the midbrain. It is involved in pain suppression, serves as a link between the fear-perceiving amygdala and the autonomic nervous system nerve pathways that control flight-or-fight and contains 2 nuclei giving rise to cranial nerves III and IV. 446

Oculomotor Nuclei

periaqueductal gray matter also includes nuclei that control two cranial nerves the ___________ and Trochlear nuclei 446

Trochlear nuclei

periaqueductal gray matter also includes nuclei that control two cranial nerves the ___________ and Trochlear nuclei 446

Corpora Quadrigemina

located in the midbrain; contains reflex centers for vision and audition –raise 4 domelike portursions on dorsal midbrain surface 446

Superior Colliculi

Paired gray matter structures of the dorsal midbrain that receive visual information and are involved in direction of visual gaze and visual attention to intended stimuli. 446

Inferior Colliculi

midbrain structures that control sound localization 446

Substantia Nigra

a layer of deeply pigmented gray matter in the midbrain 446

Red Nucleus

A brainstem structure related to motor control. –deep to substantia nigra 446

Reticular Formation

a complex neural network in the central core of the brainstem 447


–bulging brain stem region wedged between teh midbrain and medulla oblongata –dorsally forms part of anterior wall of 4th ventricle –pons = bridge –conduction tracts –two different directions –deep projection fibers fun lingitudinally –complete pathway between higher braincenters and spinal cord a brain structure that relays information from the cerebellum to the rest of the brain 447

Middle Cerebellar Peduncles

extending laterally from pons; large rope-like; contains axons from basis pontis neurons 447

Pontine Nuclei

–relays for "conversations" between motor cortex and cerebellum –trigeminal –abducens –facial nerves 447


the main sensory nerve of the face and motor nerve for the muscles of mastication –issue from pontine nuclei 447


a small motor nerve supplying the lateral rectus muscle of the eye –issue from pontine nuclei 447

Facial nerves

motor and sensory nerves and helps with facial expression and salivary glands –issue from pontine nuclei 447

Medulla Oblongata

lower or hindmost part of the brain –most inferiro part of brain stem at level of foramen magnum of skull 447


large longitudinal ridges –flanking midline on medulla ventral aspect –formed by large pyramidal (corticospinal ) tracts — decend from motor cortex 447

Decussation of the pyramids

area of the medulla where descending motor tracts cross the midline and descend to the body 447

Inferior cerebellar peduncles

fiber tracts connecting medulla and cerebellum –dorsally 447


–lateral to pyramids –oval swellings –do resemble olives –caused by wavy folds of gray matter 447

Inferior Olivary Nuclei

that fold of gray matter that cause the olive oval swellings. These nuclei relay sensory information on the state of stretch of muscles and joints to the cerebellum 447

Hypoglossal nerves

manage tongue (speaking/chewing/swallowing) –emerge from groove between pyramid and olive on each sid of the brain stem 448

Medulla, Cranial nerves

hypoglossal –glossopharyngeal –vagus vestibulocochlear –cochlear nuclei 448

Cochlear Nuclei

Second-order relay neurons (i.e., dorsal and ventral cochlear nuclei); located at the medullopontine junction; associated with the transmission of auditory impulses. 448

Vestibular Nuclear Complex

vestibular nuclei; mediate responses that maintain equilibrium 448

Nucleus Gracilis

receives general sensory info from the lower half of the body –somatic sensory information ascends from spinal cord to somatosensory cortex 448

Nucleus Cuneatus

receives general sensory info from the upper half of the body 448

Medial Lemniscus

Major ascending sensory pathway arising from the nucleus gracilis and nucleus cuneatus, mediating conscious proprioception and tactile sensations from the limbs to the contralateral ventral posterolateral thalamic nucleus. 448

Visceral Motor Nuclei in Medulla

1 Cardiovascular Center 2 Respiratory Centers 3 Various other centers , regulate vomiting, hiccupinng, swallowing, coughing, sneezing –hypothalmus exerts control over many visceral functions by relaying insturctions through medullary reticular centers which carry them out 449

