CNS Exam 2 Flashcards
The spinal cord has how many nerves?
31 pairs or 62 nerves
What is the superior boundary of the spinal cord ?
Superior most ventral root of the 1st cervical spinal nerve. Forman magnum
What is the inferior boundary of the spinal cord
Disc between vertebral levels L1 and 2
bell magendi law states what
Dorsal roots are to sensory and afferent fibers. ventral roots are to motor and efferent fibers
How many neurons are in the spinal cord
100 million
What level of the spinal cord takes up 75% of vertebral canal
C5 - C6
CNS contains what
Brain and spinal cord
PNS contains what
Roots, rootlets, nerves, and rami.
C1 exits where
between occipital and atlas
C4 exits where
Between c3 and c4
C8 exits where
between C7 and T1
T1 exits where
Between T1 and t2
T6 exits where
Between T6 and t7
L1 exits where
Between L1 and L2
L5 exits where
Between L5 and S1
S1 through S4 exit where
Dorsal and ventral sacral foramina
S5 and Co1 exit where
They exit the sacral hiatus
The first 3 months of embryonic development the cord and vertebral levels are
The same length
At adult hood what levels is the spinal cord at
Co1 cord level is found at L1 and L2
What is the tapering end of the cord called
Conus medullaris
The cauda equina ( horse tail) at end of spinal cord is found where
Lumbar cistern
Dorsal horn function
Receives sensory afferent to CNS from DRG
Lateral horn function
present at cord levels t1-l2 and s2-s4. They are preganglionic autonomic neurons.
Ventral horn function
Takes motor info away from CNS (muscle)
What is the funiculus
Longitudinal bundle of white matter fibers
Gray mater is what
dense concentrations of neuron cell bodies. Thick dendritic mats are unmyelinated dense capillary beds.
White matter
Dense concentration of neuron fibers, myelinated, less vascular than gray matter.
rexed lamina 1 is what
Thin cap over dorsal horn
Rexed Lamina 2 deals with what
pain reception
rexed lamina 3 and 4 is what
The proper nucleus and deals with touch and pressure.
rexed lamina 5 is what
cervical cords only, cell bodes send axons to cotralateral spinothalamic tracts.
Rexed lamina 6 is
Not present in all cord levels.
Rexed lamina 7 is
In the intermediate gray area, lateral horn. many descending tract fibers. This is the Clarkes nucleus it goes from C8 to L3. Ribbon cell bodies send axons to post spinocerebellar tract.
Rexed lamina 8 is
The medial aspect of anterior horn
rexed lamina 9 is
Class A alpha, motor neurons. They are the largest, fastest, motor conducting neurons. They carry initiation.
Rexed lamina 10 is
Anterior and posterior commissures. Unmyelinated fibers.
What holds together fasciculi / tracts
NCAMs Nerve cell Adhesion Molecule
can you observe tracts with staining techniques?
Nope
Where do you find the gracilis tract
In medial aspect of the Dorsal funiculus. All cord levels. Synapse in nucleus gracilis of MO
Where do you find the cuneatus
lateral aspect of dorsal funiculus. T6 and up. Synapse in nucleus cuneatus of MO.
Functions of gracilis and cuneatus
2 point touch, vibratory sensations. Kinesthetic sensation. Conscious proprioception.
Romberg test
Put feet together and close eyes. See if they can keep their balance. It is not a cerebellar test, it tests the posterior column.
Explain the 3 neuron pathway
1 is the dorsal root ganglion
2 is contra lateral, it goes to other side via internal accurate fibers. To the MO.
3 Goes to the thalamus VPL
Which 2 tracts are formed by axons that come from cell bodies in the gray horns.
Lateral and anterior spinothalamic tracts
The lateral spinothalamic tract Is
Located in the lateral funiculus, present in all cord levels, deals with pain and temperature . It crosses quickly.
The anterior spinothalamic tract is
Located in the anterior funiculus, present in all cord levels, deals with light touch/ and deep touch/pressure. it crosses gradually.
Which tracts make up a large part of the anterolateral system?
Lateral and anterior spinothalamic tracts
What is analgesia
Loss of pain sensation
What is thermoanaesthesia
Loss of temperature sensation
What is the gracilis and cuneatus called together?
Posterior columns
Where do you find the anterior spinocerebellar tract?
lateral funiculus, anterior to the post spinocerebellar tract.
What does the anterior spinocerebellar tract fibers do ?
The fibers cross in the cord, most cross back again. They cross twice. Fiber origin are in the lumbosacral cords gray laminae. Terminate in cerebellum via superior peduncle.
The anterior spinocerebellar sends what information?
gross movements of lower body.
Thalamus is to conscious thought as cerebellum is to ?
