12-2 ASCENDING NS Pathways

Question 1

What is the Dorsal Column Pathway important for? [3]

Answer 1

1. Proprioception (position sense due to muscle spindle & golgi tendon receptors)
2. Vibration sense [ex. tuning fork or sitting on dryer]
3. 2 Point discrimination (stereognosis)

Question 2

A: Describe Area 312 and Area 4

B: Explain why there is NO HEAD in the Homunculus and why Dorsal Column Pathway isn’t involved with Head

C: Stroke of RIGHT Cortex wipes out Vibration/Position/2Point of the ____[Right/Left] Body! Why is this?

Answer 2

A: Area 312 is AKA the POST-central Gyrus for sensory info
vs.

B: Homunculus for DCP has no Head becuz pain/vibration/position OF HEAD are carried out by [Trigeminal/CN5]

C: A stroke of the RIGHT Cortex wipes out Vibration/Position/2Point of the LEFT Body—-> because DCP Crosses Over in the Pyramid of Lower Medulla

Question 3

A: In Myelin Stains…Fibers are ____…and cells are _____

B: Where is the [OLIVE Nucleus] and Pyramids located? What is the significance of the Pyramids?

C: LEG SENSORY information travels via ____ ______ so it bends/enters in Fasciculus ______ to synapse in the nucleus ____

D: Dorsal Column Pathway represents ____[Conscious/UNconscious] position/vibration/2point. What pathway represents the Opposite?

E: Fasciculus are also known as _____

Answer 3

A: In Myelin Stains…FiBers are BLacK…and [nuclei/cells] are white

B: Squiggly [inf. OLIVE Nucleus] and Pyramids are located in the MEDULLA. Pyramids are where the [Corticospinal Motor Tract] are located

C: LEG SENSORY information travels via DCP MEDIALLY so it bends/enters in MG [MEDIAL (fasciculus GRACILIS) ] to synapse in the nucleus GRACILIS

D: Dorsal Column Pathway represents CONSCIOUS position/vibration/2point.

**DORSAL SPINOCEREBELLAR represents UNconscious position/vibration/2point

E: Fasiculus are AKA Columns

Question 4

A: What 2 things are contained in Dorsal Root Columns

B: In [Tabes Dorsalis], ______ destroys _______ which leads to —–>ATROPHY of ________ . Pt will show positive ______ sign because they’ve LOST ____ from _____ RECEPTORS

Answer 4

A: Dorsal Root Columns = [Fasciculus cuneatus] & [Fasciculus Gracilis]

B: In [Tabes Dorsalis], Neurosyphilis destroys {DRG} DORSAL ROOT GANGLION CELLS—–>ATROPHY of [Dorsal Root Columns] . Pt show positive ROMBERG sign (stomping gait) because they’ve LOST proprioreception from JOINT RECEPTORS

Question 5

What are 3 signs of POSITIVE Romberg Sign ?

B: What causes POSITIVE Romberg Sign

Answer 5

Positive Romberg Sign <—-Neurosyphilis destroying [Dorsal Root Ganglion Cells]

1. Pt requires vision to stand steady
2. [+ Sensory ATaxia] but [ - cerebellar ataxia]
3. STOMPING GAIT

Question 6

What are 2 big landmarks of the Midbrain

Answer 6

1) Midbrain has 2 GIANT [Crus Cerebri Cerebrum peduncle] that make it look like upside down Micky Mouse
2) Also Has Substantia Nigra

Question 7

1) What is Syringomyelia
2) Why Are Sacral Fibers of Spinothalamic tract usually the Last destroyed in this dz?
3) What is “Vested” Loss?
4) What 2 senses are Spared?

Answer 7

1) Vacuole Hole or tube forms near central canal and grows eventually transecting the cord = Syrinx
2) SACRAL Fibers of Spinothalamic Tract are more Lateral so are LAST to be destroyed by Syrinx = Sacral Sparing of Pain & Temp
3) “Vested” Loss = Syrinx wipes out STT fibers ONLY at level of CERVICAL region…and Sacral/lumbar fibers are spared
4) Proprioreception and Vibration

Question 8

How would a Stroke of 1 Hemisphere affect the Spinothalamic Tract and Dorsal Column Pathway?

B: On a Hemisected Spinal Cord DCP will be affected ______ and STT will be affected _______. Why is this?

Answer 8

Stroke of 1 hemisphere would wipe out BOTH STT(cross in spinal cord) and DCP(cross in lower medulla) on OPPOSITE side because BOTH cross further down

B: On a Hemisected cord DCP will be affected IPSILATERALLY (because it crosses higher up in LOWER medulla) and STT will be affected contralaterally

Question 9

MOST Cerebellar injury signs are _____[Contralateral/Ipsilateral]

Answer 9

MOST Cerebellar injury signs are IPSILATERAL

Question 10

A: [Ventral Spinocerebellar Tracts] crosses Midline at what 2 locations?

B: What is the purpose of the [Ventral Spinocerebellar Tract]? Can this be Clinically Assessed?

C: What type of Peripheral Input does [Ventral Spinocerebellar Tract] receive?

Answer 10

The [Ventral Spinocerebellar Tract] crosses

1. in Spinal Cord
2. in [SUPERIOR cerebellar peduncle] before entering Cerebellum Vermis

B: samples spinal cord interneurons and relays their “state of being” to cerebellum. CAN NOT BE CLINICALLY ASSESSED.

C: DOES NOT RECEIVE ANY PERIPHERAL INPUT!!!!!!

Question 11

What are the 6 Sensory Receptors that utilize the [Dorsal Spinocerebellar Tract] Pathway for ______ ______ ______.

Answer 11

5 Sensory Receptors that utilize the [Dorsal Spinocerebellar Tract] Pathway for UNCONSCIOUS IPSILATERAL PROPRIORECEPTION

MMM JRP

1. Meissner’s Corpuscle
2. Pacinian Corpuscle
3. Merkels Disk
4. Ruffini
5. Joint Receptors
6. Muscle Spindles

Question 12

Causes of Syringomyelia (3)

Answer 12

1. [Abnormal CSF flow/pressure 2º to malformation]
2. Tumor
3. Residual of Trauma