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HA. Ch. 13 (14)

The Nervous System II: The Central Nervous System

the brain provides for voluntary/involuntary movementes
the brain functions in interpretation and integration of sensation
the brain provides consciousness and cognitive function
the brain also is involved in innervation of the head through the cranial nerves
basic organization of the brain (4 basic parts) cerebral hemispheres (cerebrum), diencephalon, brain stem(midbrain, pons, medulla) cerebellum
gray matter is mostly cell bodies of neurons (some short unmyelinatede axons and dendrites; some neuroglia)*
white mater is mostly myelinated axons (or fibers) of neurons
brain stem is white matter external to central gray matter
cerebrum and cerebellum additional external cortex of gray matter
the ventricles are expansions of the brain's central cavity
the ventricles are filled with crebrospinal fluid (CSF)
the ventricles are lined with ependymal cells
CSF functions in floating and cushioning the brain and the spinal cord
lateral ventricles (2) span both the cerebral hemispheres, separated by the septum pellucidum
third ventricle is enclosed by the diencephalon
cerebral aqueduct is located in the midbrain; connects the 3rd and 4th ventricles
fourth ventricle is located in the hindbrain; continues inferiorly as the central cavity in the spinal cord
choroid plexus is the vascular complex in the roofs of the 3rd and 4th ventricles
choroid plexus is responsible for CSF production
features of the cerebral hemispheres grooves on and around the hemispheres
fissures deepest grooves, which separate major portions of the brain
transverse cerebral fissure separates cerebrum from cerebellum inferiorly
longitudinal fissure separates the right and left cerebral hemispheres
sulci (furrow) the many grooves on the surface of the cerebral hemispheres
gyri (twister) twisted ridges of the brain tissue (lumpy bumps)
each cerebral hemisphere has five major lobes separated by sulci
frontal lobe is separated from parietal lobe by the central sulcus
another lobe of the cerebral hemispheres which has no additional information parietal lobe
occipital lobe lies farthest posteriorly; separated from parietal lobe by the parieto occipital sulcus
temporal lobe lateral side of hemispheres
temporal lobe is laterally separated from the parietal and frontal lobes by the lateral sulcus
temporal lobe is inferiorly separated from the occipital lobe by the calcarine sulcus
insular lobe is buried deep within the lateral sulcus and forms part of its floor
the insular lobe is covered by parts of the temporal, parietal and frontal lobes
internal structure of cerebrum consists of the three largest regions within the cerebrum
3 largest regions of cerebrum cerebral cortex of gray matter, cerebral white matter, basal nuclei
cerebral cortex of gray matter superficial layer
cerebral white matter internal
basal nuclei deep in the white matter
cerebral cortex is the site of conscious sensory perception, voluntary initiation of movements, higher thought functions
cerebral cortex contains billions of neurons arranged into 6 layers
cerebral cortex has...areas brodmann; 52 structurally different areas identified by Korbinian Brodmann
there are three functional areas of the cerebral cortex known as the motor/sensory/association areas
primary motor cortex is located along the precentral gyrus
the pyramidal axons in the...signal...to bring about...of the body...especially the primary motor cortex...motor neurons....precise or skilled voluntary movements...forearms, fingers, facial muscles
contralateral projections of primary motor cortex R and L motor cortices control muscles on the left and right sides of the body
motor homunculus body map on the motor cortex
the motor neurons for the human body are represented spatially in the primary motor cortex of each hemisphere
the pyramidal cells or large motor neurons that control hand movements are in...those that control foot movement are in one place...another; etc.
