310-319 Flashcards
Cerebellum
Lies posteroinferior to cerebrum, superoposterior to brain stem.
■ Morphologically divided:
■ Two lateral hemispheres.
■ Middle portion (Vermis).
cerebeluum
Functions (excitatory):
■ Maintains muscle tone.
■ Coordinates muscle movement.
■ Controls balance.
The basal ganglia and cerebellum modify movement on a —— basis. The output of the cerebellum is —— whereas that of
the basal ganglia is —–.
The basal ganglia and cerebellum modify movement on a minuteto-
minute basis. The output of the cerebellum is excitatory, whereas that of
the basal ganglia is inhibitory.
These two systems work together to achieve —– —–movement.
These two systems work together to achieve smooth, coordinated movement.
Connects dorsally with the cerebellum.
■ Large voluntary motor nerve tracts pass through.
Midbrain (Mesencephalon
Location of:
■ CN III, IV nuclei (connect with VI via MLF).
■ Substantia nigra. (See also “Parkinson’s Disease” in Neuropathology
midbrain
Between the midbrain and medulla.
■ Connects to the cerebellum posteriorly.
PONS
PONS
Location of:
■ CN V, VI, VII, VIII nuclei.
Most inferior segment of vertebrate brain.
■ Continues with the spinal cord below.
■ Joins the spinal cord at foramen magnum
med. obl.
Contains:
■ Important regulatory centers:
■ Area postrema—vomiting.
■ Swallowing.
■ Cardiac.
■ Vasomotor.
■ Respiratory.
med. obl.
CN IX, X, XI, XII nuclei.
MEd. Obl.
Afferent neurons: From sensory receptors to CNS.
■ Efferent neurons: From CNS to muscles, organs, and glands (and their
associated ganglia and plexuses)
PNS
https://drive.google.com/open?id=0B8uJUY-tie8GWDFqU1plQkhUOFk
https://drive.google.com/open?id=0B8uJUY-tie8GSDlwSFc1MzRMSEk
BASIC ANATOMIC PATHWAY
Preganglionic neuron (within CNS).
↓
xxxxxx
↓
Postganglionic neuron (outside of the CNS).
↓
yyyyyy
BASIC ANATOMIC PATHWAY
Preganglionic neuron (within CNS).
↓
Ganglion (cell bodies of postganglionic neurons; outside of the CNS).
↓
Postganglionic neuron (outside of the CNS).
↓
Effector organ
Autonomic Ganglia
■
Collections of cell bodies of the postganglionic neurons (unmyelinated).
Sympathetic: Sympathetic —- —– (near spinal cord) (paravertebral):
—– preganglionic neuron.
—–postganglionic neuron.
Sympathetic: Sympathetic chain ganglia (near spinal cord) (paravertebral):
■ Short preganglionic neuron.
■ Long postganglionic neuron.
Parasympathetic: Ganglia at, within organ (eg, celiac ganglion):
■ Long preganglionic neuron.
■ Short postganglionic neuron.
Parasympathetic: Ganglia at, —– organ (eg, celiac ganglion):
x preganglionic neuron.
y postganglionic neuron.
Craniosacral: Composed of:
■ CN nuclei (ie, III-ciliary, VII- submandibular and pterygopalatine, IX-otic).
——(pelvic splanchnic).
■ Major nerve is the xxx nerve (CN X): Originates in yyyyyy.
Craniosacral: Composed of:
■ CN nuclei (ie, III-ciliary, VII- submandibular and pterygopalatine, IX-otic).
■ S2–S4 (pelvic splanchnic).
■ Major nerve is the vagus nerve (CN X): Originates in medulla.
Preganglionic neuron (myelinated)
■ Cholinergic (releases xxxx).
■ Binds yyyyy cholinergic receptors on postganglionic neurons (zzz)
Preganglionic neuron (myelinated)
■ Cholinergic (releases Ach).
■ Binds nicotinic cholinergic receptors on postganglionic neurons (ganglia
within effector).
Postganglionic neuron (unmyelinated)■
Cholinergic (releases Ach).
■ Binds muscarinic cholinergic receptors in the tissue
https://drive.google.com/open?id=0B8uJUY-tie8GcXpGODNjMUdoUFk
https://drive.google.com/open?id=0B8uJUY-tie8GaUNtbFRPcTZSTkE
All xxxxx autonomic neurons (both sympathetic and parasympathetic)
and all yyyyy parasympathetic neurons are ——
(use zzzz as NT).