Subconscious thought
Where do you find the posterior cerebellar tract
Lateral funiculus posterior to the anterior spinocerebellar tract.
What does the posterior cerebellar tract fibers do?
Most fibers do not cross, Fiber origins are in nucleus dorsalis. Tract is not found below L3. It is ipsilateral.
Where does the posterior cerebellar tract terminate
Cerebellum via the inferior peduncle
The posterior cerebellum sends what info?
proprioceptive, dealing with fine movements in the muscle. Follows up the gracilis.
Where is the anterior corticospinal tract?
In the anterior funiculus
What is the anterior corticosinal tract?
Has 5-15% of total corticospinal fibers. Most fibers cross in the pineal cord. They terminate by mid thoracic. Influence axial neck and shoulders.
Where is the lateral corticospinal tract?
Lateral funiculus
What is the lateral corticospinal tract
It contains 85-95% of corticospinal fibers. Fibers cross in the pyramids of the MO. It runs the entire length of th spinal cord.
What is the function of the lateral corticospinal tract?
Initiating and accomplishing precise and skilled voluntary muscle movements, especially in distal extremities.
The corticospinal tracts have how many neurons start to finish?
1 neuron
Where do the corticospinal tracts synapse?
rexed laminae 7, they communicate with 9
Which fibers begin in the cerebral cortex and run uninterrupted to the spinal cord?
Corticospinals
There is a decrease in corticospinal fibers as they descend the cord, why?
They terminate, 55% in cervical, 20% in thoracic, and 25% in the lumbar.
What are lower motor neurons?
They originate in spinal cord or brain stem and extend into the PNS to innervate somatic muscle. Example is Class A alpha motor neurons.
What are upper motor neurons?
neurons that are entirely in the CNS, they do not leave. They influence and initiate. Example- anything cortico…..
Upper motor neuron lesions
Reduction or absence of voluntary movement . Hyperreflexia. Increased muscle tone. cerebral palsy.
Which fibers go straight to rexed laminae 9
Betz cells/ giant pyramidal
Lower motor neuron lesions
Reduction of voluntary movement. Hyporeflexia. Decreased muscle tone and atrophy.
What are pyramidal neurons?
Upper motor neurons that are involved with initiation of skilled voluntary movements. In the cord, pyramidal fibers are corticospinals.
What are extrapyramidal neurons?
Upper motor neurons that originate in the brain stem and extend down the cord. They influence posture, muscle tone, enhance reflexes, and voluntary movements.
origin of the tectospinal tract (extrapyramidal)
What do the fibers do?
Midbrain’s tectum
Fibers cross as they descend
Most fibers terminate in the upper four cervical cord levels.
What is the function Of the tectospinal tracts?
Sight and auditory stimuli. Adjustments of the muscles trapezius and sternocleidomastoid. Cranial nerve 11.
origin of rubrospinal tract?
Red nucleus midbrain’s tegmentum
Rubrospinal tract fibers do wat?
Fibers cross as they descend, reach all cord levels, influence FLEXOR muscles. They are contra lateral.
Vestibulospinal tract origin?
Lateral vestibular nucleus in MO.
Vestbulospinal fibers do what?
They do not cross as they descend. They reach all cord levels. They are ipsilateral. EXTENSOR musculature, they inhibit flexors. Maintains orientation when falling.
What syndrome uses a hemisection
brown square syndrome
What is tabes dorsalis
bacterial tertiary syphylis - wasting of dorsal funiculus - fasciculus gracilis
Someone with tabes dorsalis would lose what function?
Vibration, kinesthetic proprioception of lower extremities.
What is multiple sclerosis
destruction of CNS myelin. More common in women
What is ALS?
Amyotrophic lateral sclerosis, destruction of upper motor neurons and lower motor neurons . lateral corticospinal tract. More common in men.
What is another name for the Pons/
Metencephalon
What is the function of the pons?
It is the relay center, uses cranial nerves
What is meant by rhom met mye
The rhombencephalon seperates into the myecephalon which is the M.O
and the metencephalon turns into the pons and cerebellum.
What parts make up the brain stem?
Midbrain, pons, and M.O
Brain stem origin?
Where cranial nerves appear to be attached to the surface
Brain stem nucleus of origin?
Nucleus that contribute motor fibers to the CNS. Muscle innervation.
Brain stem nucleus of termination?
nucleus that receive incoming afferent input from cranial nerves. Sensory.
What is the medulla oblongata ?
Most inferior part of rhombencephalon and brain stem.
Functions of the M.O
Passive fiber conduction. relay nuclei gracilis and cuneatus. Cranial nerves 5-12, not 6
What is the basilar sulcus?
median longitudinal groove along ventral bulge
What is the trigeminal nerve?
nerve 5,
What do the olives do ?
