Unit 2_Ascending Neural Pathways Flashcards
What are two major sensory pathways conveying information from the body to the brain?
- Dorsal Column Medial Lemniscal (DCML) for touch and conscious proprioception
- Anterolateral System (ALS) for pain and temperature
What major sensory pathway conveys touch and conscious proprioception from the body to the brain?
Dorsal Column Medial Lemniscal (DCML)
What major sensory pathway conveys pain and temperature from the body to the brain?
Anterolateral System (ALS)
How can we differentiate whether something might be a problem at the nerve root vs the peripheral nerve?
See if patients have sensory losses that follow specific patterns known as dermatomes
If patients have a sensory loss in a dermatome area, where has the injury likely occurred?
In the CNS (nerve root, spinal cord, cortex)
If patients have a sensory loss in a peripheral nerve pattern, where has the injury likely occurred?
Outside the CNS
What dorsal root ganglia branch (peripheral nerve –> dorsal horn) organization deals with touch and proprioception, includes Group I and Group II nerve fibers from muscle spindle and GTO, and a beta from skin?
Medial Bundle Branches (DCML)
What dorsal root ganglia branch (peripheral nerve –> dorsal horn) organization deals with pain and temperature, includes Group III and Group IV nerve fibers from muscle, and a delta and C from Skin?
Lateral Bundle Branches (ALS)
Where do the peripheral nerve (somatosensory) pathways for DCML and ALS terminate?
Parietal Cortex
What steps do the following describe?
- First order neurons
DRG-dorsal root ganglia
(or cranial nerve nuclei or ganglia) - Second order neurons
Spinal cord or brainstem
Axons cross - Third order neurons
Thalamus (VPL and VPM; Intralaminar nuclei) - Internal capsule
- Termination in parietal cortex
General Organization of Primary Somatosensory Pathways
Where is the sensory version of the homunculus located?
In the partietal cortex
What structure is made up of white matter and include axon tracts that are going to travel up to the parietal cortex where cell bodies are found (gray matter)?
Internal Capsule
What order of neurons include the DRG-dorsal root ganglia (or cranial nerve nuclei or ganglia)?
First order neurons
What order of neurons pick up at the spinal cord or brainstem and where axons cross?
Second order neurons
What order of neurons pick up at the thalamus and include VPL and VPM; Intralaminar nuclei?
Third order neurons
What areas, where synapses take place, are not simply relay areas? These are the areas where our experience is being shaped including developing complex receptive fields.
In the medulla and cerebral cortex
What nuclei take information from the face and body and related to somatic sensation and travel to the primary somatosensory cortex?
Ventral Posterior Medial (VPM)
Ventral Posterior Lateral (VPL)
What system carries the following sensations:
1. Light touch/pressure
2. Tactile discrimination
Two-point discrimination
Stereognosis
3. Conscious Proprioception
Static position sense
Kinesthetic sense
Vibration
Dorsal Column/Medial Lemniscal System (DCML)
What nuclei is responsible for all body sensations?
Ventral Posterior Lateral Nucleus (VPL)
What nuclei is responsible for face sensation?
Ventral Posterior Medial Nucleus (VPM)
What nuclei carries upper extremity sensation?
Cuneate
What nuclei carries lower extremity sensation?
Gracile
If an individual has an injury at the spinal cord level, what side will the injury affect?
The same side of the injury
If an individual has an injury at the brainstem level, what side of the body will the injury affect?
The opposite side of the injury
What sensory pathway conveys Unconcious Proprioception, Static position sense, Kinesthetic sense and Vibration?
It provides sensory information to the cerebellum to allow it to coordinate movement and balance.
Structures include nucleus dorsalis and spinocerebellar tracts.
Tracts exit the brainstem and the level of pons and medulla to go to cerebellum.
No synapses in thalamus, no termination in cortex.
Spinocerebellar Pathways
What sensory pathway conveys Coarse touch, Pain, Temperature, Itch and Tickle?
Anterolateral System (ALS)
What sensory pathways make up the Anterolateral System?
Lateral spinothalamic & Ventral/anterior Spinothalamic
Spinoreticular
Spinomesencephalic
What Anterolateral System sensory pathway receives signals from lateral bundle of the dorsal root?
Follows the same course as Lateral Spinothalamic to brainstem.
Terminates in reticular nuclei in brainstem.
Connects to:
Intralaminar nuclei of thalamus
Hypothalamus
Limbic system
Function: Autonomic, affective responses to pain.
Spinoreticular
What Anterolateral System sensory pathway receives signals from lateral bundle of the dorsal root?
Follows the same course as Lateral Spinothalamic to brainstem.
Terminates in periaqueductal gray matter
Function; endogenous pain modulation.
Spinomesencephalic
What ascending pathway system does referred pain use, and will show up as a referred pain pattern (general region of pain)?
Anterolateral System
What ascending pathway system causes loss of the following:
- Light touch/pressure
- Tactile discrimination
Two-point discrimination
Stereognosis - Conscious AND Unconscious Proprioception (spinalcerebellar)
Static position sense
Kinesthetic sense
Vibration
Lesions in the Dorsal Column/Medial Lemniscal System
What ascending pathway pattern causes patients to have difficulty with balance, coordination, and skin integrity?
*Spinocerebellar degeneration – Friedrich’s ataxia
Lesions in the Dorsal Column/Medial Lemniscal System
What ascending pathway pattern causes loss of the following:
Coarse touch
Pain
Temperature
Itch
Tickle
Lesions in the Anterolateral system
System
What ascending pathway pattern causes patients to have difficulty with risk of injury as they can not feel pain?
Lesions in the Anterolateral system
System
What are deficits on the opposite side of the lesion?
Contralesional
What are deficits on the same side of the lesion?
Ipsilesional
Because projection axons of the ALS ascend as they cross, a spinal hemisection produces a loss of pain, temperature, and itch one to two segments caudal to the lesion. In contrast, loss of mechanical sensations (DCML) begins at the level of the lesion. What syndrome is this known as?
Brown-Sequard
What does heat information from the leg and spinothalamic pathway travel in the thalamus?
Ventro posteriolateral (VPL)
*Where sensory info from the body travels
Which of the following neurotransmitters is primarily excitatory?
GABA
Glutamate
Seratonin
Dopamine
Glutamate
What is an example of a second messenger involved in long-term synaptic changes?
cAMP (cyclic AMP)
Which of the following best describes the impact of glucocorticoids (cortisol) on long-term synaptic changes?
It binds to Ca2+ receptors
It is inhibitory
It interacts with glutamate’s synaptic functions
It causes neuronal death
It interacts with glutamate’s synaptic
