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70 Cards in this Set
- Front
- Back
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Which of the following is a brainstem surface feature (what does each do?):
- brachium of inf colliculus - central tegmental area - medial lemiscus - medial longitudinal fasciculus - trapezoid body |
- brachium of inf colliculus
* carries auditory afferent fibers from the inf colliculus to the medial geniculate nucleus - the central tegmental area is in the midbrain and pons * Transmits information to the thalamus - Medial lemiscus - in the brainstem, * Carries proprioceptive or touch sensory information from the gracile and cuneate nuclei to the thalamus - Medial Longitudinal Fasiculus (MLF) - situated near the midline of the brainstem * Carries information about the direction in which the eyes should move. It yokes the III, IV, and VI nuclei together and integrates movements in the paramedian pontine reticular formation (PPRF) - Trapezoid body - located in the pontine tegmentum. The superior olivary nucleus is situated on the dorsal surface * Fibers from the cochlear nucleus |
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Where does the hypoglossal nerve emerge from the brainstem?
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In the pre-olivary sulcus, just posterior to the pyramid
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What would be diminished in a nucleus gracilis lesion?
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Sense of feel and proprioception
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Which of the following structures contributes fibers to the inferior cerebellar peduncle? What are their functions?
- abducens nucleus - inf olivary complex - crus cerebri - lateral lemniscus - central tegmental area |
- the inf olivary complex - part of the medulla
* closely associated with the cerebellum, and is therefore associated with coordination - Abducens nucleus - located beneath the fourth ventricle in the pons, medial to sulcus limitans * makes up part of the facial colliculus, responsible for lateral eye movement, abduction - crus cerebri - anterior portion of the cerebral peduncles - lateral lemniscus - situated with the inferior colliculus of the midbrain * carries information about sound from the cochlear nucleus to various brainstem nuclei, and eventually the inferior colliculus |
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What is the substantia nigra?
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It is located in the midbrain, and is responsible for dopaminergic neurons. Lesions in this area lead to Parkinson's disease
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If a patient's left eye is deviated medially on straightforward gaze and the right eye does not adduct past midline on horizontal gaze to the left, what nerve is affected?
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L abducens
Ipsilateral effect on eye Abducens nerve innervates lateral rectus |
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Where is the solitary nucleus located, and what does it convey?
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Located along the length of the medulla. It conveys visceral sensation and taste from the VII, IX and X cranial nerves
Receives general visceral afferents |
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What supplies the sensory and motor limb, respectively, of the corneal wisp reflex?
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- Sensory supplied by trigeminal V
- Motor supplied by facial VII |
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If a patient does not have a corneal wisp reflex, and the physician wants to know if the motor nerve or sensory nerve is affected, what reflex would indicate the motor nerve being affected?
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The acoustic startle reflex
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What nerve does the pupillary light reflex test?
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Depends. It gives us information about the optic II and oculomotor III nerves.
Indication for optic - When shining light into the affected side (e.g. R), the affected eye will not constrict, nor will the consenual pupil. Indication for oculomotor - When shining light into the affected eye, the pupil remains dilated, but the other eye still retains consensual constriction |
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If there is hemorrhage or stroke in the dorsal column in the rostral medulla, would there be deficits in the left or right side of the body. What deficits?
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If there is stroke in the rostral medulla, deficits would be noticed contralaterally. E.g. Stroke in the R side, would cause loss of vibration and proprioception in the L arm and leg.
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If a patient can stand steady with eyes open, but becomes unsteady and falls when when eyes are closed, what part of the spinal cord is involved?
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Posterior column
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What do the spinothalamic tracts and spinomesencephalic tracts have in common?
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They both cause alertness during nociception.
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How do nociceptive afferents differ from non-nociceptive afferents?
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Nociceptive afferents tend to have lower sensitivity and higher thresholds to stimulation than non-nociceptive afferents
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What does the spinomesencephalic tract do? What is it?
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Fibers originate in the spine and end in the midbrain.
Plays a role in the descending modulation of pain. Sends information to the periaqueductal gray matter |
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What are the neurotransmitters of the periaqueductal gray matter?
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Enkaphilin and endorphin
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Which structure is responsible for the fast, stinging sensation of pain?
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A delta fibers
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If a patient's chronic low back pain disappears while listening to music or sunbathing, what area of the brain is responsible for the relief?
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Cortical influences on the dorsal horn
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The posterior communicating artery continues posteriorly as which artery?
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Posterior cerebral
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Which of the following arteries is not considered a branch of the vertebral artery?
- anterior inferior cerebellar - posterior spinal - anterior spinal - posterior inferior cerebellar |
Anterior inferior cerebellar
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The basilar artery gives rise to what arteries prior to brachning into the posterior cerebral arterie?
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Superior cerebellar
THink: Super before Posterior |
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Would a tongue deviation to the L implicate L or R sided lesion?
