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Glossary of 325-final

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What are the four general functions of the nervous system
1. regulates functions of systems of body 2.provides awareness of changes in internal, external environments, 3. responsible for organization and storage of sensory information, 4. initiation of motor activities.
proper name for a nerve cell
neuron
name for supportive connective tissues
neuroglia
do neuroglia take part in transmission of messages
no
name the parts of a neuron
central nucleus with cytoplasm containing mitochondria, golgi apparatus, processes including short branched dendrites and long axon which carries impulses.
another name for axon
nerve fibre
another name for the core of the nerve fibre in nerve trunk
axis cylinder
name for coating on an axis cylinder
myelin sheath
myelin sheath made of?
fatty material
myelin sheath does?
insulates the fibre from neighboring fibres, keeps the nervous impulse in the fibre.
names of the constrictions on a myelin sheath?
nodes of ranvier or neurofibril nodes
outermost covering of a nerve fibre
neurilemma
what does the neurilemma do?
assists in regeneration of injured axons
why is white matter white?
presence of myelinated axons
why is gray matter gray?
collections of nerve cells (which are gray)
what is a name for a cluster of nerve cells with similar function?
nuclei
what are the bundles of processes of clusters of nerve cells called?
tracts
what is a ganglion?
in the peripheral nervous system, it is an aggregation of similarly functioning neurons.
example of a ganglion
collection of cell bodies of sensory fibres in a cranial or spinal nerve, known as a sensory root ganglion.
what is the proper name for a sensory neuron
afferent
what does an afferent neuron do
carries impulses from sense organs or skin, muscle, joint or other organs TO the brain. info on sight, pain, touch, etc.
What is the correct term for a motor neuron?
efferent
what does a motor neuron do?
conveys impulses from the brain and spinal cord to effectors (either muscles or glands)
What are the functions of neurons?
motor or sensory, not both.
Can nerves contain a mixture of sensory and motor fibres?
yes. Most nerves are mixed.
what is a nerve impulse?
an electrical message
what is the term for the ability of a neuron to respond to a stimulus and convert it into an impulse?
excitability
what is the term for the ability of a neuron to transmit an impulse to another neuron or tissue?
conductivity
what is the name for a junction between two neurons?
synapse
what is required for the transmission of an impulse across the synapse?
release of a neurotransmittor substance
Is impulse conduction at a synapse one way, or two way?
one way: from the axon of one neuron to the dendrite or cell body of the next neuron.
what are the components of the central nervous system?
the brain and spinal cord
brain location
in cranial cavity, continuous with spinal cord at foramen magnum
spinal cord location
continuous with brain, and occupies the vertebral canal
peripheral nervous system made up of
all nerves and ganglia external to brain or spinal cord. includes the autonomic nervous system
what is the ANS
autonomic nervous system is the involutnory nervous system. Controls parts of the body which we’re not aware of controlling
cns=
central nervous system: brain, spinal cord. covered by bone and meninges
pns=
peripheral nervous system: nerves, ganglia and nerve plexuses
ans=
autonomic nervous system – sympatheic and parasympathetic nervous system – control actionos fo visceral organs & skin
meninges
group of three fibrous membranes covering CNS
Names of three meninges
dura mater arachnoid pia mater
CSF
clear watery medium buoys and maintains homeostasis in brain and spinal cord
neuron
structural and functional cell of nervous system: nerve cell
motor (efferent) neuron
transmits action potentials from CNS to an organ
sensory (afferent) neuron
transmits action potentials from organs to CNS
plexus
convergence or network of nerves
somatic motor nerve
innervates skeletal muscle – causes muscle contraction
autonomic motor nerve
innervates smooth muscle, cardiac muscle, and glands. impulses cause or inhibit contraction of smooth, cardiac muscle and secretion of glands
ganglion
cluster of neuron cell bodies outside CNS
nucleus
cluster of neuron cell bodies within CNS
tract
bundle of nerve fibres connecting regions of CNS
changes inside and outside the body are called
stimuli
two “location” divisions of nervous system
central and peripheral
two “functional” divisions of nervous system
somatic and autonomic or voluntary and involuntary
autonomic nervous system includes
sympathetic and parasympathetic division
what are the tiny projections on dendrites called, and what is their function?