Brain Regions, Major / Functions

Table 449

Cardiovascular Center

the region of the brain stem (medulla oblongata) that regulates the heart 449

Vasomotor Center

adjusts blood vessel diameter to regulate blood pressure 449

Cardiac Center

adjusts rate and force of heart beat 449


the "little brain" attached to the rear of the brainstem; it helps coordinate voluntary movement and balance –11% of brain mass 450

Cerebellar hemispheres

2 lateral hemispheres make up cerebellum along w/vermis in midline 450


the narrow central part of the cerebellum between the two hemispheres –wormlike 450


Small page-like gyri of the cerebellum 450

Cerebellum Fissures

Anterior posterior flocculonodular 450

Dentate Nuclei

The cerebellum has a cortex of gray matter, internal white matter and the____________, small, deeply situated paired masses of gray matter. 450

Purkinje Cells

cell bodies–flat cells in sequential planes. transmits inhibitory message to cells in the nuclei of the cerebellum and vestibular nuclei of the brainstem which in turn sends information to the midbrain and the thalamus 450

Arbor vitae

cerebellar white matter –resembles branching tree 450

Cerebellar Peduncles

Three large pairs of tracts (inferior, middle, and superior) that connect the cerebellum to the rest of the brain stem. 450


on or relating to the same side (of the body) 450

Superior Cerebellar Peduncles

caary instructions from neurons in the deep cerebellar nuclei to the cerebral motor cortex via thalamic relays 450

Middle Cerebellar Peduncles

carry one way communication from the pons to the cerebellum, advising the cerebellum of voluntary motor activities initiated by the motor cortex 450

Inferior Cerebellar Peduncles

connect medulla and cerebellum; convey sensory information to the cerebellum from (1) muscle prorioceptors throughout the body and (2) the vestibular nuclei of the brain stem, which are concerned with equilebrium and balance 450

Cerebellar Processing, Functional Scheme

1 motor areas of cerebral cortex notify cerebellum of intent to initiate voluntary muscle contractions 2 at same time, cerebellum recieves info from porprioceptors through out body > cerebellum evaluates body position and momentum > where body is and where its going 3 cerebelllar cortex calculates best way to coordinate force, direction and extent of meuxle contraction to prevent overshoot, maintain posture, and ensure smooth cordinated movements 4 via superior peduncles, cerebellum dispatches to cerebral motor cortex ‘blueprint’ for coordinating movement cerebellar fibers send information to brain stem muclei > influence motor neurons of spinal cord 450

Cerebellum, Cognitive Function


Brain systems, functional

Lilmbic system Reticular Formation 451

Limbic system

a system of functionally related neural structures in the brain that are involved in emotional behavior –located on medial aspect of cerebral hemisphere and diencephalon 452


–septal nuclei –cingulate gyrus –parphippocampal gyrus –dentate gyrus –C shaped hippocampus –amygdala 452


an almond-shaped neural structure in the anterior part of the temporal lobe of the cerebrum 452

Diencephalon, limbic structures

hypothalamus anterori thalamic nuclei –fornix link systems regions together 452

Anterior Thalamic Nuclei

it relays/ relay nucleus to the limbic system 452


an arched bundle of white fibers at the base of the brain by which the hippocampus of each hemisphere projects to the contralateral hippocampus and to the thalamus and mamillary bodies 452

Cingulate Gyrus

a long curved structure on the medial surface of the cerebral hemispheres 452


hippoamus and amygdala play role in memory 452

Reticular Formation

a complex neural network in the central core of the brainstem –extends through cnetral core of medulla oblongata, pons, and midbrain –loosly clustered neurons inwhat is otherwise white matter –form 3 broad columns along length of brain stem 1 raphe nuclei 2 medial large cell group 3 lateral small cell group of nuclei 452

Raphe Nuclei

a group of nuclei located in the reticular formation of the medulla, pons, and midbrain, situated along the midline; contain serotonergic neurons 452

Medial large cell group


Lateral small cell group of Nuclei


Reticular Activation System

RAS –99% of all sensory stimuli from RAS and cerebral cortex disreguarded as uniportant –damage could reslut in permanent coma specialized nerve fibers through which the reticular formation sends impulses to the cerebral cortex; the reticular formation and reticular activation system are responsible for alertness during the day and can prevent sleeping at night 453