the body is represented upside down
the face and hand representations are disproportionately large in order to provide more pyramidal cells to control for the delicate and skilled movements
somatotopy general principle of body mapping
premotor cortex anterior to the precentral gyrus (area 6)
premotor cortex controls more complex movements than does the primary motor cortex
frontal eye field anterior to the premotor cortex (area 8)
frontal eye field controls voluntary movements of the eyes
broca's area anterior to the inferior part of the premotor cortex; in the L cerebral hemisphere only
broca's area manages...and controls... speech production...movements necessary for speaking
sensory areas are located in the parietal, temporal, and occipital lobes
sensory areas are cortical areas with conscious awareness of sensation
there is a disticnt cortical area for each of the major senses
primary somatosensory cortex is located along thee postcentral gyrus
primary somatotosensory cortex is involved with conscious awareness of the general somatic senses
primary somatosensory cortex = spatial discrimination and collateral projections
sensory homunculus is the same as the motor homunculus except that it deals with sensory neurons instead
the .... are the most sensitive body parts lips and hands which is why they are disproportionally large in the homunculus
somatosensory association cortex/area lies posterior to primary somatosensory cortex
somatosensory association cortex integrates different sensory inputs into a comprehensive understanding of what is being felt
visual areas: overall, -30 cortical areas are involved in visual processing involving the occipital, temporal, and parietal lobes
primary visual cortex (striate) largest cortical sensory area(posterior and medial portion of occiptal lobe)
most of the primary visual cortex is located within the deep calcarine sulcus on medial aspect of occipital lobe
the primary visual cortex receives visual info that originates on the retina of the eye
visual association area surrounds the primary visual area and covers much of the occipital lobe
the visual association area communicates with the primary visual area and continues processing of visual info by analyzing color, form, and movement
primary auditory cortex is the superior edge of temporal lobe, primarily inside the lateral sulcus
primary auditory cortex performs conscious awareness of sound
auditory association area lies just posterior to primary auditory cortex
auditory association area permits evaluation of a sound (speech)
the auditory assocation area is usually located in the left hemisphere in the center of Wernicke's area
gustatory cortex lies on the roof of the lateral sulcus
gustatory cortex performs conscious awareness of taste stimuli
vestibular cortex (equilibrium) posterior part of insula
vestibular cortex performs conscious awareness of the sense of balance
olfactory cortex is the medial aspect of cerebrum in the piriform lobe
olfactory cortex performs conscious awareness of smell
assocation areas = " higher-order processing areas"
some of the association areas make associations between the different kinds of sensory info received
prefrontal cortex is the large region of the frontal lobe, anterior to motor area
prefrontal cortex is the most complicated cortical region
prefrontal cortex performs many cognitive functions
general interpretation area posterolateral cerebral cortex at the interface of the visual, auditory and somatosensory association areas
general interpretation area integrates all these types of sensory info (visual/auditory/somatosensory)
language area is a complex of functional areas that surround the lateral sulcus in the left hemisphere
language area is involved in various functions related to language
language area has 5 sections broca's area, wernickes, lateral prefrontal cortex, lateral andinferior temporal lobe, insula
broca's area speech production
wernickes area speech comprehension
lateral prefrontal cortex deep conceptual analysis of spoken words
most of the lateral and inferior temporal lobe coordination of auditory and visual aspects of language
parts of the insula initiation of word articulation and recognition of rhymes and sound sequences
corresponding areas on the right hemisphere act in the creative interpretation of words and in controlling emotional overtones of speech (not involved in mechanics of speech)
insula's function is not well known
insula; some parts function in language and in the sense of balance
other parts of the insula have visceral functions including conscious perception of visceral sensations and behavioral influences on cardiovascular activity
the white matter of the cerebrum is comprised of many axons through which the different areas of the cerebral cortex extensively communicate
most of the fibers in the white matter are myelinated and bundled into large tracts
the fibers of white matter are classified according to where they run
commissures are composed of commissural fibers that run between the two hemispheres
fibers of white matter interconnect corresponding gray areas of the left and right hemispheres
corpus callosum (fibers of white matter) the largest commissure, superior to lateral ventricles, deep within the longitudinal fissure