dendritic spinules – to increase surface area, providing more contact points for other neurons.
how much more abundant are glial cells to neurons
five times more abundant
can neurons divide mitotically?
no, but some can regenerate a severed portion under some circumstances
what are glial cells?
neuroglia. supportive cells of nervous system
what is the function of glial cells?
support nervous tissue, aid function of neurons
where are the longest axons in the body, and how long are they?
over a metre, and between the spinal cord and the distal extremities
what are the side branches on an axon called?
collateral branches
name three kinds of neuroglia
astrocytes, oligodendrocytes, and neurolemmocytes (schwann cells/microglia).
what does a schwann cell do?
creates myelin coating around axons in PNS
what does an oligodendrocyte do?
creates myelin coating around axons in CNS
what does an astrocyte do?
structural support between capillaries of CNS, contributes to blood brain barrier. Has podocytes – foot like processes.
what is the purpose of the neurofibril nodes of ranvier?
propagate a nerve impulse along a myelinated axon
what is another name for an interneuron?
association neuron.
what protects the central nervous system?
meninges, skull, vertebral column
how much does the average brain weigh?
1.3kg
what are the three main divisions of the brain, based on their embronic positions, and which structures of the brain make them up?
forebrain (prosencephalon: cerebrum and diencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon-cerebellum, pons, medulla oblongata.)
what are the two main parts of the forebrain called?
the cerebral hemispheres
what is the name of the deep cleft between the two cerebral hemispheres?
longitudinal fissure
what are the names of the convolutions on the external surface of the cerebrum?
gyri
what are the deptressions between the gyri called?
sulci
What are the names of the lobes of the cerebral hemispheres called?
frontal lobe, occipital lobe, temporal lobe, parietal lobe
What is the name of the sulci that separates the frontal and parietal lobes?
central sulcus
what is the name of the sulci that separates the temporal lobe from the frontal and parietal lobes?
lateral sulcus
Name five of the functional areas of the brain
precentral gyrus, postcentral gyrus, motor speech area, visual area, auditory area
what does the cerebrum do?
thought, intelligence, memory, reason
what does the precentral gyrus do (and where)?
monitors voluntary control over activities (in the opposite side of the body)
how is the body represented in the precentral gyrus?
inverted image, i.e. injury to superior portion means paralysis of lower body, and vice versa.
what is the postcentral gyrus?
main sensory area of cerebrum.
what would an injury to the postcentral gyrus interfere with?
conscious perception of sensation
where is the motor speech area?
left inferior gyrus of the frontal lobe.
where is the visual area?
occipital lobe
what does the visual area do?
receives visual sensory impulses from the eyes
where is the auditory area?
superior temporal lobe, adjacent to lateral sulcus
what does the auditory area do?
receives auditory impulses
what is the purpose of the basal ganglia
regulate gross unconscious movements (swinging arms while walking)
where are the basal ganglia?
grey matter in depths of each hemisphere
where do the basal nuclei receive fibres from?
motor area of cerebral cortex and efferent to many parts of nervous system
what does an injury to basal ganglia cause?
muscular rigidity and persistent tremors of limbs
what is another name for the interbrain
diencephalon
where is the diencephalon
between the midbrain and the cerebrum
what two structures make up the diencephalon?
thalamus and hypothalamus
what are the walls of the diencephalon made of?
large masses of gray matter called thalami
what does the thalamus do?
important sensory centre. receives impulses of touch, muscle sense. relays messages to cerebral cortex. initial autonomic response to pain
what is the hypothalamus connected to?
pituitary gland
what does the hypothalamus regulate? (5 things)
autonomic system, body temperature, fat, carbohydrate and water metabolism, food intake, sleep sexual activity and emotional responses.
what structures make up the brainstem?
midbrain, pons, and medulla oblongata
what does the midbrain do?
connects pons and cerebellum with cerebral hemispheres
what are the cerebral peduncles?
pair of bundles of fibres – motor fibres that convey impulses from cerebral cortex to the pons and spinal cord, and sensory fibres that pass from spinal cord to thalamus. main avenue for connections between spinal cord and cerebrum.
what are the four round eminences of the dorsal portion of the midbrain called, and what do they do?
corpora quadrigemina – reflex centres form movements of eyeball and head in response to visual and auditory stimuli.
where is the pons located?
between the medulla and the midbrain
what does the pons do?