Reticulospinal Tracts

Integrates information from the motor systems to coordinate automatic movements of locomotion and posture.Facilitates and inhibits voluntary movement, influences muscle tone 453

Reticular Motor Nuclei

–vasomotor –cardiac –respiratory centers of medulla are autonomic centers that regulate visceral motor functions 453


monitoring surface electrical activity called brain waves by connecting electrodes on the scalp –EEG 453

Brain Waves

patterns of neuronal electrical activity recorded; generated by synaptic activity at the surface of the cortex 453

Alpha Waves

the relatively slow brain waves of a relaxed, awake state –regular and rhythmic –low amplitude, synchronous –8-13 Hz 454

Beta Waves

rapid brain waves appearing when a person is awake –rhythmic 14-30 Hz 454

Theta Waves

4-7 Hz –more irregular –common in children –uncommon in awake adults / may appear when concentrating 454

Delta Waves

Lowest frequency, Highest Amplitude. Stage 3-4 DEEP SLEEP. Sleepwalking, bedwetting, and NIGHT TERRORS. –retuclar activatin system is damped, such as during anesthesia –awake adults, indicate brain damage 454

Epileptic Seizures

usually have a sudden onset and in most instances stop spontaneously They are usually brief – seconds to minutes Seizures are frequently followed by a period of drowsiness and confusion (post-ictal) –electrical discahrges –no messages can get through — 1 in 100 454

Absence Seizures

May be seen in children who are accused of inattention in class and confused with ADHD. 454

Petit Mal

a seizure (or a type of epilepsy characterized by such seizures) of short duration characterized by momentary unconsciousness and local muscle spasms or twitching 454

Tonic clonic

stiffening-jerking; a major motor seizure involving all muscle groups; previously termed grand mal (big bad) seizure 454

Grand Mal

old name for generalized tonic-clonic seizure 454


a sensation (as of a cold breeze or bright light) that precedes the onset of certain disorders such as a migraine attack or epileptic seizure 454

Vagus Nerve Stimulator

localized limitation – Implanted device Stimulates left vagus nerve 30 seconds/5min 30% experiences 50% reduction Complications: shortness of breath hoarseness sore throat, coughing ear and throat pain nausea and vomiting 454


an alert cognitive state in which you are aware of yourself and your situation 1 involves simultaneous activity of large areas of the cerebral cortex 2 superimposed onother types of neural activity 3 holistic and totally interconnected 455

Consciousness; defined on continuum

1 alertness 2 drowsiness or lethargy 3 stupor 4 coma


a sudden, and generally temporary, loss of consciousness and postural tone, due to inadequate flow of oxygenated blood to the brain (fainting) 455


a state of deep and often prolonged unconsciousness 455

Brain Death

death when respiration and other reflexes are absent 455

Sleep, types

Non rapid eye movement NREM rapid eye movement REM –1st 30-45 min pass through 2 stages of NREM and into NREM satges 3 & 4 called slow wave sleep –blood pressure and heart rate also dercrese with deeper sleep –90 min after sleep NREM stage 4 has been achieved 455

Non-Rapid eye Movement

a recurring sleep state during which rapid eye movements do not occur and dreaming does not occur 455

Rapid Eye Movement

rapid eye movement sleep, a recurring sleep stage during which vivid dreams commonly occur. Also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active. 455

Slow Wave Sleep

The last two stages of sleep, characterized by slow brain waves, deep breathing, and calm heartbeat 455

Sleep Patterns

REM NREM stage 1; relaxation begins; EEG shows alpha waves, arousal is easy –NREM stage 2; irregular EEG with sleep spindles; arousal is more difficult –NREM stage 3; sleep deepens; theta and delta waves appear; vital signs decline –NREM stage 4; EEG is dominated by delta waves; arousal is difficult; bed-wetting, night terrors and sleepwalking may occur 455-456

Circadian Rhythm

the biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle. 455

Sleep Importance

–deprivation of REM becomes moody and depressed –varous personality disorders — 16 hrs for infants –7 1/2 – 8 1/2 in early adult hood –stage 4 often disappears in those over 60


important functionof brain –practically all of the association cortex on left side is involvoed in one way or another 457


loss of spoken or written language due to injury or disease 457

Wernicke’s Area

controls language reception-a brain area involved in language comprehension and expression;usually in the left temporal lobe 457