All preganglionic autonomic neurons (both sympathetic and parasympathetic)
and all postganglionic parasympathetic neurons are cholinergic
(use Ach as NT).
Cholinergic effects of xxxx autonomic systems (at ganglia of sympathetic
and parasympathetic systems) are zzz
Cholinergic effects of preganglionic autonomic systems (at ganglia of sympathetic
and parasympathetic systems) are excitatory
Cholinergic effects of xxxx parasympathetic fibers are either yyyy
or zzzz, depending on the tttt (eg, parasympathetic fibers
innervating heart vvv HR).
Cholinergic effects of postganglionic parasympathetic fibers are either excitatory
or inhibitory, depending on the end-organ (eg, parasympathetic fibers
innervating heart ↓ HR).
SNS
Thoracolumbar.
■ Composed of spinal segments T1–L3.
Sym nervous system
Exerts widespread effect because of high ratio of postganglionic to preganglionic
fibers.
■ Each sympathetic preganglionic neuron branches extensively and
synapses with numerous postganglionic neurons
Preganglionic neuron (myelinated)
Cholinergic (releases Ach).
■ Binds nicotinic cholinergic receptors on postganglionic neurons (ganglia
within effector).
■ Each preganglionic parasympathetic neuron synapses with many postganglionic
parasympathetic neurons
Postganglionic neuron (unmyelinated)
■ Adrenergic (releases NE).
■ Binds adrenergic receptors in the tissue except sweat glands and skeletal
muscle blood vessels.
ADRENERGIC RECEPTORS■
Membrane receptor proteins.
■ G-protein-coupled receptors.
■ Located on autonomic effector organs.
■ Bound by catecholamine ligands (epinephrine, norepinephrine).
■ Norepinephrine (NE) stimulates mainly alpha receptors.
■ Epinephrine stimulates both alpha and beta equally
https://drive.google.com/open?id=0B8uJUY-tie8GbFFjNkUyY2lSLVE
https://drive.google.com/open?id=0B8uJUY-tie8GazRlOXBKdlZyVnc
https://drive.google.com/open?id=0B8uJUY-tie8GVUl5dXQwLXd3Y0E
https://drive.google.com/open?id=0B8uJUY-tie8GdjlUaGl2YkV6R3c
https://drive.google.com/open?id=0B8uJUY-tie8GMVp3czVNSVV4NlE
https://drive.google.com/open?id=0B8uJUY-tie8GRGdfRk85MTAyTFk
https://drive.google.com/open?id=0B8uJUY-tie8GR1BkdC1OVWN3WW8
https://drive.google.com/open?id=0B8uJUY-tie8GRTQtY3MzcXVWZjg
https://drive.google.com/open?id=0B8uJUY-tie8GLVdDQmhtNU1pM28
https://drive.google.com/open?id=0B8uJUY-tie8GR1h2Z1BDVVhHczg
receptor
■ Receive information from internal or external environment.
■ Send nerve impulses to CNS.
■ Two broad types: According to location of stimuli.
Exteroreceptors: Receive external stimuli (from body surface):■
Touch.
■ Pressure.
■ Pain.
■ Temperature.
■ Light.
■ Sound.
Interoreceptors (visceroreceptors): Receive input from internal environment
of body:
■ Pressure.
■ Pain.
■ Chemical changes.
PROPRIORECEPTORS
■ Type of interoceptor.
■ Relays information concerning position of body parts (in space).
propioception
Separate from visual input.
■ Kinesthetic sense
■ Located in muscles, tendons, joints.
■ Communicate with the vestibular apparatus.
https://drive.google.com/open?id=0B8uJUY-tie8GQ2cxSlpDZEhWTVU
https://drive.google.com/open?id=0B8uJUY-tie8GcnQwOGI1SWZwM1U
https://drive.google.com/open?id=0B8uJUY-tie8GSEw2ckIzMjhBbFE
https://drive.google.com/open?id=0B8uJUY-tie8Gc0RsTTZFOXY2Z00
https://drive.google.com/open?id=0B8uJUY-tie8GRnItQ19CXzROMnc
https://drive.google.com/open?id=0B8uJUY-tie8GU0hTcjJNSy1QUGM
SPINOTHALAMIC TRACT (ANTEROLATERAL SYSTEM )
■ Lateral spinothalamic tract: T
■
transmits pain and temperature.