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Lesion would be ipsilateral to the side of deviation, i.e. the side of weakness Therefore, it would be a L sided lesion.
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What are some signs and symptoms of a lesion on the R side of the medulla resulting in damage to the ipsilateral medial lemniscus, corticospinal tract, and hypoglossal nucleus?
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decreased propriosensation, hypertonia, increased tendon reflexes in the L upper and lower limbs, and fasiculations on the R side of the tongue
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What artery could be responsible for L Horner syndrome, absent L gag reflex, ataxia of L arm and leg with normal strength, and normal upper and lower limb reflexes?
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L posterior inferior cerebellar artery
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Would impairment of CN V Trigeminal be ipsilateral or contralateral in a corneal reflex test?
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Ipsilateral
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What is trigeminal neuralgia?
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AKA, Tic douloureux
Causes intense pain in the eyes, lips, nose, scalp, forehead Sx would cause pain upon closing mouth on one side, causing drool to come out of that side Think sensory and motor, which is what the trigeminal does |
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What is Wallenberg syndrome?
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Sx: Contralateral loss of pain and temperature from spinothalamic lesion; Horner's syndrome from loss of descending sympathetic fibers; ipsilateral loss of facial sensation
Sx: ataxia, facial pain, vertigo, nystagmus, Horner's, diplopia, dysphagia Usually caused by a PICA occlusion |
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What Sx would indicate a L5-S1 disc herniation?
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Decreased sensation in R S1 distribbution, radicular pain radiating down the right leg to the foot, slight weakness in standing on the toes, atrophy of the gastrocnemius muscle, no clonus, decreased right ankle jerk, and no difficulty with bowel/bladder
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What is the action that opioids have on the CNS?
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They activate the periaqueductal gray-raphe nucleus pain control system
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Where is the red nucleus located and what does it do?
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It's located in the rostral midbrain and is involved in motor coordination
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Occlusion of the ASA at the T10 level would result in?
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Loss of pain and temperature sensation below the level of the lesion; bladder dysfunction; paralysis of both legs, extensor plantar responses
NOTE: does not affect proprioception! |
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Does Wallenberg syndrome normally result in contralateral hemiparesis?
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No
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If a pt came to the ED and complained that hot water did not feel hot on the R side of the face, nor the L side of the body, and pupillary reflex was absent in the R eye, what could be a possible explanation?
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Wallenberg syndrome. The constriction of the R pupil is due to Horner's. Lack of hot sensation is due to affect on the spinothalamic tracts.
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Does the pyramid contain ipsilateral or contralateral corticospinal fibers?
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Ipsilateral. The pyramidal decussation is inferior to the pyramid, and therefore has not decussated yet. Once past the pyramidal decussation, still 15% of the CST has not decussated
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What are some examples of nuclei associated with the vagus nerve?
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- spinal trigeminal nucleus
- nucleus ambigus - dorsal motor nucleus - solitary tract (tractus solitarius) nucleus |
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What are the 5 functional components of the CN X?
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- SVE - fibers originate from nucleus ambigus and innervate striated m. of larynx, pharynx, palatoglossus m., levator veli palatini
- GVE - fibers originate from inf. salivatory nucleus in the RF of rostral medulla; innervate the smooth muscle and glands of pharynx and larynx - GVA - Fibers distribute to the solitary nucleus; convey sensory info from larynx and pharynx, esophagus, thoracic and abdominal viscera, stretch receptors in aortic arch, chemoreceptors in aortic bodies - SVA - Distribute to the rosstral part of the nucleus of teh solitary tract; taste information related to hard and soft palate - GSA - Distribute to the trigeminal nuclei; provide sensory information to part of the external acoustic meatus, external surface of the tympanic membrane, skin behind the ear and the pharynx |
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What type of information does the tractus solitarius convey?
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Visceral sensation (e.g. intestinal cramps)
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What type of fibers does the hypoglossal nerve supply to the tongue?
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Contains alpha motor neurons to the tongue
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If a patient has double vision upon gazing to the left, would the R or L MLF be affected?
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The R
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Muscles from the branchial arches are innervated by what?
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Facial motor nucleus
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What are the duties of CN VII? How does one differentiate a peripheral vs. central lesion?
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VII does facial expression, parasymmpathetics for tears and salivary production, and taste on ant. 2/3 of tongue.
Peripheral (LMN) lesion - ipsilateral muscles affected (all of them) Central (UMN) lesion - only the muscles contralateral in the lower half of the face will be weak. This is because the upper part is innervated by the corticobulbar tracts |
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If a pt has a sudden paresis on the L side of the body and has a medial strabismus of the R eye, what region of the brain could be affected?
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R caudal pons
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Where is the third synapse of the posterior column/medial lemniscus pathway from the periphery to the cortex?