Short Term Memory STM Long Term Memory LTM, — the power of retaining and recalling past experience 457

Short Term Memory

activated memory that holds a few items briefly, such as the seven digits of a phone number while dialing, before the information is stored or forgotten 457

Long Term Memory

the relatively permanent and limitless storehouse of the memory system. Includes knowledge, skills, and experiences 458

Memory, Transfer

1 Emotional state – Norepinephrine, neurotransmitter involved in memory released in emotionally charged event which helps with recall 2 Rehearsal – enhances memory 3 Association – tying new memory to old memory 4 Automatic Memory Figure 12.22 458

Memory Consolidation

The physical and psychological changes that take place as the brain organizes and restructures information to make it a permanent part of memory. 458

Memory, Categories

Declarative – fact – memories Procedural – skills – memories Motor Memory – riding bike Emotional memory – heart pounding when you hear a rattle snake nearby 458

Declarative memory

The part of long-term memory where factual information is stored, such as mathematical formulas, vocabulary, and life events. 458

Procedural Memory

Memory of learned skills that does not require conscious recollection 458

Motor Memory

Memory that is said to exist "in the hands of a musician." That is, it is unconscious and functions by allowing each action in a series to trigger the next move. A musician, for example, who only has motor memory for a certain piece would be able to physically play that song but unable to mentally rehearse it. 458

Emotional Memory

an acting technique pioneered by Stanislavsky in which the actor recalls the visual and auditory images, or physical circumstances of a real life (or imagined) event in order to relive the emotions accompanying it; also called sense memory or affective memory 458

Memory, Brain Structures Involved

memory stored in regions of bran that need them so new inputs can be associated withh the old –visual memories stored in occipital cortex –memories of music in temporal cortex Sensory and motor inputs > Association Cortex > Basal Nuclei> Thallamus> Premotor Cortex –sensory and motor input flows throught association cortices and relayed via basal nuclei –Dopamine released from Substantia Nigra is necessary for this circuit fot function Picture……… 459

Antograde Amnesia

Caused by damage to hippocampus, Disrupts long-term memory, Can’t form any permanent NEW memories 459

Retrograde Amnesia

loss of memories that were stored before a traumatic event 459

Memory, Molecular Basis

1 neuronal RNA content is altered and newly synthesized mRNA’s are dilivered to axons and dendrites 2 dendritic spinnes change shape 3 unique extracellualr porteins are diposited at synapses involved in LTM 4 number and size off presynaptic terminals may increase 5 more neurotransmitter is released by the presynaptic neurons –aspect of LTP – Long term Potential 460

Long Term Potential

An increase in a synapses firing potential after a brief rapid stimulation. Believed to be the neural basis for learning and memory 460

NMDA Receptor

A hippocampal receptor site that influences the flow of information from one neuron to another across the synapse by controlling the initiation of long-term potentiation. 460

Brain, Protection

–Skull –Membranes / Meninges –Watery cushion / cerebrospinnal fluid –blood-brain barrier / protection from harmful substances 461


three membranes that cover the brain and spinal cord, consisting of the –dura mater / external — pia mater, and –arachnoid mater / internal 1 Cover and protect CNS 2 protect blood vessels and enclose venous sinuses 3 contain cerebrospinal fluid 4 form partitions in the skull 461


singular for meninges

Dura Mater

the outermost (and toughest) of the 3 meninges –two layered sheet –fibrous connective tissue –superficial ——periosteal layer / attached to inner surface of skull – periosteum –deeper ——–Meningeal layer / forms true external covering of brain, continues caudally in vertebral canal as the spinal dura mater 461 – picture

Periosteal layer

Its outer layer forms the periosteum of the skull 460

Meningeal Layer

deeper layer of dura mater forms true external covering of brain 461

Dural Venous Sinuses

Are large veins that drain blood from the brain into the internal jugular 461 – picture

Dural Septa

flat partitions the subdivide cranial cavity; limit excessive movement of brain within the cranium including…. — Falx Cerebri, –Falx Cerebelli, and —-Tentorium Cerebelli 461 – picture

