Lecture 10: Ascending Pathway I Flashcards
True or False: The DC-ML is concerned with conscious appreciation of fine touch, two point discrimination, conscious proprioception, and vibrations
True
True or False: The DC-ML deals with highly localizable and discriminative sensations
True - they’re known as epicritic sensations
Where are the first, second, and third order neurons of the DC-ML located?
1st: DRG
2nd: Dorsal column nuclei (medulla)
3rd: VPL nucleus (thalamus)
True or False: The first order neuron of the DC-ML is a pseudounipolar neuron with a peripheral and central axonal process
True
Which three tactile mechanoreceptors are associated with the DC-ML?
Which two structures are involved in conscious proprioception in the DC-ML?
Tactile Mechanoreceptors:
1. Meissner’s and 2. Pacinian corpuscles; 3. Free nerve endings on hair follicles
Conscious Proprioception:
1. Muscle Spindles (Ia and II)
2. Golgi Tendon Organs (Ib)
True or False: In the DC-ML, Meissner Corpuscle is associated with two point discrimination/fine touch while Pacinian Corpuscle is associated with pressure and vibration
True
Where do the peripheral axonal processes of the DC-ML originate from? where do they end up?
Peripheral receptors to cell body in DRG
True or False: Both the peripheral and central axonal process of the DC-ML are associated with large, heavily myelinated fibers
True
Type Ia, Ib, and II are associated with ______
A. Central axonal processes
B. Peripheral axonal processes
B. Peripheral axonal processes
Once in the spinal cord, the central axonal process will give off small collateral branches that will terminate in the spinal gray matter to facilitate ___
reflexes
The main axon of the first neuron of the DC-ML will leave the dorsal gray matter without synapsing and enter the ___ ____ to help form either the ___ or ____
dorsal funiculus; FG; FC
Which two structures make up the Dorsal (Posterior) Column?
FG and FC
___ is located at ALL spinal cord levels and carries sensory information to the lower extremities
A. Fasiculus cuneatus
B. Fasiculus gracilis
B. Fasiculus gracilis
___ is located only at spinal cord levels T6 and above and carries sensory information to the UE
A. Fasiculus cuneatus
B. Fasiculus gracilis
A. Fasiculus cuneatus
In the DC-ML, the sacral spinal levels are most ___ while fibers of the cervical spine are most ___ to dorsal columns
A. medial; lateral
B. lateral; medial
A. medial; lateral
True or False: The arrangement of the body parts represented in the dorsal column pathway is a good example of somatotophy
True
True or False: The somatotopic organization of the DC-ML persists throughout entire course of the ascending pathway
True
Which axonal processes of the DC-ML terminate (synapse) on neurons in the dorsal column nuclei (NG and NC) in the caudal medulla?
A. Peripheral Axonal Processes
B. Central Axonal Processes
B. Central Axonal Processes
The NG receives axons of the ___ and corresponds to the gracile tubercle
The NC receives axons of the ___ and corresponds to the cuneate tubercle
FG
FC
True or False: Axons of the dorsal column nuclei neurons are small and minimally myleinated
False - they are large and heavily myelinated
Which neurons of the DC-ML course ventromedially through the medullary tegmentum, ultimately crossing midline?
A. First order neurons
B. Second order neurons
C. Third order neurons
B. Second order neurons
Once second order neurons of the DC-ML cross midline, they enter the ____
IAF (interarcuate fibers)
The internal arcuate fibers will coalesce on the contralateral side of the medulla, dorsal to pyramidal tracts, known as ___
ML (medial lemniscus)
Ventral fibers arise from ____
Dorsal fibers arise from ____
Nucleus gracilis
Nucleus cuneatus
What three things happens when the medial lemniscus travels through the brainstem?
- Changes relative position and orientation
- Terminates in thalamus
- Synapses on third order neuron
Where do the fibers of the medial lemniscus synapse?
Neurons in the VPL (ventral postero-lateral nucleus of thalamus)
Where do axons of the VPL neurons project out of, then enter, then terminate in?
Thalamus =>
Posterior limb (internal capsule) =>
Somatosensory Cortex
Where is the primary somatosensory cortex located (S-I)
A. Post-central gyrus
B. Superior parietal lobule
C. Parietal cortex
A. Post-central gyrus
Which Brodmann Areas correspond to the Primary Somatosensory Cortex?
Which Brodmann Areas correspond to the Somatosensory Association Cortex?
Primary Somatosensory Cortex
- Brodmann 3, 1, and 2
Somatosensory Association Cortex
- Brodmann 5 and 7
What are the four subdivision of the primary somatosensory cortex?
Brodmann Area 3a, 3b, 1, and 2
Where do most thalamic outputs of The Primary Somatosensory Cortex terminate?
A. Area 1 and 2
B. Area 3a and 3b
C. Area 3a and 3c
D. Area 1 and 3b
B. Area 3a and 3b
Each subdivision of the primary somatosensory cortex contains a sensory homunculus. Which body part has a disproportionately larger cortical representation?
Fingers
In the subdivisions of the primary somatosensory cortex (S-I) - the leg is represented more ___, while trunk, arm, fact are represented more ____
medially; laterally
Where is the Parietal Association Cortex (Somatosensory Association Cortex) locate?
A. Cortex of inferior parietal lobe
B. Cortex of superior parietal lobe
B. Cortex of superior parietal lobe
Which of the following gets input from: S-I, S-II, Pre-motor cortex, limbic system, vestibular system, auditory, and visual systems?
A. Primary Somatosensory Cortex
B. Posterior Parietal Lobe (Somatosensory Association Cortex)
B. Posterior Parietal Lobe (Somatosensory Association Cortex)
True or False: Higher order processing of somatosensory information, coupled with other information, occurs in the Somatosensory Association Cortex
True
Which of the following aids in formation of a mental “image” of the body
A. Primary Somatosensory Cortex
B. Posterior Parietal Lobe (Somatosensory Association Cortex)
B. Posterior Parietal Lobe (Somatosensory Association Cortex)
Lesions in which cortical area will often result in hemineglect syndrome?
A. Parietal Association Cortex / Somatosensory Association Cortex
B. Primary Somatosensory Cortex
A. Parietal Association Cortex / Somatosensory Association Cortex
Information about unconscious proprioception from the body is conveyed to the cerebellum via ____
spinocerebellar tracts
Dorsospinalcerebellar tract projects through the _____ while Ventral spinocerebellar tracts project through the ___
ICP (inferior cerebellar peduncle); SCP (superior cerebellar peduncle)
