Week 10 NEURO pt 1 Flashcards
Facilitates voluntary muscle control of muscles of the face, head and neck via upper motor neurons that synapse with cranial nerve motor nuclei in the pons and medulla.
The corticobulbar tract
Carries upper motor neuron input to motor nuclei of trigeminal, facial, glossopharyngeal, vagus, accessory and hypoglossal nerves.
The corticobulbar tract
50% of neurons synapse with lower motor neurons on ipsilateral side.
50% decussate and synapse with lower motor neurons on the contralateral side.
The corticobulbar tract.
What is the pathway of the corticobulbar tract?
Travel to pons and synapse with trigeminal and facial motor nuclei and in the medulla the hypoglossal nucleus and the nucleus ambiguus (vagus nerve, glossopharyngeal nerve).
Facilitates voluntary control of skeletal muscles through the body
Corticospinal Tract (Pyramidal System)
Primary pathway for voluntary, willed motor control.
Corticospinal Tract (Pyramidal System)
Comprised of massive collection of upper motor neurons with long axons that descend from the cerebral cortex to the spine and initiate and regulate voluntary movement.
Corticospinal Tract (Pyramidal System)
In regard to the Corticospinal Tract (Pyramidal System) pathway:
In the medullary pyramids,
Approximately 90% of neurons decussate (crossover) to contralateral side – known as (1) _________corticospinal tract in the white matter of the spinal cord.
Approximately 10% of neurons stay ipsilateral and make up the (2) _________ corticospinal tract.
(1) lateral
(2) anterior
Arise from high up in central nervous system in cerebral cortex
In corticospinal tract, transport signals from cerebral cortex to lower motor neurons
In corticobulbar tract, transport signals from cerebral cortex to synapse with cranial nerve motor nuclei in the pons and medulla
Upper Motor Neurons
Located in ventral horn grey matter of spinal cord
Transports signals from upper motor neuron to effector muscle to perform a movement
Receives signal from upper motor neuron synapse which then travels from ventral horn to ventral root/ramus out to skeletal muscle
Releases acetylcholine which binds with nicotinic cholinergic receptors on skeletal muscles resulting in muscle contraction
Lower Motor Neurons
The pathway of the Corticospinal Tract (Pyramidal System) is complex but we are expected to know it. Try to list the steps in which neurons travel through this system.
This is probably just a card to stare at and hope for some retention…
Upper motor neuron originates from cerebral cortex
through the internal capsule to the cerebral peduncles in the midbrain
descends through the pons proper
into the medullary pyramids
–Approximately 90% of neurons decussate (crossover) to contralateral side
Approximately 10% of neurons stay ipsilateral and make up the anterior corticospinal tract
then descends into the spinal cord and runs down through anterior or lateral corticospinal tract.
At target level, anterior corticospinal tract decussates prior to synapsing to neuron in the anterior horn of grey matter
Lateral corticospinal tract synapses to neuron in ventral horn of grey matter when they get to appropriate level
Then travels through ventral root into ramus to skeletal muscles
Which is CN VII?
The facial nerve
Is the innervation of CN VII (the facial nerve) motor, sensory, or motor AND sensory?
Motor and sensory.
What are the functions of CN VII, the facial nerve?
Facial expressions
Supplies motor fibres to Lacrimal (tears) and salivary glands
Taste (carries sensory fibres from taste buds of anterior part of tongue
Which is CN VIII?
CN VIII – Vestibulocochlear (acoustic)
Is the innervation of CN VIII (the vestibulocochlear or acoustic nerve) motor, sensory, or motor AND sensory?
Sensory
What are the functions of CN VIII, the vestibulocochlear nerve?
Transmits sense of equilibrium (vestibular branch)
Transmits sense of hearing (cochlear branch)
Which is CN IX?
CN IX = glossopharyngeal nerve
Is the innervation of CN IX (the glossopharyngeal nerve) motor, sensory, or motor AND sensory?
Motor and sensory
What is the function of CN IX, the glossopharyngeal nerve?
Motor fibres serve pharynx and salivary glands (gag and swallow reflex)
Carries signals from pharynx, posterior tongue (taste) and pressure receptors of carotid artery
What is the most common type of headache?
Tension headache.
What are some epidemiological factors of tension-type headache (TTH)?
Average age of onset is second decade of life
Affects all genders equally, 31% to 74% of the population
Occurs in 90% of school-aged children
Increased risk with family history
What type of headache occurs due to contraction of muscles of the scalp and neck?
Predisposing factors:
-tension/stress
-cervical or back disorders
Tension-type headache (TTH).
Episodic tension-type headache (TTH) is associated with which pain mechanism and sensory nerves?