“bridge” – connects spinal cord and medulla with upper brainstem and carries impulses from cerebrum to cerebellum
where is the cerebellum
under the posterior cerebrum
what is the surface of the cerebellum called?
cerebellar cortex
what are the parallel ridges of the cerebellum called?
gyri
what are the gray matter masses within the cerebellum?
cerebellar nuclei
what does the cerebellum connect to?
brainstem and cerebral cortex
what does the cerebellum do?
promotes motor activity below the level of consciousness – sensory input from muscles, and joints of limbs etc, and organs of equilibrium in internal ear. co-ordinates muscular activity,maintains balance and posture
what does damage to the cerebellum cause?
muscle weakness, loss of muscle tone, inability to direct movements of skeletal muscles.
what is unusual about the cerebellar hemispheres?
they control actions on the SAME side of the body – not opposite.
where is the medulla oblongata
continuous with upper portion of spinal cord
what nerve tracts are represented in the medulla?
all efferent and afferent tracts of the spinal cord
what makes up the white matter of the medulla?
all efferent and afferent tracts of the spinal cord
what is the name of the swellings on the ventral surface of the medulla?
pyramids
what is the decussation of the pyramids?
crossing over of the motor fibres from the right to the left pyramid within the medulla
what is the name of the heterogenous mixture of cell bodies and nerve fibres within the medulla?
reticular formation
where else is the reticular formation found?
spinal cord, pons, diencephalon
what does the reticular formation do?
functions in consciousness, and has three vital centres: cardiac centre, respiratory centre, and vasoconstrictor centre
what does the cardiac centre do?
regulates heart beats
what does the respiratory centre do?
regulates depth and rate of breathing
what does the vasoconstrictor centre do?
adjusts the diametre of the blood vessels
where are the meninges located?
between the bone and the soft tissue of the CNS
what connects the two halves of the brain?
corpus callosum (large tract of white matter)
where is the precentral gyrus?
immediately anterior to the central sulcus
where is the postcentral gyrus?
immediately posterior to the central sulcus
what is the basal nuclei?
specialized paired masses of grey matter located deep within the white matter.
which is the most prominent of the basal nuclei?
corpus striatum
which is the uppermost basal nuclei?
caudate nucleus
what is the name of the two basal nuclei masses beneath the thick band of white matter under the caudate nucleus?
the lentiform nucleus, which is made up of the putamen and the globus pallidus.
what is the name of the motor speech area?
broca’s area
what does the wernickes area do?
controls language comprehension
what is the fibre tract that connects wernickes area to the motor speech area?
arcuate fasciculus
where is cerebrospinal fluid produced?
choroid plexus – the inside lining of the roof over the third ventricle.
where is the pituitary gland located?
sella turcica of the sphenoid bone
what is the proper name for the anterior pituitary?
adenohypophysis
what is the proper name for the posterior pituitary
neurohypophysis
why is the thalamus known as the pain centre of the brain?
plays a role in the initial autonomic response to pain, and is partially responsible for shock following serious trauma
where is the spinal cord located?
in the vertebral canal, from the medulla oblongata to the level of the first and second lumbar vertebrae.
How many pairs of nerves connect with the spinal cord?
thirty one.
why are the cervical and lumbar portions of the spinal cord enlarged?
to accommodate the large number of nerve cells that supply the extremities
do the sacral and lumbar nerves leave the vertebral column immediately?
No… the lengths of the spinal cord and the vertebral column are inequal, so the lumbar and sacral nerves that arise from the lower spinal cord descend down the vertebral canal before exiting through their intervertebral foramina.
what is the name of the gray “H” shaped porion in the centre of the spinal cord?
Gray commissure.