Relay info to the cerebellums central nuclei and cortex via climbing fibers.
Auditory function.
what is the reticular formation?
Net like, gives general arousal like wakefulness and attention. Deals with autonomic and somatic extrapyramidal actions. Reticulospinal tracts - heart rate, BP
Pyramids have what fibers?
Descending, corticospinal fibers. Upper motor neurons
The medial Lemiscus in the M.O has what fibers?
Ascending fibers
The lateral rectus goes with what cranial nerve
CN 6 abducens
Superior oblique goes to what cranial nerve
CN 4 trochlear
Which cranial nerve is responsible for eye movement
CN 3 oculomotor
Hyperreflexia affects what
Upper motor neurons
Hyporeflexia affects what
Lower motor neurons
A lesion of the dorsal horn causes
Sensory problems
Lesion of the ventral horn causes
Motor problems
A lesion of ventral root causes
Lower motor neuron problems
A lesion of the dorsal root causes
Sensory problems
A lesion of the ventral / ramus causes
Motor and sensory problems
A total transaction of spinal cord causes
Loss of function at injury and down
The medulla oblongata is ventral to the
Cerebellum
The Medulla is inferior to the
Pons
The medulla is superior to the
Spinal cord
The medulla is very small but
Very significant
What is the inferior order of the medulla
Superior most anterior rootlet of C1
Chemoreceptors in the obex detect what
Toxins like alcohol in the blood, triggers vomiting
What is the medial lemniscus
Bilateral band of ascending fibers that terminate in the thalamus, VPL. Receives accurate fibers from gracilis and cuneatus.
What nuclei is supplied by CN 3
Accessory occulomotor, edinger- Westphal. parasympathetic pupil constrictor. Motor.
occulomotor nuclei, somatic motor nerves, lower motor neurons. Move and open eyes.
What does the trochlear nucleus do
Somatic muscle control for superior oblique eye muscle. CN 4. Eyes move down and out.
What does the trigeminal mesencephalic nucleus do
Mastication, chewing, Nucleus of termination. CN 5
What does the trigeminal motor nucleus do
Somatic motor to mastication. Also tensor villi palatine, tensor tympani. Lower motor neurons, CN 5
What does the abducens nucleus do
Somatic motor of lateral rectus in eyes. CN 6
What does the facial nucleus do
Most superficial somatic motor muscles of scalp and face. Facial expression. CN 7
Superior salivary nucleus function
Parasympathetic control of tear glands and sublingual salivary glands. CN 7
Inferior salivary nucleus function
Parasympathetic control of parotid salivary gland CN 9
vestibular and cochlear nuclei function
equilibrium and hearing. Nuclei of termination CN 8
Hypoglossal nucleus function
Somatic motor control for 16/18 tongue muscles. It is a nucleus of origin. CN 12
Posterior nucleus of vagus function
Sensory and motor (parasympathetic) voice, heart , lungs,and intestines. CN 10
Nucleus ambiguus function
Efferent motor fibers, to pharynx and larynx. Lower motor neuron. CN 9, 10, 11
Nucleus solitarius function
Taste, tongue, palate and pharynx. CN 7,9, 10.
Spinal nucleus of the trigeminal nerve function
face, dealing with pain, thermal, tactile, and proprioception. The largest, CN 5,7,9,10.
Spinal nucleus of the accessory function
Somatic motor, neck muscles called sternocleidomastoid and trapezius. Upper 5 cervical cord levels and lower medulla oblongata. Very large CN 11
What is the pons
has ascending and descending fibers, derivative of metencephalon. Nucleus of origin and termination. 5 ,6,7,8, Relay center for fibers going to the cerebellum
What is the pontine reticular formation
Control center for respiratory and cardiovascular control via medial reticulospinal tracts. Sleep, REM/
The pons is ventral to the
Cerebellum
The pons is inferior to the
Midbrain
The pons is superior to the
Medulla oblongata
What is the rhomboid fossa
Dorsal part of the pons forms the ventral aspect of the 4th ventricle. MO completes the inferior aspect.
