Sensory Systems (5 Parts) Flashcards
2 main pathways of the sensory system
2 pathways (pain and temperature), (vibration and proprioception)
These pathways follow the same route through __ ___ , plexus and roots), then they diverge upon entering the spinal cord where ___ travels through the spinothalamic tract (anterior spinothalamic and anterolateral spinothalamic) and the vibration and proprioception travel through the __ __/___ __
2 pathways (pain and temperature), (vibration and proprioception)
These pathways follow the same route through peripheral nerves, plexus and roots), then they diverge upon entering the spinal cord where PAIN travels through the spinothalamic tract (anterior spinothalamic and anterolateral spinothalamic) and the vibration and proprioception travel through the dorsal columns/medial lemniscus
outline the differences in myelination of the axons in the periphery when it comes to pain and proprioception fibers
In the periphery, pain pathways travel through lightly myelinated fibers, whereas vibration and proprioception travel through myelinated fibers.
Myelin helps action potentials move A LOT faster
Info carried through the ML are going to arrive in the brain and be processed faster than those of the ST. Ie, you’ll sense pressure well before you actually feel pain
The pathways then join up again in the same nucleus of the thalamus and make their way up via the internal capsule and corona radiata to the sensory cortex.
in the periphy, pain travels up less-myelinated fibers, whereas proprioception and vibraition travels up super myelinated fibers.
The pathways then join up again in the same nucleus of the ___ and make their way up via the __ ___and __ ___ to the sensory cortex.
The pathways then join up again in the same nucleus of the thalamus and make their way up via the internal capsule and corona radiata to the sensory cortex.
Outline the spinothalamic tract pathway (CAST)
a sensory neuron (1st) depolarizes and enters the dorsal root ganglia, where it synapses with the second order neuron on the dorsal side and CROSSES OVER AT THE SPINAL CORD. then it ascends and synapses with the third order neuron in the thalamus. The third order nueron projects to the primary sensory cortex.
outline the pathway for priopioception (dorsal column) tract
ACDC
priopioception stimuli depolarizes the first order neuron, where it goes to the dorsal root ganglia and into the spinal cord. the same first order neuron ASCENTS do the cunate nucelus/medulla region, where it then synapses with a second order neuron, CROSSES OVER THE mEDIAL LEMNISCUS before ascending to the thalamus. at the thalamus, the second order neuron synapses with the third order neuron where the third neuron goes up to the primary sensory cortex
outline the findings and MOA of brown-sequard syndrome (Hemi-Cord syndrome) (IVCP)
Description: Damage to ½ of the spinal cord
Sensory fingers: IPSILATERAL vibration and proprioception loss (DCT), Contralateral pain and temp loss (ST).
Motor findings: ipsilateral motor loss
outline the symptoms and causes of posterior column syndrome
recall; posterior column is where the dorsal horn is. Dorsal horn is where the sensory findings go.
etiology: neurosyphilis, B12 deficiency.
Sensory Findings: loss of proprioception and vibration (DCT), spared ST. NO MOTOR FINDINGS
Impaired proprioception, wide-based gait, positive Romberg (dorsal columns affected)
Spasticity and increased DTRs in both legs (corticospinal tract UMN)
Forgetfulness.
Syphilis won’t give UMN findings.
Key features of lateral medullary syndrome (wallenberg syndrome), and main etiologies
Lateral medullary syndrome, also known as Wallenberg syndrome, is a clinical syndrome caused by an acute ischemic infarct of the lateral medulla oblongata. This is most commonly due to occlusion of the intracranial portion of the vertebral artery followed by PICA and its branches
Main Symptoms: HORNERS SYNDROME (anhydrosis, ptosis and miosis)
ipsilateral facial pain and temp loss, contralateral body pain and temp loss, vertigo N/V, ipsilateral Homers(horners?).
- HICCUPS, decreased gag reflex , dysphagia, nystagmus, diplopia, hoarseness, palatal myoclonus.
damage to the lateral femoral cutaneous nerve: Meralgia Paresthetica– patch of numbness and burning ((neuropathic pain) in __ aspect of thigh.
Associated with tighter clothes, tumors, hematomas, abscesses that can grow and compress the nerve, iatrogenic, pregnancy due to compression of the LFCn. .
damage to the lateral femoral cutaneous nerve: __ __– patch of numbness and burning ((neuropathic pain) in __ aspect of thigh.
Associated with tighter clothes, tumors, hematomas, abscesses that can grow and compress the nerve, iatrogenic, pregnancy due to compression of the LFCn. .
Glove and Stocking Pattern: Causes and Investigations
- Drugs and Toxins
- Infections
- Connective tissue
- Metabolic
- Paraneoplastic
- Inherited
- Vitamin deficiency
- Endocrine
- paraproteinemia
- Drugs and Toxins: Alccohol, chemotherapy
- Infections: Leprosy
- Connective tissue: Sjogren’s
- Metabolic: Diabetes, chronic renal failure
- Paraneoplastic: carcinoma of the lung and ovary
- Inherited: charcot-marie tooth disease
- Vitamin deficiency: B12
- Endocrine: Hypothyroidism
- paraproteinemia: monoclonal gammopathy of undetermined signifance (MGUS)
Which gender is affected most by trigeminal neualgia? Causes?
How do you treat it?
Trigeminal Neuralgia
Epi: F>M. Middle aged and elderly, Caused by Herpes Zoster or viral inflammation, sometime tumors
Etiology: idiopathic (classic); compression by tortuous blood vessel, cerebellopontine angle tumor, MS.
Symptoms: recurrent episodes of sudden onset, excruciating unilateral paroxysmal shooting “electrical” pain in trigeminal root territory (V3>V2>V1). Pain lasts for seconds-minutes. Episodes occur over days-weeks and then remit for weeks- months.
Management: 1st line: carbamazepine/oxcarbazepine, 2nd line: baclofen/lamotrigine
Important Roots (in lecture)
C8 = __ level
T4= ___ level
T10= ___
L5= must know– compression of L5 is the most common radiculopathy that can affect the ___ region. Can test using hip abduction and knee flexion.
Important Roots (in lecture)
C8 = pinkie
T4= nipples
T10= umbilicus
L5= must know– compression of L5 is the most common radiculopathy. can affect the peroneal region
L5 root vs Peroneal Nerve Injury
Sensory territories are almost identical
It comes down to looking at MUSCLE WEAKNESS: the presentation will be FOOT DROP– “i keep tripping on steps”
L5 muscles innervate hip abductors, foot inverted and those involved in knee flexion.
the peroneal nerve would just have a foot drop
Crossed sensory findings/asymmetrical hemisensory loss only localizes to the __ ___ . Describe.
3 conditions which can occur in the brainstem that lead to sensory findings:
loss only localizes to the BRAIN STEM. this only applies to pain and temp. Ipsilatearl pain and temp loss in the face.
3 conditions which can occur in the brainstem that lead to sensory findings:
- stroke (lateral medullary syndrome/wallenburg)
- multiple sclerosis
- tumor/lymphoma
which sensory fibers are used as part of the reflex arc?
A: Myelinated fibers– the proprioception, vibration and sensation fibers are myelinated.
ex/ hitting knee with reflex hammer is proprioception