What is the central canal of the spinal cord continuous with?
fourth ventricle of the medulla
what are the anterior and posterior limits of the gray commissure called and what do they do?
anterior and posterior gray horns. Anterior represents the motor portion, and the posterior represents the sensory portion.
what are the lateral regions between the anterior and posterior gray horns called?
lateral gray horns. preganglionic fibres of autonomic nervous system. Most prominent in thoracic and lumbar.
what are the three areas of white matter on each side of the spinal cord called?
anterior column (funinculus), lateral column, and posterior column.
what are the nerve fibres in the white matter columns divided into?
groups called tracts
what do the tracts do?
long ascending tracts are sensory axons conducting spinal cord impulses to the brain. Long descending tracts take impulses down from brain to spinal cord. shorter tracts containing sensory and motor fibres convey impulses from one level of the spinal cord to another
what is the main function of the spinal cord?
convey sensory impulses from the periphery to the brain, and to conduct motor impulses from the brain to the periphery. Also important for reflex actions.
What is a reflex?
autonomic involuntary act produced by stimulation of certain nerve fibres.
what is a reflex called that is carried out through the neurons of the brain?
cerebral reflex
what is a reflex that is carried out by neurons of the spine?
spinal reflex
what are the components of a reflex pathway?
receptor, sensory neuron, motor neuron, effector. (and possibly intermediate nerve cells between the sensory and motor neurons.
describe the location of the meninges (general)
cover the brain and spinal cord
describe the structure of the meninges
sheets of connective tissue
describe the functions of the meninges
support and protection of CNS
what are the names of the three meninges?
dura mater, pia mater, arachnoid mater
Describe the location, structure & function of duramater
most superficial of the meninges – dense fibrous sac protecting entire CNS. Cranial dura mater has two layers. Outer:periosteal, inner: meningeal. Spinal only one layer.
What is a dural sinus?
Area where the layers of the crainal dura mater are not fused. Instead, separate and collect venous blood. drain it to internal jugular vein.
What is a dural sheath
tough, tubular spinal duramater that surrounds the spinal cord. No connection between dural sheath and vertebrae, but a cavity.
What is the cavity called that is between the dural sheath and the vertebrae
epidural space (highly vascular and filled with loose fibrous and adipose connective tissues to form pad around spinal cord.)
location, structure, function of arachnoid mater
intermediate layer of connective tissue, surrounding brain and spinal cord. bridges fissues and sulci – loosely attached to the pia mater by webs of arachnoid tissue
location, structure and function of pia mater
delicate conective tissue layer, closely bound to the surface of the brain and spinal cord. Carries blood to underlying brain tissue. Is highly vascular.
What separates the arachnoid mater from the pia mater?
the subarachnoid space, filled with cerebrospinal fluid.
what attaches the spinal cord to the dura mater?
the ligamentum denticulatum, which is partially formed by the pia mater.
what protects the central nervous system from injury?
cerebrospinal fluid
where does the cerebrospinal fluid circulate?
through the four ventricles of the brain, and through the subarachnoid space around the brain and the central canal of the spinal cord.
How does the CSF return to the circulatory system?
drains through the walls of the arachnoid villi to the venous blood system.
Name the ventricles of the brain.
two lateral ventricles, third ventricle, fourth ventricle
What connects the ventricles?
lateral ventricles connected by interventricular foramen to third ventricule (between thalami), mesencephalic aqueduct connects third to fourth ventricles. Fourth ventricle connects to two lateral and one median apertures, which return CSF to arachnoid villi.
Describe the flow of CSF
secreted by choroid plexuses in ventricular walls, circulates through ventricles and central canal, enters the subarachnoid space, is reabsorbed into blood of dural sinuses through arachnoid villi. (Diag:VDG, p383.)
What is CSF made up of?
like plasma. contains proteins, glucose, urea, white blood cells. More sodium, chloride, magnesium and hydrogen. Fewer calcium and potassium ions than plasma.
what are the other functions of the cerebrospinal fluid
protects and bathes brain, maintains shape of the brain(fills ventricles), compensates for blood volume changes, shock absorber, circulates nutritive substances filtered from blood.
what is hydrocephalus?
blockage of free communication in ventricular system or subarachnoid space. CSF accumulates in ventricles proximal to blockage, causing pressure increase within ventricular system.
what can happen if fluid increases during hydrocephalism?