The lateral aspect of the pons houses what feature
Middle cerebellar peduncle, the largest
What is the tegmentum
The dorsal division of the pons
What is the basilar
Ventral division of the pons
What is the cerebellum
Derivative of the metencephalon. Host of sensory input, momentary status of muscle contraction, joint tension, visual and auditory input on equilibrium. Coordination. Compensation
What is ipsilateral
Traveling from the left side to left side
What is contra lateral
Traveling from the right to left, and left to right
The cerebellum is attached to the MO by the
Inferior cerebellar peduncle
The cerebellum is attached to the pons via
Middle cerebellar peduncle
The cerebellum is attached to the midbrain via
Superior cerebellar peduncle
What fibers are in the inferior peduncle
Both, but afferent dominate
Fibers in the middle peduncle
Afferent only
Fibers in the superior
Both present, efferent dominate
20% of childhood cancers are what
Medulloblastomas
External division medially is called the
Vermis
What seperates the terror lobe from posterior lobe
Primary fissure
What is the floccular nodule
Houses the vestibulocerebellum, posture, balance
Tell me about the vestibulocerebellum
Synonyms- archicerebellum, very very old
lobes- flocculonodular
inputs- vestibular nucleus
functions- posture, balance
Tell me about the spinocerebellum
Synonyms- paleocerebellum, oldest
lobes- anterior, vermis, medial posterior
inputs- spinocerebellar and cuneocerebellar
functions- muscle tone, trunk, and limb movements
Tell me about the cerebrocerebellum division
Synonyms- neocerebellum, newest
lobes- lateral posterior
inputs- corticopontocerebellar
functions- planning and coordination of skilled movement
What is corpus medullary
White matter
What are extensions of white matter called
Arbor vitae
Gray matter is inside or outside
Outside
What are the most common neuron cell types? Explain them
Purkinje-take messages away from cerebellar cortex. Specifically the cortex.
What are the3 layers of the neuron cells
Outer- molecular
middle- purkinje cell body layer
inner- granular layer
What are the two types of outside axons that bring input to cerebellar cortical laminae
Mossy-
climbing-
Mossy and climbing fibers are special because they what
Reach the cerebellar cortex
What are the largest cells of cerebellar cortex
Purkinje , they are also flask shaped Their dendrites extend into the molecular layer.
Are climbing fibers smooth or spines ?
Smooth
Mossy fibers are spiked or smooth?
Spined
What neurotransmitter is released by purkinje axon
GABA, it’s inhibitory
The axon of granular cells ascend into the molecular layer where it then
Splits or bifurcates, synapses with spined purkinje
The neurotransmitter from granular neuron is
Glutamate, extremely excitatory. It is the most abundant.
Are there more mossy fibers or climbing
There are more mossy fibers
Climbing fibers are extremely extremely excitatory, what do they release
Aspartate
Go to smooth
What are the 4 nuclei that exist deep within the white matter. The deep or central cerebellar nuclei.
Denate, emboliform, globose, fastigial
Denate is the
Largest and most lateral
Emboliform and globose together is the
Interposed nuclei
Fastigial is the
Most primitive, medial, and smallest
Climbing fibers originate where
In the inferior Olivary nucleus
What fibers synapse with the neurons of the deep central nuclei?
Purkinje axons from the cortex of the vestibulocerebellum, spinocerebellum, cerebrocerebellum
Axons from the vestibulocerebellum go to the
Vestibular nucleus
Axons from the spinocerebellum go to the
Interposed nucleus and the fastigial nucleus
Axons from the cerebrocerebellum go to the
Denate nucleus
The inferior olive sends
Excitatory input
Fastigial nuclei fibers exit the inferior cerebellar peduncles to terminate in the
Vestibular nucleus, reticular formation and nuclei for CN 3,4, 6
Interposed nucleus axons extend to the
Red nucleus and reticular formations via the superior cerebellar peduncles.
Denate axons reach the thalamus with what
Collateral branches being sent to the red nucleus, via the superior cerebellar peduncles.
What neurotransmitters are excitatory
Glutamate and aspartate
Which neurotransmitter is inhibitory
GABA
Denate means
Notched or toothlike
What causes equilibrium disturbances
Lesions in the archicerebellar lobe
What is flocculonoddular syndrome
patient fights against falling backwards
Muscle tone changes are common signs of
lesions or a disorder
Electrical stimuli can be applied to the cerebellar cortex to relieve what
Hypertonicity.
What is ataxia
Lack of order or coordination, lesions of the neocerebellum
What are the symptoms of ataxia
Abnormal performance of the motor acts, staggering. Inability to rapidly supinate and pronate hands. That’s called dysdiadokokinesia.
What is an intention tremor
When you try to make precise movements you develop an exaggerated tremor.
Parkinson’s syndrome
Digits and lips tremor while at rest. Influenced out of the neocerebellar lobe.
What is it called when you under or overshoot your target
Dysmetria
What is nystagmus
Jerking movement of the eyeballs. Cerebellar lesions can result in horizontal nystagmus. CN 3,4,6 operate the 6 extraocular eye muscles.
Cerebellar cortex lesions are known for
Great compensatory recovery. Not the case with deep centeral cerebellar nucleus.
Which tract deals with decussation
Lateral corticospinal