association fibers connect different cortical areas within the same hemisphere (run horizontally)
projection fibers are fibers that run vertically to and from the brian stem and spinal cord
projection fibers either descend from the cerebral cortex to more caudal parts of the CNS or ascend to the cortex from lower regions
through the projection fibers, sensory info reaches the cortex and motor instructions are then relayed to effectors
internal capsule of white matter projection fibers that form a compact bundle b/w the thalamus and some of the basal nuclei
corona radiata of white matter projection fibers to and from cerebral cortex, which fan out
basal nuclei are paired masses of gray matter embedded deep within the cerebral white matter
basal nuclei hae coordinates with the cerebral cortex to control complex movements
caudate nucleus arches superiorly over the thalamus, and lies medial to internal capsule
caudate nucleus functions in subconscious adjustment and modification of voluntary motor commands
amygdaloid body or nucleus is on the tip of the tail of the caudate nucleus, but it functionally belongs to the limbic system
three masses of gray matter (...) lie between the bulging surface of the (claustrum, putamen, globus pallidus) unsula and the lateral wall of the diencephalon
claustrum appears to be involved in visual information processing at the subconscious level, by focusing attention on specific patterns or relevant features
lentiform nuclei consists of the medial globus pallidus and the lateral putamen
lentiform nuclei functions as same as caudate nucleus
corpus striatum caudate + lentiform nuclei
the dienchephalon forms the central core of the forebrain: surrounded by the cerebral hemispheres
the diencephalon consists of 3 paired structures, enclosing the 3rd ventricle
thalamus egg-shaped or football shaped
both the right and left thalami form the walls of the diencephalon and the superolateral walls of the 3rd ventricle
interthalamic adhesion is a medial projection of gray matter, from the thalamus on either side, that extends into the 3rd ventricle
the two intermediate masses fuse in the midlkine, interconnecting the right and left thalami
the thalamic nuclei provides the switching and relay centers for both sensory and motor pathways
the sensory information from the ... and...are not processed by the thalamic nuclei before the information is relayed to the cerebrum or brain stem olfactory nerve and the spinocerebellar tracts
the thalamus contains about a dozen major nuclei which send axons to particular portions of the cerebral cortex
the thalamus is concerned primarily with the relay of sensory info to the basal nuclei and cerebral cortex
five major groups of nuclei are anterior, medial, ventral, posterior, lateral
anterior nuclei is part of the limbic system and plays a role in emotions, memory and learning
medial nuclei provide a conscious awareness of emotional states
ventral nuclie relay info to and from the basal nuclei and cerebral cortex
ventral anterior relays info regarding somatic motor commands form the basal nuclei and cerebellum to the primary motor cortex and premotor cortex
ventral lateral is the same as ventral anterior
ventral posterior relay sensory info concerning tough, pressure, pain, temp, and proprioception from the spinal cord and brain stem to the primary sensory cortex of the parietal lobe
posterior nuclie contains the pulvinar, lateral geniculate nuclei, medial geniculate nuclei
pulvinar integrates sensory info for projection to the association areas of the cerebral cortex
lateral geniculate nuclie (LGN) receives visual info from the eyes via the optic tract
medial geniculate nuclei (MGN) relay auditory info to the auditory cortex from the specialized receptors of the inner ear
lateral nuclei: relay stations in feedback loops that adjust activity in the cingulate gyrus and parietal lobe
some nuclei act as relay stations for sensory info which ascend to the primary sensory areas of the cerebral cortex
ventral posterolateral nuclei recieve...LGN and MGN receive general somatic sensory info...visual and auditory info
every part of the brain that communicates with the cortex must relay its signals through a nucleus of the thalamus
hypothalamus is the inferior portion of the diencephalon
the hypothalamus is the most important visceral control center
the hypothalamus contains centers involved with emotions and visceral processes that affect the cerebrum and other components of the brain stem
the hypothalamus forms the link between the nervous system and endocrine systems
the hypothalamus controls a variety of autonomic functions
the hypothalamus regulates sleep cycles, hunger, thirst, body temp, secretion of the pituitary gland and the autonomic nervous system
the hypothalamus regulates some emotions and behaviors
the hypothalamus lies between the optic chiasma or optic chiasm and the posterior border of the mamillary bodies
infundibulum is located posterior to the optic chiasma and connects the hypothalamus to the pituitary gland
the pituitary gland projects inferiorly from the hypothalamus and secretes many hormones
tuberal area is the floor of the hypothalamus which contains nuclei involved with the control of pituitary gland function
the hypothalamus forms the inferolateral walls of the 3rd ventricle
