Sensory Pathways Flashcards
Fast pain fibers make up the ____ tract while the slow pain fibers make up the _____ tract.
- NEO-spinothalamic
2. PALEO-spinothalmic
Cold Nerve endings are mainly transmitted through what fiber type?
A-delta
Ascending pathways for CONSCIOUS Perception
- Spino-THALAMIC system
2. Medial Lemniscal system
Which layers of the Somatosensory Cortex receive input from LOWER brain centers?
I & II
Superficial Layers
Characterized headaches are caused by what?
- Meningitis
- Migraines
- Removal of Spinal fluid
Widespread bilateral excision of Somatosensory Area 1 causes loss of ability to do what?
- Localize sensations
- Judge pressure
- Judge weights
- Judge shapes or forms
- Judge texture
Three types of receptors that incriminate THERMAL gradations
- Cold
- Warmth
- Pain
What sensory information is carried by the Anterior Spino-Thalamic Tract?
- Pressure
- Tickle
- Itch
Headaches are a result of what?
Pain REFERRED to the Surface from DEEP Head structures
What type of fibers are pain fibers?
C fibers
Warm Nerve endings are mainly transmitted through what fiber type?
C fibers
Characteristics of FAST Pain
- Felt w/in 0.1 sec after stimulus
- NOT felt in DEEPER tissues
Referred pain for the Heart? Esophagus?
Heart:
- Shoulder
- Arm
- Forearm
Esophagus
- Upper Chest
- Shoulder
Purpose for Lateral Inhibition
- Important in blocking the lateral spread of excitatory signals
- Increases the degree of contrast in the cerebral cortex
Which layers of the Somatosensory Cortex are the deepest
V & VI
What type of pain fibers are carried by Fast pain?
A-delta
Where do Tertiary Neurons Terminate?
SOMATOSENSORY Cortex
Somatosensory Area 2 receives signals from where?
- Brainstem
- Somatosensory Area 1
- Visual and Auditory
The Tertiary fibers of the Lateral Spino-Thalamic tract synapse where?
POST-Central Gyrus
- Somatic sensory areas 3, 1, 2
Layers of the Somatosensory Cortex
I -> VI
Primary Sensory Neurons originate from where?
- Originate from PERIPHERAL receptors such as Merkel’s receptors
What are most ascending pathways made up of?
3 orders of Neurons
In the Dorsal Column pathway, the Axons from the UPPER limb travel in what portion of the 2 Dorsal columns
LATERAL
Fasciculus CUNEATUS
Secondary Neurons Characteristics
- Travel through spinal cord in one of the myelinated columns
- make up tracts in spinal cord
- DECUSSATE (Crossover)
Two point discrimination
The ability to Distinguish TWO SEPARATE points as close as 2mm apart
Purpose of the ANALGESIA System.
To Ignore Pain
Referred Pain
- Occurs when pain fibers stimulate fibers that conduct pain signal to the SKIN
Primary Sensory Neurons Characteristics
- Enter spinal cord or brain via DORSAL roots of Spinal/Cranial nerves
- Cell bodies of these Neurons are located in the Dorsal root ganglia
Lateral Spinothalamic Tract carry what type of sensation?
PAIN and TEMP
Which layers of the Somatosensory Cortex sends info through the Corpus Callosum to the OPPOSITE hemisphere?
II & III
Pain travels through what pathway?
Anterolateral
Where do Primary Sensory Neurons Synapse?
- In Spinal cord
- With Secondary Neurons
Where do slow pain fibers terminate?
Layers II and III of dorsal horns
Characteristics of SLOW Pain?
- Felt about 1sec after stimulus
- Increases over several seconds
- Aching, SLOW burning
The Major Components of the Analgesia System
- Peri-Quaductal Gray/ Periventricular regions
- Raphe Magnus
- Pain Inhibitory complex
T/F: Visceral pain is only of the Chronic suffering pain.
True
Where do Secondary Neurons Synapse?
THALAMUS w/ tertiary neurons
Which layers of the Somatosensory Cortex receive incoming sensory signal ?
Layer IV
What are the 3 order of Neurons?
- Primary SENSORY Neurons
- Secondary Neurons
- Tertiary Neurons
Where do Nociceptors terminate?
In Lamina of the Dorsal Horns
Where do Secondary Neurons Originate?
In the GRAY MATTER of the spinal cord
The Ascending order of the pathway?
Start: Primary (Low)
Middle: Secondary
End: Tertiary (Highest)
Nociceptors
- Pain receptors
- FREE Nerve endings
Ascending pathways for UNCONSCIOUS Perception
- Spino-CEREBELLAR
- Spino-OLIVARY (Brainstem)
- Spino-TECTAL (Mesencephalon)
- Spino-RETICULAR (Ret. Formation)
Dorsal Column-Medial Lemniscal Pathway
AKA Posterior Column system
- Carries Sensations for 2-point sensation
- Primary fibers ascend ENTIRE length of spinal cord and synapse w/ Secondary neurons in medulla
In the Dorsal Column pathway, the Axons from the LOWER limb travel in what portion of the 2 Dorsal columns
MEDIAL
Fasciculus GRACILIS
Tertiary Neurons Characteristics
-Travel from the Thalamus to Primary Sensory Cortex
- Travel through Internal capsule
Myelinated pathway b/w Thalamus and some of the basal Nuclei