Peripheral pain mechanism-sensitization of myofascial sensory nerves
Chronic tension-type headache (CTTH) is associated with which pain mechanism and cranial nerve?
Associated with central pain mechanism- hypersensitivity of pain fibers from the trigeminal nerve that leads to central sensitization.
What is the time course to diagnose a patient with chronic tension-type headache (CTTH)?
Chronic Tension Type Headaches: diagnosed when patient has TTH at least 15 days per month for at least 3 months.
These are s/s of which type of headache?
-Mild to moderate bilateral headache with a sensation of a tight band or pressure around the head with onset of pain
-not aggravated by physical activity
-no other associated features
Tension-type headache.
What are some treatment options for tension-type headache?
Mild: ice/heat for muscular tension
Mod-severe: NSAIDS, Acetaminophen, ASA, caffeine
Prevention strategies include
-stress reduction, daily exercise, massage, dental appliances for teeth grinding/clenching at night
CTTH: tricyclic antidepressants and behavioral/relaxation therapy
Botox injections are beneficial for some
Where would a lower motor lesion occur?
In anterior/ventral horn of spinal cord and motor nuclei of brainstem.
Axon from these cell bodies bring impulses from upper motor neurons to skeletal muscles through anterior spinal roots or cranial nerves.
Lesions here impair both voluntary and involuntary movement.
Lower motor neurons.
What will you see in terms of muscle tone in a patient with a lower motor lesion?
Hypotonia, flaccidity
What types of involuntary movements might you see in a patient with a lower motor lesion?
Fasciculations - muscles rippling or quivering under the skin.
How do lower motor lesions affect reflexes?
Hyporeflexia/areflexia
Decreased muscle stretch reflexes.
The plantar reflex is absent.
You see the following pattern of muscles weakness? What type of motor lesion do you suspect?
Individual muscles may be affected, mild weakness, marked muscle atrophy.
Can be asymmetrical and may involve one limb in beginning to become generalized w disease progression.
Lower motor lesion.
What kind of seizures are notable for EEG changes as both hemispheres of the brain are involved?
Almost all of these types of seizures involve loss/impaired consciousness.
May be preceded by an aura
Generalized seizures.
What are the four subtypes of generalized seizures?
Tonic Clonic (grand mal seizures)
Absent seizures (petit mal seizures)
Atonic Seizures (drop seizures)
Myoclonic Seizures
What might you see with a tonic clonic (grand mal) seizure?
Generally last one to two minutes
Notable for falls, cries, rigidity (tonicity), jerking (clonicity), with possible cyanosis, and urinary incontinence.
May be preceded by a prodome of unease or irritability (hours or days).
A grand mal seizure is followed by a postictal phase.
What might you see with an absent (petit mal) seizure?
Usually last 2 to 15 seconds
Notable for beginning and ending abruptly.
Symptoms noted include staring, eye flutters or eye rolling, and automatisms.
First aid is not required.
What might you see with atonic (drop) seizures?
Characterized by abrupt loss of muscle tone, loss of posture, or sudden collapse.
These seizures tend to be resistant to medication.
Protective headgear may be needed.
Generally first aid is not required unless an injury occurs.
What might you see with myoclonic seizures?
Characterized by rapid, brief contraction of muscles (sudden jerks or clumsiness), usually on both sides of the body, arm, or sudden jerk of a foot during sleep.
First aid is generally not required.
A single spasm upon transition to sleep is considered normal.
What are some general physical characteristics on non-REM sleep?
Begins when the hypothalamus releases inhibitory signals.
Sympathetic tone decreases, and parasympathetic activities increase (remember rest and digest).
Men can experience penile erections; women can experience clitoral engorgement.
Basal metabolic rate decreases from 5-10%.
Pupil constriction occurs.
How many stages of non-REM sleep are there?
3
What are some characteristics of the
non-REM sleep stage N1?
Brain activity is theta waves (high frequency, low amplitude waves).
Very light sleep, alternating from dozing to wakefulness.
Hypnic jerks, or muscle twitches occur.
Hypnogogic hallucinations occur – false sensory experiences where people often see someone standing in the room or hear their name called, for example.
What are some characteristics of the
non-REM sleep stage N2?
Brain activity is still in theta (high frequency, low amplitude waves), but sleep spindles and K-complexes are seen on EEG.
Sleep spindles are brief bursts of high brain activity.
K-complexes are brief spikes in elevation of waves, quickly normalizes.
A theory behind spindles and K-complexes is that information is trying to process but the thalamus is filtering it out to help us remain asleep.
What are some characteristics of the
non-REM sleep stage N3?
Brain activity is delta waves (low frequency, high altitude waves).
Deep sleep, very difficult to wake from N3.
Growth hormones are released, cell repair is underway.
Parasomnias (sleep disorders) occur, such as sleep walking/talking, bed wetting.
