Lecture 5, General Sensory Information Flashcards
What are types of special senses?
- visions
- hearing
- smell
- taste
- equilibrium
Where do exteroreceptive sensations originate from?
- surface of the body
What type of sensations refer to the physical state of the body?
-proprioceptive sensations
What type of sensations can be categorized as proprioceptive?
- body position
- muscle and tendon sensation
- pressure
- equilibrium
What type of sense is stimulated by mechanical displacement of body tissue, that includes tactile and position?
-mechanoreceptive somatic senses
What is the primary sensory neuron ascending pathway?
- Starts at external receptors
- Travels through dorsal root of spinal cord
- Synapse with secondary neurons
What is the pathway of secondary sensory neurons (ascending)?
- these form tracts in the spinal cord and brain stem
- Normally terminate in thalamus
- Also synapse with the tertiary neurons
What is a tertiary sensory neuron ascending pathway?
- Travels from the thalamus to primary sensory cortex
2. Then travel through the internal capsule
Which ascending pathways are used for conscious perception?
- Spinothalamic system
2. Medial Lemniscal system
Which ascending pathways are used for unconscious perception?
- Spinocerebellar
- Spino-olivary
- Spinotectal
- Spinoreticular
The ascending pathways consist of three-neuron pathways to get from the external receptor to the primary sensory cortex. How much truth is there to this statement?
Not much as a majority of interneurons and other components are being excluded for simplicity
What type of information is carried in the lateral spinothalamic tract?
- Pain
2. Temperature
How many spinal cord segments do primary fibers of the lateral spinothalamic tract ascend or descend before synapsing with secondary fibers?
1-2 fibers
What regions do the secondary axons of the lateral spinothalamic tract decussate through?
Anterior gray and white commissures
In what region of the spinal cord does the lateral spinothalamic tract travel?
Lateral column of the spinal cord, formed by secondary axons
What information does the trigeminothalamic tract carry?
Pain and temperature from face and teeth
True/False
Secondary fiber collaterals of the lateral spinothalamic tract project to reticular formation stimulate wakefulness and consciousness.
True
Where do the secondary and tertiary fibers of the lateral spinothalamic tract synapse?
The ventral posterolateral (VPL) nucleus of thalamus
Where do the tertiary fibers of the the lateral spinothalamic tract synapse?
- Postcentral gyrus
- this corresponds to somatic sensory areas 1,2,3
What type of information is carried by the anterior spinothalamic tract?
- Light touch (crude)
- Pressure
- Tickle
- Itch
How many spaces can a primary neuron skip before connecting with seccondary neurons of the anterior spinothalamic tracts?
Skip 8-10 spinal cord segments
Where do fibers of the anterior spinothalamic tract decussate at?
Anterior gray or white commissures
Where do the secondary and tertiary fibers synapse, of the anterior spinothalamic tract?
Ventral posterolateral nucleus of the thalamus
Where do the tertiary fibers of the anterior spinothalamic tract ascend to synapse at?
Ascend through the internal capsule to the primary sensory cortex.
What information does the medial lemniscus system carry?
Sensation for two-point sensation (fine-touch) pressure and vibration
What is the pathway of primary neurons of the medial lemniscus system to the synapse with secondary neurons?
Primary ascend the length of spinal cord.
-synapse in the medulla at the fasciculus gracilis and fasciculus cuneatus
What region of sensation do the fibers of the fasciculus gracilis and nucleus gracilis relay?
This synapse relays information inferior to the midthoracic level
Fibers of the medial lemniscus system that has the synapse of fasciculus cuneatus and nucleus cuneatus convey sensation from what region of the body?
Superior to the midthoracic level
- proprioceptive sensation of arms to cerebellum
Where is the synapse of the secondary and tertiary neurons of the medial lemniscus system?
Ventral posterolateral region of the thalamus
The primary somatosensory area is formed by what areas?
- Brodmann’s area 1, 2, 3
Brodmann’s areas 5 and 7 make up what region?
Somatosensory association area.
What information is received in the somatosensory area I?
Information from:
- thigh
- thorax
- neck
- shoulder
- hand, fingers
- tongue
- intra abdominal region
What information is collected from somatosensory area II?
- leg
- arm
- face
Where does the somatosensory area II receive information from?
- brain stem, which transmits signals upwards from both sides of body,
- also receives information from somatosensory area I.
The superficial layers of the somatosensory cortex, layers I and II receive signals from where?
Input signal from lower brain centers
Layers II and III of somatosensory cortex receive what type of information?
Send information across corpus callosum to other hemisphere
Where do layers V and VI send information?
Layer V: information to basal nuclei, brain stem, and spinal cord
Layer VI: information to thalamus
Add in where layer IV sends information to!
Huh?
What type of information is collected by somatic senses from all over the body?
- received by mechanoreceptors
- thermoreceptors
- pain
- -these are from external sources
