Spinal cord, Brainstem, Cerebellum Flashcards
Purpose of spinal cord
Means for communication from brain to body & from body to brain
Three layers of meninges
- pia mater
- arachnoid
- dura mater
Pia mater
inner
arachnoid
web-like, filled cerebral spinal fluid
dura mater
tough, outside layer
Spinal cord form (5 sections)
- Cervical (neck)
- Thoracic (chest)
- Lumbar (lower back)
- Sacral (pelvis)
- Coccygeal (tailbone)
Information superhighway conveys ..
Motor (efferent) and Sensory (afferent) info between brain and body
Spinal nerves emerge from
spinal cord, innervate parts of neck and BELOW the neck
4 fiber types
- General Somatic Efferent
- General Visceral Efferent
- General Somatic Afferent
- General Visceral Afferent
General Somatic Efferent (GSE) Fibers
to skeletal muscles
General Visceral Efferent (GVE) Fibers
to smooth muscle, heart, glands
General Somatic Afferent (GSA) Fibers
from skin
General Visceral Afferent (GVA) Fibers
from lungs and digestive tract
Funiculi
Each white matter region contains multiple tracts or fasciculi
Fasciculi
carries info up and down spinal column
Dorsal Root Ganglion
- collection neuronal cells
- signals to CNS from PNS (afferent)
Dorsal Ramus
part of spinal nerve after the nerve exits intervertebral foramen
Upper Motor Neuron
- originates in brain
- send signals down spinal cord
- “COMMANDS” movement
in CNS
Damage to UMN
typically spasticity and hyperflexia
(spastic muscle and flexes too much)
Lower Motor Neuron
- originates in spinal cord
- control muscles by sending signals on to the muscles and glands
- “CARRIES OUT” the action
in PNS
Damage to LMN
flaccid paralysis, muscle atrophy, decreased reflexes
Descending Motor Tracts
BRAIN TO SPINAL CORD
- lateral corticospinal
- anterior corticospinal
- rubrospinal
- vestibulospinal
Ascending Sensory Tracts
- Dorsal columns/somatosensory pathways
- Ventral spinothalamic
- Lateral spinothalamic
- Ventral spinocerebellar
- Dorsal spinocerebellar
Lateral corticospinal tract
- originates in motor cortex
- decussates (crosses over) at lower medulla
- from cortex to brainstem
- contralateral body movement
Anterior/Ventral corticospinal tract
- originates in motor/premotor areas of frontal lobe
- ipsilateral control of trunk muscles
- smaller lateral cortical spinal tract
Rubrospinal tract
- originates in midbrain
- decussates in ventral midbrain
- inputs into ventral horn
- modulates flexor tone in upper limbs/shoulder
Vestibulospinal tract
- originates in medulla
- ipsilateral
- inputs into ventral horn
- controls extensor tone in limbs/neck
1st order neuron
directly receive info from periphery to spinal cord
(carry sensory signals from receptors)
2nd order neuron
within spinal cord - may decussate- input to thalamus or brainstem
3rd order neuron
in thalamus, carry to specific areas of cerebral cortex
4th order neuron
in cerebral cortex, interpret signal
Dorsal Columns are also known as
- Somatosensory Pathways
- Dorsal column medial lemniscus
Dorsal Columns
sensory receptors –> spinal cord decussates –> thalamus –> somatosensory cortex
relay fine touch, pressure, proprioception
Ventral/Anterior spinothalamic tract
anterior part of spinal cord
relays light/crude touch and pressure
Lateral spinothalamic tract
lateral part of spinal cord
relay pain and temperature
Pathway of spinothalamic tract
from PNS –> spinal cord –> thalamus –> somatosensory cortex
Ventral spinocerebellar tract
ventral portion spinal cord –> dorsal horn –> decussates to cerebellum
Dorsal spinocerebellar tract
dorsal portion spinal cord –> dorsal horn –> ipsilaterally to cerebellum
The spinocerebellar tracts provide..