the hypothalamus contains roughly a dozen nuclei of gray matter
supraoptic nucleus produces antidiuretic hormone which restircts water loss at the kidneys
paraventricular nucleus produces oxytocin, which stimulates smooth muscle contractions in the uterus and prostate gland and myoepithelial cell contractions in the mammary glands
preoptic area controls physiological responses to changes in body temp
suprachiasmatic nucleus is the body's biological clock which regulates the timing of many daily (circadian) rhythms
the suprachiasmatic nucleus: it's output adjuts the activites of other hypothalamic nuclei, the pineal gland, and the reticular formation
epithalamus is the most dorsal part of the diencephalon
the epithalamus forms part of the roof of the third ventricle
the epithalamus consists of one tiny group of neuclei and the pineal gland which secretes the hormone melatonin
melatonin is involved in the regulation of day-night cycles
the brain stem produces the rigidly programmed, automatic behaviors necessary for our survival
the brain stem acts as a passageway for all the fiber tracts running between the cerebrum and the spinal cord
the brain stem is heavily involved with innervation of the face and head (10 of the 12 cranial nerves attach to it)
the internal structure of the brian stem contains inner region of gray matter, external white matter, nuclei of gray matter is located within white matter
3 brain stem regions from rostral to caudal midbrain, pons, medulla oblongata
midbrain lies between the diencephalon and the pons
the midbrain; its central cavity...divides it into a... cerebral aqueduct...tectum (roof) dorsallly and a pair of cerebral peduncles ventrally
cerebral peduncles are pyramidal fiber tracts that form vertical pillars which appear to hold up the forebrain
cerebral peduncles contain (1) ascending fibers that synapse in the thalamic nuclei
cerebral peduncles contain (2) descending fibers of the corticospinal pathway that carry voluntary motor commands from primary to motor cortex of each cerebral hemisphere
corpora quadrigemina is a large group of nuclei that make up the tectum, which act in the startle response
corpora quadrigemina processes visual and auditory info and generate reflexive responses to these stimuli
superior colliculi is a paired nuclei that act in visual reflexes
inferior colliculi is a paired nuclie that act in auditory reflexes
the corpora quadrigemina contains the major nuclei of the reticular formation (RF)
each side of the midbrain contains a pair of red nuclei and substantia nigra
red nucleus is a nucleus with abundant blood vessels, which give it a rich red coloration
red nucleus integrates ... and issues info from the cerebrum and cerebellum...involuntary motor commands concerned with the maintenance of muscle tone and limb position
substantia nigra lies lateral to the red nucleus
substantia nigra's gray matter contains darkly pigmented cells giving it a black colorations
substantia nigra plays an important role in regulating the motor output of the basal nuclei
the pons; anteriorly it forms a bulging region that is wedged b/w the midbrain and the medulla oblongata
dorsally, the pons is separated from the cerebellum by the 4th ventricle
the pons forms a ventral bridge b/w the right and left halves of the cerebellum
on either side, the pons is attached to the cerebellum by three cerebellar peduncles (superior, middle and inferior)
pontine nuclei relay nuclei by which the motor cortex communicates with the cerebellum and is involved in coordination of voluntary movements
nuclei of the pons are concerned with the involuntary control of respiration on each side of the brain, the RF in this region contains two respiratory centers which modify the activity of the respiratory rhythmicity center in the medulla oblongata
the medulla oblongata is the most caudal part of the brain and is continuous with the spinal cord at level of the foramen magnum
the medulla oblongata physically connects the brain with the spinal cord and many of its functions are directly related to this connection
the medullary pyramids flank the ventral midline
the medullary olives lie lateral to each pyramid and contain the inferior olivary nuclei
other nuclei in the medulla oblongata are grouped by function
relay states are ascending tracts that synapse in sensory or motor nuclei
nucleus gracilis (relay station) relays somatic sensory info to the thalamus fromt he lower body
nucleus cuneatus (RS) same as nucleus gracilis, afferents from the upper body
olivary nuclei relay sensory info from the spinal cord, the cerebral cortex, diencephalon, and brain stem to the cerebellar cortex
nuclei of cranial nerves sensory and motor nuclei associated with five of the cranial nerves which innervate muscles of the pharynx, n eck, back and also visceral organs of the thoracic and peritoneal cavities
autonomic nuclei RF nuclei and centers that are responsible for the regulation of vital autonomic functions
cardiofascular centers adjust heart rate, the strength of cardiac contractions and the blood vlow through peripheral tissues
respiratory rhytmicity centers set the basic pace for respiratory movements and their activity is regulated by inputs from the apneustic and pneumotaxic centers of the pons