Anterior spinothalamic tract: T
transmits light touch
pathway spinothalamic tract
Sensory nerve
↓
xxxxxx
↓
Cross to opposite side of cord via anterior white commisure (decussate at level
enters cord) via Lissaure’s tract; secondary neuron
↓
yyyyyyy
↓
Thalamus (tertiary neuron, in VPL)
↓
zzzzz
Sensory nerve
↓
Dorsal horn of spinal cord gray matter (travel in Lissauers tract and then
synapse on secondary neurons)
↓
Cross to opposite side of cord via anterior white commisure (decussate at level
enters cord) via Lissaure’s tract; secondary neuron
↓
Ascend contralateral spinal cord (through anterior and lateral white matter
columns/tracts)
↓
Thalamus (tertiary neuron, in VPL)
↓
Somatosensory cortex (parietal lobe)
DORSAL COLUMN , MEDIAL LEMNISCUS SYSTEM
■ Conveys touch, pressure, and vibration
Sensory nerve
↓
Dorsal horn of spinal cord gray matter
↓
yyyyy
↓
Posterior columns: Fasciculus gracilis (fibers from lower extremities) and
Fasciculus cuneatis (fibers from upper extremities)
↓
Synapse in medulla (nucleus gracilis and cuneatis)
↓
xxxxxx
↓
Thalamus
↓
zzzzz
Sensory nerve
↓
Dorsal horn of spinal cord gray matter
↓
Ascend ipsilateral spinal cord
↓
Posterior columns: Fasciculus gracilis (fibers from lower extremities) and
Fasciculus cuneatis (fibers from upper extremities)
↓
Synapse in medulla (nucleus gracilis and cuneatis)
↓
Internal arcuate fibers decussate and ascend contralateral brain stem in medial
lemniscus
↓
Thalamus
↓
Somatosensory cortex
https://drive.google.com/open?id=0B8uJUY-tie8GMUJhLTJnNEFSLU0
https://drive.google.com/open?id=0B8uJUY-tie8GRlNlZHhhU3I5V1U
https://drive.google.com/open?id=0B8uJUY-tie8GR2ZoUjFuVEJHcHM
https://drive.google.com/open?id=0B8uJUY-tie8GWS1GY0JsWjJfUHc
Descending Motor Tracts (Efferent or Descending Pathways)
■
The upper motor neuron tracts sending signals from the brain muscles
MOTOR PATHWAY
Motor area of brain (precentral gyrus of frontal lobe)
↓
xxxxx
↓
Lower motor neurons
↓
yyyy
MOTOR PATHWAY
Motor area of brain (precentral gyrus of frontal lobe)
↓
Upper motor neurons (= descending motor tracts, eg, corticospinal tract)
↓
Lower motor neurons
↓
Skeletal muscle
Upper Motor Neurons■
Originate in white matter of brain.
■ Form two major systems:
■ Corticospinal tract (pyramidal system).
■ Extrapyramidal system.
Corticospinal Tract (Pyramidal System)
Two components:
■ Lateral (70–90%).
■ Anterior/ventral (10–30%).
Travel via primary motor cortex through internal capsule to medulla.
■ Decussate in medulla (pyramids).
■ Continue down opposite side of spinal cord →
anterior horn → lower motor neurons → muscles.
■ Right brain controls left somatic muscles
corticocpinal tract
Control fine, skilled movements of skeletal muscle.
corticospinal tract
(red nucleus in midbrain—voluntary movements).
■ Important for somatic muscle control, posture
Rubrospinal
Reticulospinal—
important for somatic motor control and autonomic
function control (reticular nuclei, pons, and medulla) (reticular formation
(diffuse brain stem nuclei); coordinate locomotion, mediate
autonomic).
Olivospinal (
inferior olive—motor learning).
Vestibulospinal (
vestibular nuclei—control limb extensors, head and
neck (gaze)) mediates vestibular end organ and cerebellum upon
extensive muscle tone and balance
Tectospinal
(superior colliculus—coordinate neck, head, and eye
movements).
Travel from premotor area of frontal lobe (and other areas) to pons.
■ Decussate in pons.
■ Continue down opposite side of spinal cord →
anterior horn → lower motor neurons → muscles.
■ Right brain controls left lower motor neuron.
extrapyramidal
extrapyramidal system
Controls gross motor movement, posture, and balance.
