A 11 Spinal Cord Pathways Flashcards
What laminae in the spinal cord does the spinothalamic 1st order neuron synapse on? What might it ascend before doing so?
- Laminae 1,4,5,6 for A Delta’s
- Lamina 2 for SOME C fibers
What is the function of the raphespinal tract?
-Autonomics, thermoregulation, pain modulation, and adrenal gland secretion of epinephrine (damage=Horner’s syndrome)
What 3 nuclei does the bulbospinal tract come from?
- Periaqueductal gray (PAG) in midbrain
- Locus Ceruleus in pons
- Nucleus Raphe Magnus in medulla (synapse from PAG)
The the acronym TINNTING mean?
It describes the 8 different ways that causes lesions of neurons.
1) trauma
2) ischemia
3) neoplasm
4) neurodegenerative diseases
5) Toxins
6) Infection
7) Nutritional deficiencies
8) Genetic
pain, temperature and crude touch is mediated through which systems?
1) spinothalmic (from body)
2) trigeminothalmic (from head)
discriminative touch and conscious proprioception is mediated through which systems?
1) DCML (from body)
2) Trigeminothalmic (from head)
Non-conscious proprioception is mediated through which systems?
1) Dorsal spinocerebellar
2) Ventral spinocerebellar
3) Cuneocerebellar
motor to the head is through which system? Is it autonomic of voluntary?
cortical bulbar
Its voluntary motor
motor to the body is through which system?
cortical spinal
Which areas fine tune/adjust the motor function?
1) cerebellum
2) basal ganglia
pain, temperature, itch, and tickle come from follow which tract?
spinothalmic tract
where do the secondary axons from the spinothalmic tract cross? Where to they synapse?
They cross through the ventral white commisure at the level that they enter. They first synapse in the dorsal grey horn, cross, then go to the thalamus.
discriminative touch, conscious proprioception, and visceral pain from the body follow which tract?
DCML
Which nerve fibers run in fasciculus gracilis?
first order neurons of DCML below T-5
which nerve fibers run in fasciculus cuneatus?
first order neurons of DCML originating at or above T-5
where do the axons of the DCML pathway synapse? Where do the fibers cross?
1st= medulla in gracilis or cuneatus nucleus.
The secondary fibers cross in the medulla after synapsing in the nuclei.
signs of a lesion in the DCML system would include?
diminution of the following;
2 point discrimination
vibration sense
limb position
Information in the spinocerebellar tracts mainly comes from where?
muscle spindles
GTO
T/F Lesions of the spinocereballar tracts do not usually produce any obvious signs?
True, although lateropulsion (walking to one side) can occur.
The corticospinal system innervates lower motor neurons and influences mostly what?
The hand muscles.
The corticobulbar system innervates cranial nerves and innervates mostly what?
face, jaw, and tongue muscles for speech.
where do corticobulbar fibers synapse?
on cranial nerve motor nuclei in the brain stem. All nuclei are innervated bilaterally except for the facial nerve nucleus.
where do corticospinal fibers cross?
The majority (90%) cross in the decussations of the medulla, but the rest remain on the same side and eventually cross in the ventral white commisure where they control.
where do the corticospinal fibers synapse? (AKA upper motor neurons)
They synapse in the ventral horn of the spinal cord to the lower motor neurons.
Lesions in UMN’s result in?
paresis (weakness)
hypertonia & hyperreflexia (b/c loss of inhibition)
Return of the babinski sign. (recall babinski goes away because of myelination of the UMN)
where do all of the common effector motor neurons converge to innervate a group of muscles?
Lower motor neurons (all motor pathways eventually converge on LMN from all levels)
A lesion of LMN’s would result in what characteristics?
1) weakness
2) paralysis
3) atrophy
4) loss of reflex
5) fasciculations
What size fibers are the 1st order neurons in the dorsal spinocerebellar tract and cuneocerebellar tract? The ventral spinocerebellar tract?
- 1a and 1b
- 1b
Clarke’s nucleus if found at what levels?
C8-L3 (Dorsal Spinocerebellar)
Lesion above what level results in spastic bladder?
- T12 (L1/L2 cord level)
- Below this level results in flaccid (atonic) bladder
- Bowel control follows the same pattern
At what levels is Onuf’s nucleus located?
-S1-S4
Damage to S1-S4 would destroy ability to empty bladder by destroying somatic bladder control, visceral, or both?
Trick! Only parasympathetics empty the bladder. (S2-S4). (This would occur in cauda equina and conus medullaris syndrome) However:
-Somatic=Onuf (think pudendal) allows control of urethral & bowel sphincters