What are some characteristics of the Rapid Eye Movement (REM) sleep stage?
Brain activity resembles wakefulness, or theta in N1.
Most dreaming occurs in REM – these are the dreams we are most likely to remember.
AKA paradoxical sleep. The paradox is that we have a very active brain but also have muscle paralysis.
We can experience irregular heart rate, resp rate, and a change in body temperature.
This stage is important for memory and learning. If we learned something new that day and then did not have a great sleep with enough REM, we may have difficulty retaining that information.
The cycle typically cycles through
N1-> N2-> N3-> REM-> N1 or 2-> REM-> N1 or 2-> REM etc.
The first REM stage typically occurs after the first hour of sleep.
How many cycles of sleep are recommended, or ‘typical’ of a good night’s sleep?
4-6
Specific areas of the brain are responsible for different stages of our sleep cycle. The areas are:
-hypothalamus
-pontine reticular formation
-thalamocortical network
-pons and mesencephalon
What does each area influence in terms of sleep?
Hypothalamus: Major sleep centre. Secretes the neuropeptides acetylcholine and glutamate that promote wakefulness, and prostaglandin D2, adenosine, melatonin, serotonin, l-tryptophan, GABA and growth factors which promote sleep.
Pontine reticular formation: Mainly responsible for creating REM sleep.
Thalamocortical network: Projections produce non-REM sleep.
Pons and Mesencephalon: Control REM sleep through REM-on and REM-off neurons.
This cranial nerve is a special sensory nerve which carries the signals for vision
CN II – Optic
This cranial nerve has somatic and visceral motor functions and is responsible for movement of the extraocular muscles – which direct the eyeball, movement of the eyelid, iris and ciliary body
CNIII – Oculomotor
This cranial nerve is a special sensory nerve which carries the signals for the sense of smell
CN1 – Olfactory
This cranial nerve had the somatic motor function of controlling motor fibers to lateral rectus muscle and proprioceptor fibers from the same muscle to the brain
CN VI – Abducens
This cranial nerve has the somatic nerve function of providing proprioceptor and motor fibers for superior oblique muscle (extraocular muscle) of the eye
CN IV – Trochlear
This CN has both somatic motor and sensory functions, It:
Provides motor and sensory impulses for the face
Conducts sensory impulses from the mouth, nose, surface of the eye, and dura mater
Contains motor fibres that stimulate chewing muscles
CN V - Trigeminal
This cranial nerve is a motor nerve, responsible for the Sternocleidomastoid (turning the head) and trapezius (shrugging your shoulders) muscles. As well as muscles of the soft palate, pharynx, and larynx (plays a role in swallowing and breathing)
CN XI – Accessory
This cranial nerve has both motor and sensory functions - carries sensory and motor signals to the pharynx, larynx and esophagus (responsible for coughing, sneezing, swallowing and vomiting)
Parasympathetic motor fibres supply smooths muscle of abdominal organs (responsible for digestion, HR and RR)
Somatic sensation from the skin behind the ear, outer ear canal and throat.
CN X – Vagus
This cranial nerve has only motor functions and is responsible for the muscles of the tongue responsible for speech
CNXII – Hypoglossal
List the cranial nerves I – XII
List the cranial nerves I – XII
I – Olfactory
II – Optic
III – Oculomotor
IV – Trochlear
V – Trigeminal
VI – Abducens
VII – Facial
VIII – Vestibulocochlear
IX – Glossopharyngeal
X – Vagas
XI – Accessory
XII – Hypoglossal
(Ooh, ooh, ooh, to touch and feel very good velvet, always heaven.) or whichever mnemonic you prefer
List which nerves are sensory, motor or both
Some say marry money, but my brother says big brains matter more.
I – Olfactory - SENSORY
II – Optic - SENSORY
III – Oculomotor - MOTOR
IV – Trochlear - MOTOR
V – Trigeminal - BOTH
VI – Abducens - MOTOR
VII – Facial - BOTH
VIII – Vestibulocochlear - SENSORY
IX – Glossopharyngeal - BOTH
X – Vagas - BOTH
XI – Accessory - MOTOR
XII – Hypoglossal - MOTOR
Which headache is characterised by a headache lasting 4-72 hours with 2 of the following: unilateral head pain, throbbing pain, pain worsening with activity, moderate or severe pain intensity; and at least one of the following: nausea and/or vomiting, or photophobia and phonophobia.
Migraines
Why are women thought to have a higher incidence of migraines than men?
Biologic sex: higher in females: 12% of women; 5% of men in Canada
In women, migraines most frequently occur before & during menstruation; decreased during pregnancy & post menopause. The cyclic withdrawal of estrogen & progesterone may trigger attacks.