Arachnoid Mater

delicate web-like layer of the meninges; middle layer 461 – picture

Subdural Space

between dura and arachnoid– contains small amount of lymphatic fluid which reduces friction 461

Subarachnoid Space

a space in the meninges beneath the arachnoid membrane and above the pia mater that contains the cerebrospinal fluid 461

Arachnoid Villi

structures that return cerebrospinal fluid to the venous blood in the dural sinuses 461

Pia Mater

the highly vascular innermost of the 3 meninges –delicate connective tissue –clings tightly to brain like cellopane wrap 463


infectious disease characterized by inflammation of the meninges (the tissues that surround the brain or spinal cord) usually caused by a bacterial infection 463


inflammation of the brain usually caused by a virus 463

Cerebrospinal Fluid

fluid in the space between the meninges that acts as a shock absorber that protects the central nervous system –reduce brain weight by 97% –helps nourish brain –carries cheical signals –contains more Na+, CI -, and H+ than blood plasma –150 ml replaced every 8 hours –500 ml of CFS produced daily 462 – picture

Choroid Plexuses

hang from roof of each ventricle form CSF; frond shaped clusters of broad thin walled capillaries enclosed first by pia mater and then by layer of ependymal cells lining the vetricles; permeable –cleanse by removing waste products and unnecessary solutes 463


an abnormal condition in which cerebrospinal fluid collects in the ventricles of the brain 463 – picture

Blood Brain Barrier

Blood vessels (capillaries) that selectively let certain substances enter the brain tissue and keep other substances out 463

Brain, Homeostatic Imbalances

Traumatic Brain injury –concussion –contusion –subdural or subarachnoid hemorrhage –cerebral edema Crebrovascular Accidents –Ischemia –transient ischemic attacks Degenerative Brain Disorders –Alzheimers –Parkinson’s Disease –Huntingtons Disease 464-466


also known as a counter blow, is an injury that occurs beneath the skull opposite to the area of impact 464


injury to the brain caused by a blow 464


an injury that doesn’t break the skin but results in some discoloration 464

Subarachnoid hemorrhage

bleeding caused by a ruptured blood vessel just outside the brain (usually a ruptured cerebral aneurysm) that rapidly fills the space between the brain and skull (subarachnoid space) with blood; the patient may experience an intense, sudden headache accompanied by nausea, vomiting, and neck pain 464

Cerebral Edema

Swelling of the brain 464

Cerebrovascular Accidents

CVA –‘Strokes’, caused by blood clots in the brain 464


to hold back blood; decreased blood flow to tissue caused by constriction or occlusion of a blood vessel 464


paralysis of one side of the body 464

Transient Ischemic Attacks

temporary stroke; lasts 5-50 minutes; numbness, impaired speech, etc 464


a major excitatory neurotransmitter; involved in memory 465


After brain injury neurons deprived of oxygen begin to disintegrate unleashing cellular euivalent of buckets of glutamate, –Glutamate act as ___________ literally exciting surrounding cells to death 465

Alzheimers Disease

Characteristic physiologic changes are neurofibrillary tangles and amyloid plaques (deposits of protein), found throughout the cortex, which interfere with cells’ ability to transmit impulses are found in what disease? 465

Parkinsons Disease

A chronic, progressive disease that affects the brain area that controls movement. Depletion of dopamine interferes with inhibition of excitatory impulses w/result in dysfunction of extra-pyramidal tracts, which results in dysfunctions of extrapyramidial tracts. 465

Huntingtons Disease

genetic disorder that causes progressive deterioration of brain cells. caused by a dominant allele. symptoms do not appear until the age of 30 or so 466

Spinal Cord, Embryonic Development

–develops from caudal portion of embryonic neural tube –6th week each side of developinng cord 2 recgnizable cluster off neuroblasts –dorsal alar plate –ventral basal plate 466 – picture

Alar Plate

dorsal portion of the neural tube – future site for sensory neurons and tracts 466

Basal Plate

Region of the developing nervous system situated ventral to the sulcus limitans that will become motor in function. 466

Spinal Cord, Gross Structure

467 – picture

Spinal Cord

a major part of the central nervous system which conducts sensory and motor nerve impulses to and from the brain –two way conduction pathway to and from the vbrain 466