Can compress and damage brain tissue. If it happens prior to fusion of sutures, increased intracranial pressure can produce enlargement of head by widening of sutures and fontanels. Usually causes brain tissue damage and mental retardation
What percentage of the body weight does the CNS contribute, and how much of the blood supply does it receive?
2%, >15%.
Can nerve cells withstand more than a few minutes of blood deprivation?
No. They’re sensitive to metabolic disturbances, and there are serious consequences if there is blood deprivation.
How does blood reach the brain?
two internal carotid arteries and two vertebral arteries.
Where do the carotid arteries enter the skull?
carotid canal in temporal bones
What does the carotid artery supply?
frontal, parietal, and temporal lobes
What is the vertebral artery a branch of?
the subclavian artery
Where does the vertebral artery pass?
through the transverse foramina of the upper six cervical vertebrae
where does the vertebral artery enter the skull?
foramen magnum (of the occipital bone)
Where do the vertebral and carotid arteries converge?
At the lower border of the pons
What do the vertebral and carotid arteries form when they converge?
basilar artery.
What does the basilar artery supply?
temporal and occipital lobes, midbrain and hindbrain.
What is an anastomosis?
convergence of blood vessels (or nerves) that forms a network.
What is the name for the anastomoses formed by the two internal carotid arteries, and the basilar artery, and what is its purpose?
Circle of willis. Branches provide blood to various areas of the brain. Provides an alternate pathway for blood to reach the brain in the event that there is blockage of one of the arteries.
what are dura mater septa and what is the function?
four locations where the meningeal layer of the dura mater forms partitions between major brain surface structures. They partiction brain surface structures and anchor the brain to the inside of the cranial case.
Name the four cranial dura mater septa and what they partition.
falx cerebri. partitions left and right cerebral hemispheres (is in the longitudinal fissure.) Tentorium cerebelli. separates occipital and teporal lobes from the cerebellum. falx cerebelli partitions the left and right cerebellar hemispheres. diaphragma sellae forms the roof of the sella turcica.
What is the sella turcica (reminder)
little hole in the sphenoid bone that the pituitary fits into.
what are ganglia
collections of nerve cell bodies outside the CNS.
What are the two regions of the peripheral nervous system
cranial and spinal regions
what is another part of the peripheral nervous system?
autonomic nervous system
what does the ANS do?
supplies smooth muscles, cardiac muscle, glands
What are the two points of attachment of a spinal nerve to the spinal cord?
ventral root and dorsal root.
where are the spinal nerve attachments?
lateral to intervertebral foramen
what is a spinal ganglion?
the swelling where the dorsal roots contain cell bodies of sensory neurons.
What kind of nerves are spinal nerves?
Mixed nerves. Contain sensory fibres in posterior root, and motor fibres in the anterior root.
Where does the first cervical pair of spinal nerves emerge?
between the atlas and occipital bone.
How many of each type of spinal nerves are there in the 31 pairs?
8 cervical, 12 thoracic, 5 lumbar and 5 sacral, 1 coccygeal.
What is a ramus?
a branch (of bone, vessel, or in this case, nerve.)
What are the two major branches called after the spinal cord leaves the intervertebral foramen?
ventral and dorsal rami.
What does the dorsal ramus supply?
muscles and skin of the back
What does the ventral ramus supply?
all structures of the extremities and the lateral and anterior trunk.
Which rami makes up the major part of the spinal nerve?
ventral rami
What do the ventral rami of the spinal nerves except T2 – T12 communicate to form?
Plexuses.
Name the four plexuses.
cervical, brachial, lumbar, sacral.
What is each plexus named after?
area that they supply (cervical, brachii, lumbar, sacral)
What is the term given to a nerve that arises from a plexus?
peripheral nerve
define a nerve plexus
anterior rami of spinal nerves combine and then split again as networks of nerves called plexuses. (4)
describe the location and functions of the major nerves emerging from the four nerve plexuses
cervical plexus location
either side of neck adjacent to first four cervical vertebrae
Cervical plexus formed by
ventral rami of first four cervical nerves
cervical plexus innervates
skin and muscles of the neck and upper part of the shoulder
cervical plexus nerves emerge about where?
near middle posterior border of sternocleidomastoid.