the cerebellum (functions) smooths and coordinates body movements that are directed by other brain regions
the cerebellum helps maintain posture and eqpuilibrium
2 cerebellar hemispheres are connected medially by the vermis
the surface of the cerebellum is folded into follia which are separated by fissures
primary fissure separates the two major lobes of each hemispheres
each cerebellar hemisphere is divided into 2 major lobes and one slender lobe
anterior lobe lies superior to posterior lobe and assists along with the posterior lobe, in the planning, execution and coordination of limb and trunk movements
posterior lobe lies inferior to anterior lobe and posterior to flocculonodular lobe
flocculonodular lobe lies anterior and inferior to the cerebellar hemisphere and is important in maintaining the balance and control of eye movement
outer cerebellar cortex of gray matter contains large, highly branched purkinje cells
outer cerebellar cortex functions in subconscious coordination and control of ongoing movements of body parts
internal white matter: arbor vitae (" the tree of life"); the white matter forms a branching array that resembles a tree
deep cerebellar nuclei of gray matter - a relatively small portion of the afferent fibers synapse within these nuclei before projecting to the cerebellar cortex
cerebellar peduncles are thick tracts of nerve fibers that connect the cerebellum to the brain stem
superior cerebellar peduncles connect cerebellum to nuclei in the midbrain, diencephalon, and cerebrum
the middle cerebellar peduncles connect cerebellum to pons via a broad band of fibers that cross the ventral surface of the pons at right angles to the axis of the brain
inferior cerebellar peduncles connect cerebellum to nuclei in the medulla oblongata
inferior cerebellar peduncles carry ascending and descending cerebellar tracts from the spinal cord virtually all fibers that enter and leave the cerebellum are ipsilateral
the limbic system emotional brain
the limbic system consists of a group of structures on medial aspect of each cerebral hemisphere and the diencephalon forming a broad ting along the border between the cerebrum and diencephalon
the functional systems of the limbic system includes septal nuclei, cingulate gyrus, hippocampal formation, amygdaloid body
the fornix is a tract of white matter connecting the hippocampus with the hypothalamus
the fornix and other fiber tracts link the limbic system together
mammillary bodies are the prominent nuclei in the floor of the hypothalamus, to which many of the fibers of the fornix end or connect
the mammillary bodies are concerned with feeding refleces and behaviors
the limbic system establishes emotional states and related behavioral drives
the limbic system links the conscious intellecutal functions of the cerebral cortex with the unconscious and autonomic functions of other portions of the brain
the limbic system consolidates and retrieves memories
the reticular formations (RF) is a group of neurons that runs through the central core of the medulla, pons and midbrain
the RF controls arousal of the brian as a whole due to the widespread connections of reticular neurons to other brain regions
the RF contains the Reticular activating system (RAS) which maintains consciousness and alertness
the RAS also functions in sleep, and in arousal from sleep
RF is depressed by general anesthesia, alcohol, tranquilizers and sleep-inducing drugs
the meninges are comprised of 3 membranes of CT that lie just external to the brain and spinal cord
the meninges the cover and protect the CNS
the meninges enclose and protect the blood vessel supplying the CNS
the meninges contain CSF
layers of the meninges dura mater, arachnoid mater, pia mater
dura mater (tough mother) is a 2 layered sheet of fibrous CT
periosteal layer of dura mater attaches to internal surface of skull bones
meningeal layer forms true external covering of the brain
dural sinuses are ares where both periosteal and meningeal layers separate to enclose these blood-filled sinuses, which act as veins
falx cerebri ligamentous membrane that attaches anteriorly to crista galli of the ethmoid bone
falx cerebri stablizes the brian within the cranial cavity of the skull
falx cerebelli ligamentous membrane that continues inferiorly from the posterior part of falx cerebri and runs along vermis of the cerebellum in the posterior cranial fossa
arachnoid mater subdural space b/w the dura mater and the arachnoid mater
arachnoid mater contains a film of CSF
subarachnoid space is deep to arachnoid mater
subaracnoid space spanned by web-like threads that hold arachnoid mater to underlying pia mater
subarachnoid space is filled with CSF and contains the largest blood vessels supplying the brain
arachnoid villi act as valves that allow CSF to pass from the subarachnoid space to dural sinuses
dura mater and arachnoid mater surround the brain loosely
pia mater (gentle mother) is a layer of delicate CT richly vascularized with fine blood vessels
pia mater clings tightly to the brain surface, following every convolution
cerebrospinal fluid is a watery broth located in and around the brain and spinal cord
CSF provides a liquid cushion or buoyancy to the CNS structures
CSF helps nourish the brain
CSF removes waste produced by neurons
CSF transmits neurotransmitters b/w different parts of the CNS