Spinal Dura Mater

single layered; not attached to bony walls of vertebral column 466

Epidural Space

separates the dura mater from the inner walls of the vertebral canal 468

Lumbar Tap

468 – picture, the process of obtaining a sample of cerebrospinal fluid by inserting a needle into the sucarachnoid space of the lumbar region to withdrawl fluid

Conus Medullaris

where the spinal cord tapers to a conical tip, which is at or inferior to the level of the first lumbar vertebrae (L1) 468

Filum Terminale

a strand of fibrous tissue, originating at the conus medullaris and extending through the vertebral canal to the second sacral vertebra, ultimately becoming part of the coccygeal ligament 468

Denticulate Ligaments

Lateral extensions of pia mater that pass through the arachnoid layer and attach to the internal surface of the dura mater • Function to anchor the spinal cord 468

Spinal Nerves

31 pairs of nerves arising from the spinal cord –attach by paired roots 468

Cervical Enlargements

expanded regions with increased gray matter to provide innervation of the pectoral girdle and upper limbs 468

Lumbar Enlargements

expanded region of the spinal cord with increased gray matter to provide innervation of the pelvic girdle and lower limbs 468

Cauda Equina

collection of spinal nerves below the end of the spinal cord 468

Ventral Median Fissure

the anterior spinal artery sits in the 468

Dorsal Median Sulcus

Shallow midline groove on the dorsal surface of the entire length of the spinal cord. 468

Gray commissure

surrounds the central canal 468

Dorsal Horns

the two dorsal arms of the spinal gray matter 468

Ventral Horns

The anterior columns of the gray matter of the spinal cord. 468

Lateral Horns

additional pair of gray matter columns; present in thoracic and superior lumbar segments of the cord 468

Ventral Roots

These nerve roots carry motor impulses from the spinal cord and brain to the body/muscles. Aka Anterior 468

Dorsal Roots

These nerve roots carry sensory impulses from the body to the brain. Aka Posterior 468

Spinal Cord, Anatomy

489 – picture

Dorsal Root Ganglion

AKA; spinal ganglion A group of sensory neuron cell bodies found just posterior to the spinal cord on either side. A pair of root ganglia exists for each spinal nerve that expands from the spinal cord. The ganglia are part of the peripheral nervous system (PNS). 470

Spinal Ganglion

enlargement of the posterior root where cell bodies of sensory nerurons are located AKA Dorsal root ganglion 470

Spinal Gray Matter

looks like a butterfily or a modified "H" and is more centrally located than the white matter; the gray matter is divided into the anterior, lateral, and posterior gray horns and consists of nerve cell bodies and dendrites –4 zones –somatic sensory –visceral – autonomic sendory –visceral motor –somatic metor 470- picture

Spinal Cord White Matter

–myelinated and unmyelinated nerve fibers –allow communication in spinal cord and to brain –fibers run 3 directions —–ascending to higher sensory inputs —–descending down to dord form brain or within cord to lower levels – motor outputs —–transversely across / commissural fibers divided into 3 white columns / funiculi according to position –dorsal lateral ventral 470


white matter columns on each side of the cord; 3 on each side 470

Spinal Tracts

The white columns of the spinal cord that provide two-way conduction paths to and from the brain; ascending tract carries information to the brain, whereas descending tracts conduct impulses from the brain 1 decussation 2 relay 3 somatotopy 4 symmetry 470

Brain, Ascending Pathways

–conduct sensory impulses upward –3 successive neurons First order Second order Third order Dorsal column medial lemniscal Anterolateral / spinothalamic spinocerebellar 471

First Order Neurons

soma reside in dorsal root or cranial ganglia, and conduct impulses from the skin to the spinal cord or brain stem 471

Second Order Neurons

their cell bodies reside in the dorsal horn of the spinal cord or in meduallry nuclei, and they transmit impulses to the thalamas or to the cerebellum where they synapse 471

Third Order Neurons

located in the thalamus and conduct impulses to the somatosensory cortex of the cerebrum 471

Somatosensory Information

3 pathways –dorsal column medial lemniscal –spinothalamic / anterolateral –spinocerebellar 471