proprioceptive information
Function of the spinal cord
relay efferent and afferent information between body & brain
(also mediate reflexes)
reflexes
- controlled at level of spinal nerves and cord
- signal goes to spinal cord and returns via reflex arc
Process of reflex
muscle stimulated –> muscle spindles detect stretch –> info sent thru sensory neurons to dorsal root (gray matter)–> info sent to interneurons –> motor message sent via ventral root
then muscle contracts
Spinal Cord Injury
damage to spinal cord often thru traumatic causes
- vehicular accidents
- result in paresis/plegia
Paraplegia/Paraparesis
involves legs
Quadriplegia/Quadriparesis
involve arms and legs
Myelitis
Inflammation of spinal cord
- caused by virus, bacteria, fungi, parasites and toxic agents
- types include polio, Leuko, transverse
Poliomyelitis
affects gray matter (motor loss)
Leukomyelitis
affects white matter (sensory loss)
Transverse
affects both gray and white matter (motor and sensory loss)
Peripheral Neuropathy
inflammation of PNS
- degeneration of spinal nerves (feet)
- caused by untreated diabetes, toxins, infections, nutritional issues
- leads to paresthesia or anesthesia
Paresthesia
abnormal sensation skin may feel tingling, burning, itching, numbness
Parts of the brainstem
Midbrain
Pons
Medulla
Brainstem functions
- regulating major life functions
- mediate head/neck reflexes
- regulate alterness and wakefulness
Medulla
- lowest part of brainstem
- ventral to cerebellum
- connects to cerebellum via inferior cerebellar peduncle (little bridge)
- contains descend. motor tracts & olive
Inferior olive nucleus
integrates signals from spinal cord to cerebellum, functions coordination
Medulla autonomic nerves system nuclei
cardiac, vasoconstrictor, gastrointestinal motility, respiratory, swallowing centers
mediates reflexes: vomit, cough, gag, swallow
Pons
superior to medulla, inferior to midbrain, anterior to cerebellum
- acts as bridge, relaying tracts cerebral cortex, cerebellum, lower structures medulla and spinal cord
Pons nuclei
regulate: respiration, swallowing, hearing, eye movement, facial movement, sensation
-sup olivary nucleus & lateral lemniscus (important function in auditory info)
Midbrain
inferior to diencephalon, superior to pons
- colliculus/tetum
- tegmentum
- peduncles
Colliculus/Tetum
contains
inferior colliculus (auditory processing)
superior colliculus (visual processing)
Tegmentum
dorsal part, spreads length brainstem
- tracts/nuclei important motor control and sensory processing
Tegmentum NUCLEI
- substantia nigra (dopamine produced)
- red nucleolus (coordination of move)
- reticulum form (consciousness, sleep-wake cycle, cardiovascular, respiration)
- periaqueductal gray matter (suppress pain)
Peduncles (Crus Cerebri)
ventral part (leg of brain) pair of fibers
- connect brainstem to forebrain
- main highway signals transported between cortex to part of CNS
- important in coordination
Cerebellum
“little brain”
- 2 hemispheres connected by vermis
- 3 lobes (anterior, posterior, flocculonodular)
gray matter: tightly folded, forms cerebral cortex (folia)
white matter: beneath cerebellar cortex
Divisions of cerebellum
cerebrocerebellum
spinocerebellum
vestibulocerebellum
Cerebrocerebellum
largest division, involved in planning movements & motor learning
(receives cerebral cortex to thalamus/red nucleus)
Spinocerebellum
vermis and intermediate zone
error correction movement & proprioception
Vestibulocerebellum
input from vestibular system to vestibular nuclei
controls balance and ocular reflexes
Cerebellum macroscopic anatomy
80% total neurons in brain
Neuron arranged 3 layers
3 layers of cerebellum neurons
- molecular
- purkinje (GABAergic cells inhibit cerebelluim)
- granular
Cerebellar pathways
- vestibulocerebellar
- vermal spinocerebellar
- paravermal spinocerebellar
- pontocerebellar
Motor function of cerebellum
Planning, monitoring, correction of motor movement using sensory feedback, coordinates fine motor activity, monitors head/body position, learning new motor skills
Linguistic function of cerebellum
perception of speech/lang, verbal working memory, verbal fluency, grammar processing, writing/reading
Cerebellar Damage Symptoms
dysmetria, dysdiadochokinesia
ataxia
nystagmus
intention tremor
speech (slurred/ scanning) ataxic dysarthria
hypotonia
DANISH
Cerebellar Hemispheric Syndrome
damage in hemisphere cerebellum (stroke, tumor, MS)
Vermal syndromes
damage to vermis
primarily effects trunk muscles