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- contralateral somatic sensory cortex
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What is the 3 neuron pathway in the posterior column/medial lemniscus pathway?
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1. Sensory neurons in periphery send AP which course in the fasciculus gracile in the lower body, and the fasciculus cuneate in the upper body. They eventually synapse in the medulla with their respective nuclei, gracile and cuneatus.
2. From the nuclei gracile and cuneatus, the secondary neurons cross over to the other side of the medulla via internal arcuate fibers, forming the medial lemniscus. The fibers continue, with the arm fibers more dorsal, and the leg fibers more ventral. The axons synapse in the thalamus via the ventral posterolateral nucleus (body sensation) and posteromedial nucleus (head sensation) 3. From the thalamus, axons move towards the sensory cortex via the internal capsule, eventually synapsing there. |
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Definition of pain
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Actual or perceived noxious chemical, mechanical, or thermal stimulus
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Definition of nociception
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Complex series of electrochemical events, which occur between the site of tissue damage and the perception of pain
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What is Brown Sequard Syndrome and what type of deficits would be found?
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It is caused by a hemisection of the spinal cord.
Sx - Ipsilateral loss of sensation and propriosensation, vibration, two point discrimination and motor output - Contralateral loss of pain and temperature sensation |
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What parts of the brain would be affected by a CVA of the R anterior cerebral artery?
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Medial aspect of frontal and parietal lobes
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What does the posterior cerebral artery branch from?
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Basilar artery
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What does the superficial middle cerebral vein drain into?
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The cavernous sinus
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Deficits in lower motor neurons involves what?
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Anterior horn (ventral) of spinal cord
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What artery is affected in Wallenberg's Syndrome
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PICA
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What nerve is associated with facial sensation?
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Trigeminal
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If a pt is unable to move his left eye medially, what portion of the brainstem has had a stroke?
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Ventral midbrain - trochlear nerve
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What is central cord syndrome?
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Defined as injuries where the hands are more severly comprimised than the legs
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ASIA A
ASIA B ASIA C ASIA D ASIA E |
A - loss of motor and sensory below lesion
B - loss of motor, but not sensory below lesion C - Motor strength less than 3/5 with preserved sensation D - Motor strength greater than 3/5 with preserved sensation E - Normal |
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What are some attributes of cauda equina syndrome?
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- Loss of sacral (perineum) sensation
- Bladder and bowel dysfunction - Urinary incontinence - Seen w/ acute lumbar disc herniations |
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What are characteristics of anterior cord syndrome?
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Interruption of ascending spinothalamic tracts and descending motor tracts
- loss of pain and temp sensation along with motor control |
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Characteristics of dissociated sensory loss?
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Band of sensory loss, with normal sensation below the area
- decussating fibers located along the central canal are impaired resulting in decreased or loss of pain in temp |
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Why is the reticular formation affected by general anesthetics?
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The RF abounds in synapses and general anesthetics affect synaptic transmission
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What is muscle tone and how is it produced?
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It is the force with which a muscle resists being lengthened.
It is produced by gamma motor neurons, which pull the muscle spindle, and activate Ia fibers, which then activates the alpha neurons to create contraction of the muscles Note: gamma motor neurons regulate alpha motor neurons in the muscle tone reflex |
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What is the difference between voluntary movement and muscle tone in terms of motor neurons?
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For voluntary movement, gamma motor neurons are not required; the signal goes directly to the alpha motor neurons.
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How does the RF regulate muscle tone?
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2 systems
1. Excitatory - contributions from the pontine and rostral medullary RF * Driven from below! 2. Inhibitory - contribution form the medullary (caudal) RF * Driven from above! |
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Why do patients with stroke have hypertonia?
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Stroke affects the basal ganglia, which are the major source of the excitatory input to the medullary RF. Since the medullary RF is ultimately inhibitory, this attribute gets knocked out, and can no longer inhibit alpha motor neurons
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Why do patients with spinal cord injury have spacticity?
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Both medullary and pontine RF are disconnected from the alpha motor neurons in the ventral horn. This means that muscle tone is now under teh control of local spinal reflexes, such as the stretch reflex which are hyperactive in an isolated spinal cord
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What does an infarct of the medial lemniscus result in?
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Contralateral loss of proprioception and light touch
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What would cause central pontine myelonolysis, characterized by symmetrical degeneration in the basis pontis?
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Over rapid correction of hyponatremia
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If a patient had deficits in hearing, vestibular, and facial motor problems, where would you suspect a tumor?
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Cerebellopontine angle
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What does the pretectal area do?
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It is involved in the pupillary light reflex. Modulates by receiving affferent signal from II and sending information to the Edinger Westphal nuclei
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Red nucleus?
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Involved in motor pathways. Moves the shoulders and upper arms.
Relays information from the motor cortex to the cerebellum |