Important nerve of cervical plexus and what it innervates
phrenic nerve, supplies motor fibres of diaphragm
injury to spinal cord above level of origin of prhenic nerve can cause what?
paralysis of diaphragm. (bad.)
Brachial plexus formed by what
ventral rami of spinal nerves C5 to C8, and T1. C4 and T2 contribute a bit.
What does the brachial plexus innervate
muscles of the neck and upper limb (rhomboids, scalenes, serratus anterior, subclavius, supraspinatus, pectoralis major, pectoralis minor, infraspinatus.)
what are the major nerves of the brachial plexus ?
musculocutaneous, median, ulnar, radial, axillary,
which is the largest nerve of the upper limb?
radial nerve
where is the musculocutaneous nerve and what does in innervate?
musculocutaneous nerve – down front of arm – supplies motor fibers to coracobrachialis, brachialis, and biceps brachii (nerve injury causes forearm flexion problems);
where is the median nerve and what does in innervate?
median nerve – supplies superficial muscles of front of forearm, and thenar eminence muscles – receives sensory input from lateral hand – damage results in inability to pronate forearm and to flex wrist, fingers, or thumb.
where is the ulnar nerve and what does in innervate?
ulnar nerve – supplies flexor carpi ulnaris, medial half of flexor digitorum profundus, intrinsic hand muscles, and skin on medial third of hand. Damage results in inability to flex, adduct wrist or abduct fingers. interferes with fine movements. Paralysis of intrinsic hand muscles causes “clawed” appearance of hand.
where can the ulnar nerve be felt?
It’s the “funny bone” nerve. Just behind medial epicondyle of humerus.
where is the radial nerve and what does in innervate?
LARGEST NERVE OF UPPER LIMB. posterior surface of arm and forarm – supplies extensor muscles, skin on posterior arm, forearm and hand.
what happens if the radial nerve is injured.
(Usually during fracture to humeral shaft), results in inability to extend forearm, hand, and fingers, hand becomes pronated, wrist and fingers flex (“wrist drop”)
where is the axillary nerve and what does it innervate?
branch of the posterior cord, related to the shoulder joint capsule – supplies deltoid and teres minor.
What happens if the brachial plexus is injured?
Usually serious. Can cause loss of function of the limb.
What are the intercostal nerves?
Spinal nerves T2 – T12, in subcostal groove of ribs
what do the intercostal nerves supply?
intercostal muscles. T2 – T6 also pierce thoracic wall near sternum to supply skin over axilla, and anterior and lateral chest. Lower intercostal nerves T7 – T12 supply abdominal muscles and the skin of the abdominal wall.
What forms the lumbar plexus?
ventral rami of spinal nerves L1 – L4.
Where is the lumbar plexus located?
inferolaterally deep into the psoas major muscle, where it gives rise to peripheral nerves.
What does the lumbar plexus innervate?
sensory and motor innervation to skin of anterior abdominal wall, external genitalio, anteromedial aspect of thigh and leg.
What are the two largest branches of the lumbar plexus?
femoral and obturator nerves
where is the femoral nerve and what does it innervate?
enters thigh deep to the inguinal ligament and supplies psoas major, iliacus, pectinius and anterior thigh, and supplies skin over anterior and medial thigh, leg, and foot.
what does injury to the femoral nerve result in?
inability to extend knee joint, and loss of sensation over anteromedial thigh.
wher is the obturator nerve and what does it innervate?
enters thigh through obturator foramen and innervates obturator externus, gracilis, pectineus and adductors.
What forms the sacral plexus?
ventral rami of L4, L5, S1 – S4.
Where is the sacral plexus?
on piriformis muscle in pelvis
what does the sacral plexus innervate?
nerves and muscles of skin of gluteal region, pelvic organs and lower extremities.
What other large nerve comes from the sacral plexus?
sciatic nerve – it’s the largest nerve in the body.
Where is the sciatic nerve located and what does in innervate?
through greater sciatic foramen, descends in middle of posterior thigh – supplies muscles of back of thigh and adductor magnus.
what two terminal branches does the sciatic nerve divide into in the lower thigh?
tibial and common peroneal nerves.

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