Dorsal Column Medial Lemniscal Pathways

mediate precise, straight through transmission of inputs from a single type of sensory receptor that be localized precisely on the body surface (such as discriminative touch and vibrations); — formed by paired tracts of dorsal white column of spinal cord – –fasciculus cuneatus and –fasciculus gracilis – and –medial lemniscus 471

Dorsal White Column

ascending tracts sending sensory information to brain 471

Fasciculus Cuneatus

First-order sensory neurons contained in the dorsal funiculus that project to the nucleus cuneatus and that convey the modalities of conscious proprioception and tactile sensation from the ipsilateral side of the upper limb. 471

Fasciculus Gracilis

First-order sensory neurons contained in the dorsal funiculus that project to the nucleus gracilis and that convey the modalities of conscious proprioception and tactile sensation from the ipsilateral side of the lower limb. 471

Medial Leminiscus

What are crossed over sensory fibers called? –arises in medulla and terminates in thalamus 471

Anterolateral Pathways

recieve input from many different types of sensory receptors and make multiple synapses in the brain stem; these pathways are largley formed by lateral and ventral (anterior) spinothalamic tracts; 471

Lateral Spinothalamic Tracts

tracts whose functions are crude touch, pain, and temperature 471

Ventral Spinothalamic Tracts

pathway from the spinal cord to the thalamus that carries info about pain and temp 471

Spinocerebellar Tracts

ventral (anterior) and dorsal (posterior) tracts convey information about muscle or tendon stretch to cerebellum, which uses this information to coordinate skeletal muscle activity; do not contribute to conscious sensation; these fibers do not cross over twice (decussate) 471

Spinal Cord Tracts, ascending

472 – picture 473 Table

Spinal Cord, Descending Pathways and Tracts

–deliver efferent impulses –brain to spinnal cord 2 groups –direct pathways = pyramidal tracts –indirect pathways, all others 473 474 – table / 475 – picture

Direct Pyramidal system

originate mainly with pyramidal neurons located in precentral gyri; these neurons send impulses through brain stem via large pyramidal (corticospinal) tracts , maintenance of muscle tone, controlling speed and precision of skilled movements 474

Pyramidal Corticospinal tracts

Major motor pathways concerned with voluntary movement; descend from pyramidal cells in the frontal love of each cerebral hemisphere 474

Indirect Extrapyramidal system

includes brain stem motor nuclei and all motor pathways except pyramidal pathways; these tracts are formerly lumped together as extrapyramidal sytem because their nuclei of origin were presumed to be independent of the pyramidal tracts 476

Extrapyramidal system

system that provides unconscious control (reflex like that can be overriden) by modulating or altering sensitivity of lower motor neurons to descending pyramidal control output; helps control gross and precise movements 476

Multineuronal Pathways


Indirect pathways

involved with coordination of body movements, skeletal muscle tone, posture & equilibrium 476

Reticulospinal Tracts

maintain balance by varying the tone of postural muscles 476

Vestibulospinal Tracts

Controls Fine Motor, Balance (Postural Reflexes), & Tone-Descending Tracts 476

Rubrospinal Tracts

control flexor muscles476

Tectospinal Tracts

Assists in Head Turning Responses in Response to Visual Stimuli 476

Superior Colliculi

Visual movement (tracking 476


Abnormal sensations such as burning, numbness, or tingling 476

Flaccid Paralysis

weakness or loss of muscle tone resulting from injury or disease of the nerves innervating the muscles 476

Spastic Paralysis

a loss or deficiency of motor control with involuntary spasms caused by permanent brain damage present at birth 476

Amyotorphic Lateral Sclerosis

Lou Gehrigs 476


both lower limbs paralyzed; caused by a cut of the spinal cord between T1 and L1 476

Spinal Shock

Cessation of motor, sensory, autonomic, and reflex impulses below the level of injury; characterized by flaccid paralysis of all skeletal muscles, loss of spinal reflexes, loss of sensation, and absence of autonomic functions below the level of injury. Aka Neurogenic shock 476

cerebral Angiography

X-ray record of blood vessels in the brain after intravenous injection of contrast material. 477

Central Nervous System, Developmental Aspects



a congenital defect of the central nervous system in which a sac containing part of the spinal cord and its meninges protrude through a gap in the vertebral column 477

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