most of the CSF is made in the choroid plexuses
the blood brain barrier (BBB) are tight junctions of endothelium of brain capillaries' walls, which help form a barrier b/w the brain and the rest of the body
the bbb is not an absolute barrier bec all nutrients and ions required by neurons can pass through the barrier
what easily diffuses through the bbb and reach the brain lipid-soluble molecules, like alcohol, nicotine and anesthetics
the spinal cord in adults extend 45 cm from the foramen magnum to L1 or L2 vertebra
the spinal cord is protected by bone, meninges and CSF
spinal meninges are a group of specialized membranes that provides physical stability and shock absorption for the neural tissues of the spinal cord
spinal dural sheath dura mater layer but does not attach to surrounding bone
spinal dural sheath corresponds to meningeal layer only
spinal cord is involved in sensory and motor innervation of the entire body inferior to the head
spinal cord provides a 2 way conduction pathway for signals b/w the body and the brain
spinal cord is the major center for reflexes
there are...pairs of spinal nervess 31
the pairs of spinal nerves attach to the spinal cord through the dorsal and ventral nerve roots
the 31 pairs are subdivided into cervical spinal nerves (8), thoracic spinal nerves (12), lumbar spinal nerves (5), sacral spinal nerves (5), coccygeal spinal nerve (1)
each of the 31 segments of the spinal cord is associated with a pair of DRG and pairs of dorsal roots and ventral roots
each spinal nerve is ensheathed by a series of CT layers similar to those in muscle tissue
epineurium is a dense network of collagen fibers surrounding the entire nerve
perineurium partitions the nerve into fascicles and forms the nerve blood barrier
endoneurium is delicate CT fibers that surround individual axons of the fascicles
cervical and lumbar enlargements the enlarged areas of the anterior horns of gray matter arise from these segments
dura mater is a tough, fibrous layer that covers the spinal cord, whose caudal end froms the coccygeal ligament
epidural space is external to dural sheath and separates the dura mater from the inner walls of the vertebral canal and is filled with fat and veins
epidural sapce is where anesthetics are injected
subdural space separates the dura mater from the arachnoid mater
subarachnoid space is internal to the arachnoid mater and contains the arachnoid trabeculae which is a network of collagen and elastic fibers and CSF
CSF functions as shock absorber and diffusion medium for dissolved gases, nutrients, chemical messengers and waste products
pia mater is firmly attached to the underlying neural tissue
denticulate ligaments are comprised of supporting fibers that bind the spinal pia mater and arachnoid mater to the dura mater
denticulate ligaments function in preventing either lateral or inferior movement of the spinal cord
conus medullaris inferior tapered end of spinal cord
filum terminale is a strand of fibrous CT covered with pia mater
filum terminale extends through the vertebral canal to S2 vertebra
filum terminale attaches to the coccyx inferiorly and anchors the spinal cord in place
filum terminale ultimately becomes part of the coccygeal ligament
cauda equina (horses tail) consists of the lumbar and sacral nerve roots at the inferior end of vertebral canal, including the filum terminale
posterior median sulcus and anterior median fissure are two deep grooves that run the length of the spinal cord and partly divide it into right and left halves
surrounding the central canal is a central core of gray matter which is a mixture of motor neuron cell bodies, short unmyelinated axons and dendrites of sensory neurons, association neurons are neuroglia
gray commissure posterior and anterior to the central canal
gray commissure consists of axons of inerneurons that corss from one side of the spinal cord to the other side
nuclei of spinal cord groups of nueron cell bodies in the spinal cord gray mater
posterior horns consist of all interneurons
outside the spinal cord, the cell bodies are in the dorsal root ganglia and the axons are in the dorsal roots
posterior horns contain somatic and visceral sensory nuclei
anterior horns are the largest areas in the cervical and lumbar regions which innervate the upper and lower limbs
anterior horns provide somatic motor control
lateral horns are present in the thoracic and superior lumbar segments of the spinal cord
lateral horns consists of visceral motor neurons
dorsal roots and ventral roots contain sensory and motor neuron fibers
dorsal and ventral roots form the spinal nerves, therefor spinal nerves are mixed nerves in that they contain both sensory and motor neurons fibers
the white matter on each side of the spinal cord is divided into three white columns or funiculi
posterior funiculus is suvdivided into fasciculus gracilis, fasciculus cuneatus
fasciculus gracilis contains axon fibers supplying the lower body
fasciculus cuneatus contains axon fibers supplying the upper body
anterior funiculus is continuous with lateral funiculus
ascending tracts are groups of fibers that relay sensory info from the spinal cord to the brain
descending tracts are groups of fibers that relay motor info fromt eh brain to the spinal cord
Created by: handrzej